Plausible scenarios for climate change: 2020-2050

Reposted from Dr. Judith Curry’s Climate Etc.

Posted on February 13, 2020 by curryja |

by Judith Curry

A range of scenarios for global mean surface temperature change between 2020 and 2050, derived using a semi-empirical approach. All three modes of natural climate variability – volcanoes, solar and internal variability – are expected to act in the direction of cooling during this period.

In the midst of all the angst about 1.5oC or 2.0oC warming or more, as defined relative to some mythical time when climate was alleged to be ‘stable’ and (relatively) uninfluenced by humans, we lose sight of the fact that we have a better baseline period – now. One advantage of using ‘now’ as a baseline for future climate change is that we have good observations to describe  the climate of  ‘now’.

While most of the focus of climate projections is on 2100, the period circa 2020-2050 is of particular importance for several reasons:

  1. It is the period for meeting UNFCCC targets for emissions reductions
  2. Many financial and infrastructure decisions will be made on this time scale
  3. The actual evolution of the climate over this period will influence 1) and 2) above; ‘surprises’ could have adverse impacts on decisions related to 1) and 2).

Global climate/earth system models have little skill on decadal time scales. To address this issue, CMIP5 and CMIP6 are conducting initialized, decadal scale simulations out to 35 years. While I haven’t seen any CMIP6 decadal results yet, I do follow this literature. Punchline is that there is some skill in simulating the Atlantic Multidecadal Oscillation (AMO) out to 8-10 years, but otherwise not much overall skill.

I have previously criticized the interpretation CMIP5 simulations as actual climate change scenarios – instead, these simulations show the sensitivity of climate to different emissions scenarios. They neglect scenarios of future solar variability, volcanic eruptions, and the correct phasing and amplitude of multidecadal variability associated with ocean circulations. The argument for dismissing these factors is that they are smaller than emissions forcing. Well, cumulatively and on decadal to multi-decadal timescales, this is not necessarily true.

And in the CMIP6 era, we now have sufficient information and understanding so that we can generate plausible scenarios of volcanic and solar forcing for the 21st century, as well as for the AMO.

I have developed a semi-empirical approach to formulating 21st century climate change scenarios that rely only indirectly on climate models. Multiple scenarios are generated for each driver of the forecast (natural and anthropogenic), with an emphasis on plausible scenarios (rather than extreme scenarios that cannot completely be ruled out).

Note: in what follows, many references are cited. I don’t have time now to pull together a full bibliography, but I have provided hyperlinks to the key references.

Manmade global warming

The approach used here is to use as much as possible the new information becoming available for CMIP6: new emission scenarios, new considerations regarding climate model sensitivity to CO2.

Similar to the recent IPCC SR1.5 Report, no attempt is made to use CMIP6 Earth System Model outputs. Following the IPCC SR1.5, scenarios of global warming are driven by scenarios of cumulative emissions. The individual cumulative emission scenarios between 2020 and 2050 are then translated into a global temperature increase using a range of values of the Transient Climate Response to Cumulative Carbon Emissions (TCRE). This approach is illustrated in the following figure:

Figure 1: CO2-induced warming as a function of cumulative emissions and TCRE. Millar et al

Emissions scenarios

For the forthcoming IPCC AR6, a new set of emissions scenarios (SSP) have been issued.

The 2019 World Energy Outlook Report from the International Energy Agency (IEA) challenges the near term SSP scenario projections through 2040. They examined three scenarios: a current policy scenario (CPS) where no new climate or energy policies are enacted by countries, a stated policies scenario (STPS) where Paris Agreement commitments are met, and a sustainable development scenario (SDS) where rapid mitigation limits late 21st warming to well below 2°C. Both the IEA CPS and STPS scenarios can be considered as business-as-usual where either current policies or current commitments continue, but no additional climate policies are adopted after that point.

Figure 2 compares the IEA fossil fuel emissions projections to scenarios being used in the IPCC AR6. The figure indicates that the IEA CPS emissions are between the SSP2- RCP4.5 and SSP4-RCP6.0 scenarios and the IEA STPS scenario is slightly below SSP2-RCP4.5.

screen-shot-2020-02-12-at-3.24.09-pm

Figure 2: Annual CO2 emissions from fossil fuel and industry in CPS and STPS IEA scenarios compared to the range of baseline scenarios examined in the SSP Database, as well as a subset of the baseline and mitigation scenarios chosen for use in the forthcoming IPCC AR6 report. Ritchie and Hausfather (2019) https://thebreakthrough.org/issues/energy/3c-world

In view of these considerations, I select a single scenario for consideration here: SSP2-4.5. For the timescale of this analysis (2020-2050), there is little difference between 4.5 and 6.0, and we are not currently on the 7.0 trajectory.

Cumulative emissions for SSP2-4.5 calculated from 2020 to 2050 are reported in Table 1 for both cumulative CO2 and cumulative C (carbon). Cumulative C is used in calculating the transient climate response to cumulative carbon emissions (TCRE); note that 1000 GtC is the carbon content of 3667 GtCO2.

Table 1: Projections of cumulative CO2 (GtCO2) and C concentrations (GtC) between 2020-2050, for 3 SSP emissions scenarios. Data from IIASA database.

For reference, the IPCC SR1.5 Report assessed that amount of additional cumulative CO2 emissions (50th percentile) from a reference period 2006-2015 to keep additional warming to within 0.5°C is 580 GtCO2, and to keep additional warming to within 1.0°C is 1500 GtCO2.

TCRE

Translating the emissions scenarios into a global temperature increase has traditionally been conducted using global climate or earth system model simulations. However, the CMIP6 simulations using the new SSP scenarios and their analysis are currently underway. The recent IPCC SR1.5 Report chose to use values of the transient climate response to cumulative carbon emissions, or TCRE, to relate global temperature change to the cumulative emissions in the SSP scenarios.

The amount of warming the world is projected to experience from emissions is approximately linearly proportional to cumulative carbon emissions (for an overview, see Matthews et al. 2018). This relationship between temperatures and cumulative emissions is referred to as the transient climate response to cumulative carbon emissions, or TCRE. For a give value of TCRE, we can calculate the amount of warming expected over a future period in response to scenarios of cumulative carbon emission.

The IPCC AR5 provided a likely range for TCRE of 0.8°C to 2.5°C. Matthews et al. (2018) state that the current generation of full-complexity Earth-system models exhibits a range of TCRE values of between 0.8 and 2.4°C, with a median value of 1.6°C. An observationally-constrained TCRE estimate gave a 5%–95% confidence range of 0.7 −2.0°C, with a best-estimate of 1.35 ◦C (Gillett et al 2013). A more recent observationally-constrained estimate is provided by Lewis (2018), who determined a best estimate of 1.05°C.

In view of these assessments, I select the following values of TCRE for scenarios: 1.0, 1.35, 1.65, 2.0°C as constituting a range of plausible values.

Table 2 provides calculations of the amount of warming between 2020 and 2050, based on SSP2-4.5 and four values of TCRE. As expected from the range of TCRE values used here, there is a factor-of-two range in the amount of emissions-driven warming expected for the period 2020-2050.

Table 2: Warming scenarios (oC) for 2050 from a 2020 baseline based on the SSP2-4.5 cumulative emissions scenario (GtC) and four values of TCRE (oC)

Projections of natural climate variability

Scenarios of future variations/changes are presented for 2030-2050 for the following:

  • Solar variations
  • Volcanic eruptions
  • Decadal-scale ocean circulation variability

Solar variations

With regards to solar scenarios for the 21st century, there are two issues:

  • How much total solar insolation (TSI) will change
  • How much warming, given a specific TSI.

According to the IPCC AR5, the influence of the Sun on our climate since pre-industrial times, in terms of radiative forcing, is very small compared to the variation of radiative forcing due to added anthropogenic greenhouse gases: 0.05 W/m2 vs. 2.29 W/m2. Thus, the IPCC AR5 message is that changes in solar activity are nearly negligible compared to anthropogenic forcing.

This interpretation has been challenged:

  • There is substantial disagreement on trends in solar activity, even in the satellite era. Several papers in the last decade have claimed that solar activity in the second part of the 20th century was higher than any time in the past 10,000 years. Some studies claim that the Sun could have contributed at least ∼ 50% of the post 1850 global warming.
  • The IPCC AR5 considered only the direct solar effects on global temperatures. It has been found that over the eleven- year solar cycle the energy that enters the Earth’s system is of the order of 1.0–1.5 W/m2. This is almost an order of magnitude larger than what would be expected from solar irradiance alone, and suggests that solar activity is getting amplified atmospheric processes. Candidate processes include: solar ultraviolet changes; energetic particle precipitation; atmospheric-electric-field effect on cloud cover; 
cloud changes produced by solar-modulated galactic cosmic rays; large relative changes in its magnetic field; strength of the solar wind.
  • The relations between solar variations and Earth climate are many and complicated. Most of them work locally and regionally, and many are non-linear. Strong solar influences have been seen in the Pacific and Indian Oceans and also in the Arctic, among other regions.

As summarized by Svensmark (2019), satellite data demonstrate that TSI varies by as much as 0.05–0.07% over a solar cycle. At the top of the atmosphere this variation amounts to around 1 W/m2 out of a solar constant of around 1361 W/m2. At the surface, this is only 0.2 W/m2, after taking geometry and albedo into account. Model simulations and observations have shown a response of global surface temperature to TSI variations over the 11-year solar cycle of about 0.1oC (Matthes et al. 2017).

The current solar cycle 24 is the smallest sunspot cycle in 100 years and the third in a trend of diminishing sunspot cycles. Is the Sun is currently moving into a new grand minimum or just a period of low solar activity? Many solar physicists expect the sun to move into a new minimum during the 21st century: a century-level low, although several predict a minimum comparable with the Dalton or even the Maunder Minimum.

In CMIP5, climate projections were based on a stationary-Sun scenario, obtained by simply repeating solar cycle 23, which ran from April 1996 to June 2008, which is the third strongest solar cycle since 1850. Clearly, such a stationary scenario is not representative of true solar activity, which exhibits cycle-to-cycle variations and trends. Therefore, in CMIP6 more realistic scenarios were developed for future solar activity, exhibiting variability at all timescales (Matthes et al. 2017). Matthes et al. present the following two scenarios (Figure 3): a reference scenario and a Maunder minimum scenario for the second half of the 21st century.

Figure 3: CMIP6 scenarios for solar forcing (TSI): reference scenario (top); Maunder minimum scenario (bottom). Matthes et al. (2017)

If a Maunder minimum-scale event were to occur in the 21st century, how much cooling would this cause? As summarized by Svensmark (2019), a majority of reconstructions find only small changes in overall secular solar radiative output: since the Maunder Minimum, TSI is believed to have increased by around 1 W/m2, which corresponds to 0.18 W/m2 at the Earth’s surface – this is the same magnitude of the amplitude of the 11 year solar cycle. Jones et al. (2012) used a simple climate model to estimate that the likely reduction in the warming by 2100 from a ‘Maunder minimum’ scale event to be between 0.06 and 0.1 °C. Fuelner and Rahmstorf (2010) estimated that another solar minimum equivalent to the Dalton and Maunder minima would cause 0.09°C and 0.26°C cooling, respectively. Meehl et al. (2013) estimated a Maunder minimum cooling of 0.3°C.

These calculations ignored any indirect solar effects, which would arguably increase these numbers by up to a factor of 3 to 7. Shaviv (2008) used the oceans as a calorimeter to measure the radiative forcing variations associated with the solar cycle. Shaviv found that the energy that enters the oceans over a solar cycle is 5–7 times larger than the 0.1% change in TSI, thus implying the necessary existence of an amplification mechanism. Scafetta (2013) showed that the large climatic variability observed since the medieval times can be correctly interpreted only if the climatic effects of solar variability on the climate have been severely underestimated by the climate models by a 3 to 6 factor. Svensmark (2019) made a comparable argument using borehole temperatures for the period since the Medieval Warm Period, finding an amplification of a factor of 5 to 7 over the warming expected from a drop in TSI. If an amplification factor is included of these magnitudes, then a surface temperature decrease of up to 1oC (or even more) from a Maunder minimum could be expected.

Three scenarios for solar variability are used here:

  • No variability (CMIP5)
  • CMIP6 reference scenario, with factor of two amplification by solar indirect effects
  • CMIP6 Maunder Minimum scenario, with factor of four amplification by solar indirect effects (note: the period 2020-2050 has lower values of TSI than the reference scenario, but the actual Minimum is in the latter half of the 21st century).

Note: the CMIP6 values of changes in TSI are ‘eyeballed’ from Figure 3 (I did not download the CMIP6 solar projections). I would greatly appreciate other interpretations of the values of surface cooling to infer from the CMIP6 solar scenarios.

Table 3. Scenarios of solar cooling (oC), relative to the CMIP5 solar cycle

Volcanoes

The 21st century CMIP5 climate model simulations did not include any radiative forcing from future volcanic eruptions. While volcanic eruptions are not predictable, a scenario of zero radiative forcing from volcanoes in the 21st century is a poor assumption. Further, assuming a repeat of the 20th century volcanic radiative forcing is not a very good assumption, either.

In the past decade, there have been two major paleoclimate reconstructions of volcanic eruptions in the recent millennia. Gao et al. (2008) examined ice core records and their following reconstruction for sulfate ejection from volcanic eruptions. A more recent reconstruction by Sigl et al. (2015) is provided below, presented in terms of global volcanic aerosol radiative forcing. These reconstructions put into perspective the relative low level of volcanic activity since the mid 19th century.

Figure 4: Reconstruction of global volcanic aerosol radiative forcing for the past 2500 years. Sigl et al. (2015)

Because volcanic eruptions are unpredictable events, they have generally been excluded from twenty-first century climate projection protocols. Most recent projections either specify future volcanic forcing as zero or a constant background value. Bethke et al. (2017) explored how sixty possible volcanic futures, consistent with ice-core records, impact climate variability projections of the Norwegian Earth System Model (NorESM; ECS=3.2C) under RCP4.5. Clustered occurrence of strong tropical eruptions has contributed to sustained cold periods such as the Little Ice Age, where the longer- term climate impacts are mediated through ocean heat content anomalies and ocean circulation changes. Extreme volcanic activity can potentially cause extended anomalously cold periods.

Figure 5: Annual-mean GMST. Ensemble mean (solid) of VOLC (stochastic volcanic forcing; blue), VOLC-CONST (average 1850-2000 volcanic forcing; magenta) and NO-VOLC (red/orange) with 5–95% range (shading) and ensemble minima/maxima (dots) for VOLC and NO-VOLC; evolution of the most extreme member (black). Bethke et al. (2017).

Based on the results of Bethke et al. (2017), three volcanic scenarios for cooling are used, related to the decadal values shown in Figure 5:

  • No forcing
  • 50th percentile value: mean forcing
  • 95th percentile value: large forcing

Figure 6. Decadal means of GMST relative to pre-industrial. Ensemble mean (solid) with 5–95% range (shading) of VOLC (blue) and NO-VOLC (red).

Table 4 shows the decadal scenarios of volcanic cooling, consistent with Figure 6.

Table 4. Decadal scenarios of volcanic cooling (oC). From Bethke et al. (2017)

Internal variability

Variations in global mean surface temperature are also associated with recurrent multi-decadal internal variability associated with large-scale ocean circulations. However, separating the internal variability from forced variability is not always straightforward owing to uncertainties in external forcing.

The multi-decadal internal variability (50-80 year band) has been estimated to have a peak-to-peak amplitude of global surface temperature as high as 0.3-0.4oC (Tung and Zhou, 2012), accounting for about half of the late 20th century warming. DelSole et al. (2010) estimated a peak-to-peak global temperature change of 0.24oC from internal variability. By contrast, Stolpe (2016) estimated a maximum peak-to-peak amplitude of 0.16oC. Knutson et al. (2016) used the GFDL CM3 model, which has strong internal multidecadal variability, to identify several periods that exceed 0.5oC for global mean surface temperature, indicating that data records of ~160 years are too short for a full sampling of multi-decadal internal climate variability.

Most analyses have identified Atlantic Multidecadal Variability as having the dominant imprint on global and Northern Hemisphere temperatures. Identification of ENSO as a driver of global mean temperature variations or response signal remains contentious, with conflicting results. Bhaskar et al. (2017) characterizes ENSO as a secondary driver of variations in global mean temperature, accounting for 12% of variability over the last century, with ENSO and global mean surface temperature mutually driving each other at varied time lags.

Not taking multi-decadal variability into account in predictions of future warming under various forcing scenarios may run the risk of over-estimating the warming for the next two to three decades, when the Atlantic Multi-decadal Oscillation (AMO) is likely to shift into its cold phase.

Analysis of historical and paleoclimatic records suggest that a transition to the cold phase of the AMO is expected prior to 2050. Enfield and Cid-Serrano (2006) used paleoclimate reconstructions of the AMO to develop a probabilistic projection of the next AMO shift. Figure 7 shows the probability of an AMO shift relative to the number of years since the last regime shift. The previous regime shift occurred in 1995; hence in 2020, it has been 23 years since the previous shift. Figure 7 indicates that a shift to the cold phase is expected to occur within the next 15 years, with a 50% probability of the shift occurring in the next 6 years.

Figure 7. Probability of an AMO regime shift relative the number of years since the last regime shift. Source: Enfield and Cid-Serrano (2006)

The timing of a shift to the AMO cold phase is not predictable; it depends to some extent on unpredictable weather variability (Johnstone, 2020). Johnstone’s analysis shows that low-frequency changes in North Atlantic SSTs since 1880 are objectively identified as a series of alternating ‘regime shifts’ with abrupt (~1-year) transitions dated to 1902, 1926, 1971 and 1995 (Figure 8).   In the recent historical record (back to 1880), these sharp changes punctuate longer quasi-stable periods of 24 years (1902-1925), 45 years (1926-1970), and 24 years (1971-1994), while the latest, and warmest regime on record has persisted with little net change from 1995 through 2019 (25 years). Previous cool shifts in 1902 and 1971 shared similar -0.2°C amplitudes, following extended periods of relative warmth (1880-1901), (1926-1970). A negative (cool) shift within a shorter time frame (~5 years) might be tentatively inferred from a steep 2015 SST decline in the subpolar North Atlantic, behavior that might presage broader North Atlantic cooling based on early subpolar appearance of the most recent cool shift of 1971.

Figure 8.   Annual SST anomalies in the subpolar (blue) and tropical (red) North Atlantic. A sharp subpolar cooling is evident in 2015. Johnstone (2020)

Guided by the above analyses, three scenarios for global temperature change associated with the AMO are presented in Table 5.

Table 5. Decadal scenarios of temperature change from internal variability (oC), associated with a transition to the cool phase of the Atlantic Multidecadal Oscillation.

Integral scenarios of temperature change: 2050

The final integral temperature change is the sum of temperature changes driven by

  • Emissions (4 scenario)
  • Volcanoes (3 scenarios)
  • Solar (3 scenarios)
  • AMO (3 scenarios)

There are 108 possible different combinations of these scenarios.  Table 6 shows extreme high and low warming scenario, plus the scenario using all of the mid range values.

Table 6. Integral scenarios of global mean surface temperature change for 2020-2050.

All of the components of natural variability point to cooling during the period 2020-2050. Individually these terms are not expected to be large in the moderate scenarios.   However, when summed their magnitude approaches the magnitude of the warming associated with the moderate values of TCRE – 1.35 and 1.65 oC. If the natural cooling exceeds the expected value, or TCRE is at the low end (1.0 to 1.35oC), then there could be net cooling.

The possibility and probability of 21st century decades being characterized by net cooling has been addressed by several papers. This depends on model value of ECS, and the magnitude of the predicted natural variability. Knutson et al.  (2016) used the GFDL climate model (relatively high value of ECS; high internal variability) to determine that probability of global temperature trend <0 for period of 20-30 years is 2%.  Bethke et al. (2017) used NorESM (ECS=3.2C) with RCP4.5. This paper examined the combination of scenarios of internal variability and volcanic eruptions. They found that occurrences of decades with negative GMST trend become more frequent if accounting for volcanic forcing, with the probability increasing from 10% in NO-VOLC to more than 16% in VOLC. The probability of decades with negative GMST trend more than doubles from 4% to 10% if the analysis is limited to the first half of the century—before the stabilization period of RCP4.5. Volcanic-induced cooling becomes increasingly important in facilitating neutral or negative temperature trends on longer timescales, in conjunction with natural internal variability effects.

In summary, decade(s) during the period 2020-2050 with zero warming or even cooling should not be particularly surprising.

Conclusions

Three main conclusions:

  • We are starting to narrow the uncertainty in the amount of warming from emissions that we can expect out to 2050
  • All three modes of natural variability – solar, volcanoes, internal variability – are expected to trend cool over the next 3 decades
  • Depending on the relative magnitudes of emissions driven warming versus natural variability, decades with no warming or even cooling are more or less plausible.

If you prefer your scenarios on the high side, you can include scenarios with RCP7.0 and TCRE=2.4oC, but these values don’t change the fundamental narrative presented here. You can also add 1.2oC to the values in Table 6, to make the numbers look higher. But if you want plausible scenarios, look to my Table 6, which I think bounds the range of plausible outcomes for global mean surface temperature from 2020-2050.

But what about the 2nd half of the 21st century and 2100? Uncertainties regarding emissions are much greater in the 2nd half of the 21st century. The CMIP6 solar scenarios (Reference and Maunder) show more cooling in the second half of the 21st century. Volcanic eruptions could be larger in 2nd half of 21st century (or not). After the projected cool phase of the AMO, a return to the warm phase is expected, but there is no confidence in projecting either a warm or cold phase AMO in 2100.

Apart from the ‘wild card’ of volcanic eruptions, the big uncertainty is solar indirect effects. Based on the literature survey that I’ve conducted, solar UV effects on climate seem to be at least as large as TSI effects. A factor of 2-4 (X TSI) seems completely plausible to me, and serious arguments have been presented for even higher values. I also note here that almost all estimates of ECS/TCR from observations do not include any allowances for uncertainties associated with solar indirect effects. Scafetta (2013) included solar indirect effects in an estimate of ECS, and determined an ECS value of 1.35 oC.

Neither the effects of AMO or solar indirect effects have been included in attribution analyses of warming since 1950.

So why does this analysis ‘matter’?

  • For those that are urgently worried about the impacts of AGW and the need to act urgently to meet deadlines related to emissions, the natural climate variability may help slow down the warming over the next few decades, allowing for time to make prudent, cost effective decisions that make sense for the long term.
  • Failure to anticipate and understand periods of stagnant warming or even cooling detract from the credibility of climate science and may diminish the ‘will to act.’

I look forward to your comments.  I encourage you to critique and check my numbers, especially related to solar.

84 thoughts on “Plausible scenarios for climate change: 2020-2050

    • Chas, I assume by “that big yellow H bomb in the sky” you are referring to the threat of nuclear weapons.

      IMHO you are correct, climate change pales in comparison. For me, and many others, the man made global warming crisis is nothing more than a story that’s right up there with the flying reindeer and the grassy knoll.

      However, as always, we live in interesting times.

  1. I highly respect and applaud Dr. Judith Curry for her science skills and for maintaining her outstanding website.

    Thus, with all due respect, I have to ask: why weren’t TCRE values all the way down to zero considered?

    Is there empirical data which proves TCRE must now be above some minimum positive value, taking into account science-based arguments that the greenhouse effect of atmospheric CO2 concentration may have “saturated” at some lower level than we have at present, say, at around 200 ppm?

    • The sun is a very weak energy producer? I think if it went out we would all notice. And be dead soon thereafter. If I stand outside in sunlight, it burns my skin. Garden compost heaps do not produce enough energy to do this, even though I am able to approach to touching distance. Therefore I refute your ridiculous assertion.

    • Leif, so you’re saying that my compost heap can produce Carrington-like events that could melt the wiring in my house and destroy all my personal electronic devices? I’d better move it farther from the kitchen I guess!
      If the sun is such a “weak energy producer” could you please list all the other types of energy you use for housing, transportation and communication needs. I’m sure the rest of us ignoranti would like to be enlightened!

      • If your compost heap were as big as the sun, you would, indeed, be advised to move away a bit. The crucial distinction is that a ‘bomb’ is an explosion while the sun and the compost heap are not.

        • It’s possible that Chaswarnertoo was referring to hydrogen fusion occurring within the sun and not that it was a literal bomb.

          It would be obvious that if it were a bomb, then we would not be here writing about it. We might be able to write about it if it were a compost pile that was part of our garden, however.

          • It behaves pretty much exactly the same way as a Nuke would if you exploded it in space, so by that definition a nuke in space is not a bomb but a compost pile.

            Even in 1957 they knew that
            https://history.nasa.gov/conghand/nuclear.htm

            However it apparently is a news to Leif.

            It begs the question with no atmosphere to develop a shockwave is there anything Leif would describe as a bomb in space?.

          • Nuke would if you exploded it in space, so by that definition a nuke in space is not a bomb but a compost pile.
            The solar core is not a vacuum [like ‘space’], but a gas with a density a hundred times that of water… So, there will be enormous ‘blast waves’.

    • Hi Doc
      Your Solar cycles maximum prediction formula has worked well in past, so we expect it to do OK in future. Ordinary cycle max prediction is fine but could you possibly tell us weather we could expect a Grand Solar Minimum at any time of this century.

      • Minima vary in depth. Really ‘Grand’ minima are rare, so I would not expect one. A not so deep minimum [like 1810, 1900, 2008] are top be expected. Perhaps we already had one [2008]. But I don’t believe in actual [strict] cycles, so can only guess.

        • Thanks.
          In their paper of 2013 Steinhilber & Beer show prediction of a GM in the second half of this century. I did spectral analysis of about 4 Ky of their solar data and using just 3 major components was able to reproduce their result as shown in this link

        • What about the magnetic polar excursion and possible reversal? Wouldn’t that lead to a significant increase in cosmic ray flux?

    • Leif Svalgaard posted, referring to the Sun, “. . .on a volume basis only about the same as a typical garden compost heap.”

      Sorry, this cannot be true if interpreted literally and scientifically. The temperature of the “surface” of the Sun (defined as the outmost portion of the Sun’s photosphere) is at a temperature of around 6,000 K. In comparison, the highest temperature throughout a compost pile is probably no hotter than the boiling point of water, 373 K . . . for simplicity, let’s conservatively assume that this temperature exists at the surface of the compost pile.

      Radiation power scales as absolute temperature to the fourth power (assuming the same radiating surface area and surface emissivity), so one cc volume of the Sun’s surface will conservatively radiate more than ((6,000/373)^4, or around 67,000 times, the power of one cc volume of a compost pile’s outer surface, for a given thickness.

      And the Sun’s temperature increases as one moves from the surface toward the core.

      Even if we considered the emissivity of the compost pile to be 0.7 versus the Sun’s photosphere emissivity of ~1.0 (yes, it is close to blackbody radiation at it’s high temperature), it would make little difference in the argument that Sun is in no sense comparable to a compost heap.

      • Mass of the sun 2×10^30
        Watts out 4×10^26 watts
        gives 2×10-4 watts/kg
        I have no idea if this calculation is even in the ballpark.
        Thats very little, I am sure a compost heap will produce more heat than that. 10 000 kg compost should be able to heat maybe a small households running water? Im just guessing, I have no idea but the sun burns incredibly slowly.

        • I found a possible source for Leif Svalgaard’s claim that the Sun, “. . .on a volume basis only (emits) about the same (energy) as a typical garden compost heap.” See: https://www.abc.net.au/science/articles/2012/04/24/3483573.htm

          However, it is not the full volume of the Sun—nor the full mass of the Sun (as in your calculation)—that emits the radiation that reaches and warms the Earth.

          The Stefan-Boltzmann equation for power radiated by any body due to its temperature being above absolute zero is a function of surface area (NOT volume and NOT mass), emissivity and absolute temperature.

    • This is dumb. The only portion of the sun that generates heat is the dense core. The rest of the sun merely transfers that energy to the surface by radiation and conduction through a huge but inert and diffuse volume of gases. You need to recalculate your comparions to the reactive areas of the core, where heat is generated. Compare the heat generating volume of a compost pile to that of the sun, and you will see a significant differnce.

      • One has to be careful in substituting the word “heat” for the word “energy”.

        Hydrogen-to-helium fusion occurring in the Sun’s core generates mostly gamma wavelength radiation, of which only a tiny fraction of the associated energy would be perceived as heat by the human body (most gamma rays would just pass through human body tissues unabsorbed).

        It is only outside the core, in the radiative zone covering 24% to 70% of the Sun’s optical disk radius, that the repeated absorption and re-radiation of gamma rays by hydrogen and helium at less than 100% efficiency gradually transforms the gamma ray energy output to a wider spectrum of lower energy level radiations (such as UV, visible and IR, which we perceive on Earth as “heat” from the Sun.
        — Ref: https://www.abc.net.au/science/articles/2012/04/24/3483573.htm

        The energy dispersion processes occurring in the Sun’s radiative zone are, in a very real sense, far more important to life on Earth that what’s happening in the Sun’s core, fully acknowledging that the former could not exist and function without the latter. Without the conversion of gamma ray energy into the UV-visible-IR radiation spectrum of energy, photosynthesis would not be possible and advanced life forms could not see optically and and natural UV destruction of airborne and upper water surface bacteria and viruses would not occur.

  2. Even NASA knows about this. Why is it being ignored?

    1. David Archibald shows how the effect of increasing CO2 decreases logarithmically as CO2 increases in the following:
    http://wattsupwiththat.com/2013/05/08/the-effectiveness-of-co2-as-a-greenhouse-gas-becomes-ever-more-marginal-with-greater-concentration/
    There is also another article on the Logarithmic heating effect of CO2:
    http://wattsupwiththat.com/2010/03/08/the-logarithmic-effect-of-carbon-dioxide/
    An important item to note is that the first 20 ppm accounts for over half of the heating effect to the pre-industrial level of 280 ppm, by which time carbon dioxide is tuckered out as a greenhouse gas.

    • I don’t understand why there isn’t more mention of it (logarithmic effect). It would seem to be critical to the debate.

      • It’s factored into the climate sensitivity to a DOUBLING of CO2 in the atmosphere.

        Yes, there are people who can’t comprehend this, but even alarmists work on this unit of climate sensitivity, except for the more egregious liars of course.

        • **It’s factored into the climate sensitivity to a DOUBLING of CO2 in the atmosphere.**
          Maybe. If it is factored in at 400 ppm, then the increase should be a fraction of a degree, maybe 0.1 deg.
          However the excuse I get from the AGW’s is positive feedbacks (they ignore negative feedbacks which would include cloud). In calculating forcings to get the RCP figures cloud is ignored. In my opinion the RCP calculations are based on ASSUMPTIONS similar to the ASSUMPTION that CO2 will cause most of the forecast warming.

    • Nah. That won’t say that.
      After our current “12 years” are up they’ll say we only have (yet another) “12 years” to save or prevent something or other.

        • Goal posts on wheels; they’re easy to move and hard to pin down. Latitude, if I change my name to Longitude would we work well together or would we always be at cross purposes? Incidentally, have you read the book by Dava Sobel or seen the A&E series about John Harrison and the search for longitude? Good stuff!

          • LONGITUDE Dana Sobel

            Chapter 1
            “When I’m playful I use the meridians of longitude and parallels of latitude for a seine, and drag the Atlantic ocean for whales” Mark Twain

            Fantastic informative reading!

        • A reasonable person might expect that at some point even the Greta Thunbergs of this world might notice that imminent doom has been predicted for much if not all of their life, yet still isn’t happening.

          The recent low frequency of proper weather disasters such as hurricanes is perhaps nature playing a cruel trick on us. Middle-aged and older people can well remember such events from their youth. In the long run the media will struggle to maintain the fiction of weirding weather, especially because fossil-fueled wealth has made us far less vulnerable than in the past. Insurance companies know this, and occasionally say so in unguarded moments.

          • I spoke with my Mum in the UK today and asked her about the imminent doom they were promised by the Brexit crisis crisis folks. Nope, nada, no economic meltdown yet. The big thing (no pun intended) was guys having guys as dance partners in that ballroom dancing show.

  3. Grand Solar Minimum, AMO & other natural cycles …..
    Timing of the next solar grand minimum is the critical factor of the natural variability that governs the North Hemisphere’s temperature trends. However there is an elephant in the room, nothing to do with the CO2, in form of a undercurrent periodicity which is due to peak in about 60 to 70 years. Since the ~60 year AMO periodicity characteristic for the NH is at its peak the next 30 years will lead to some cooling but the extent of it depends on if and when the next solar grand minimum occurs. In this link
    http://www.vukcevic.co.uk/NH-GM.htm
    I looked at possible alternatives:
    – If the grand minimum (GM) doesn’t start during the next 4-5 cycles then cooling will be minimal, about 0.2- 0.3 degrees (faint blue line)
    – Since grand minima tend to last (intriguingly?) around 60 years, if a the next GM is about to start with SC25 then it’s greatest effect might coincide with the AMO just lifting of the floor with total fall of about 0.7- 0.8, since the cumulative solar GM cooling is about 0.5C (dark green line).
    In about 60+ years time the AMO will be hitting next peak and any pending solar GM may well be over, resulting in the temperature rise of about 0.5C on the current level. It could be expected that the NH’s temperature gets up to about 1.5C on preindustrial levels. From there on is all way down hill.
    (i compiled the above estimate couple of years ago)

  4. Going off of past direct observations I say it is plausible that climate will continue to change and nothing humans do will cause it or stop it. And now for some plausibility studies that matter! How ya think them Pirates gonna do this season?!?!?

  5. Interesting and useful. I like the train of thought as its a logical approach to the potential “pluses and minuses” of future temperature change. Too often, only the “pluses” are considered.

  6. Your analysis seems to assume that CO2 is a driver of climate change. I see no evidence in your data (or anywhere else, for that matter) that CO2 has any influence on any climate variable including global temperature. There has been a slight increase in global temperature over the last 150 years, according to most reports, but we know there was a little ice age, so it is a fair assumption that, whatever the combination of forces, there has been a “natural” bounce back which is continuing into the present with minor up and down variations. There is no reason to believe that the very small fraction of the atmosphere that is CO2 has any effect on the total. Even if there is some effect, it is likely to be so small as to be unmeasurable with present technologies of measurement. To put it most simply, there has been no “hockey stick.” No hockey stick, i.e. no sudden upswing of temperatures which correlates meaningfully with human CO2 production upswing. Even if there were a hockey stick, it would not be clear evidence of causation because there is plenty of reason to believe that increasing world temperature might cause increase in that tiny portion of the atmosphere is CO2.

    • I couldn’t have said it better myself, Ronald.

      There are still way too many assumptions associated with CO2 and climate science.

      Maybe these kinds of assumptions will be enough. As is plain, the estimates for a doubling of CO2 in the atmosphere are going lower and lower, just barely above 1C now, close to the point where we don’t need to take any action regardless of whether CO2 is adding warmth to the atmosphere that is not offset by some other natural occurrence such as an increase in clouds.

      Instead of assuming CO2 adds a certain amount of warmth to the atmosphere, we should be studying all the related feedbacks and add them into the mix of our computer studies. There are studies out there that say any warmth added to the atmosphere by CO2 could be offset by a two percent increase in cloud cover. So add “no warmth from CO2” to your models.

      • The problem with feedbacks is they are almost impossible to measure. I believe that is why the AGW’s are getting away with the CO2 assumption.

        • It’s not clear to me that feedback mechanisms are impossible to measure.

          If you don’t know what mechanisms are in play, and don’t know the effect of a forcing function on the system (whether the system with feedback or the system without) then indeed all you can measure is “the system as it is”.

          But if you don’t know any of that, then making predictions of the behavior of the system-as-it-is when input X is changed is fraught with danger, unless you’ve been lucky enough to observe the system with the various possible forcing functions exhibiting rising and falling behaviours over periods longer than the natural time constant of the system as it is.

          Oh, wait 🙂

    • The reality is CO2 induce climate was disproved over 20 years ago, they know it failed yet it the horse they are still riding. An you know it paid well!

    • CO2 concentration growth is unresponsive to human emissions changes. (https://tambonthongchai.com/2018/12/19/co2responsiveness/ ). The correlation of temperature to cumulative emissions is probably spurious as it is comparing two time series with positive trends for which one can always show correlation.
      CO2 concentrations follow temperature changes on all time scales so nearly all of the recent increase of atmospheric CO2 can be attributed to recent warming (since the little ice age) . It seems that a better estimate of CO2 growth would be to fit the Keeling curve and project that to 2050. That curve could be considered an upper bound for anticipated CO2.

  7. I’m not going to worry about the weather in 2050 because I will be dead and the weather will still be as variable as it is today.

    • **I’m not going to worry about the weather in 2050 because I will be dead and the weather will still be as variable as it is today.**
      That goes for most of the “scientists” making those predictions so they are not too concerned with making them.

  8. “The individual cumulative emission scenarios between 2020 and 2050 are then translated into a global temperature increase using a range of values of the Transient Climate Response to Cumulative Carbon Emissions (TCRE)”

    The TCRE is illusory and has no interpretation in the real world because it is based on a spurious correlation.

    https://tambonthongchai.com/2018/05/06/tcre/

    https://tambonthongchai.com/2018/12/03/tcruparody/

    https://tambonthongchai.com/2019/11/08/remainingcarbonbudget/

    https://tambonthongchai.com/2019/12/25/the-remaining-carbon-budget-anomaly-explained/

  9. “Check your numbers? Critique your work?” But that’s not how climate science is done!

    Thank you Doctor Curry. You are a treasure.

    • Here hear, Dr Curry at her best, giving an easily read balanced overview of the more probable ups and downs of climate change. Thanks a heap

  10. “Failure to anticipate and understand periods of stagnant warming or even cooling detract from the credibility of climate science and may diminish the ‘will to act.’
    Well, that is another phrase of plausible deniability to put into my lexicon. Stagnant warming!!
    What the heck does stagnant warming mean? Is it the same as stagnant cooling?
    It is a bit worrying when the rational scientists involved in climate science like Judith adopt such contrived meaningless words.

    • Cut JC a little slack. She has to play the game a little. She does not have to debunk every bit of crap science every time she writes something.

  11. “All three modes of natural variability- solar, volcanoes and internal variability…..”
    I want to concentrate on internal variability.
    In June 2009, a rare event happened in Australia.
    The Chief Scientist and other ‘orthodox‘ scientists were asked 3 questions by 4 sceptical scientists representing Senator Fielding who was doubtful about CAGW.-
    1.Is it the case that CO2 increased by 5% since 1998 whilst global temperatures cooled over the same period?
    If so, why did the temperature not increase; and how can human emissions be to blame for dangerous level of warming?
    2. Is it the case that the rate and magnitude of warming between 1979 and 1998 ( the late 20th century phase of global warming ) was not unusual in either rate or magnitude as compared with warmings that have occurred earlier in the Earth’s history?
    If the warming was not unusual, why is it perceived to have been caused by human CO2 emissions; and in any event, why is warming a problem if the Earth has experienced similar warming’s in the past?
    3. Is it the case that all GCM computer models projected a steady increase in temperature for the period 1990-2008, whereas in fact there were only 8 years of warming followed by 10 years of stasis and cooling?
    If so, why is it assumed that long term climate projections by the same models are suitable as a basis for public policy making?
    The Wong-Fielding exchange in the form of these Questions and Replies and Commentary thereon is readily available online.
    I will direct attention to the first question.
    The Australian Government’s reply was –
    “When climate change scientists talk about global warming they mean warming of the climate system as a whole, which includes the atmosphere, the oceans,and the Cryosphere” and then added “ in terms of global warming ,change in ocean heat content is most appropriate”.
    On natural variability in air temperatures, the government asserted that “at times of around a decade (or two?), natural variability can mask the atmospheric warming trend caused by the increasing concentration of greenhouse gases.”
    As the sceptics noted ,it is widely agreed that there is considerable natural variability in air temperature on decadal timescales and longer. It was the IPCC who had previously denied the effect of natural variability.
    In retrospect none of this is surprising.
    If ocean temperature is the guide to global warming , the various posts at WUWT over the last decade expose the threadbare claim to any significant warming this century especially via the Argo buoys.
    Lastly, by AR5 the same scientists who denied a pause or hiatus from 1998 onwards were acknowledging it as fact and advancing their own views on the cause.
    England et al 2014, “ Recent intensification of wind driven circulation in the Pacific and the ongoing Warming Hiatus” is a perfect example.
    But now they have disappeared the hiatus.
    Thanks, Judith for another important post.

  12. I believe Curry’s analysis could benefit from some additional players.

    1)Geoff Sherrington’s analysis of the effect of convection ( mainly advection in his analysis using Triton) as having a significant ‘greenhouse’ type effect that greatly diminishes attribution of CO2 as a warming mechanism in the atmosphere (of the earth).

    The idea behind CO2 warming is that LWIR from the earth’s surface is intercepted by molecules of CO2 and re-emitted in all directions, some back toward the surface while the sun continues to add its regular insolation to the surface. In the simplest terms, this mechanism delays re-emission of added heat to space. Indeed, any mechanism that moves heat away from the planet’s surface ultimately to space at a rate less than the speed of light, will cause atmospheric warming. It is a no-brainer that convection/advection does exactly this.

    2) The “Great Greening” is another factor in play. It seems to have caught the C science folk by surprise, certainly by its magnitude. The sequestration acts on the question at hand on two fronts. Its exponential removal of CO2 from the action means at some not too distant future it will reach an equilibrium plateau lower than generally thought even with business as usual. Second, sequestration of ‘carbon’ is an endothermic reaction, i.e. a sequestration of some of the solar insolation.

    The ‘leafing out’ and expansion of earth’s forest extent over 40 yrs is a matter of easy calculation of effects that could be used to forecast the equilibrium level in the atmosphere and the reduction in earth’s surface heat.

    Judith, I believe your best estimates for carbon dioxide’s contribution to warming are quite a bit too high – too much CO2 in play and too high a sensitivity. Give half of the greenhouse effect as coming from convection, and add cooling from the leafing out photosynthesis.

  13. “There are 108 possible different combinations of these scenarios. Table 6 shows extreme high and low warming scenario, plus the scenario using all of the mid range values.”
    It seems that one just has to keep saying it – scenarios are not predictions. Yet this article seems to be trying to make them into predictive items on their own. They aren’t any use as actual scenarios. The purpose of scenarios is to take a few plausible possibilities and calculate their consequences. To offer 108 possible combinations is pointless.

    Trying to turn scenarios into predictions is just hand-waving. You should specify a scenario and then do proper calculations based on it.

    • Nick,
      This is a standard way to approach a mess of proposed variables, to help see if a stats method like analysis of variance might be helpful. As well you know. What specific point did you try to make? Geoff S

    • Nick, scenarios make assumptions then predict what would happen should those assumptions come true. There is the real possibility that the prediction of the scenario won’t come true even if the assumptions do. In that case, your entire theory – your model – is wrong.

      It is entirely correct to discuss a SCENARIO and whether or not its PREDICTION is accurate should the assumptions be correct.

      The PREDICTIONS made by most climate change SCENARIOS have already been proven wrong, even though the assumption they used that atmospheric CO2 would increase became true. This is the worst outcome for them. When your assumptions are right, and the outcome is wrong then your model is wrong.

      I was paid a hefty salary to research and write scenarios for a large company. BTW, you failed at your task if one of your scenarios did not reasonably predict the future. Why else would you go through the exercise?

      One of the processes was sensitivity testing of your assumptions. Starting out with 108 possible combinations would not be pointless if they converged around similar outcomes. It demostrated that your results were insensitive to some of your assumptions, meaning you could simplify your scenario. If they showed wildly divergent answers, you were looking at a chaotic system which scenarios could not address. Either way resulted in worthwhile endeavor.

      Did you ever write one?

      • “The PREDICTIONS made by most climate change SCENARIOS have already been proven wrong”
        No, that makes no sense. At most one scenario of a group can happen. For the others the predictions weren’t proved wrong; the scenario just didn’t happen. In fact no scenarios ever fit the course of events that followed. So you are always trying to match the outcome with the prediction of the scenario that fitted best to what unfolded.

  14. Dr. Curry, you know I love you to pieces, but can we PLEASE stop using the terms that are essentially the result of semantic infiltration by the alarmists. The term SKILL in reviewing the results of climate models is a term of propaganda. IF we mean that the CMIP climate models APPEAR to match some amalgamation of “physical observations” means that a CMIP climate model has SKILL, then we’re really just saying that for some very temporary and ephemeral physical realities, projected into editorialized statistics, then SKILL simply means somewhat correlated. My problem is that SKILL implies the correct interpretation, analysis or evaluation of causality. But SKILL in this case, no such expertise has been placed into evidence.

    Climate models do NOT have SKILL. They have a hypothesis. Nothing more.

    If anyone is tempted to say that “oh, well, this is just the reality of discussing climate, and we should just forget it and move on” I say, NO, not this time. We are already saddled with “greenhouse gas, greenhouse effect, ocean acidification and many other terms whose propaganda value via circular reasoning pollutes real science. No more. Push back, please.

    • Have you ever noticed how real scientists (sceptical or alarmist) readily accept the terms greenhouse gas & greenhouse effects?

      CO2 is a ‘greenhouse’ gas. There is no argument about this. Even Steve McIntyre, who once he had looked at the issue, acknowledged this fact in 2008.

      The question is – how much of an effect can we expect from increasing levels of CO2.

      • A better term is IR active gases. Depending on the concentration of both a particular gas and other gases the effect varies considerably to any changes and may actually lead to cooling rather than warming. The term greenhouse gas is questionable and real scientists would be careful when using it.

  15. The most underrated part of these scenarios on emissions will be population growth which is consistently lagging predictions. 2050 global population may well be lower than today despite the UN consensus.

    Wealth creation rapidly drops birth rate above a certain level. It’s not linear and not well modeled. Most of the slowing population growth occurs in the biggest immersing countries. The EIA and IEA consumption forecasts have generally been on the high side to begin with (and don’t get me started on the unbearably laughable RCP 8.5).

    • If you read Empty Planet by Daniel Bricker, he believes stabilisation of world population will happen far faster than the mid century UN forecasts. This is because urbanisation is much more important than wealth and education as population drivers. Urbanised developing populations no longer require as many children to plant the rice, milk the cows etc. In fact in a small urban apartment they hardly need or want children any more.

  16. The ONLY reasons CAGW is still a thing is because: 1) there hasn’t been a strong La Niña since 2010, 2) the 2015/16 Super El Niño and 3) the “30-year” PDO and AMO cool cycles haven’t started yet.

    Once a strong La Niña occurs, the 2015/16 Super El Niño be negated, and when the PDO and AMO cool cycles finally start, global temps will begin to cool as they did from 1890~1915 and 1945~1975.

    The PDO/AMO cooling will likely be enhanced over the next 30~50 years from the Grand Solar Minimum which already started as occurred during the Wolf, Sporer, Maunder and Dalton GSMs.

    I’m tired of guessing when the PDO/AMO cool cycles, and the next strong La Niña event will all start, but start they will, and when they do, the silly CAGW hoax will be more laughable than it already is.

    • Once a strong La Niña occurs, the 2015/16 Super El Niño be negated, and when the PDO and AMO cool cycles finally start, global temps will begin to cool as they did from 1890~1915 and 1945~1975.

      Do you want to bet on this?

      There have been strong La Nina since 1998
      The AMO was negative between 1970 & 2000.
      The PDO has fluctuated over the past 20 years. It’s been more or less neutral on average over since 2000.
      We’ve just experienced the weakest solar cycle in over a century – yet the highest global temperatures
      The 2015/16 El Nino was 4 years ago. The heat should have been lost by now.

      That aside, your 30 year warm cycles seem to be ~45 years long & counting. Face facts, we are warming due to enhanced greenhouse gases in the atmosphere.

      • John-san:

        1) There hasn’t been s strong La Niña since 2010, which is why global temps have not fallen much since the 2015/16 Super El Niño event.

        2) The AMO started its 30-year WARM cycle in 1996, so it will likely switch to it’s 30-year cool cycles around 2025 or so…

        3) The PDO warm cycle started in 1980 and hasn’t yet switched to its 30-year cool cycle yet, but it will eventually; when is anyone’s guess.

        4) The strongest 63-year Grand Solar Maximum event in 11,400 years just ended in 1996… From 1996~2015, global temp trends flatlined, despite record CO2 emissions over that time… Then The 2015/16 Super El Niño event occurred, which caused a temporary spike in global temps and, as explained, a strong La Niña cycle hasn’t occurred since 2010, which is why it has lingered a bit..

        5) “30-year” warm/cool ocean cycles are an average; some last longer and some last shorter than 30-years.. The PDO is “overdue” but come it will and the AMO will likely start around 2025, if not sooner…

        6) CO2 is a very weak GHG… All physics and empirical evidence puts ECS at around 0.7C, which is 2~5 times less than the silly CAGW hoax predicted…

        Cheers, mate!

      • Everyone has an opinion on the ocean cycles. They are affected by ENSO which makes it difficult to be specific. Here’s another view:

        AMO went negative in the early 1960s and positive in the early 1990s. Because of the Pinatubo eruption it is difficult to be specific. Most likely will go negative sometime in the the early 2020s. It has been positive for at least 25 years.

        There as a recent paper which showed the PDO phase length varies and can be as little as 8 years. With this in mind the PDO was went positive in 1977 which ended in 2005. It was then negative from 2006-2013. Then, it went positive in 2014. It could go negative again as soon as 2022. Overall, it has been positive for around 80% of the last 40 years.

        The 2014-2016 El Nino lost its warming effect by the summer of 2018 when we immediately moved into another weak El Nino which is still having an effect. The weak El Nino was boosted by the Pacific blob which has just recently started to fade.

        Individual solar cycles are less important than the long term average across many cycles. Solar energy warms the oceans which acts as a huge storage buffer for the energy. As oceans warm from this solar energy they share some of that warmth with the atmosphere.

        When all these factors are considered there is no evidence that IR active gases like CO2 are warming the planet.

  17. The Congressional Budget Office is required to score the dollar impact of major new policies. We need to mandate that U.S. “Green” policies are scored similarly in the most likely range of these models without the assumption that other countries act accordingly. I highly suspect that even accepting man made global warming is real, the U.S. policy solutions being touted by all the current candidates will show they are not real or significantly measurable. The economic costs in higher energy costs would, however, be very real and significant.

  18. “So why does this analysis ‘matter’?
    For those that are urgently worried about the impacts of AGW and the need to act urgently to meet deadlines related to emissions, the natural climate variability may help slow down the warming over the next few decades, allowing for time to make prudent, cost effective decisions that make sense for the long term.

    Failure to anticipate and understand periods of stagnant warming or even cooling detract from the credibility of climate science and may diminish the ‘will to act.’”

    A) Coddling, catering to, or worse satisfying the emotionally disturbed to the detriment of civilization is absurd.

    B) Earth Optimums are well documented and very poorly understood. Earth’s current Optimum is no different.
    • 1) ‘Climate Science’ alarmists have already destroyed all credibility in their pseudo science.
    • 2) Climate alarmist ‘doctored ‘high temperatures’ and absurd climate doom prophecies fail to establish any proof that Earth responds to mankind’s civilizations.
    • 3) All indications point towards Earth being in a warming cycle that started at the end of a cooling cycle.
    • 4) “act urgently to meet deadline”: Again, disrupting and demonetizing civilization to placate the emotionally disturbed is absurd. Their urgencies are over dramatic demands for attention by delusional egocentrics.
    • 5) Parts of the proof are evident in their pleading screeds. When they sense being ignored, the screeds and prophecies get deadlier, more dramatic and more urgent… Just like toddler tantrums.

    “Why does this analysis ‘matter’?” being dependent upon “For those that are urgently worried about the impacts of AGW” assumes that the majority of civilization that is only moved the the overwhelming pressure of fake news and deluded tax hungry politicians, are willing to destroy their civilizations to satiate over emotional unreasonable demands of activists…

    That is a classic cart pushing the horse problem.

    • ““For those that are urgently worried about the impacts of AGW” assumes that the majority of civilization that is only moved the the overwhelming pressure of fake news”

      the the should be by the

    • “Why does this analysis ‘matter’?”

      That was my first question reading the title. Tho I respect Curry, such studies are a waste of time & simply encourage useless worry and speculation.

  19. It is not possible to take the “experts” on climate change unless they address the primary cause/solution population control.

  20. If one examines global temperatures versus CO2 emissions for the periods of 1940-1975 and 1998-2015, one can see that the TCRE for these periods was negative and zero, respectively.

    Therefore, why weren’t scenarios with TCRE less than +0.8 C/TtC considered in the analyses described in the above article?

    To the best of my knowledge, the global cooling and temperature-rise “hiatus”, respectively, for these two periods have not been attributed to solar variability, volcanic eruptions, or the phasing and amplitude of multidecadal variability associated with ocean circulations.

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