Guest essay by Wim Röst
The best kept secret in the ‘climate world’ probably is: the cooling capacity of the deep sea. Some attention is paid to the heat uptake by the oceans, but there is no attention for the cooling capacity of the deep sea. That capacity is huge and might be (and might have been) of decisive importance in climate and climate change.
Fig. 1. Temperatures in a North South section of the Atlantic Ocean
Source: http://i.stack.imgur.com/rugfb.png
The oceans are on the average 3.688 meter deep. The surface layer, directly connected to the atmosphere, is only 100-200 meter thick. Below this layer we find cold to very cold water. And, as we know, water has an enormous capacity to absorb heat. Which means that it also has an enormous capacity to cool.
The temperature of the top surface layer is on average 18 ºC. There is a big difference in temperature between the surface layer and the layer 200 meters deeper. According to AR5 (fig. 3.1d) the surface layer on the average is 6,3 ºC warmer than the layer 200 meters below. Nearly all upwelling will affect the temperature of the surface layer in a way that it is cooling the surface strongly.
Below a 1000 meter temperatures are only 5 degrees ºC or lower.
Fig. 2. Thermocline in a tropical ocean
Source: https://upload.wikimedia.org/wikipedia/commons/c/cb/THERMOCLINE.png
The total water content of the oceans is enormous. One cubic kilometre contains a billion m3. And there are nearly 1,3 billion cubic kilometres of water in the ocean. But, with a surface area of 362 million km2 the top layer of the oceans (the upper 200 meters) ‘only’ has a content of 72.4 million km3. Most ocean water (95%) is cold ‘deep water’.
There is a considerable mixing of water masses in the top layer of the ocean. Mostly driven by wind.
Fig. 3 Areas with upwelling waters
Source: NOAA
The coldest and deepest ocean water takes (at the most) an estimated 1000 years to reach the surface layer. Which means that other less deep ocean layers are welling up faster.
Every year the [average] surface layer is cooled down by a huge quantity of cold ocean water welling up. When reaching the surface, that cold water is heated by the sun.
In the ‘climate world’ it is assumed that there is a constant cooling of the surface layer by upwelling waters.
At least one million cubic kilometres of cold ocean water is welling up every year*. If this one million cubic kilometres in any year would become two million cubic kilometres or, only half a million cubic kilometres, this change would have a substantial effect on the surface temperature of the Earth’ oceans. And therefore on the temperature of the atmosphere.
Upwelling is driven by wind and because wind is not constant – being dependent on changes in pressure – the changes in upwelling quantities might be considerable. Variations in pressure exist.
The most simple calculation is the following. Heat content is measured in ºC/million km3.
After year 1 the total heat content of the surface layer will be 1303,2 minus 18 plus 5 = 1290,2. The temperature of the surface layer (this example excludes the effect of heating by the sun) will be 1290,2 / 72,4 = 17,84 ºC after one year. The surface of the ocean cooled substantially by 0,18 degrees C in only a year.
In case the heating by the sun remains the same every year, a doubling of the upwelling in one year will result in a net cooling of 0,18 ºC of the ocean surface. And, on the other hand, half of the upwelling will cause a warming of the ocean surface by 0,09 ºC in one year.
Of course upwelling can diminish (or increase) during a number of years by smaller percentages as well. A century with a two percent decrease of upwelling results in 2 x 0,18 = 0,36 ºC warming of the ocean surface waters, all other things remaining the same.
The cooling potential of the oceans is huge. Even with minor changes in water flows.
Therefore, all warming of the ocean surface since the Little Ice Age could have been the result of a relatively small diminished upwelling of cold deep ocean water.
To judge ‘warming’, we must first know everything there is to know about cooling.
With regards to commenting: please adhere to the rules known for this site: quote and react, not personal. Factual information in regard to this topic is welcome.
About the author: Wim Röst studied human geography in Utrecht, the Netherlands. The above is his personal view. He is not connected to firms or foundations nor is he funded by government(s)
* Some data on ocean water volume, deep water and bottom water (sinks) production and upwelling of deep water
Source:https://www.nap.edu/read/10136/chapter/18#234
Abrupt Climate Change – National Research Council (2002)
PLATE 4b (…) representation of the global ocean circulation (…) simplified from Ganachaud and Wunsch (2000), as estimated from modern oceanographic data.
From the above figure:
Data in Sv (Sverdrup). One Sverdrup is equivalent to a flow of 1 million m3 in a second. Which makes one cubic kilometre in 1000 seconds. There are 31 556 926 seconds in a year.
Total ocean volume: 1.335 million km3 (1,3 billion km3)
(source NOAA:https://www.ngdc.noaa.gov/mgg/global/etopo1_ocean_volumes.html )
For comparison:
One Olympic Swimming Pool has a water content of 2.500.000 L = 2.500 m3
One cubic kilometre has a water content of 1.000.000.000 : 2.500 = 400.000 Olympic Swimming Pools
A million cubic kilometers have a total water content of 400.000.000.000 (400 billion) Olympic Swimming Pools.
Total Ocean content is 1.335 million km3 of Ocean Water, 95% of which is cold Deep Water
‘The oceans are on the average 3.688 meter deep’
Appears shallow even for small freighter.
What’s going on with the Southern Oscillation Index? On 23 December the 90 day average was positive 0.49. Overnight it dived to minus 7.06. That’s verging on El Niño territory! To get the SOI down there, the index on 23 December is reportedly -670.93. Wow. Maybe too much Christmas bubbly at the website’s admin office?
https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/30daysoivalues/
P.S. I’ve emailed the website about the self-evident glitch, but no response.
What about the equal quantity of downwelling water, what effect does that have?
How many thermometers would you need to accurately measure the temp of the swimming pool? Compare that to how many you’d need to measure the ocean.
Very interesting conjecture. What mechanisms could change the ocean vertical over turn rate?
There are some issues to this.
If for some reason massive upwelling cools the sea surface temperature (SST), there is no direct reason why this would translate into cooler land temperatures. We’ve seen heat waves in Europe together with large Atlantic SST cold spots. Why? low sst inhibits evaporation, causing aridness, cloudless conditions, unrestricted sunshine, change in air mass build ups and weather patterns, etc.
But there have been many cold SST events in the Pleistocene, with the effects most probably misinterpreted.
One theory I read is the millennial cycle, responsible for the Minoan, Roman, Medieval and Modern warm periods, is caused by changes in the speed of the MOC (global ocean circulation). At higher speeds we have more upwelling cold water which leads to slow cooling over time. At slower speeds we have less upwelling and a slow warming.
If this is true, the most likely cause of the speed change is gravity. That is, more dense water at depths slows the MOC. One possible cause of the difference in density could be the melt water pulses at the beginning of the Holocene interglacial.
Wim, I think you’re spot on…
Around 2005-2006 it was reported that trade winds were slowing…making it warmer (not overturning deep water)
…then around 2014 it was reported that trade winds were speeding up…..masking/hiding global warming because the overturning of deep water was keeping it cooler.
I have two questions from what I notice in the very informative graphics that you posted 1) that upwelling for non-tropical regions of both the Atlantic and Pacific are not included. Is there a reason for this? (and on a related note – how accurate are the upwelling measurements?) 2) The downwelling (listed in Antarctica as 21 Sv) is not included as a measure of heat removed from the surface layer. In terms of heat flow should this also be included in the calculation of the cooling effect on the surface layer? If not, what is the explanation?
Thanks for your help.
I’m too old to figure this out, but my mind works this way:
1. If you have a *static* column of water, say X km. dia., and as deep as the ocean, the temp. gradient is presumably a function of [contained] convection and exogenous heat inputs, which cd be core-warming flux, surface temperature changes, and marginal heat-transfers between this and adjacent columns.
2. Nota bene that beneath every 1 sq.m. of ocean surface, there’s averagely 3,680 m. of water, so insolation just cannot be a major influence in the oceanographic context. (However, by contrast, insolation at surface and tropospheric levels is most certainly a major factor.)
3. Wim usefully points-out the potential for *huge* thermal inertia in the oceans.
4. A corollary is that there *must* be *huge* energy fluxes to get the oceanic mixing that Wim indicates graphically. WHAT GENERATES THESE MECHANISMS?
5. My layman’s hypothesis is that the quantum of these fluxes has to be huge-enough to power major paleo-climatic events such as successive ice-ages and retreats. Maybe long-cycle oceanic fluxes are the *major* causes of such events?
6. Which raises the question: what is this quantum of flux-energy (per cycle? per annum?) and how does it compare with corresponding AGW quanta? (I suspect AGW is — by comparison — a match struck-alight in the dark of a vast cavern!)
Can someone explain this please?
“Therefore, all warming of the ocean surface since the Little Ice Age could have been the result of a relatively small diminished upwelling of cold deep ocean water.”
How can “cold” up-welling water cause “warming” of surface waters?
So if the climate gets too warm then we can install a number of huge propellers at the bottom of the oceans to circulate the ocean water more.
Here’s one of those irritating “told you so” posts but I’ve been saying repeatedly for years that so great are the (a) heat capacity of the oceans and (b) the vertical gradient of temperature in the oceans, that changes in vertical mixing in the ocean, alone, are sufficient in principle to account for climate change on many if not all timescales. So there.
Actually not.
“We propose that variations in the strength of oceanic tides cause periodic cooling of surface ocean water by modulating the intensity of vertical mixing that brings to the surface colder water from below. The tides provide more than half of the total power for vertical mixing, 3.5 terawatts (4), compared with about 2.0 terawatts from wind drag (3), making this hypothesis plausible.”
Keeling, Charles D., and Timothy P. Whorf. “The 1,800-year oceanic tidal cycle: A possible cause of rapid climate change.” Proceedings of the National Academy of Sciences 97.8 (2000): 3814-3819.
And yes. It is that Charles Keeling.
And if you think that the wind can explain “Warming by [less] Upwelling of Cold Ocean Water” then at the very least you should have checked what the wind has been doing since 1976, when global warming started its last leg.
http://www.bluehill.org/climate/annwind.gif
And yes, again. That result is consistent for a major part of the globe. In most places surface wind speed has been on the decrease for the past decades:
Vautard, Robert, et al. “Northern Hemisphere atmospheric stilling partly attributed to an increase in surface roughness.” Nature Geoscience 3.11 (2010): 756-761.
“Surface winds have declined in China, the Netherlands, the Czech Republic, the United States and Australia over the past few decades1–4. The precise cause of the stilling is uncertain. Here, we analyse the extent and potential cause of changes in surface wind speeds over the northern mid-latitudes between 1979 and 2008, using data from 822 surface weather stations. We show that surface wind speeds have declined by 5–15% over almost all continental areas in the northern mid-latitudes, and that strong winds have slowed faster than weak winds. In contrast, upper-air winds calculated from sea- level pressure gradients, and winds from weather reanalyses, exhibited no such trend.”
Your article can benefit from a little more research.
A 98% match (R^2 = 0.98) 1895-2015 of calculated to measured average global temperatures is obtained considering only three factors, one of which is an ocean surface temperature fluctuation of +/- 0.18 K with a 64 year period.
Wim Rost’s post points to an important facet of climate, that the ocean, repository of nearly all the climate’s heat, has a long memory and can provide centuries, even millennia of climate change from its inevitable internal chaotic oscillations.
The implication of this is startlingly simple. Climate changes by itself. Talk of climate change requiring forcing therefore misses this dominant attribute of the climate system and fails before it has even started.
The real climate debate is not between “it’s CO2” and “no it’s not CO2”. Instead it’s between the camps that see climate as passive or active. Like at the start of some episodes of the Apprentice, his changes who os pn which side.
In the passive climate together are both the “nothing but CO2” brigade and also the “peleton” of solar cyclists (“nothing but the sun”).
In the active camp are those recognise that climate changes itself, that “climate change” is a meaningless expression, a vacuous tautology. Climate is always changing naturally because that’s what open dissipative far-from-equilibrium friction containing and excitable systems, do. Yawn.
Those that argue for a dominant solar effect on climate are on the same side as CAGW advocates. And as this thread shows, the solar peleton always come out against internally generated climate variability since, just like their CAGW comrades, they require a passive climate system.
Wim
Some minor comments.
I don’t think it’s only wind that drives upwelling. Ocean currents and the dynamics thereof play an independent role. In any case, winds on the ocean are caused by spatial differences in SSTs, so causation is circular between ocean and wind (a condition for chaotic dynamics).
Also, your maps of ocean circulation and mixing might underestimate the significance of the Antarctic, which is almost a “Grand Central Station” of the THC:
https://www.google.co.uk/search?q=antarctic+deep+ocean+circulation&prmd=ivn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiDtIzjh5PRAhXMelAKHUC1Ad0Q_AUIBygB&biw=375&bih=559#imgrc=pcGuysAskwVZIM%3A
For me its the CLIMAP of the LGM that shows a key role that the oceans play in climate change, and that’s its ability as a huge heat store. According to CLIMAP during the LGM large parts of the Pacific Ocean were warmer during that time then they are now.
This to me would make a lot of sense.
Because it shows to me that during the LGM a lot of heat was been used to warm up the Pacific Ocean rather then warming up the NH landmasses. This heat been stored in the Pacific rather then been spread across the planet. Plus the cooling effect that the snow and ice cover would have had over the NH landmasses. This to me would go a long way to explaining the climate cooling during the last ice age.
“In the ‘climate world’ it is assumed that there is a constant cooling of the surface layer by upwelling waters.”
Where do you get this from? I don’t think it is true in any sense. Certainly not in GCMs. They model the ocean circulation, varying in time.
The main fluctuation in upwelling variation with thermal consequences is NSO. GCMs model that well now.
The other thing to say is that all the talk about upwelling is speculative. Yes, there is a lot of cold water down there. It has been there for a very long time, and there is no reason to think it will change in a major way. The oceans are thermally stratified, and stable. It takes a lot of energy to bring cold water to the surface.
The oceans are much wider than they are deep. For this reason, it may be helpful to try to understand and model global scale deep ocean mixing by reducing the oceans’ dimensionality to 2D as suggested on this fluid mechanics paper on 2D turbulence (behind a paywall unfortunately):
http://www.annualreviews.org/doi/abs/10.1146/annurev-fluid-120710-101240#/doi/abs/10.1146/annurev-fluid-120710-101240
What’s the difference in the amount of heat that is roughly stored in ocean and the atmosphere? I imagine that the ocean’s heat content dwarfs that of the atmosphere.
It seems probable that the ocean, with stored up heat over hundreds or thousands of years, is largely controlling or seriously moderating atmospheric temperatures. That’s another reason why changes in CO2 levels would likely have a minimal impact on atmospheric temperature.
Good post.
However the scale of this mechanism is beyond most human comprehension both in size and duration.
Perhaps the demonstration model needs to be smaller, like an open unheated pool or vat in a room being heated by a forced air furnace and wall mount thermostat.This would certainly help demonstrate which effect is dominant.
As to what drives the path of water currents, do we know enough to even speculate intelligently?
A water dominated globe, spinning at 19000? mile per hour.
Surface drag on the water from?
An irregular below water surface..
Induced electric currents and magnetic fields.
Gravity..lunar influences
Thermal gradients.
As depicted above we have some cute models of what we think is happening.
The information from the sea surface network buoys is starting to paint a picture.
The satellite info is improving.
Certainly the remarkable stability of geological climate points to the dominance of water on our world.
It is a fact that the paleo record shows that the high latitude regions of the planet have in the past cyclically warmed and in all cases every warming phase has followed by a cooling phase with the cycles correlating with solar changes.
http://www.agu.org/pubs/crossref/2003/2003GL017115.shtml
http://wattsupwiththat.com/2012/09/05/is-the-current-global-warming-a-natural-cycle/
http://wattsupwiththat.files.wordpress.com/2012/09/davis-and-taylor-wuwt-submission.pdf
Observations continue to support the assertion that the solar cycle has been interrupted which is different than a simple slowdown in the solar cycle, different what is expected a simple reduction in the number of sunspots and/or a change in the length of the solar cycle.
If the warming in the last 150 years was caused by solar cycle changes, rather than the increase in atmospheric CO2, there is no CAGW or AGW problem to solve.
http://www.ospo.noaa.gov/data/sst/anomaly/2016/anomnight.12.26.2016.gif
Anyone who adds to our working list of known unknowns is doing important work. Thank you, sir. Most here will have seen this, and yet I like to repost occasionally to give a visual sense of all the water in the world. Large sphere is salt water, small is fresh. http://water.usgs.gov/edu/pictures/full-size/global-water-volume-fresh-large.jpg
What would have caused the huge warm blobs of water to have formed in the Pacific Ocean during the LGM.?
Persistent high pressure blocking within these areas .
Which along with the intense cold over N America and NW eurasia. Point the fact that there was a major slow down in the movement of the weather patterns across the globe during the LGM.