The Sun-Climate Effect: The Winter Gatekeeper Hypothesis (III). Meridional transport

Reposted from Dr. Judith Curry’s Climate Etc.

by Javier Vinós & Andy May

“The atmospheric heat transport on Earth from the Equator to the poles is largely carried out by the mid-latitude storms. However, there is no satisfactory theory to describe this fundamental feature of the Earth’s climate.” Leon Barry, George C. Craig & John Thuburn (2002)

3.1 Introduction

Nearly all the energy that powers the climate system and life on Earth comes from the sun. Incoming solar radiation is estimated at 173,000 TW. By contrast geothermal heat flow from radiogenic decay and primordial heat is estimated at 47 TW, human production of heat at 18 TW, and tidal energy from the Moon and the Sun at 4 TW. Other sources of energy, like solar wind, solar particles, stellar light, moonlight, interplanetary dust, meteorites, or cosmic rays, are negligible. Solar irradiance, thus, constitutes over 99.9 % of the energy input to the climate system.

The energy received from the sun changes over the annual cycle by 6.9 % due to the changing Earth-Sun distance. The Earth is closest to the sun (perihelion) around the 4th of January and farthest (aphelion) around the 4th of July. Although half the Earth is illuminated by the sun at any given time (50.2 % due to the difference in size), the changes in the Earth’s axis orientation towards the sun, the irregular distribution of land masses, changes in albedo, and regional changes in surface and atmosphere temperature, cause important seasonal changes in the amount of reflected solar shortwave radiation (RSR) and outgoing longwave radiation (OLR). As a result, the temperature of the Earth is always changing and the planet is never in energy balance.

Contrary to what could be naively expected, the Earth is warmest just after the June’s solstice, when it is farthest from the sun, and coldest just after the December’s solstice, when it is receiving 6.9 % more energy from the sun. Earth’s average surface temperature is c. 14.5 °C (severe icehouse conditions), but during the year it warms and cools by 3.8 °C (Fig. 3.1). As expected, the Earth emits more energy (total outgoing radiation, TOR) when it is cooling and less when it is warming, regardless of what it is receiving at the time, so the idea of an energy balance at the top of the atmosphere (TOA) is clearly wrong. The Earth displays little interannual temperature variability but there is no reason to think we properly understand the mechanisms involved in Earth’s thermal homeostasis.

Fig 3.1

Fig. 3.1. Yearly temperature and radiation change. The global surface average temperature of the planet (thick line) changes by 3.8 °C over the course of a year, mostly because the NH (thin line) varies by 12 °C. The planet is coldest during the month of January, despite receiving 6.9% more total solar irradiance (TSI, dotted yellow line) in early January when the Earth is in perihelion. The planet has two peaks of energy loss (TOR, Total Outgoing Radiation, outgoing longwave and reflected shortwave, dotted red line) when each hemisphere cools, with the highest during the cooling of the NH. Between November and January, the planet emits more energy (TOR) than at any other time. SH, dashed line. NH winter, light grey area. 1961–1990 temperature data from Jones et al. 1999. Radiation data from Carlson et al. 2019.

What it is clear from figure 3.1 is that although the climate system is entirely powered by solar irradiance, what determines the Earth’s temperature is what the climate system does with that energy, and the climate system is extremely complex. As Barry, et al. (2002) say in the quote at the top of this part, modern climatology lacks a proper theory of how energy is moved within our planet’s climate system. It is possible to model what it is not properly understood, even if very complex, but to believe such a model is foolish.

The energy from the sun comes in a straight line from its surface, as can be clearly appreciated during a total eclipse. The sun has an apparent size of 0.5° of arc in Earth’s sky and is located in the plane of Earth’s solar orbit, called the ecliptic. The ecliptic is the projection of Earth’s orbital plane onto the sky, it is also the path the most vertical rays from the Sun make around the globe, at the local noon, during a 24-hour day. Due to Earth’s axial tilt, the sun is not always directly above the equator, and moves from being above 23.44°N at the June solstice to 23.44°S at the December solstice. The position of the sun at any given daytime determines the angle of incidence of its radiation. At a higher angle of incidence (sun lower on the horizon) the energy arriving from the sun is spread over a larger surface area, decreasing the amount of energy per unit of horizontal area. The flux of solar radiation per unit of horizontal area for a given locality is the solar insolation, and it is higher at solar noon the closer in latitude to the declination of the sun, which marks the position of the ecliptic with respect to the equator. Solar insolation is the most important determinant of local surface temperature.

As a result of the position of the sun with respect to the Earth, most energy enters the climate system in the tropics. However, OLR increases with the absolute temperature of the surface, and decreases with the greenhouse effect, and cloud cover. As the average absolute temperature of the surface does not vary that much with latitude (278–300 K between 60°N–60°S), and greenhouse gas concentration and cloud cover tend to be higher in the tropics, OLR does not vary much with latitude. The result is that the net radiation flux at the TOA is positive (more incoming than outgoing) on the annual average between c. 30°N-30°S and negative between c. 30° and the pole. However, during the Dec-Feb season the net flux is negative north of 15°N (Fig. 3.2), and most of the Northern Hemisphere is losing energy. The resulting cooling from reduced insolation and a net energy deficit creates a latitudinal temperature gradient (LTG). Energy is moved from latitudes where there is a net gain of energy (energy source) to latitudes where there is net loss of energy (energy sink to space), along the LTG (Fig. 3.2), by meridional transport (MT).

Fig 3.2

Fig. 3.2. Net radiation flux at the top of the atmosphere for Dec-Feb. Positive net flux values (red area) indicate a net energy flow into the climate system, and negative values (blue area) indicate a net energy sink, that is, a net flow to space. Areas are not proportional to the amount of energy due to the geometry of the Earth. Meridional transport moves energy, among other things, from regions with an energy surplus to regions with an energy deficit along the gradient in temperature (dashed line, near-surface air temperature for January). Meridional transport moves a lot more energy towards the winter pole. Temperature data from Hartmann 1994. Radiation data from Randall 2015.

Without MT, the temperature of the regions where the net flux of energy at the TOA is negative would decrease continuously until OLR emissions are sufficiently low to match insolation. In the polar night regions that temperature would be close to absolute zero (–273.15 °C). MT is carried out by the atmosphere and the ocean along the temperature gradient and is variable over time. It transports a lot more energy (stronger MT) in the winter hemisphere (Fig. 3.2).

3.2 The latitudinal temperature gradient defines the planet’s climate

In the physical universe processes tend to happen spontaneously along gradients, whether they are gradients in mass, energy, or any manifestation of them, like gravity, pressure, or temperature. The Earth’s surface LTG is a direct consequence of the latitudinal insolation gradient. Enthalpy (energy adjusted for volume and pressure) tends to move along the LTG from regions of higher to regions of lower enthalpy. This is the basis of MT, but given the complexity of the climate system, it is far from a passive process that depends only on the temperature difference between the tropics and the poles. Instead, it is a highly regulated process that can drive more energy for a smaller temperature difference and less energy for a larger temperature difference. As will be shown in the next part, MT has increased in the first two decades of the 21st century, despite the Arctic being warmer, reducing the LTG.

We know that the Earth’s LTG has varied a lot over the geological past of the planet. We saw in Part I that Wladimir Köppen, the Russo-German scientist who studied the sun-climate effect in the 19th century, established a climate classification that is still in use with modifications. Climate zones are defined in terms of temperature, precipitation, and their seasonal distribution. Many groups of plants and animals are restricted to a habitat with a narrow range of temperatures; and some geological processes are also temperature dependent. Using this type of information Christopher Scotese has mapped past climate history with his Paleomap Project(1). The information thus obtained allows him to geographically reconstruct half a dozen climate zones every few million years, and from that to reconstruct the changing LTG of the Earth’s past. Scotese et al. (2021) defines the climate and global temperatures of each period based on their LTG, demonstrating that it is a fundamental climate variable. Scotese defines the present (21st century) LTG and global temperature as severe icehouse conditions, as demonstrated by the massive permanent ice sheets over Antarctica and Greenland.

The existence of very different past climates of the Earth creates an unsurmountable problem for modern climatology. During the last glacial maximum (LGM), 20,000 years ago, the energy received from the sun was the same as now. Not only that, but the precession and obliquity values were the same as now, and the orbital eccentricity was very similar. The distribution of solar energy over the Earth and the latitudinal insolation gradient were nearly identical to now, yet the climate was very different. Energy input to the climate system must have been lower, because albedo was higher and the greenhouse effect lower. A lower energy input and a larger LTG ought to have drained the tropics of heat via a much stronger MT, but that was not the case. There is still controversy about tropical temperatures during the LGM, but it appears that they were only 1–2 °C colder than present (Annan & Hargreaves 2015). This is consistent with evidence presented by Scotese et al. (2021) that tropical temperatures have not changed much over the course of the past 540 million years despite huge changes in the average temperature of the planet (9–30 °C).

If the LGM creates a problem for how MT operates during a glacial period, the equable climate of the early Eocene results in a paradox that modern climatology cannot solve. Currently the Earth is in a severe icehouse climate with a very steep LTG. Temperature falls by 0.6–1 °C/°latitude from the equator to the winter pole. Such cold or colder conditions as of today have been relatively rare during the past 540 Myr (less than 10 % of the time). The early Eocene Earth had an average temperature estimated at 23.8 °C, that Scotese describes as hothouse conditions. The early Eocene LTG was very shallow, at 0.25–0.45 °C/°latitude, with temperatures at the North Pole above freezing all year round, as attested by the presence of frost-intolerant biota. These hothouse conditions have been even rarer. Over 80 % of the Phanerozoic Eon the Earth had an average temperature of 17–20 °C (Scotese et al. 2021).

Fig 3.3

Fig. 3.3. The Earth’s climate is defined by its latitudinal temperature gradient. a) Climatic belts of the early Eocene hothouse (top) deduced from fossil and geochemical evidence by Scotese et al. 2021, and the present severe icehouse (bottom). Equatorial wet (dark green), subtropical arid (yellow), warm temperate (light green), cool temperate (brown) and polar (light blue) belts. Temperature is the estimated global mean average. b) Latitudinal temperature gradient inferred for the early Eocene (red) and the present (blue) versus measured (black, fine line). After Scotese et al. 2021

The climate of the early Eocene, the Cretaceous, and early Paleogene, is defined as equable, characterized by a warm world with reduced LTG and low seasonality. The failure of modern climate theory to explain these periods has been termed the “equable climate problem” (Huber & Caballero 2011). To reproduce the early Eocene warm continental interior temperatures and above freezing winter high latitudes, models have to raise CO2 levels to 4700 ppm and tropical temperatures to 35 °C. However, the best CO2 estimates for the early Eocene climatic optimum (Beerling & Royer 2011; Steinthorsdottir et al. 2019) place CO2 levels at 500–1000 ppm, and it is unclear that a tropical temperature above 30 °C is possible. The survivability wet-bulb temperature limit for mammals is 35 °C, at which point they become unable to lose heat (Sherwood & Huber 2010). The highest wet-bulb temperature on Earth today is 30 °C, and there is no reason to think that it has been higher at any time in the past at places where mammal fossils are found.

At the root of the equable climate problem lies the “low gradient paradox” (Huber & Caballero 2011). Conceptually, we believe that to have warm poles more heat must be transported there, to compensate for the insolation deficit. Heat MT is a very important part of the planetary energy budget, and it is generally believed that without it the poles would be much colder. But MT depends on the LTG since much of the poleward transport in the present climate is through atmospheric eddies resulting from baroclinic (where temperature gradients exist at constant pressure surfaces) instability. The paradox arises because, counterintuitively, the warm poles of the early Eocene and their much shallower LTG imply a reduced MT. It is no wonder that climate models have such a problem reproducing it. In Part VI a possible solution to the paradox will be offered.

3.3 Meridional transport is mainly carried out by the atmosphere

The lower atmosphere is a thin film of gas, just 1/600 of the Earth diameter (c. 10 km), that has the crucial role of always maintaining a land surface temperature compatible with complex life, something it has done for at least the past 540 Myr. To do that it has to compensate for surface temperature differences arising from differences in insolation. First, it must compensate the difference between day and night. It does so mainly through the greenhouse effect that reduces night cooling, and through the effect of clouds, that increase albedo during the day and reduce night cooling. Then, it must compensate for the latitudinal decrease in insolation and its seasonal changes due to the axial tilt of the planet. It does so through meridional heat transport.

Of these three factors responsible for Earth’s thermal homeostasis, greenhouse effect, clouds, and MT, modern climatology has focused exclusively on the first, developing the CO2 “control knob” climate hypothesis (Lacis et al. 2010). The effect of clouds and their variability on climate change is still largely unknown. With respect to MT, and as figure 3.2 suggests, energy is only exchanged between the climate system and the outside through the TOA, this results in MT necessarily having a net zero value when integrated over the climate system. Moving energy from one region to another does not alter the amount of energy within the system. This fact has resulted in the general belief that changes in MT cannot constitute a significant cause for climate change, producing the most fundamental mistake of modern climatology.

The atmosphere has the outstanding capacity of moving a great amount of energy, fast and efficiently, over the entire surface of the Earth. As a result, MT is carried out mainly by the atmosphere. Only within the deep tropics (10°S–10°N) the atmosphere is inadequate for MT requirements. This is the region where most energy enters the climate system (Fig. 3.4 black dashed line). But the Hadley cell’s upper branch transports dry static heat (sensible + geopotential; Fig. 3.4 red dotted line) poleward, and this is partly compensated for by the lower branch’s equatorward transport of latent heat (Fig. 3.4 red dashed line). Due to this, the ocean must carry out most of the heat transport in the deep tropics. However, the ocean is less efficient at transporting heat than the atmosphere and the energy transport required in the tropics is very large, particularly in the Pacific, due to its size. ENSO is the answer to this problem, as El Niño is the way to periodically transport out of the deep tropics the excess accumulated heat that the regular MT cannot carry. ENSO is part of the global MT system.

Fig 3.4

Fig. 3.4. Meridional transport decomposition. Left, meridional transport in peta Watts calculated from velocity-potential temperature fields and represented as poleward in positive values. THT, total heat transport; OHT, oceanic heat transport; AHT, atmospheric heat transport; DSH, dry static heat (sensible + geopotential); LH, latent heat; ITCZ, inter-tropical convergence zone. After Yang et al. 2015. Right, black dashed line, CERES TOA net radiation flux in Watts/m2, positive is net inflow, or warming. After Randall 2015.

Once outside of the Hadley cell reach, the ocean transfers most of the energy it transports to the atmosphere, particularly at the western ocean basin boundary currents in the mid-latitudes, and poleward latent heat atmospheric transport becomes important. In summary, most of the energy enters the climate system at the photic layer of the tropical oceans, it is then transported outside the deep tropics mostly by the oceans and ENSO, and most of the energy is then transferred to the atmosphere that does the bulk of the transport in the middle and high latitudes. Once the sea-ice edge is reached, the transport is essentially carried out exclusively by the atmosphere, as the energy flux through the sea ice is much less than from the liquid ocean surface. Excluding solar radiation, the rest of the energy flux across the sea surface is positive towards the atmosphere nearly everywhere at every time, except for some high latitude regions during the summer (Yu & Weller 2007). Sea-surface temperature is not as important for ocean-atmosphere energy flux as wind speed and air moisture, the principal factors governing evaporation.

Figure 3.4 shows that MT is asymmetric. Poleward transport at the equator line is near zero, with a small inter-hemispheric transport (0.2 PW northward). The position of the inter-tropical convergence zone (ITCZ, the climatic equator that separates the North and South Hadley cells), varies between 15°S and 30°N, and has an annual mean position c. 6°N. Poleward transport increases with distance from the equator as heat from a bigger region is transported poleward. Northern Hemisphere (NH) MT is bigger because northern oceanic MT is bigger. This is due to a northward inter-hemispheric ocean MT of 0.4 PW, mainly through the Atlantic Ocean, compensated in part by a southward inter-hemispheric MT of 0.2 PW by the atmosphere from the ITCZ (Marshall et al. 2013). Poleward of 45° the northern atmospheric MT becomes larger than the southern, due to a larger sensible heat transport by eddies, particularly during winter. This transport reflects a larger ocean-atmosphere flux at the western boundary mid-latitude currents (Yu & Weller 2007), that is responsible for a warmer winter climate in the European mid-latitudes and for Arctic winter warming. As we can also see in figure 3.4, 70–90° TOA net radiation is more negative in the Arctic than in Antarctica. This is the obvious result of transporting more heat to the Arctic in winter.

Transport of energy by the atmosphere is linked to the transport of mass, momentum, chemicals, moisture, and clouds. It takes place in the troposphere, mainly along preferred routes over ocean basins, and in the stratosphere. As we saw in section 2.5, angular momentum is exchanged between the solid Earth–ocean and the atmosphere. In low latitudes, surface winds are easterly and flow in the opposite direction to the rotation of the Earth, so the atmosphere gains momentum through friction with the solid Earth–ocean that reduces its speed of rotation, while in middle latitudes surface winds are westerly and the atmosphere loses momentum to the solid Earth–ocean that increases its speed of rotation, so a poleward atmospheric flux of angular momentum is required to conserve momentum and maintain the speed of rotation.

Fig 3.5

Fig. 3.5. Meridional transport of energy (left) and angular momentum (right) implied by the observed state of the atmosphere. In the energy budget there is a net radiative gain in the tropics and a net loss at high latitudes; to balance the energy budget at each latitude, a poleward energy flux is implied. In the angular momentum budget, the atmosphere gains angular momentum in low latitudes due to easterly surface winds and loses it in the middle latitudes due to westerly surface winds. A poleward atmospheric flux of angular momentum is implied. Meridional transport of energy and momentum is known to be modulated by ENSO, the quasi-biennial oscillation and solar activity. After Marshall & Plumb 2008

Changes in the atmospheric angular momentum (AAM) must be balanced by changes in the speed of rotation of the solid Earth–ocean to preserve momentum, and they are mostly due to the seasonal changes in the zonal wind circulation. Zonal wind circulation is stronger in winter, when more angular momentum resides in the atmosphere due to a deeper LTG, so the Earth rotates faster in January and July, and slower in April and October, when zonal circulation is weaker. As mentioned in Part II, these small changes in the rate of rotation of the Earth are measured as micro-second changes in the length-of-day (∆LOD), the difference between the duration of the day and 86,400 Standard International seconds. Seasonal variation in ∆LOD reflects changes in zonal circulation (Lambeck & Cazennave 1973) and, therefore, in MT. The biennial component of ∆LOD reflects changes in the QBO (Lambeck & Hopgood 1981), the 3–4-year component matches the ENSO signal (Haas & Scherneck 2004), and the decadal change in ∆LOD reflects changes in solar activity (Barlyaeva et al. 2014).

The Sun, QBO and ENSO constitute three factors modulating the coupling of the tropical stratosphere to the polar vortex (PV) and the polar troposphere, regulating heat and moisture transport to the winter pole. Since they affect the zonal wind circulation it is not surprising to see they also affect the speed of rotation. But while the role of ENSO and the QBO in changing the AAM and ∆LOD is widely known and reported, the role of the sun remains largely ignored.

3.4 Winter transport to the Arctic. The biggest heat-sink of the planet

It is believed that the hemispheric difference in temperature (Fig. 3.1) is due mainly to the larger land fraction in the NH (67.3 % of global landmass) that warms and cools more than the ocean surface. The answer is however more complex, as it also involves the asymmetry in MT (Kang et al. 2015). As we have seen, some of its consequences are the preferential location of the ITCZ in the NH, and a net inter-hemispheric heat transport from the SH to the NH. Hemispheric transport asymmetry results also from the reduction in MT to the South Polar Cap, hindered by the Antarctic Circumpolar Current and the Southern Annular Mode, that climatically isolate Antarctica. The result from these asymmetries is that despite the South Pole being much colder, more energy is transported to the North Pole (Peixoto & Oort, 1992). As a result of its warmer atmosphere, the 70–90°N polar region loses c. 10 W/m2 more heat over the year than the 70–90°S polar region. The loss is much bigger during the boreal winter, when the atmosphere transports 120 W/m2 across 70°N, than during the summer, when it transports 80 W/m2 (Peixoto & Oort, 1992). Most of the transport is carried out by transient eddies and the mean meridional circulation, but the winter-summer difference is mostly due to stationary eddies along storm tracks that in winter are responsible for most of the increase (Fig. 3.6). Over 80 % of the energy transported during the warm season to the north polar region is used to melt snow and ice, and warm the ocean. About two thirds of that energy constitutes energy storage that is returned to the atmosphere during the cold season cooling and re-freezing, and mostly lost through OLR. As a result of these differences, the north polar region loses 20 % more energy than the south polar region during the respective winters, constituting the biggest heat-sink of the planet (Fig. 3.2).

Fig 3.6

Fig. 3.6. January northward heat flux by eddies. During boreal winter the NH subtropical jet has two maxima downstream of the Himalaya and Rocky Mountains over the Pacific and Atlantic oceans, respectively. These wind speed maxima result in vigorous mid–latitude cyclones following storm tracks that define the main gateways into the Arctic. Contour is 5 K m/s. Blue shading in the SH indicates southward flux. After Hartmann 2016

During winter, nearly all the energy lost at this heat-sink is transported there by the atmosphere, as the equilibrium temperature of sea water in contact with ice is practically constant regardless of the atmospheric temperature and sea-ice thickness. Sea-ice constitutes a very good insulator (K ≈ 2.2 W/m K). Compared to a loss of 310 W/m2 for exposed waters at a 30 °C temperature difference, a 2 m thick ice layer reduces the loss to only 30 W/m2 (Peixoto & Oort, 1992). It is clear that the great loss of winter sea-ice for the past 45 years constitutes a strong negative feedback on global warming.

Dry static (sensible + geopotential) heat is brought into the winter Arctic by both the middle (20–100 km height) and lower atmosphere, while latent heat (moisture) is transported almost exclusively by the lower atmosphere. Figure 3.7 shows NH winter atmospheric heat transport. Upper atmosphere transport is inter-hemispheric; however, it involves only 0.1 % of the atmosphere mass, making it irrelevant for energy considerations. The stratosphere contains 15% of the atmospheric mass, and its meridional transport is termed the Brewer–Dobson circulation (BDC). Air enters the stratosphere at the tropical pipe (Fig. 3.7), through a cold region above the tropical tropopause where it loses most of its water vapor. In the upper stratosphere the deep branch of the BDC is inter-hemispheric and moves toward the winter pole. In the lower stratosphere, the shallow branch of the BDC has a poleward direction, although it is stronger towards the winter pole. In the middle and high latitudes, the BDC air descends through the tropopause toward the surface. The BDC takes place through a meridional wind thermal balance established by the LTG and is powered by planetary and synoptic waves that release energy and momentum to the mean flow when they dissipate.

Fig 3.7

Fig. 3.7. Schematic of atmospheric circulation at the December solstice in a two-dimensional lower and middle atmospheric view. Background colors indicate relative temperatures at 10 K steps, with red being warmer and dark blue being cooler. Vertical scale is logarithmic, and the SH latitudinal scale is compressed. Westerly winds represented by thin lines; easterly winds by thin dashed lines. The tropopause (thick orange line) separates the troposphere and stratosphere, and the stratopause (thick steel blue line) the stratosphere and the mesosphere. Thick dotted lines separate the tropical pipe (ascent zone), the surf-zone (wave-breaking zone), and the polar vortex. Planetary waves (undulating lines) generate at areas of contrast (concentric lines at surface) and can pass through the stratosphere, be deflected and break at the stratosphere or be refracted back to the troposphere. The quasi-biennial oscillation (QBO) is shown with its easterly and westerly components close to the Equator. The intertropical convergence zone (ITCZ) is shown as a tall stormy cloud. The Hadley circulation is displayed in dark brown. Other atmospheric circulation is represented by yellow arrows except the lower tropospheric equatorward circulation in turquoise. The stratospheric circulation is termed the Brewer–Dobson circulation. Its deep branch (upper stratospheric) and mesospheric circulation are inter-hemispheric from the summer to the winter pole. Tropospheric circulation is carried out mainly by eddies, and the rest by the mean residual circulation. At the December solstice, regions North of 72° are in polar night. From Vinós 2022

The autumn cooling of the Arctic atmosphere causes the end of the summer polar anticyclone, as the pressure decreases and the easterly winds that prevent upward wave propagation are replaced by westerly winds. A pole-centered cyclone (low pressure center with anti-clockwise rotating winds), known as the polar vortex (PV) forms then. The winter westerly winds of the NH are so strong that they only allow vertical wave propagation to the stratosphere of planetary waves of the highest amplitude (zonal wavenumber 1 and 2). The waves release their momentum and energy in an area of the stratosphere known as the “surf-zone” (McIntyre & Palmer 1984). The effect on the zonal mean circulation is a deceleration of westerly winds disrupting the thermal structure. As the LTG cannot be maintained under weaker westerly winds, air is forced down inside the PV, warming adiabatically, and up outside the PV, cooling. The Arctic polar atmosphere can warm by 30 °C in the lower stratosphere and up to 100 °C in the upper stratosphere. Afterwards, as the Arctic atmosphere is under strong radiative cooling during the winter, the stratosphere cools and the westerlies regain speed. When wave propagation weakens, the opposite happens and temperature at 30 km above the Arctic can become as low as –80 °C.

Northward of 20°N the atmosphere becomes the main carrier of heat poleward. During the NH winter, heat is transported to the Arctic mainly by stationary eddies (planetary waves) and transient eddies (cyclones). Cyclones preferentially generate, propagate and dissipate in storm tracks and tend to form where surface temperature gradients are large (Shaw et al. 2016). The jet stream influences their speed and direction of travel. The winter eddy heat flux reveals the preferred storm track areas (Fig. 3.6; Hartmann 2016).

A few extreme events per season associated with individual weather systems are responsible for a large part of the heat and moisture transported into the Arctic winter. Large-scale atmospheric blocking conditions deflect cyclone tracks poleward, and figure 3.8 shows one of these extreme events that took place in the last days of 1999 and first days of 2000, a case studied by Woods and Caballero (2016).

Fig 3.8

Fig. 3.8. Intense intrusion event of moist warm air into the Arctic in winter. a) Daily mean temperature North of 80°N for Nov 1999–Mar 2000 (black line) from ERA40 reanalysis, and the 1958–2002 average (red line). A blue rectangle marks the event. Data from the Danish Meteorological Institute (2021). b–d) Surface air temperature anomaly in the Arctic at different times during the intrusion event. After Woods & Caballero (2016)

According to Nakamura and Huang (2018) blocking develops like a traffic jam when the jet stream capacity for the flux of wave activity (a measure of meandering) is exceeded. Large-scale blocking conditions develop to the east of each ocean basin, deflecting midlatitude cyclones poleward (Woods et al., 2013). As a consequence, a great part of the latent heat transported into the Arctic is the result of a limited number of weather systems that enter the Arctic mainly through a North Atlantic gateway (300–60°E), followed in importance by a North Pacific gateway (150–230°E), and a less important Siberian one (60–130°E; Mewes & Jacobi 2019; Woods et al. 2013). Over the Atlantic, winter blocking strongly anti-correlates with the North Atlantic Oscillation (Wazneh et al., 2021).

Knowing how heat is transported into the Arctic allows us to examine the phenomenon of Arctic amplification. General circulation models have been predicting polar amplification as a result of global warming since their beginnings. After all, as seen in figure 3.3, as the climate of the Earth changes the change in temperature is larger the higher the latitude. However, in modern global warming Antarctic amplification has not been observed, and by 1995 so little Arctic amplification had been observed despite intense global warming the previous 20 years, that Curry et al. (1996) said: “The relative lack of observed warming and relatively small ice retreat may indicate that GCMs are overemphasizing the sensitivity of climate to high-latitude processes.” That was about to change that year when Arctic amplification suddenly accelerated (Fig. 3.9). But the question is still valid. Why was Arctic amplification small before 1996, when intense global warming was taking place, and large after 1996 when global warming rate decreased (the pause)? Modern climatology does not have an answer to that.

Fig 3.9

Fig. 3.9. Arctic seasonal temperature anomaly. Black curve, summer (June–August) mean temperature anomaly calculated from the operational atmosphere model at the European Center for Medium-range Weather Forecast (ECMWF) for the +80°N region. Red curve, the corresponding winter (December–February) mean temperature anomaly for the same region. Reference climate is ECMWF– ERA40 reanalysis model for 1958– 2002. Data from the Danish Meteorological Institute.

As we have seen above (e.g., Fig. 3.2), the Arctic in winter constitutes the biggest heat-sink (net energy loss to space) in the planet. Arctic precipitable water is c. 1.5 cm in summer, but in winter it drops to c. 0.2 cm (Wang & Key, 2005), the lowest value outside Antarctica. As a result, cloud cover becomes lower in winter increasing the energy loss. With a reduced cloud cover, almost no water vapor, and no albedo effect, the Arctic in winter has essentially no feedbacks to the greenhouse effect from CO2. Even more, van Wijngaarden & Happer (2020), note that “the relatively warm greenhouse-gas molecules in the atmosphere above the cold surface cause the Earth to radiate more heat to space from the poles than it could without greenhouse gases.”

It is clear that Arctic amplification is the consequence of an increase in MT, as the Arctic has a negative annual energy budget and the increase in greenhouse effect does not make it less negative. The warming in the Arctic, particularly during the winter, can only come from an increase in the heat transported from lower latitudes. The increase in Arctic heat transport that is not exported back to lower latitudes is distributed between increased OLR and increased downward longwave radiation. The enhanced downward radiation increases surface temperature, but due to the low thermal conductivity of ice, and since the heat flux always goes from the warmer ocean to the atmosphere during winter, temperature inversions commonly result, often accompanied by humidity inversions, and the radiative cooling continues from the top of the inversion or the top of the clouds until the water vapor freezes and precipitates, restoring the original very cold condition (Fig. 3.8a).

Arctic winter heat transport is enhanced at times when high pressure conditions prevail over the pole leading to a weak or split vortex. Warm air then enters the central Arctic ascending over the cold air (isentropic lifting), pushing it outwards. As a result, cold Arctic air masses then move over the mid–latitude continents producing anomalously cold temperatures and snow. Since Arctic amplification started, the frequency of mid-latitude cold winters has increased, something that models cannot explain (Cohen et al. 2020), but something similar took place between 1920–40 (Chen et al. 2018).

In this part we have reviewed how the LTG constitutes the most fundamental climate variable, and the mechanisms by which it drives the MT of energy towards the poles. In the next part we will review what happens when those mechanisms change in a coordinated way, as it happened when Arctic amplification started after 1996.




Abbreviations and Glossary.

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jeff corbin
August 16, 2022 6:15 am


David Hoyt Bostian
Reply to  jeff corbin
August 16, 2022 11:06 am

Yes, really great. A couple of weeks ago I tried to find out some of these things but wasn’t having much luck and now here it all is. Thanks

His Majesty
August 16, 2022 6:31 am


Steve Case
August 16, 2022 6:37 am

Nearly 6000 words and 440 lines according to Microsoft Word®, so at least several hundred succinct points about energy transport in our planet’s climate system. And we are supposed to believe all those CMIP(x) models can extrapolate all that out 100 years from now and predict a catastrophic disaster that can only be avoided if capitalism is replaced with socialism.

August 16, 2022 6:51 am

Sorry to crash the party, but I think the article misses the obvious.

The warming in the Arctic, particularly during the winter, can only come from an increase in the heat transported from lower latitudes

Yes and no. There is a very simple mechanism explaining the strong warming of the Arctic and it is ice!!! It is not even about albedo- or LW radiation effects, but rather about continental vs. maritime climate.

Sea ice insulates the air from the (relatively warm) water. If the arctic is frozen, then the air temperatures can and will drop off to low, continental levels. There is no direct contact with the water below to moderate them. Also air temperatures then will largely depend on atmospheric convection, which may bring warmer, or colder (siberian) air into the arctic. Accordingly we can see extreme variations in temperature.

However, as there is some warming and sea ice declines, the Arctic gradually moves from continental towards a more maritime climate. Overall the temperatures will move closer to ice water, which is still a lot warmer by comparison. This is an extremely powerful feedback (though not necessarily a feedback in the sense of climate science), beyond the typically considered radiative issues.

Steve Case
Reply to  E. Schaffer
August 16, 2022 7:31 am

If the arctic is frozen, then …we can see extreme variations in temperature … However, a more maritime climate. Overall the temperatures will move closer to ice water.”

And the charts produced by DMI illustrate that point beautifully:

DMI Arctic Temperature 2018.png
Reply to  Steve Case
August 16, 2022 8:03 am

And the charts produced by DMI illustrate that point beautifully:

Fig. 3.8a is a piece of one of those charts, and shows very clearly that the heat is coming from lower latitudes.

Reply to  Steve Case
August 17, 2022 2:04 am

And the charts produced by DMI illustrate that point beautifully:

Nope, that is the temperature of north of 80 North which still ice-covered in summer, the variability is not decreasing in summer because the ice is absent revealing the moderating ocean below. The swings are absent because any temperature above zero melts ice and that latent heat of melting takes up any excess energy available that would otherwise raise the temperature, effectively capping the temperature at or near 0°C.

E. Schaffer is correct a major contributor to Arctic amplification is the increasing open ocean/seaice ratio.

Reply to  Loydo
August 17, 2022 2:53 am

a major contributor to Arctic amplification is the increasing open ocean/seaice ratio.

A problem with that interpretation is that the ratio (ocean/sea-ice extent) is not increasing since 2007 because extent is not decreasing, yet winter Arctic amplification >80ºN has increased greatly since 2007.

comment image

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March 2022 had 14.59 million sqkm, the same as 2007.

Hard to blame an increase on a non increase.

Last edited 1 month ago by Javier
Reply to  Javier
August 17, 2022 4:04 am

I said contributor, IOW its not the only factor. Your “non increase” has been increasing for decades.

Meantime volume has steadily trended downwards, meaning available sensible heat is trending up.

and here is the rest of your extent graph. Arctic amplification did not “start after 1996″.

and here is north of 60N, an area more than 8 times larger than north of 80N

comment image

You’re only seeing what you want to see.

Reply to  Loydo
August 17, 2022 4:59 am

Volume is a fudge-fiddle factor as it is not measured.

Your “non increase” has been increasing for decades.

March 2006: 14.42 mill. sq. km
March 2022: 14.59 mill. sq. km

Ooh whoaa! The only way for the ocean/sea-ice ratio to have increased in the past 16 years (over a decade and half) is for the ocean surface to have increased.

Are the Arctic lands quickly sinking? I thought the opposite was true.

Arctic temperature had an abysmal coverage prior to satellites, saying what the average Arctic temperature was in 1940 is pure guesswork.

You’re only seeing what you want to see.

Look who is talking.

Reply to  Loydo
August 20, 2022 7:46 pm

Why didn’t temperatures explode during the orgy of co2 emissions from 1940-1979 caused by World War 2 and the reconstruction, and the general world development during that time.

Why were temperatures rising faster 1920-1940 (eyeballing about 1.5°C) than 1980-2000 (about 1°C) in spite of the huge difference in emissions in the favour of the latter?

Looks like other, probably natural forces are dominating. However I don’t discount that soot, so2, and other manmade emissions and conditions could affect the North which are then magnified by less ice insulation.

Reply to  E. Schaffer
August 16, 2022 7:44 am

Sorry to crash the party

No need to be sorry. Even in the current low winter Arctic sea-ice climate, all of >80ºN is covered in ice, and most of the >70ºN. Anything coming from lower latitudes is considered transported to the Arctic.

comment image

Figure 3.8 in the article shows how the high temperatures are reached in the Arctic, and it is mostly from heat transported from lower latitudes.

In the next part I will show how the change in transport was quite abrupt, taking place over just a few years, and not the progressive maritimization of the Arctic climate you talk about.

That is not to say that the loss of winter sea-ice is not having an effect on climate. It is a powerful negative feedback on warming as it multiplies the loss of heat by the exposed ocean surface many times.

Reply to  Javier
August 16, 2022 7:55 am

It may be a negative feedback with regard to the total energy balance of Earth. But for the Arctic, as long as we use air temperatures 2m above sea (or ice respectively) as indicator, it is a massively positive feedback.

Reply to  E. Schaffer
August 16, 2022 8:19 am

it is a massively positive feedback.

So you say but don’t prove. The area >70ºN not covered by ice in winter is a small part and has an SST between 0-8ºC. Most of the energy lost there in winter goes to space, the rest might have a small effect. It does not explain the huge warming (+8ºC) seen at >80ºN some winters, as figure 3.9 shows.

Reply to  E. Schaffer
August 16, 2022 11:57 am

Even if the air above the arctic ocean gets a little bit warmer, so what?
Especially during the winter, the air in the arctic is so far below freezing that a few degrees warming or cooling, won’t make any difference in ice extent.
So it can’t be a feedback.

In any regards, it’s the heat budget of the entire earth that matters.

Reply to  MarkW
August 16, 2022 2:00 pm

You just reversed the logic..

Reply to  E. Schaffer
August 16, 2022 7:57 am

I agree with you, as the evidence supports it. The upward trend in HadSST3 global ocean is likely the main reason for the upward trend in Arctic 80-90N T anomalies, for the reason you gave. As the ocean warms, the ice declines, exposing more ocean to the air, warming the air.

comment image

The Arctic sea ice reaches it’s highest extent in late February/early March, leaving 2/3 of the Arctic winter with less than the maximum sea ice extent, therefore having some portion(s) of the Arctic Ocean still open. Furthermore the sea ice extent itself is defined as only at least 15% sea ice, leaving room for even more open Arctic water. Therefore I think it is a safe assumption that the tropical ocean’s poleward heat transport is one source of Arctic warm anomalies.

The specific Arctic warming spikes from the article Fig. 3.8 during 1999-2000, likely came about indirectly from high solar irradiance spikes that enhanced warming and evaporation off the ocean, providing warmth/moisture that advected northward to the Arctic, as Fig. 3.8 indicated.

Reply to  Bob Weber
August 16, 2022 8:37 am

The attached is even more compelling of more open water even in mid winter. It would not take much increase in open water yo have a huge impact on average temperature because the ice has a typical temperature differential of 50C.

This shows sea ice cover in the Arctic 80 to 90N. You can see it is reducing to lower levels and not quite fully recovering each year.

The warming is consistent with increasing sunlight due to changing precession. April sunlight over the NH oceans has increased by 2.5W/m^2 over the past 520 years.

Reply to  RickWill
August 16, 2022 12:49 pm

In your graph it is clearly seen that it was not a progressive change but a quite abrupt change between the right part after 2012 and the left part before 2006. In the next part we will get into this.

In climate it is difficult to distinguish between cause and consequence, but in the case of the Arctic sea ice decline and its effects, it is clearly a consequence because it has stabilized. The ice-albedo feedback and the ocean-atmosphere increased flux feedback discussed here did not continue driving a further sea-ice decline, as they should if they were cause and not consequence of the Arctic changes.

Reply to  Javier
August 16, 2022 4:10 pm

In your graph it is clearly seen that it was not a progressive change but a quite abrupt change between the right part after 2012 and the left part before 2006.

You are seeing something that I am not. I see a reasonably steady trend throughout with a brief recovery centred on 2010.

Reply to  RickWill
August 20, 2022 8:27 pm

I’m sorry, but are you joking? The graph has a value of about 0.9 from 1980-2005 and then changes in about just 5 yrs to a new average. Hardly a steady change over the decades.

Bob boder
Reply to  Bob Weber
August 16, 2022 9:31 am

If you look at the difference between now and the high ice levels of the late 70s early 80s it’s pretty clear that most of the lose is from warm Gulf Stream waters to the east of Greenland.

August 16, 2022 7:19 am

Tidal energy from the moon is causing the moon to drift further from the earth.
So wouldn’t that tidal energy be a negative, not a positive?

Steve Case
Reply to  MarkW
August 16, 2022 7:56 am

Tidal energy from the moon is causing …

Just barely makes first chuckle of my day status, but it is amusing that the moon’s tidal effect was included in all those hundreds of factoids. Makes one wonder if the CMIP6 models take moon shine into account as well. (-;

Reply to  Steve Case
August 16, 2022 8:31 am

Sometimes I think that the CMIP authors have ALOT of first hand experience with moonshine.

Reply to  MarkW
August 16, 2022 8:01 am

Luni-solar tides deliver energy to the Earth causing mechanical movements in the ocean and friction between the ocean and the solid Earth. They also cause atmospheric tides, but the amount of energy for those is very low.

The exchange of tidal energy between the Earth and the Moon is what causes the Moon to drift away and slow down, it also slows down Earth rotation. The Moon is already tidally locked showing always the same face. When the Earth reaches the same state the Moon will only be visible from one face of the Earth, and always invisible from the other.

Reply to  Javier
August 16, 2022 9:44 am

My understanding is that before the earth’s rotation can be slowed enough so that the same hemisphere always faces the moon, the moon will be far enough from the earth that it will be captured by the sun’s gravity and go into orbit around the sun instead of the earth.

Reply to  Javier
August 17, 2022 2:34 pm

This article suggests that the sun is stealing the moon and moon drift is not due to tidal forces.

Reply to  Renee
August 17, 2022 2:41 pm

Very interesting reference, thank you. Clearly above my level, and no doubt controversial.

Gordon A. Dressler
Reply to  MarkW
August 16, 2022 11:45 am

“Tidal energy from the moon is causing the moon to drift further from the earth.”

Um, actually it is tidal energy delivered from the Earth that is causing the Moon to drift away from the Earth.

And just for interest, the Moon’s orbital altitude around Earth is currently increasing at a rate of 3.78 cm (1.48 inches) per year, or at about the same speed at which our fingernails grow.

Reply to  Gordon A. Dressler
August 16, 2022 12:00 pm

I was trying to distinguish between tides caused by the sun from tides caused by the sun.

As to the energy going from the earth to the moon, that’s why I asked if the sign should be negative rather than positive.

Clyde Spencer
Reply to  Gordon A. Dressler
August 16, 2022 7:20 pm

And, the same order of magnitude as tectonic-plate movement.

Carlo, Monte
August 16, 2022 7:30 am

From Fig. 1, the annual ±1.9°C variance of the average is ignored and never reported, nor is the daily variance of this average, which is likely 10-20°C. How can this data be expected to resolve tiny changes of 0.1°C or less?

Richard Page
Reply to  Carlo, Monte
August 16, 2022 9:03 am

Can we actually reliably observe tiny changes of 0.1C or less?

August 16, 2022 7:54 am

Energy input to the climate system must have been lower, because albedo was higher and the greenhouse effect lower. 

This misses the state of the Earth at the time. Oceans were around 120m lower than now and most of the missing water was stacked over Europe and North America.

The altitude of the ice mountains lifted the average altitude of the land from 800m above sea level to over 1000m above sea level and the ice mountains would have been similar to Greenland and Antarctica observed now.

Lapse rate and albedo of all the ice explains the lower temperature. The Atlantic has a small equatorial zone and would not reach the 30C limit due to high latent heat transfer to warm the ice mountains around its northern shores. The cooling spreads to the South Atlantic and has some impact on the Pacific through the circumpolar current but still limiting to 30C in the tropics. The Indian Ocean still reaching the 30C limit.

Move on to 12k years ago and precession was having a huge impact on the rate of melt with June sunlight over NH land averaging 512W/m^2; 35W/m^2 more than when the ice started to melt.

Precession dominates Earth’s climate. All of the temperature trends away from the tropics can be explained by increasing or decreasing sunlight. The tropics cannot exceed 30C so are stuck there providing there is enough sunlight.

The poleward transport of heat is important but you cannot explain the increasing temperature of the Mediterranean looking at latitudinal heat transport. I get a 92% correlation of surface temperature of the Med increasing with changing ToA solar. Same thing in the Southern Ocean but cooling with 91% fit.

Mike Dubrasich
Reply to  RickWill
August 16, 2022 9:51 pm

Much of this discussion is over my head, so please excuse these simplistic questions. If, as you say, “precession dominates Earth’s climate”, and precession is a ~26,000 year cycle, then why have glacial stadials been ~100,000 years long interspersed with much shorter interglacials? Clearly those have not been cycling on and off in 26,000 year increments. The article avers that “precession and obliquity values were the same” at the LGM as today, posing “an unsurmountable problem for modern climatology”.

In addition, if ocean MT is inferior to atmospheric MT, why is Earth in icehouse conditions today compared to prior epochs? That is, why does the position of continents appear to cause ice ages? Surely the atmosphere is not impeded by continents, whereas oceanic circulation is definitely impeded.

Reply to  Mike Dubrasich
August 16, 2022 11:23 pm

why does the position of continents appear to cause ice ages?

This is discussed in part VI.

Surely the atmosphere is not impeded by continents

Meridional transport is carried out mainly by the atmosphere mainly over ocean basins. This is where storm tracks and eddy transport are mainly located.

Continents, and particularly mountain ranges, severely restrict transport by reducing wind speed and the moisture the air carries.

August 16, 2022 8:06 am

… by 1995 so little Arctic amplification had been observed despite intense global warming the previous 20 years…

The rate of global warming in the 20-years up to and including 1995 (1976-1995), which is described here as having been ‘intense’, was +0.16C per decade according to HadCRUT5 (+0.15C per decade in GISS).

The rate of global warming over the 20 most recent years, 2002-2021, was +0.21C per decade in HadCRUT5 (+0.22C per decade in GISS). I guess the last 20-years must have been a period of super-intense warming, going by that measure?

Reply to  TheFinalNail
August 16, 2022 8:24 am

comment image

Reply to  Javier
August 16, 2022 12:09 pm

And he replies with the same old detrended HatCRUT4 chart that stops 5 years ago….

Reply to  TheFinalNail
August 16, 2022 12:41 pm

You don’t knoww how to read a graph. If it is a 15-yr centered moving average, the last point graphed includes data to 7.5 years later.

Reply to  Javier
August 17, 2022 3:36 pm

(nickstokes will come along and correct your error … it is 15.08 & 7.54)

Reply to  TheFinalNail
August 16, 2022 2:05 pm

What does the following mean to you?

181-Month centered moving average

Reply to  Sunsettommy
August 16, 2022 2:32 pm

Could it mean that 60.5 months lie beyond the end of the line?? OMG, I think that’s it!

Reply to  TheFinalNail
August 16, 2022 9:46 am

Even if true, what fraction of that is natural and what fraction is caused by CO2?
And no, you can’t use models to determine this.

Reply to  MarkW
August 16, 2022 12:11 pm

You say ‘even if true’ as if you can’t check for yourself that it is true.

Reply to  TheFinalNail
August 16, 2022 8:58 pm

You don’t know is the answer.

August 16, 2022 8:44 am

Hello all. Only part way through this: good read this far, BUT I have a question about something the author states:

‘ During the last glacial maximum (LGM), 20,000 years ago, the energy received from the sun was the same as now. Not only that, but the precession and obliquity values were the same as now, and the orbital eccentricity was very similar. ‘

Aren’t the cycle for these three parameters 40, 80 and 100 K years or so? Did they all three crest, level or trough 20 k years ago? Otherwise how could they all be the same or very similar?


Reply to  JBP
August 16, 2022 9:48 am

I thought LGM stood for Little Green Men.

Tom in Florida
Reply to  JBP
August 16, 2022 11:20 am

Precession is about 23,000 years, Obliquity about 41,000 years, Eccentricity about 100,000 years.
20,000 years ago the Earth was at the middle of the obliquity cycle with perihelion close to NH winter solstice; as it is now. The main difference being that 20,000 years ago obliquity was moving towards it’s maximum from a cold world where today obliquity is moving towards it’s minimum from a warm world.

Reply to  Tom in Florida
August 16, 2022 4:37 pm

Thanks. So eccentricity is only one fifth a cycle off and obliquity is the same but headed in the opposite direction. Huh. We’re all gonna die.

Bob boder
August 16, 2022 9:35 am

Great job Javier and Andy, truly excellent and compelling. Coupled with Willis’s and RickWs work i find myself much enlightened.

Steve Richards
August 16, 2022 9:40 am

A very good article but I would say it has excessive or unnecessary use of acronyms. The overload of so many acronyms reduced the enjoyment of reading it.

David Hoyt Bostian
Reply to  Steve Richards
August 16, 2022 11:04 am

Yes, i was just thinking the same thing. I’d love for my wife to read it but she hates acronyms and would just give up.

Be nice to have a copy without all of them.

Reply to  Steve Richards
August 16, 2022 12:30 pm

Thanks for the comment, we agree and are working on a less technical book on this very new subject.

Clyde Spencer
Reply to  Andy May
August 16, 2022 7:38 pm

It isn’t just an issue of technical jargon, but that when a whole new set of meaningful terms are replaced with letters, it is difficult to remember what each acronym is addressing. How about an acronym-free version?

Reply to  Andy May
August 20, 2022 8:58 pm

Just make it so that when one hovers over an acronym the full name pops up.

Clyde Spencer
Reply to  Steve Richards
August 16, 2022 7:35 pm

I think that acronyms are mostly an anachronism. They date to the time when manuscripts were prepared with quill, and then later with a typewriter, and typesetters had to duplicate the letters with little pieces of lead.

With a word processor, the writer can use acronyms that he or she is familiar with, and then do a global search and replace for all of the acronyms. While that provides more words to read, it would save me time going back to find the definition of an acronym in order to understand what was being said.

Gordon A. Dressler
August 16, 2022 11:15 am

Let’s see:

Summer solstice [2022] = June 21
Winter solstice[2022] = December 21
Earth aphelion [2022] = July 4
Earth perihelion [2022] = January 3

June 21 to July 4 = 13 days separation.
December 21 to January 3 = 13 days separation,
Close enough to being in synch in both cases for the purposes of the following calculations.

Scaling summer:winter solar insolation based on distance (2022): = (aphelion/perihelion)^2 = (94,509,598 mi/91,406,842)^2 mi = 1.069 = 6.9% difference

Scaling summer:winter ground angle-of-incidence of solar radiation at 45° N Latitude: = Sun at max. elevation (summer solstice)/Sun at min. elevation (winter solstice) = (45°+23.4°)/(45°-23.4°)

Assuming (to first order) solar energy per ft^2 arriving at Earth’s surface is a function of the sine of the angle of arriving radiation above the local horizon (i.e., the Sun’s local peak elevation in the sky), one thus sees that:
Scaling summer:winter ground energy arrival at a 45° N Latitude = sin(45°+23.4°)/sin(45°-23.4°) = 2.53 = 253% difference.

Thus, Earth’s spin axis inclination is some 37 times more powerful than is Earth-Sun distance in affecting energy receipt at Earth’s surface, all other things being equal (which they seldom are).

On this simple basis, it is no wonder that the Earth’s NH is warmer when it is further away from the Sun.

Reply to  Gordon A. Dressler
August 16, 2022 2:53 pm

Yes, insolation is the most important factor affecting surface temperature.

What is not so obvious is that the average temperature of the Earth is warmer when it is further away from the Sun.

It demonstrates that what is most important is not how much energy the Earth receives from the sun, but what the climate system does with it. It regulates how much shortwave radiation is absorbed and how much longwave radiation is emitted.

The idea of an equilibrium between incoming and outgoing radiation at the top of the atmosphere is completely false.

Reply to  Javier
August 16, 2022 4:35 pm

It demonstrates that what is most important is not how much energy the Earth receives from the sun, but what the climate system does with it.

This is not accurate. The sun is by far the most important factor in driving climate. Orbital changes are the dominant factor in centennial and millennia scale climate change because it is changing how sunlight is presented on Earth.

The energy uptake is a function of the distribution of land and water over the surface and how each respond to changing sunlight. Ocean surfaces limit heat uptake above 26C to provide a hard temperature limit at 30C in open oceans. Sea ice provides a hard limit of -1.8C by reducing ocean heat loss once formed.

The temperature trends across the globe track changing ToA sunlight apart from the tropics approaching the 30C limit and the high latitudes where sea ice exists.

August 16, 2022 11:25 am

Studies should begin with an abstract and plain English summary of conclusions

Reply to  Richard Greene
August 16, 2022 12:32 pm

Working on it. These posts and the book Javier is publishing next month are technical. The easier to digest stuff, is down the road a bit, it is much harder to write and takes longer.

Reply to  Andy May
August 16, 2022 4:40 pm

Well if you need some help, let me know. I think can find somebody else besides me.

August 16, 2022 12:45 pm

I think you underestimate the heat from earth. I would not trust the info about this on the internet.
According to my books T goes up 3K per km down. That means to get + 0.5K on earth, I only need a shift or expansion of the inside of earth by about 200 meters. Come with me into a gold mine and meet the elephant in the room.

Gordon A. Dressler
Reply to  HenryP
August 16, 2022 2:47 pm

In physics (which encompasses geophysics), there is a distinct difference between heat flux (thermal energy per unit area reaching the surface) and thermal gradient (temperature change per unit length opposite the direction of heat flow in the thermal conductor . . . energy flowing from hot to cold).

You have hopelessly confused the two . . . and there is no associated “elephant” in the room of reality and facts.

mega weld
August 16, 2022 2:49 pm

Its hard to understand how a computer could simulate any of this information reliably. Even a supercomputer.

Reply to  mega weld
August 16, 2022 4:26 pm

NO, it’s hard to understand how a COMPUTER PROGRAMMER could understand, let alone, simulate this chaos no matter how SUPER the computer was/is.

Reply to  mega weld
August 16, 2022 5:06 pm

There is no effort being made to accurately replicate climate with computers. Nothing they produce gets close to reality and the modellers do not want to look at reality because it differs from their models. The modellers have joined forces with the record keepers to adjust the records to suit the models.

As far as I can determine, the only reliable temperature record is the NOAA/NCEP Reynolds optimally interpolated sea surface temperature. All other surface based records display inconsistent data indicative of data fiddling – some intentional and some by accident. In Australia, it is possible to observe when each station changed from manual readings to instrumented readings by looking at the data standard deviation.

All coupled climate models assume an energy imbalance and the oceans storing the extra heat. The output of climate models can actually be replicated with a two parameter model – an energy imbalance and the thermal inertia. See attached – red line in the top chart was produced with two parameters. The bottom chart is surface temperature prediction from the CSIRO Mk6 model with CMIP5 data.

Screen Shot 2022-08-17 at 10.03.15 am.png
August 16, 2022 4:01 pm

I can’t keep track of the abbreviations, please put the whole term in more often. I have a second window open to the abbreviations link, but it’s disrupting to keep going back and forth.
When/where can we get a hard copy of the whole paper?

Clyde Spencer
Reply to  Yooper
August 16, 2022 7:43 pm

My short-term memory isn’t what it once was. It is one of the more obvious declines in mental acuity that comes with age. There are a lot of us here that are of that age.

August 16, 2022 5:01 pm

Wow, that’s a lot to digest. Wouldn’t the purveyors of Catastrophic Anthropogenic Global Warming either have to accept this information and include it in their calculations or reject it and claim their hypothesis stands as is? If they reject it they need to show that it is wrong. If they accept it their hypothesis is meaningless until this information if fully included in their calculations. As interconnected as all these system appear it would seem to me one would have to accept all of it or none of it. I don’t see how you could isolate any one of them from the system as a whole.

Reply to  Bob
August 17, 2022 3:46 pm

That would depend on if you believe their main motivation is to contribute to better understanding, or rather to maximise the probability and size of their next grant. And the motivations behind that question, is purely political

Reply to  Davidf
August 17, 2022 7:39 pm

All I expect is for the green devils to be honest, I guess I am expecting too much of them.

Reply to  Bob
August 17, 2022 7:48 pm

The best that you can say, is that they are reliable.

August 16, 2022 5:21 pm

–What it is clear from figure 3.1 is that although the climate system is entirely powered by solar irradiance, what determines the Earth’s temperature is what the climate system does with that energy, and the climate system is extremely complex.–

What climate system does with the energy is the difference of ice house and greenhouse global climate. Which is huge difference but one could say it’s huge difference related
to human interests, rather then some hard to define non human interest.
A simple example is humans tend to like trees. And certain type of life in general should be something wanted.
Human like a uniform temperature- which they call room temperature.

Humans currently want to live on land. They can barely imagine living in the sky or on the ocean [which covers 70% of the entire Earth surface].
A 1/3 of land is desert and large portion of land is in the colder parts of the Northern Hemisphere.
Humans might be amazed by a huge ice sheet, but they would tend think it’s a big problem.
So a greenhouse global climate has no huge ice sheets, human being a tropical creature [though they as modern evolved in an Ice Age] could find
a greenhouse global climate more like paradise.
Though they may be against “having life so easy- based on “morality”.
Germans live in country with average temperature of 9 C, and seem to worry this average temperature could increase.
It appear like insanity.
Canada with average temperature of -3 C, also are quite concerned about having their average temperature increased-
for example having an average temperature of 1 C, is a sign of the end of world.
We recently left a centuries long period called the Little Ice Age, a time of harsher conditions, and there is regret that earth got slightly warmer,
and returning to such a slightly cooler time would be best.

But there is no realist option of getting out of this Ice Age- because of what the climate system does with the Sun’s energy.

But the climate system is mostly matter of failing to understand it, rather than being complex.
What is hard to predict is weather. Weather is not global climate. Global climate is we are in an ice house global climate. The climate system “allows”
too much cold water falling making our average temperature of the Ocean being about 3.5 C.
A greenhouse global climate has “too much” warmer water falling, making ocean warmer. Or not enough cold water falling to make it an Ice house global
So making greenhouse climate be cooler, require less warm water falling. Making ice house climate, warmer, requires more warm water falling.
But it take a long time as heat content of ocean is very large.
As our religion of global climate say, more than 90% of all recent global warming, has been warming the entire ocean. And it’s claimed
the amount has increase ocean temperature of about 3.5 C by .05 C.
And if imagined humans caused this .05 C increase, one could say it took a vast amount of effort. Though if we did it, in more rational way,
it’s could take less effort to warm ocean by .05 C, but it would take decades to do this, or centuries add .5 C.
One advantage is it would make global air temperature, slightly cooler, but would more costly to make a cold as the coldest time in the Little
Ice Age.
But governments are quite incompetent, and I would not allow them to do something like this. And amount of cooling would be hard measure in periods
as short as a year, so it would tend allow fraudulent claims of how much “cooling value” was being delivered.

Gary Pearse
August 16, 2022 5:46 pm

“The effect of clouds and their variability on climate change is still largely unknown.”

Javier, I’m sure you are aware of Le Châteliers Principle (LCP), first noted in the realm of chemical reactions but later found to be of much broader application. Simply stated for the chemist: In a multi-component interacting system (chemicals in water solution, solids and gases, available to be dissolved, T, P, V, different phases of water, etc,) a forced change in one or more of these components, say ‘T’, causes changes in all the others to resist the perturbing change and make it smaller than one would calculate assuming ceteris paribus (all other things unchanged).

One simple example is if you raise the T of the atmosphere, being unbounded it will increase in volume thereby reducing the effect of the heating. Meanwhile, the other components are all in perhaps small ways also resisting the temperature change.

Also, when water is heated, CO2 outgasses, but guess what? The outgassing is endothermic, cooling the seawater. Similarly, with the Great Greening of the planet photosynthesis is endothermic thereby sequestering both CO2 and ‘heat’. This not a small amount of either. A kg of glucose produced by the process uses 1.5mega joules or 4.2 kWh of energy. Google counted the earth’s trees and found there were 3 trillion. Greening gave rise to an expansion of new forest of 30% in 35years. I calculated this to be ~300Gt (avg tree 17yrs old, etc)

I was hoping someone more knowledgeable about such things would do such a calculation. Nowhere have I seen climate scientists talk about such an important factor. The consensus forecast an anomaly that turned out 300% too high. Possibly it should have been multiplied by an LCP coefficient of 0.33 to convert their ceteris paribus calc. to reality.

August 16, 2022 6:02 pm

Great post.
Supported in many posts by Erl Happ.

August 16, 2022 9:13 pm

Tides in Seattle run about 11ft; it just doesn’t seem like humans could expend 4.5 times the world’s tidal energy; that’s a lot of lift!

Mike Edwards
August 16, 2022 11:59 pm

“the relatively warm greenhouse-gas molecules in the atmosphere above the cold surface cause the Earth to radiate more heat to space from the poles than it could without greenhouse gases.”

This quote from Wijngaarden Happer 2020 is correct, but is associated with their calculations for the South Pole. It depends on the presence of a temperature inversion in the atmosphere. Such inversions are also present during Arctic winters, but their structure is different. The inversion is at a greater height over the south pole than over the north pole. The lower height over the north pole leads to less radiative effect of increasing greenhouse gases.

Temperatures over the south pole would be expected to decline as CO2 increases as a result of this. And this is observed. For the north pole, it is a much smaller effect. Instead, at the north pole, the impact of increasing sea temperatures, decline of sea ice area and the impact of increasing winter cloudiness is key.

Indeed, it is the more open water -> more clouds feedback that is likely the key mechanism which can enable the transition to a (relatively) warm regime at the north pole, since the presence of more clouds certainly slows down the loss of thermal energy from the surface in wintertime. This surely is the essence of arctic amplification.

Mike Edwards
Reply to  Mike Edwards
August 17, 2022 12:25 am

To back this up, here is the February sea ice extent for the arctic, clearly showing a decline – meaning more open water:

Reply to  Mike Edwards
August 17, 2022 2:03 am

What it is clear is that the increase in Arctic greenhouse gases and greenhouse effect is not contributing to make it warmer in winter. The cause is elsewhere.

Instead, at the north pole, the impact of increasing sea temperatures, decline of sea ice area and the impact of increasing winter cloudiness is key.

You and nearly all climate scientists place the cause there. We disagree. That is the effect. The cause is a change in the amount of heat transported by the atmosphere to the Arctic that took place quite abruptly in a few years after the 1997 climate regime shift that will be discussed in the next parts.

This increase in heat and moisture transport produced the rapid decline in sea-ice and increase in cloudiness that are a feature of the new Arctic regime. Yet all Arctic predictions are failing because the situation stabilized in the new regime instead of causing a positive feedback as would be the logical conclusion if you and the others were correct.

Reply to  Mike Edwards
August 19, 2022 9:30 am

What you are showing is a proxy for the AMO. There are proxy data extending the AMO back into the 1800s.

AMO ocean circulation – Bing images

Nothing new about the 40-year Arctic sea ice anomaly declines. I’m putting my money on a 40-year period of arctic sea ice anomaly increases starting now.

Gordon A. Dressler
Reply to  Mike Edwards
August 17, 2022 7:06 am

“This quote from Wijngaarden Happer 2020 is correct, but is associated with their calculations for the South Pole.”

The statement that relatively warmer gases (i.e., Earth’s atmosphere with trace greenhouse gases) will radiate more energy than relatively cooler gases (i.e., Earth’s atmosphere without trace greenhouse gases) is absolutely true, independent of any geographical location or presence of a temperature inversion layer.

It is known as the Stefan-Boltzmann law of radiation.

August 17, 2022 12:29 am

Nearly all the energy that powers the climate system and life on Earth comes from the sun. Incvming solar radiation is estimated at 173,000 TW”

Nope. Earth is not a disc, it receives radiation over a hemisphere. 173000TW is calculated using a flat Earth. Since Earth´s shadow is a cone, you can´t calculate received radiation as a disc. If Earth received radiation equal to a disc of the same radius, Earth´s shadow would be a cylinder. Earth receives much more than 173000TW

Gordon A. Dressler
Reply to  Lit
August 17, 2022 7:45 am

Not correct.

Earth’s diameter at its average distance from the Sun subtends an angle of only .0049 degrees. This means that rays of light energy arriving from the Sun are, for all intents and purposes, parallel. This, in turn, means that the shadow cast by the Earth is essentially cylindrical, having a conical divergence angle of only .0049 degrees.

Solar insolation (TOA) at Earth’s average distance from the Sun (aka, the “solar constant”) is 1368 W/m^2. So, the total Solar radiation energy intercepted by Earth is equivalent to that of a flat disk of diameter equal to that of the Earth:
E = 1368 w/m^2 * (pi/4)*(12,742,000 m)^2 = 1.74E+17 watts = 174,000 TW
(methinks your stated value, the same as that given in the above article, is off a tad)

The power from the Sun that is intercepted by Earth is indeed no more than 174,000 TW (excluding rounding errors).

But at an average albedo of about 0.3, some 30% of that power is reflected off into deep space and not absorbed into Earth’s atmosphere and surface. The authors of the above article did not make note of this.

Last edited 1 month ago by Gordon A. Dressler
Reply to  Gordon A. Dressler
August 17, 2022 8:27 am

The authors of the above article did not make note of this.

No because 173,000 is the number usually used in the bibliography for the power arriving from the sun. Albedo depends on the Earth climate and is known to change, for example in the last 20,000 years.

As another kind reader noted in a comment elsewhere, about 500 TW that are not absorbed by the atmosphere or the surface should continue travel, but are scattered by the atmosphere into the climate system. Scattered radiation is very important.

Nevertheless all these precissions and more, solar radiation is still providing 99.99% of the climate system energy.

Gordon A. Dressler
Reply to  Javier
August 17, 2022 12:23 pm

“Albedo depends on the Earth climate and is known to change, for example in the last 20,000 years.”


What you say is true, but in the spirit and context of your above article, there is no discussion of long term changes in Earth’s energy balance (such as would result from Earth’s orbital ephemeris changes per Milankovitch cycles and Earth’s spin axis precision and nutation). You article clearly focused on events (aphelion/perihelion and solstices) and their affect on the energy/climate balance in the relatively short term, say, a couple of thousand years, and I have no issue with that.

So, I don’t think it was unfair of me to state an average albedo of “about 0.3” in my comment above to Lit, since that is what has been documented by science over the last thousand years or so.

Reply to  Gordon A. Dressler
August 17, 2022 1:27 pm

Of course it was not unfair. You are right that within the context it would be better to clarify the amount of energy actually received by the climate system. We will include your suggested changes when we write that for the book. Thank you.

Gordon A. Dressler
Reply to  Gordon A. Dressler
August 17, 2022 12:04 pm

Just a note of clarification about my previous post: I made a simplification that is perhaps not warranted regarding the details of my assertion of parallel rays of sunlight and the “cylindrical” aspect of Earth’s shadow.

At the Sun’s average distance from the Earth, the Sun’s diameter subtends an angle of about 0.53 degrees. So while it is true that the Earth receives essentially parallel rays of light from any point on the Sun’s surface (per previous calculations), I glossed over the fact that rays arriving from one limb of the Sun hit Earth at an angle that is 0.53 degrees different than rays arriving from the opposite limb.

The solar constant accounts for this, so it does not affect the simple power calculation that I did, but that 0.53 degree included angle will affect the shape of Earth’s shadow slightly (but still it is very well approximated as “cylindrical”) and does need to be considered in full understanding what “parallel” rays of light from the Sun truly encompasses.

M Courtney
August 17, 2022 1:11 am

…by 1995 so little Arctic amplification had been observed despite intense global warming the previous 20 years, that Curry et al. (1996) said: “The relative lack of observed warming and relatively small ice retreat may indicate that GCMs are overemphasizing the sensitivity of climate to high-latitude processes.” That was about to change that year when Arctic amplification suddenly accelerated (Fig. 3.9). But the question is still valid. Why was Arctic amplification small before 1996, when intense global warming was taking place, and large after 1996 when global warming rate decreased (the pause)? Modern climatology does not have an answer to that.

Being cynical, the answer to that is modern climatology. The acceleration in the “observations” being caused by the publishing of a paper that noted it should be there.

Loren C. Wilson
August 17, 2022 7:06 pm

One possible explanation for the hottest average temperature of the planet being in the northern hemisphere’s summer even though it is farther from the sun is that during the southern summer, insolation falls mostly on the ocean, which is self-regulating. The incoming energy is rejected more effectively by Willis Eschenbach’s emergent cloud cover theory. The northern hemisphere contains most (2/3) of the world’s land area, where the emergent phenomena do not function as well due to the lack of easily-evaporated water. Less ocean equals higher temperatures.

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