Ocean Climate Science

More Evidence Temperatures Drive CO2 Levels, Not the Reverse

Posted on by Ron Clutz

Robbins, 2025 Figure 2: Global tropic SSTs overlaid onto monthly atmospheric CO2 increases (Mauna Loa)

Kenneth Richard posted a No Tricks Zone article: Another New Study Suggests Most – 80% – Of The Modern CO2 Increase Has Been Natural.  Excerpts in italics with my bolds and added images.

CO2 concentration increases are not the cause of rising temperature,
but an effect of rising temperature.

The 2025 paper by Bernard Robbins is Atmospheric CO2: Exploring the Role of Sea Surface Temperatures and the Influence of Anthropogenic CO2.  Excerpts in italics with my bolds and added images.

Abstract

Close examination of the small perturbations within the atmospheric CO2 trend, as measured at Mauna Loa, reveals a strong correlation with variations in sea surface temperatures (SSTs), most notably with those in the tropics. The temperature-dependent process of CO2 degassing and absorption via sea surfaces is well-documented, and changes in SSTs will also coincide with changes in terrestrial temperatures, and temperature-dependent changes in the marine and terrestrial biospheres with their associated carbon cycles.

Using SST and Mauna Loa datasets, three methods of analysis are presented that seek to identify and estimate the anthropogenic and, by default, natural components of recent increases in atmospheric CO2, an assumption being that changes in SSTs coincide with changes in nature’s influence, as a whole, on atmospheric CO2 levels. The findings of the analyses suggest that an anthropogenic component is likely to be around 20 %, or less, of the total increase since the start of the industrial revolution.

The inference is that around 80 % or more of those increases are of natural origin, and indeed the findings suggest that nature is continually working to maintain an atmospheric/surface CO2 balance, which is itself dependent on temperature. A further pointer to this balance may come from chemical measurements that indicate a brief peak in atmospheric CO2 levels centred around the 1940s, and that coincided with a peak in global SSTs.

Source: The phase relation between atmospheric carbon dioxide and global temperature OleHumlum, KjellStordahl, Jan-ErikSolheim.

Introduction

Research into the influence SSTs have on changes in atmospheric CO2 includes the work by Humlum et al. (2013). When examining phase relationships, they found a maximum correlation for changes in atmospheric CO2 lagging 11-12 months behind those of global SSTs [1]. A paper by the late Fred Goldberg (2008) noted their correlation by examining El Niño events [2]. He also considered Henry’s law [3] in relation to SSTs, i.e. a temperature-dependent equilibrium between atmospheric CO2 and its solubility in seawater. Spencer (2008) also noted similarities between surface temperature variations with changes in atmospheric CO2 [4].

For the oceans specifically, areas of surface CO2 absorption and degassing are shown in maps provided by NOAA [5] and ESA [6] for example. These maps show that colder sea surfaces towards the poles are net absorbers of CO2 whilst the warmer surface waters of the tropics are net emitters. An analogy often cited is the greater ability of carbonated drinks to retain CO2 at cooler temperatures; this ability drops as the drinks get warmer.

Figure 1: Deseasonalised atmospheric CO2 data (Mauna Loa).

A strong correlation between changes in atmospheric CO2 and SSTs can be readily discerned from the relevant datasets. To illustrate, the upper graph in Fig. 1 plots atmospheric CO2 in parts per million (ppm) as measured at Mauna Loa, Hawaii, since 1982. The data [7] has been ‘deseason-alised’ by NOAA to remove natural annual CO2 cycles.

The similarity between the two traces is striking: short-term fluctuations in CO2 readings at Mauna Loa appear particularly sensitive to tropic conditions (if tropic SSTs are substituted for global SSTs in Fig. 2, the correlation is less strong). Warm tropical seas, with surface temperatures typically around 25-30 oC, cover almost one third of the earth’s surface. The most prominent peaks in the figure coincide with strong El Niño events. Taken at face value, and ignoring any influence from anthropogenic emissions, Fig. 2  suggests that if the tropic SST anomaly dropped to around -1 oC (with related drops globally) then the concentration of CO2 in the atmosphere, as measured at Mauna Loa, would level off.

Robbins, 2025 Figure 2: Global tropic SSTs overlaid onto monthly atmospheric CO2 increases (Mauna Loa)

An important point is that changes in SSTs will coincide with those of terrestrial temperatures, temperature-dependent changes to both terrestrial and marine carbon cycles and, taking into consideration the research by Humlum et al. (2013) who found that changes in atmospheric CO2 followed changes in SSTs, an assumption in the work presented here is that nature’s influence on atmospheric CO2 levels, as a whole, follows on from changes in SSTs.

Discussion

The techniques used in Analyses 1 and 2, aimed at discerning and estimating the human contribution to recent increases in atmospheric CO2, are based on processing of monthly data from both SST and atmospheric CO2 datasets. Using the technique described in Analysis 1, no contribution from human emissions to the measured increases in atmospheric CO2, since 1995, was discerned. Given an approximate 60 % increase in annual human emissions since 1995 this suggests, by itself, that any human contribution to the measured increases is likely to be relatively small compared to nature’s contribution.

For the technique described in Analysis 2, a figure of ~27 ppm was estimated for a possible human contribution out of a total increase of 143 ppm since 1850, equating to around 19 % of the total increase in atmospheric CO2 since the start of the industrial revolution. Thus the results of these two analyses, taken together, suggest that nature appears to account for around 80 % or more of increases in atmospheric CO2 since 1995.

The technique described in Analysis 3 examines the relationship between longer-term trends in SST datasets and atmospheric CO2 measurements. This data analysis goes as far back as the late 1950s, when the ongoing acquisition of atmospheric CO2 measurements began at Mauna Loa. The resulting three graphs show an apparent almost-linear long-term relationship between SSTs and atmospheric CO2. Linear trend lines fitted to these graphs produce gradients of between ~120 and ~145 ppm/ 0C for the three SST datasets examined.

Figure 15: Atmospheric CO2 as a function of global SST trend since 1958

As for anthropogenic CO2, published figures (e.g. GCB data) suggest a roughly linear relationship between cumulative anthropogenic emissions as a function of time, and atmospheric CO2 measurements from Mauna Loa. If it’s reasoned that this mostly accounts for the linear trends as calculated in Analysis 3, this reasoning would not fit with the findings of the first two analysis methods that suggest 80 % or more of recent atmospheric CO2 increases are of natural origin.

Conclusions

Analyses of SST and atmospheric CO2 data, acquired since 1995, produce an estimated atmospheric CO2 increase, possibly attributed to human emissions, of around 20 %, or less, of the total increase since the industrial revolution, thus inferring that around 80 % or more of the increase is of natural origin.

Further data examination points to an almost linear longer-term relationship between SSTs and atmospheric CO2 since at least the late 1950s, and is suggestive of nature working to maintain a temperature-dependent atmosphere/surface CO2 balance. Recent historical evidence of such a balance may come from chemical measurements that indicate a brief peak in atmospheric CO2 levels centred around the 1940s, and that coincided with a peak in global SSTs.

Human emissions of CO2 are about 1/20-th of the natural turnover, and the findings of the analyses presented here suggest that this relatively-small human contribution is being readily incorporated into nature’s carbon cycles as they continually adjust to our constantly-changing climate.

As for surface temperatures, the research by Humlum et al. concluded that changes in atmospheric temperature are an ‘effect’ of changes in SSTs and not a ‘cause’ as some might advocate. And Humlum’s ‘take home’ message from a recent presentation was:

‘What controls the ocean surface temperature, controls the global climate’ [33]. He suggests the sun would be a good candidate, modulated with the cloud cover.

See Also

June 2025 Update–Temperature Falls, CO2 Follows

Wind And Solar Power Both Capricious and Costly

Posted on by Ron Clutz

Bill Ponton reminds us that in addition to being fickle, renewables are also costly, in his American Thinker article What are the merits of renewables?  Excerpts in italics with my bolds and added images.

The Spanish blackout made us all aware of how unstable the grid can get when renewables are in the driver’s seat, but one should also not forget that they don’t come cheaply. The idea of getting free energy from wind and solar is inaccurate. Man must build machines to extract energy from nature and those machines, windmills and solar panels, are expensive.

Usually, proponents of renewables point to the fact that once the windmills and solar panels are installed, there is no added cost for fuel. That’s true, but there is more to the story. The capital cost of capacity for onshore wind, solar, and natural gas is $1.7 /MW, $1.3/MW, and $1.2/MW, respectively, a difference, but maybe not what one would call significant.

However, there is a gross disparity between capacity factors for each with 31% for wind, 20% for solar, and 60% for natural gas, as evidenced by the figures from Texas grid operator, ERCOT, in 2023. The capacity factor is a measure of how effectively a power plant or energy-producing system is operating compared to its maximum potential output over a specific period (Capacity Factor = Actual Output / Maximum Possible Output).

It should be said that a capacity factor of 60% for natural gas is what one would expect if the operator were only dependent upon natural gas. The current situation where natural gas generation is used to backup solar and wind generation drives the capacity factor for natural gas generation down to 36%.

With these lower capacity factors, one gets a cost multiple
of over 1.5 times greater to operate a mixed energy system
versus a system with just natural gas.

My calculations are here for all to examine. Another way to look at it is that the price of natural gas would have to go up by a factor of five (x5) to make the combined system with wind, solar, and natural gas cost competitive against a system with natural gas alone. Although Texas has a lot to brag about, its use of multiple energy sources to power its grid is not one of them. Why would one expect any other result from a scheme that requires massive subsidies, mandates, and tax breaks to even exist?

So, if renewables are unreliable and expensive, who finds them appealing? The answer is folks that are so guilt-ridden about their role in a supposed climate catastrophe that they will grab on to any scheme that offers them absolution, whether it has merit or not.

 

 

 

Mann’s AMOC Collapse Hoax

Posted on by Ron Clutz

Dr. Kevin E. Trenberth, a distinguished scholar at the National Center for Atmospheric Research, commented on this movie: “I don’t recall a lot except that the whole science was incredibly wrong,”, “one does not get an ice age out of global warming.”

Likely you’ve heard the recent and previous warnings from Mann and friends about the ocean conveyor belt (including the Gulf Stream) slowing down and freezing us all.  With the COP gathering next month, something scary must be proclaimed, and Global Freezing is it, replacing Global Boiling earlier this year. The declaration signed by Mann and 43 other scientists was Open Letter by Climate Scientists to the Nordic Council of Ministers, Reykjavik, October 2024. Preface:

“We, the undersigned, are scientists working in the field of climate research and feel it is urgent to draw the attention of the Nordic Council of Ministers to the serious risk of a major ocean circulation change in the Atlantic. A string of scientific studies in the past few years suggests that this risk has so far been greatly underestimated. Such an ocean circulation change would have devastating and irreversible impacts especially for Nordic countries, but also for other parts of the world.”

 

“Given the increasing evidence for a higher risk of an AMOC collapse, we believe it is of critical importance that Arctic tipping point risks, in particular the AMOC risk, are taken seriously in governance and policy. Even with a medium likelihood of occurrence, given that the outcome would be catastrophic and impacting the entire world for centuries to come, we believe more needs to be done to minimize this risk.”

The Warning is based on Fear, not Facts

1.  The AMOC has been stable for the last four decades.

Florida Current transport observations reveal four decades of steady state Volkov et al 2024

Abstract

The potential weakening of the Atlantic Meridional Overturning Circulation (AMOC) in response to anthropogenic forcing, suggested by climate models, is at the forefront of scientific debate. A key AMOC component, the Florida Current (FC), has been measured using submarine cables between Florida and the Bahamas at 27°N nearly continuously since 1982. A decrease in the FC strength could be indicative of the AMOC weakening. Here, we reassess motion-induced voltages measured on a submarine cable and reevaluate the overall trend in the inferred FC transport. We find that the cable record beginning in 2000 requires a correction for the secular change in the geomagnetic field. This correction removes a spurious trend in the record, revealing that the FC has remained remarkably stable. The recomputed AMOC estimates at ~26.5°N result in a significantly weaker negative trend than that which is apparent in the AMOC time series obtained with the uncorrected FC transports.

Fig. 1: The Western Boundary Time Series
observing network in the Straits of Florida.

The network consists of the submarine telecommunications cable between West Palm Beach and Grand Bahama Island (cyan curve), ship sections across the Florida Current (FC) at 27°N with in situ measurements at nine stations (white circles), two bottom pressure gauges on both sides of the FC at 27°N (yellow stars), and along-track satellite altimetry measurements (magenta dotted line). CTD Conductivity-Temperature-Depth, LADCP Lowered Acoustic Doppler Current Profiler, XBT expendable bathythermograph.

Fig. 6: Florida Current (FC) volume transports corrected for
the secular change in the Earth’s Magnetic Field (EMF).

a The time series of the daily FC volume transport: (blue) not corrected for the secular change in the EMF, (red) corrected for the secular change in the EMF. The linear trends of the FC transport not corrected and corrected for the EMF are shown by the blue and red lines, respectively. b The differences between the cable and ship section transport for the cable data (blue squares) not corrected for the EMF and (red circles) corrected for the EMF. The linear trends of the differences (ΔT) not corrected and corrected for the EMF are shown by the blue and red lines, respectively.

Fig. 2: The Florida Current volume transport.

Daily transport estimates from the cable record (black; prior to corrections applied in this study); estimates from the Pegasus (orange diamonds) and Pegasus in dropsonde mode (Pegasus-DM; light blue circles) sections; estimates from the dropsonde sections (blue circles); and estimates from the Lowered Acoustic Doppler Current Profiler (LADCP) sections (red circles). The linear trends for 1982–2023, 1982–1998, and 2000–2023 periods are shown by the orange, cyan, and magenta lines, respectively.

2.  Paleo records show past AMOC changes due to seafloor shifts not climate change.

Controlling factors for the global meridional overturning circulation: A lesson from the Paleozoic, Yuan et al. 2024.

Abstract

The global meridional overturning circulation (GMOC) is important for redistributing heat and, thus, determining global climate, but what determines its strength over Earth’s history remains unclear. On the basis of two sets of climate simulations for the Paleozoic characterized by a stable GMOC direction, our research reveals that GMOC strength primarily depends on continental configuration while climate variations have a minor impact. In the mid- to high latitudes, the volume of continents largely dictates the speed of westerly winds, which in turn controls upwelling and the strength of the GMOC. At low latitudes, open seaways also play an important role in the strength of the GMOC. An open seaway in one hemisphere allows stronger westward ocean currents, which support higher sea surface heights (SSH) in this hemisphere than that in the other. The meridional SSH gradient drives a stronger cross-equatorial flow in the upper ocean, resulting in a stronger GMOC. This latter finding enriches the current theory for GMOC.

On the basis of a series of simulations for the Paleozoic, we find that the GMOC is primarily controlled by:

  • freshwater input into ocean;
  • wind-driven Ekman pumping in the midlatitudes, and
  • SH anomaly in low latitudes.

The latter two factors are especially important for the strength of the GMOC and are highly related to continental configuration. Our major conclusions find validation through Paleozoic climate simulations using the HadCM3 model by Valdes et al. (53, 67) and a non-IPCC class model, FOAM, by Pohl et al. (52) (figs. S17 and S18). This last study by Pohl et al. (52) also pointed out the unfortunate absence of proxy data for validating the direction and magnitude of the Paleozoic GMOC.

Controlling factors for the global
meridional overturning circulation

Fig. 5. Schematic of controlling factors for the GMOC during the Paleozoic. The schematic is based on the situation for 400 Ma. Three main factors are shown, the less net precipitation in the south SH; the strong westerlies, ocean surface current, and Ekman upwelling in the midlatitude region in NH; the SSH anomaly and associated pressure anomaly in the low-latitude region.

Although there has been tremendous interest in understanding the mechanisms that govern the MOC, surface topography in the westerlies region and the presence of an open seaway in the low-latitude region were previously largely overlooked. Our study thus draws attention to how the evolution of continents in these two regions affects the strength of MOC. Our study indicates that the traditional theory for MOC misses an important element, that is, the influence of a low-latitude seaway. Previous studies either did not have such a seaway (1, 34, 43) or had a partial seaway that connected the present-day Atlantic Ocean and Pacific Ocean only (32–34). Their focus was mostly on the strength of the AMOC and mechanism invoked generally involved freshwater and salinity only (32, 33, 68), while as demonstrated above, a fully open low-latitude seaway affects the MOC in a fundamentally different way.

3.  AMOC alarm presupposes Arctic “Amplification” of Global Warming

Activist scientists claim the Arctic is warming up to five times faster than lower latitudes.  This is based on models projecting scarce temperature records great distances over the Arctic ocean drift sea ice.  There are three flaws in the arctic warming claim (from Arctic “Amplification” Not What You Think)

a. Arctic Amplification is an artifact of Temperature Anomalies

Clive Best provides this animation of recent monthly temperature anomalies which demonstrates how most variability in anomalies occur over northern continents.

b. Arctic Surface Stations Records Show Ordinary Warming

Locations of 118 arctic stations examined in this study and compared to observations at 50 European stations whose records averaged 200 years and in a few cases extend to the early 1700s.

The paper is: Arctic temperature trends from the early nineteenth century to the present W. A. van Wijngaarden, Theoretical & Applied Climatology (2015).  My synopsis: Arctic Warming Unalarming

c. Arctic Warmth Comes from Meridional Heat Transport, not CO2

4.  Hypothesis that rising CO2 will collapse the AMOC is flawed.

The “AMOC is collapsing” narrative goes like this:

Ocean circulation is driven by density differences, which depend on the salinity and the temperature of the water. Cold, salty water is heavier than warm, fresh water. When flowing water reaches Greenland, it becomes very cold and salty, causing it to sink and flow south, where the water warms and rises closer to the surface again. Some compare the process to a conveyor belt going around and around.

This graphic shows a highly simplified schematic of the Atlantic Meridional Overturning Circulation (AMOC) against a backdrop of the sea surface temperature trend since 1993 from the Copernicus Climate Change Service (https://climate.copernicus.eu/). Image credit: Ruijian Gou. > High res figure.

Changing the salinity of the water messes up the way the water flows. That’s why the melting of the Greenland ice sheets is a big problem: It’s injecting a ton of freshwater into the ocean far north, where the water is usually very salty. The more freshwater, the weaker the circulation—not to mention that atmospheric temperatures are also increasing, which also makes water lighter. The new study shows that if the density dynamics change enough, the conveyor belt will eventually stop moving, aka “collapse.” That means it won’t transport any water, saline, or heat across the globe.

So the scenario is that supposed amplified Arctic warming will cause iceberg calving and glacial melting, and the freshwater will slow and eventually stop the AMOC.  Firstly, the above study shows seafloor configuration has greater impact than salinity changing.  Secondly, the spread of freshwater is not so simple.

Role of the Labrador Current in the Atlantic Meridional Overturning Circulation response to greenhouse warming, Shan et al. 2024

Abstract

Anthropogenic warming is projected to enhance Arctic freshwater exportation into the Labrador Sea. This extra freshwater may weaken deep convection and contribute to the Atlantic Meridional Overturning Circulation (AMOC) decline. Here, by analyzing an unprecedented high-resolution climate model simulation for the 21st century, we show that the Labrador Current strongly restricts the lateral spread of freshwater from the Arctic Ocean into the open ocean such that the freshwater input has a limited role in weakening the overturning circulation. In contrast, in the absence of a strong Labrador Current in a climate model with lower resolution, the extra freshwater is allowed to spread into the interior region and eventually shut down deep convection in the Labrador Sea. Given that the Labrador Sea overturning makes a significant contribution to the AMOC in many climate models, our results suggest that the AMOC decline during the 21st century could be overestimated in these models due to the poorly resolved Labrador Current.

5.  The “Tipping Point” scare is unscientific.

Uncertainties too large to predict tipping times of major Earth system components from historical data, Ben-Yami et al. 2024

Abstract

One way to warn of forthcoming critical transitions in Earth system components is using observations to detect declining system stability. It has also been suggested to extrapolate such stability changes into the future and predict tipping times. Here, we argue that the involved uncertainties are too high to robustly predict tipping times. We raise concerns regarding

(i) the modeling assumptions underlying any extrapolation of historical results into the future,

(ii) the representativeness of individual Earth system component time series, and

(iii) the impact of uncertainties and preprocessing of used observational datasets, with focus on nonstationary observational coverage and gap filling.

We explore these uncertainties in general and specifically for the example of the Atlantic Meridional Overturning Circulation. We argue that even under the assumption that a given Earth system component has an approaching tipping point, the uncertainties are too large to reliably estimate tipping times by extrapolating historical information.

“The conclusions of this study are certainly in line with my understanding of the current state of the art,” says Gavin Schmidt, a climate scientist and professor at Columbia University and the director of NASA’s Goddard Institute for Space Studies (GISS). Schmidt was not involved in the new work, but has extensively researched climate variability and systems like AMOC.

“I have not been impressed by previous or recent efforts to predict upcoming tipping points in either AMOC or ice sheets — there is more going on than just patterns in time series and we still don’t have sufficiently complex and calibrated models to have a robust idea of what will happen,” says Gavin Schmidt, director of NASA’s GISS.

Footnote

In researching for this post I discovered an informative website Ocean to Climate  Science news & articles on topics related to ocean and climate by oceanographer Sang-Ki Lee.  Some additional examples of studies for further reading on this issue are below.

Gulf Stream’s fate to be decided by climate ‘tug-of-war’

A stable Atlantic Meridional Overturning Circulation in a changing North Atlantic Ocean since the 1990s

Detectability of an AMOC Decline in Current and Projected Climate Changes

Global surface warming enhanced by weak Atlantic overturning circulation

Nonstationarity of the Atlantic Meridional Overturning Circulation’s Fingerprint on Sea Surface Temperature

 

 

 

 

 

2024 El Nino Collapsing

Posted on by Ron Clutz

Meteorologist Cliff Mass explains at his blog El Nino’s Collapse Has Begun.  Excerpts in italics with my bolds, added images and ending comment.

The entire character of this winter has been characterized by a strong El Nino.

El Nino impacts have included low snowpack over Washington State, huge snowpack and heavy precipitation over California, and warm temperatures over the Upper Plains states.

However, El Nino’s days are numbered and
its decline is proceeding rapidly right now.

First, consider the critical measure of El Nino: the sea surface temperatures in the central tropical Pacific (see graph above showing the Nino 3.4 area). The warmth of this El Nino peaked in late November (about 2.1°C above normal) and is now declining fairly rapidly (currently at roughly 1.3°C above normal).

But the cooling is really more dramatic than that:
a LOT of cooling has been happening beneath the surface!

To demonstrate this, take a look at subsurface temperatures (the difference from normal) for the lowest 300 m under the surface for a vertical cross-section across the Pacific (below).

On 8 January, there was a substantial warm layer extending about 100 m beneath the surface.

But look at the same cross-section on 27 February.

Wow–what a difference! The warm water has dramatically cooled, with only a thin veneer of warmth evident for much of the Pacific. Rapidly cooling has occurred beneath the surface and this cool water is about to spread to the surface.

If you really want to appreciate the profound cooling take a look at the amount of heat in the upper ocean for the western tropical Pacific (below, the difference from normal is being shown).

A very, very dramatic change has occurred. The heat content of the upper ocean peaked in late November and then plummeted. Declined so much that the water below the surface is now COOLER than normal.

El Nino fans will be further dismayed to learn that models are going for a continuous decline….so much so that they predict a La Nina next year!

My Comment: Why this shift from El Nino to La Nina matters

Global temperatures typically increase during an El Niño episode, and fall during La Niña.  El Niño means warmer water spreads further, and stays closer to the surface. This releases more heat into the atmosphere, creating wetter and warmer air.

Air temperatures typically peak a few months after El Niño hits maximum strength, as heat escapes from the sea surface to the atmosphere.

In 2021, the UN’s climate scientists, the IPCC, said the ENSO events which have occurred since 1950 are stronger than those observed between 1850 and 1950.  But it also said that tree rings and other historical evidence show there have been variations in the frequency and strength of these episodes since the 1400s.

The IPCC concluded there is no clear evidence that Climate Change™ has affected these events.

Barrier Reef Great Again

Posted on by Ron Clutz

Last night I watched an extraordinary netflix documentary which took us on a journey discovering the rich variety of reef life, including microscopic creatures not shown in videos before. It was highly educational and thoroughly delightful . . . until suddenly it wasn’t.  Spoiler Alert:  Puff returns as an adult to the reef where he was born after leaving it to mature in a mangrove marsh.  Alas, he finds the coral dead and blackened, and the narrator warns us:  Warming oceans kiiled the reef and we must change the way we live for the sake of Puff and the other reef creatures.  There may have been more to the fire and brimstone ending, but I was so turned off that I turned it off.

Why must nature documentaries resort to doomsday guilt trips to destroy any good feelings about our world?  Chris Morrison provides the antidote in his Daily Sceptic article Coral at the Great Barrier Reef Holds on to Recent Record Gains, Defying All Doomsday Predictions.  Excerpts in italics with my bolds.

Coral at the Great Barrier Reef (GBR) faces another year of exile from the climate scare headlines with news that the record levels reported in 2021-22 have been sustained in the latest annual period to May 2023. A small drop in the three main areas of the reef was well within margin of error territory, with the Australian Institute of Marine Science (AIMS) reporting that regional average hard coral cover in 2022-2023 was similar to last year at 35.7%. Most reefs underwent little change during the year.

Coral at the reef has been bouncing back sharply for a number of years, with a record 36-year high reported in 2022. But the news of this spectacular recovery has been largely ignored in most media since it had previously been a go-to poster scare story for collectivist Net Zero promoters. But connecting the fate of tropical corals to global warming was always a difficult ask since they grow in waters between 24-32°C. Short boosts in local temperatures can cause temporary bleaching, but it is scientifically impossible to pin it on human-caused climate change, although pseudoscientific ‘attribution’ computer models try very hard.

In the latest year, there was a short local temperature rise,
but little bleaching was reported during the 2023 summer.

No cyclones hit the reef and crown-of thorns starfish attacks were limited. Nevertheless, natural stresses will always affect the eco-system and AIMS states that these paused the growth of hard coral on some of the reefs.

Like most state-funded scientific bodies, The Australian Institute of Marine Science (AIMS) is fully signed up to climate extremism and delivering politically correct messages to promote the Net Zero solution. Despite reporting what is now a substantial multi-year recovery, it notes that the future is predicted to bring more frequent, intense and enduring marine heatwaves, alongside the persistent threat of crown-of thorns starfish outbreaks and tropical cyclones. More frequent mass coral bleaching is a sign that the GBR is experiencing the consequences of climate change, it claims. However, in a different part of its latest report, AIMS accepts that the recent substantial recovery occurred despite two mass coral bleaching events in 2020 and 2022.

There is an acceptance that this underlines that “widespread coral bleaching
does not necessarily lead to extensive coral mortality”.

But pockets of extremist catastrophism remain in the mainstream media, notably in the Guardian, fighting to keep the coral destruction story going. A year ago, the newspaper reported that the GBR still had “some capacity” for recovery, but the window was closing fast as the climate continued to warm. Of course the Guardian has form as long as your arm on this score. Back in 1999, George Monbiot told its readers that the “imminent total destruction of the world’s coral reefs is not a scare story but a fact”.

Coral reefs have been around in one form or another for hundreds of millions of years. Current global temperatures are towards the lower end of the paleoclimatic record. One might wonder how corals manage to survive temperatures up to 10°C higher in the past?

Back in the real world, we can see how the recent solid recovery
was sustained across the three main areas of the GBR.

The recovery in the northern GBR actually started around 2017. Last year the coral declined slightly from 36.5% to 35.7%, and was easily within the margin of error calculated by the AIMS. Typhoon Tiffany passed through at the end of the previous reporting season, and could have been responsible for some loss.

In the centre of the reef, the strong recovery of hard coral cover to 32.6% last year eased slightly, but again, as the AIMS noted, it was within the margin of error.

The southern end of the GBR has generally had higher coral cover than elsewhere, but has shown greater variability over the observed record. Last year’s cover was 33.8%, compared with 33.9% the year before. Some coral was reported to have been lost due to starfish predations.

The GBR is the largest reef system on Earth and runs for
over 1,400 miles down the eastern side of Australia.

It is also the most surveyed reef in the world and the results of scientific endeavour are widely distributed. While this work is often politicised, it is clear that recent evidence shows that temporary spikes in temperature, which occur naturally in the oceans, can cause bleaching. However, this bleaching process can rapidly go into reverse when local conditions stabilise. These findings have been confirmed elsewhere, notably in the remote Palmyra Atoll, 1,200 kms south of Hawaii. A 10-year survey recently observed sudden changes in temperature up to 3°C on two occasions, leading to substantial damage to the coral. A 2015-16 spike led to 90% of the coral bleaching, but the researchers found that within a year only 10% of the coral had died. Within two years, the corals had returned to pre-bleached levels.

The researchers concluded that the coral structures
“show evidence of long-term stability”
– but don’t expect to see that on the front page.

Palmyra Atoll, 1,200 kms south of Hawaii.

Ocean Climate Flywheel Science (Updated)

Posted on by Ron Clutz

A continuing theme at this blog has been our planetary fact that Oceans Make Climate.  The initial inspiration came from Dr. Arnd Bernaerts’ insightful phrase:  “Climate is the continuation of ocean by other means.”

Posts on this topic can be accessed by the category link Ocean Climate Science.

An early post provides relevant background to today’s discussion:  The Climate Water Wheel

6m (20ft) flywheel, weighs 15 tonnes. Used at Gepps Cross, Adelaide, South Australia Meatworks

The image at the top is the cover of a fresh presentation of the ocean flywheel paradigm written by William Kininmonth, and posted at GWPF Rethinking the Greenhouse Effect.

Dr. Ralph Alexander summarized the paper in his article Ocean Currents More Important than the Greenhouse Effect.   Excerpts in italics with my bolds and added images.

A rather different challenge to the CO2 global warming hypothesis from the challenges discussed in my previous posts postulates that human emissions of CO2 into the atmosphere have only a minimal impact on the earth’s temperature. Instead, it is proposed that current global warming comes from a slowdown in ocean currents.

The daring challenge has been made in a recent paper by retired Australian meteorologist William Kininmonth, who was head of his country’s National Climate Centre from 1986 to 1998. Kininmonth rejects the claim of the IPCC (Intergovernmental Panel on Climate Change) that greenhouse gases have caused the bulk of modern global warming. The IPCC’s claim is based on the hypothesis that the intensity of cooling longwave radiation to space has been considerably reduced by the increased atmospheric concentration of gases such as CO2.

But, he says, the IPCC glosses over the fact that the earth is spherical,
so what happens near the equator is very different from what happens at the poles.

Most absorption of incoming shortwave solar radiation occurs over the tropics, where the incident radiation is nearly perpendicular to the surface. Yet the emission of outgoing longwave radiation takes place mostly at higher latitudes. Nowhere is there local radiation balance.

ERBE measurements of radiative imbalance.

In an effort by the climate system to achieve balance, atmospheric winds and ocean currents constantly transport heat from the tropics toward the poles. Kininmonth argues, however, that radiation balance can’t exist globally, simply because the earth’s average surface temperature is not constant, with an annual range exceeding 2.5 degrees Celsius (4.5 degrees Fahrenheit). This shows that the global emission of longwave radiation to space varies seasonally, so radiation to space can’t define Earth’s temperature, either locally or globally.

In warm tropical oceans, the temperature is governed by absorption of solar shortwave radiation, together with absorption of longwave radiation radiated downward by greenhouse gases; heat carried away by ocean currents; and heat (including latent heat) lost to the atmosphere. Over the last 40 years, the tropical ocean surface has warmed by about 0.4 degrees Celsius (0.7 degrees Fahrenheit).

But the warming can’t be explained by rising CO2 that went up from 341 ppm in 1982 to 417 ppm in 2022. This rise boosts the absorption of longwave radiation at the tropical surface by only 0.3 watts per square meter, according to the University of Chicago’s MODTRAN model, which simulates the emission and absorption of infrared radiation in the atmosphere. The calculation assumes clear sky conditions and tropical atmosphere profiles of temperature and relative humidity.

The 0.3 watts per square meter is too little to account for the increase in ocean surface temperature of 0.4 degrees Celsius (0.7 degrees Fahrenheit), which in turn increases the loss of latent and “sensible” (conductive) heat from the surface by about 3.5 watts per square meter, as estimated by Kininmonth.

So twelve times as much heat escapes from the tropical ocean to the atmosphere as the amount of heat entering the ocean due to the increase in CO2 level. The absorption of additional radiation energy due to extra CO2 is not enough to compensate for the loss of latent and sensible heat from the increase in ocean temperature.

The minimal contribution of CO2 is evident from the following table, which shows how the amount of longwave radiation from greenhouse gases absorbed at the tropical surface goes up only marginally as the CO2 concentration increases. The dominant greenhouse gas is water vapor, which produces 361.4 watts per square meter of radiation at the surface in the absence of CO2; its value in the table (surface radiation) is the average global tropical value.

You can see that the increase in greenhouse gas absorption from preindustrial times to the present, corresponding roughly to the CO2 increase from 300 ppm to 400 ppm, is 0.62 watts per square meter. According to the MODTRAN model, this is almost the same as the increase of 0.63 watts per square meter that occurred as the CO2 level rose from 200 ppm to 280 ppm at the end of the last ice age – but which resulted in tropical warming of about 6 degrees Celsius (11 degrees Fahrenheit), compared with warming of only 0.4 degrees Celsius (0.7 degrees Fahrenheit) during the past 40 years.

Therefore, says Kininmonth, the only plausible explanation left for warming of the tropical ocean is a slowdown in ocean currents, those unseen arteries carrying the earth’s lifeblood of warmth away from the tropics. His suggested slowing mechanism is natural oscillations of the oceans, which he describes as the inertial and thermal flywheels of the climate system.

Kininmonth observes that the overturning time of the deep-ocean thermohaline circulation is about 1,000 years. Oscillations of the thermohaline circulation would cause a periodic variation in the upwelling of cold seawater to the tropical surface layer warmed by solar absorption; reduced upwelling would lead to further heating of the tropical ocean, while enhanced upwelling would result in cooling.

Such a pattern is consistent with the approximately 1,000-year interval between the Roman and Medieval Warm Periods, and again to current global warming.

See also About Meridional Cooling and Climate Change

Arctic “Amplification” Not What You Think

Climate Dissonance: Ocean Warming or Cooling?

Posted on by Ron Clutz

Climatists are manifesting cognitive dissonance, or maybe factional conflict.  They simultaneously claim the ocean current warming the North Atlantic is slowing down bringing colder weather, while also claiming the increasing ocean heat content is warming the ocean faster than ever.  The cooling alarm was noted and rebutted in a recent No Tricks Zone article 3 New Studies Show Atlantic Tipping Point Unrealistic…”Muted Response”…”Changes To Be Viewed With Caution”.

My own critique of the alarm was this post: The Cooling Also Not Our Fault

Turning Attention from the Freezing to the Overheating Ocean

The Ocean Heat scare was included in the recent UN Climate report, alongside four other claims I rebutted in the post UN False Alarms from Key Climate Indicators.The Ocean Heat Content is more complex, requiring this post of its own. The key message was this:

Ocean heat was record high. The upper 2000m depth of the ocean continued to warm in 2021 and it is expected that it will continue to warm in the future – a change which is irreversible on centennial to millennial time scales. All data sets agree that ocean warming rates show a particularly strong increase in the past two decades. The warmth is penetrating to ever deeper levels. Much of the ocean experienced at least one ‘strong’ marine heatwave at some point in 2021.

Figure 4. 1960–2021 ensemble mean time series and ensemble standard deviation (2 standard deviations, shaded) of global OHC anomalies relative to the 2005–2017 average for the 0–300 m (grey), 0–700 m (blue), 0–2 000 m (yellow) and 700–2 000 m (green) depth layers. The ensemble mean is an update of the outcome of a concerted international data and analysis effort.

Context and Background Information

Media alarms are rampant relying mostly on a publication Record-Setting Ocean Warmth Continued in 2019 in Advances in Atmospheric Sciences
Authors: Lijing Cheng, John Abraham, Jiang Zhu, Kevin E. Trenberth, John Fasullo, Tim Boyer, Ricardo Locarnini, Bin Zhang, Fujiang Yu, Liying Wan, Xingrong Chen, Xiangzhou Song, Yulong Liu, Michael E. Mann.

Reasons for doubting the paper and its claims go well beyond the listing of so many names, including several of the usual suspects. No, this publication is tarnished by its implausible provenance. It rests upon and repeats analytical mistakes that have been pointed out, but true believers carry on without batting an eye.

It started with Resplandy et al in 2018 who became an overnight sensation with their paper Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition in Nature October 2018, leading to media reports of extreme ocean heating. Nic Lewis published a series of articles at his own site and at Climate Etc. in November 2018, leading to the paper being withdrawn and eventually retracted. Those authors acknowledged the errors and did the honorable thing at the time, resulting the paper’s retraction 25 September 2019.

Then a revised version of the paper was published 27 December 2019 with the same title and stands today.  The 2019 abstract is exactly the same as the 2018 abstract (retracted), except for one sentence.

♦  2018:  We show that the ocean gained 1.33 ± 0.20 × 10^22 joules of heat per year between 1991 and 2016, equivalent to a planetary energy imbalance of 0.83 ± 0.11 watts per square metre of Earth’s surface.

♦  2019:  We show that the ocean gained 1.29 ± 0.79 × 10^22 Joules of heat per year between 1991 and 2016, equivalent to a planetary energy imbalance of 0.80 ± 0.49 W watts per square metre of Earth’s surface.

Figure 1. Argo float operation. There are about 3,500 floats in the ocean, and a total of ~10,000 floats have been used over the period of operation.

In the discussion and graphs, readers should note that 1 Zettajoule (ZJ) = 1 x 10^21 joules, and that these are energy units, not temperatures. Willis Eschenbach did a fine analysis of this OHC issue, since it depends mostly upon ARGO float measurements. From that essay:

The first thing that I wanted to do was to look at the data using more familiar units. I mean, nobody knows what 10^22 joules means in the top two kilometres of the ocean. So I converted the data from joules to degrees C. The conversion is that it takes 4 joules to heat a gram of seawater by 1°C (or 4 megajoules per tonne per degree). The other information needed is that there are 0.65 billion cubic kilometres of ocean above 2,000 metres of depth, and that seawater weighs about 1.033 tonnes per cubic metre.

The first thing is to note that 3500 floats are sampling 0.65 billion cubic km of the ocean, and the record began in 2005. The next thing is to appreciate the impact of increasing energy upon the ocean temperature.

Yes, those are ocean warming increments of a few 1/100ths of a degree kelvin.  Applying the math to Resplandy et al., we should also note the ranges of uncertainty in these estimates (ocean temps to 1/100 of a degree, really?)

Resplandy 2018: Claim 103 to 153 ZJ/decade, or warming between 0.03 to 0.05 C/decade.

Resplandy 2019:  Claim  50 to 208 ZJ/decade, or warming between 0.02 to 0.07 c/decade

And the Climate Show Goes On

Benny Peiser of GWPF objected in writing to IPCC, saying inter alia:

Your report (SROCC, p. 5-14) concludes that
” The rate of heat uptake in the upper ocean (0-700m) is very likely higher in the 1993-2017 (or .2005-2017) period compared with the 1969-1993 period (see Table 5.1).”

We would like to point out that this conclusion is based to a significant degree on a paper
by Cheng et al. (2019) which itself relies on a flawed estimate by Resplandy et al. (2018).
An authors’ correction to this paper and its ocean heat uptake (OHU) estimate was under
review for nearly a year, but in the end Nature requested that the paper be retracted
(Retraction Note, 2019).

That was not the only objection. Nic Lewis examined Cheng et al. 2019 and found it wanting. That discussion is also at Climate Etc. Is ocean warming accelerating faster than thought? The authors replied to Lewis’ critique but did not refute or correct the identified errors.

Now in 2022 the same people have processed another year of data in the same manner and then proclaim the same result. The only differences are the addition of several high profile alarmists and the subtraction of Resplandy et al. from the References.  It looks like the group is emulating MIchael Mann’s blueprint:  The Show Must Go On.  The Noble cause justifies any and all means.

Show no weaknesses, admit no mistakes, correct nothing, sue if you have to.

Footnote: Q: Is the Ocean Warming or Cooling?  A: Nobody Knows.

To enlarge, open image in new tab.

 

 

 

The Cooling Also Not Our Fault

Posted on by Ron Clutz

With the lack of global warming and the steep decline of surface temperatures the last 6 to 8 months, climatists are pivoting to the notion invented by the infamous M. Mann, AKA Mr. Hockey Stick (aiming to erase the Medieval warming period).  The reasoning is convoluted, as you might expect given the intent to blame cold weather on global warming.  The claim is that burning fossil fuels causes the North Atlantic Current to slow down and bring cold temperatures to the Northern Hemisphere.  The video below is an excellent PR piece promoting this science fiction as though it were fact.

 

The link below allows you to view it in its natural habitat (USA Today)

https://www.usatoday.com/videos/tech/science/2019/03/20/ocean-conveyor-belt-slowdown-could-lead-major-climate-changes/3223463002/

Science Facts to Counter Science Fiction

Natural variability has dominated Atlantic Meridional Overturning Circulation since 1900
Mojib Latif et al. published April 2022 Nature Climate Change.  Excerpts in italics with my bolds.

Abstract

There is debate about slowing of the Atlantic Meridional Overturning Circulation (AMOC), a key component of the global climate system. Some focus is on the sea surface temperature (SST) slightly cooling in parts of the subpolar North Atlantic despite widespread ocean warming. Atlantic SST is influenced by the AMOC, especially on decadal timescales and beyond. The local cooling could thus reflect AMOC slowing and diminishing heat transport, consistent with climate model responses to rising atmospheric greenhouse gas concentrations.

Here we show from Atlantic SST the prevalence of natural AMOC variability since 1900. This is consistent with historical climate model simulations for 1900–2014 predicting on average AMOC slowing of about 1 Sv at 30° N after 1980, which is within the range of internal multidecadal variability derived from the models’ preindustrial control runs. These results highlight the importance of systematic and sustained in-situ monitoring systems that can detect and attribute with high confidence an anthropogenic AMOC signal.

Main

Global surface warming (global warming hereafter) since the beginning of the twentieth century is unequivocal, and humans are the main cause through the emission of vast amounts of greenhouse gases (GHGs), especially carbon dioxide (CO2)1,2,3. The oceans have stored more than 90% of the heat trapped in the climate system caused by the accumulation of GHGs in the atmosphere, thereby contributing to sea-level rise and leading to more frequent and longer lasting marine heat waves4. Moreover, the oceans have taken up about one third of the total anthropogenic CO2 emissions since the start of industrialization, causing ocean acidification5. Both ocean warming and acidification already have adverse consequences for marine ecosystems6. Some of the global warming impacts, however, unfold slowly in the ocean due to its large thermal and dynamical inertia. Examples are sea-level rise and the response of the Atlantic Meridional Overturning Circulation (AMOC), a three-dimensional system of currents in the Atlantic Ocean with global climatic relevance7,8,9,10.

[Comment: The paragraph above is the obligatory statement of fidelity to the Climatist Creed. All the foundational claims are affirmed with references to prove the authors above reproach, and not to be dismissed as denialists.  As further evidence of their embrace of IPCC consensus science, consider the diagrams below.

a, The NAWH SST index (°C), defined as the annual SST anomalies averaged over the region 46° N–62° N and 46° W–20° W. Observations for 1900–2019 from ERSSTv.5 (orange) and Kaplan SST v.2 (yellow), and ensemble-mean SST for 1900–2014 (dark blue line) from the historical simulations with the CMIP6 models and the individual historical simulations (thin grey lines) are shown. b, Same as a but for the NA-SST index (°C), defined as the annual SST anomalies averaged over the region 40° N–60° N and 80° W–0° E. c, Same as a but for the AMO/V (°C) index, defined as the 11-year running mean of the annual SST anomalies averaged over the region 0° N–65° N and 80° W–0° E. The SST indices in a–c are calculated as area-weighted means. d, NAO index (dimensionless) for 1900–2019 (red), defined as the difference in the normalized winter (December–March) sea-level pressure between Lisbon (Portugal) and Stykkisholmur/Reykjavik (Iceland). The blue curve indicates the equivalent CO2 radiative forcing (W m−2) for 1900–2019, which is taken from the Representative Concentration Pathway (RCP) SSP5-8.5 after 2014.

Chart d shows the NAO fluxes compared to a CO2 forcing curve based upon the much criticized RCP 8.5 scenario, which is not “business-as-usual” but rather “business-impossible.” Using it shows the authors bending over backwards to give every chance for confirming the alarming slowdown narrative.  The next paragraph gives the entire game away]

Climate models predict substantial AMOC slowing if atmospheric GHG concentrations continue to rise unabatedly1,11,12,13,14. Substantial AMOC slowing would drive major climatic impacts such as shifting rainfall patterns on land15, accelerating regional sea-level rise16,17 and reducing oceanic CO2 uptake. However, it is still unclear as to whether sustained AMOC slowing is underway18,19,20,21,22. Direct ocean-circulation observation in the North Atlantic (NA) is limited9,23,24,25,26,27. Inferences drawn about the AMOC’s history from proxy data28 or indices derived from other variables, which may provide information about the circulation’s variability (for example, sea surface temperature (SST)21,29,30, salinity31 or Labrador Sea convection32), are subject to large uncertainties.

Discussion

Observed SSTs and a large ensemble of historical simulations with state-of-the-art climate models suggest the prevalence of internal AMOC variability since the beginning of the twentieth century. Observations and individual model runs show comparable SST variability in the NAWH region. However, the models’ ensemble-mean signal is much smaller, indicative of the prevalence of internal variability. Further, most of the SST cooling in the subpolar NA, which has been attributed to anthropogenic AMOC slowing21, occurred during 1930–1970, when the radiative forcing did not exhibit a major upward trend. We conclude that the anthropogenic signal in the AMOC cannot be reliably estimated from observed SST. A linear and direct relationship between radiative forcing and AMOC may not exist. Further, the relevant physical processes could be shared across EOF modes, or a mode could represent more than one process.

A relatively stable AMOC and associated northward heat transport during the past decades is also supported by ocean syntheses combining ocean general circulation models and data76,77, hindcasts with ocean general circulation models forced by observed atmospheric boundary conditions78 and instrumental measurements of key AMOC components9,22,79,80,81.

Neither of these datasets suggest major AMOC slowing since 1980, and neither of the AMOC indices from Rahmstorf et al.20 or Caesar et al.21 show an overall AMOC decline since 1980.

Contextual Background

From the Energy MIx Changes in Atlantic Current May Fall Within Natural Variability.  

In the February, 2022, edition of the journal Nature Geoscience, researchers at the University of Maryland Center for Environmental Science urged more detailed study of the notoriously complex Atlantic Meridional Overturning Circulation (AMOC). Now, oceanographer Mojib Latif and his team from the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany are repeating that call in a paper just published in the journal Nature Climate Change.

The latest study describes the AMOC as a “three-dimensional system of current in the Atlantic Ocean with global climatic relevance.”

The February study responded to an August 2021 warning from the Potsdam Institute
that the AMOC has become wildly unstable and dangerously weak
due to global warming caused by human activity.

The authors of the latest study affirm that the Earth’s oceans have taken up more than 90% of the accumulated heat and roughly a third of all CO2 emissions since the dawn of the industrial age, leading to clearly measurable and devastating impacts like marine heat waves, sea level rise, and ocean acidification.

But it isn’t easy to confirm that the Atlantic circulation is actually slowing, partly because the ocean possesses such “large thermal and dynamical inertia.”

It is also extremely difficult to directly observe ocean circulation patterns in the North Atlantic, and proxies like sea surface temperature are “subject to large uncertainties,” the scientists say. Based on the available data, the GEOMAR study attributes localized sea surface cooling in the North Atlantic since 1900 to natural AMOC variability—not, as had been hypothesized, to a global heating-induced breakdown in the AMOC’s capacity to transfer heat.

Footnote:

See also from Science Norway Researchers and the media need to stop crying ‘wolf’ about the Gulf Stream

 

Why Ocean Keeps Its Cool at 4 Celsius

Posted on by Ron Clutz

Water (H2O) has magical properties that make our planet suitable for us.  The video explains why most of the ocean water is about 4 degrees Celsius.  A transcript from another presentation draws the implications. Excerpts in italics with my bolds.

At the surface, ocean water can vary wildly in temperature – the water at the equator is around 30 degrees Celsius and the water at the poles is, well, freezing.  But surface waters are only a small fraction of the total water in the ocean.  Dive a little deeper, and you’ll find that a whopping 75 percent of the ocean’s water is all at the same temperature…and we’re not talking averages or anything – the vast majority of ocean water is 4 degrees Celsius.  And that’s not just a coincidence – it’s because water is weird.

As a liquid cools, its molecules slow down and the liquid generally gets denser and denser.  That’s how molten metals, wax, nacho cheese, and basically everything else behaves – except water.  Water does become denser as it cools though, but only up to a point.  Then it reverses course and actually gets less dense.

This happens because once water molecules slow down enough, intermolecular forces due to the water molecule’s unique shape start pushing the molecules apart until – at zero degrees and below – they form a lattice-like structure.  That’s why ice is less dense than water.

But the magic temperature where water is actually densest is 4 degrees Celsius. This weird maximum density is what causes the vast majority of the ocean to be stuck at the same temperature.

By about 1000 meters down, water has cooled to around four degrees. Any water here, or below, that happens to warm up – say, via heat from a hydrothermal vent or underwater volcano – will get a little less dense and float upwards, as less-dense things tend to do – out of this 4-degree zone.  Strangely, water cooler than 4 degrees will behave the same way; any water that loses a little bit of heat will also become a little less dense and balloon upwards.

As a result, all the ocean water below 1000 meters or so is about 4 degrees. 
Well, almost all the water. 

The very deepest parts of the ocean can get just a tiny bit colder, because of salt.  When salt ions are stuck to water molecules, they weigh them down, making saltier water a little denser than less salty water.  So when polar ice forms, salt gets pushed into the surrounding water, making it super-salty.  This super-salty water is most dense slightly below 4 degrees, in addition to being a little denser than less salty water, so, it has the tendency to plummet straight to the seafloor.

This heavier, colder water makes the deepest depths of the ocean slightly colder and denser than the water above.  Expeditions to the deepest parts of the ocean, like the Challenger Deep of Mariana’s Trench have recorded temperatures of 1 degree.  However, the same rules apply down there as they do in the rest of the water column – any water that warms or cools, even a bit, will become less dense and float away into the higher, less dense layers above.

If these weird water density rules didn’t apply – if water behaved like, say, nacho cheese – ocean water would just solidify from the bottom up as it’s cooled, and we wouldn’t have liquid oceans at all.

 

 

Why Climate Models Fail to Replicate the North Atlantic

Posted on by Ron Clutz

screenshot-2021-06-07-at-12.17.38-1024x539-1

A recent paper employed expert statistical analysis to prove that currently climate models fail to reproduce fluctuations of sea surface temperatures in the North Atlantic, a key region affecting global weather and climate.  H/T to David Whitehouse at GWPF for posting a revew of the paper.  I agree with him that the analysis looks solid and the findings robust.  However, as I will show below, neither Whitehouse nor the paper explicitly drew the most important implication.

At GWPF, Whitehouse writes Climate models fail in key test region (in italics with my bolds):

A new paper by Timothy DelSole of George Mason University and Michael Tippett of Columbia University looks into this by attempting to quantify the consistency between climate models and observations using a novel statistical approach. It involves using a multivariate statistical framework whose usefulness has been demonstrated in other fields such as economics and statistics. Technically, they are asking if two time series such as observations and climate model output come from the same statistical source.

To do this they looked at the surface temperature of the North Atlantic which is variable over decadal timescales. The reason for this variability is disputed, it could be related to human-induced climate change or natural variability. If it is internal variability but falsely accredited to human influences then it could lead over estimates of climate sensitivity. There is also the view that the variability is due to anthropogenic aerosols with internal variability playing a weak role but it has been found that models that use external forcing produce inconsistencies in such things as the pattern of temperature and ocean salinity. These things considered it’s important to investigate if climate models are doing well in accounting for variability in the region as the North Atlantic is often used as a test of a climate model’s capability.

The researchers found that when compared to observations, almost every CMIP5 model fails, no matter whether the multidecadal variability is assumed to be forced or internal. They also found institutional bias in that output from the same model, or from models from the same institution, tended to be clustered together, and in many cases differ significantly from other clusters produced by other institutions. Overall only a few climate models out of three dozen considered were found to be consistent with the observations.

The paper is Comparing Climate Time Series. Part II: A Multivariate Test by DelSole and Tippett.  Excerpts in italics with my bolds.

We now apply our test to compare North Atlantic sea surface temperature (NASST) variability between models and observations. In particular, we focus on comparing multi-year internal variability. The question arises as to how to extract internal variability from observations. There is considerable debate about the magnitude of forced variability in this region, particularly the contribution due to anthropogenic aerosols (Booth et al., 2012; Zhang et al., 2013). Accordingly, we consider two possibilities: that the forced response is well represented by (1) a second-order polynomial or (2) a ninth-order polynomial over 1854-2018. These two assumptions will be justified shortly.

If NASST were represented on a typical 1◦ × 1◦ grid, then the number of grid cells would far exceed the available sample size. Accordingly, some form of dimension reduction is necessary. Given our focus on multi-year predictability, we consider only large-scale patterns. Accordingly, we project annual-mean NASST onto the leading eigenvectors of the Laplacian over the Atlantic between 0 0 60◦N. These eigenvectors form an orthogonal set of patterns that can be ordered by a measure of length  scale from largest to smallest.

DelSole Tippett fig1

Figure 1. Laplacian eigenvectors 1,2,3,4,5,6 over the North Atlantic between the equator and 60◦N,  where dark red and dark blue indicate extreme positive and negative values, respectively

The first six Laplacian eigenvectors are shown in fig. 1 (these were computed by the method of DelSole and Tippett, 2015). The first eigenvector is spatially uniform. Projecting data onto the first Laplacian eigenvector is equivalent to taking the area-weighted average in the basin. In the case of SST, the time series for the first Laplacian eigenvector is merely an AMV index (AMV stands for “Atlantic Multidecadal Variability”). The second and third eigenvectors are dipoles that measure the large-scale gradient across the basin. Subsequent eigenvectors capture smaller scale patterns.  For model data, we use pre-industrial control simulations of SST from phase 5 of the Coupled Model Intercomparison Project (CMIP5 Taylor et al., 2012). Control simulations use forcings that repeat year after year. As a result, interannual variability in control simulations come from internal dynamical mechanisms, not from external forcing.

DelSole Tippett fig2Figure 2. AMV index from ERSSTv5 (thin grey), and polynomial fits to a second-order (thick black) and ninth-order (red) polynomial.

For observational data, we use version 5 of the Extended Reconstructed SST dataset (ERSSTv5 Huang et al., 2017). We consider only the 165-year period 1854-2018. We first focus on time series for the first Laplacian eigenvector, which we call the AMV index. The corresponding least squares fit to second- and ninth-order polynomials in time are shown in fig. 2. The second-order polynomial captures the secular trend toward warmer temperatures but otherwise has weak multidecadal variability. In contrast, the ninth-order polynomial captures both the secular trend and multidecadal variability. There is no consensus as to whether this multidecadal variability is internal or forced. 

DelSole Tippett fig4

Figure 4. Deviance between ERSSTv5 1854-1935 and 82-year segments from 36 CMIP5 pre-industrial control simulations. Also shown is the deviance between ERSSTv5 1854-1935 and ERSSTv5 1937-2018 (first item on x-axis). The black and red curves show, respectively, results after removing a second- and ninth-order polynomial in time over 1854-2018 before evaluating the deviance. The models have been ordered on the x-axis from smallest to largest deviance after removing a second-order polynomial in time.

Conclusion:

The test was illustrated by using it to compare annual mean North Atlantic SST variability in models and observations. When compared to observations, almost every CMIP5 model differs significantly from ERSST. This conclusion holds regardless of whether a second- or ninth-order polynomial in time is regressed out. Thus, our conclusion does not depend on whether multidecadal NASST variability is assumed to be forced or internal. By applying a hierarchical clustering technique, we showed that time series from the same model, or from models from the same institution, tend to be clustered together, and in many cases differ significantly from other clusters. Our results are consistent with previous claims (Pennell and Reichler, 2011; Knutti et al., 2013) that the effective number of independent models is smaller than the actual number of models in a multi-model ensemble.

The Elephant in the Room

Now let’s consider the interpretation reached by model builders after failing to match observations of Atlantic Multidecadal Variability.  As an example consider INMCM4, whose results deviated greatly from the ERSST5 dataset.  In 2018, Evgeny Volodin and Andrey Gritsun published Simulation of observed climate changes in 1850–2014 with climate model INM-CM5.   Included in those simulations is a report of their attempts to replicate North Atlantic SSTs.  Excerpts in italics with my bolds.

esd-9-1235-2018-f04

Figure 4 The 5-year mean AMO index (K) for ERSSTv4 data (thick solid black); model mean (thick solid red). Dashed thin lines represent data from individual model runs. Colors correspond to individual runs as in Fig. 1.

Keeping in mind the argument that the GMST slowdown in the beginning of the 21st century could be due to the internal variability of the climate system, let us look at the behavior of the AMO and PDO climate indices. Here we calculated the AMO index in the usual way, as the SST anomaly in the Atlantic at latitudinal band 0–60∘ N minus the anomaly of the GMST. The model and observed 5-year mean AMO index time series are presented in Fig. 4. The well-known oscillation with a period of 60–70 years can be clearly seen in the observations. Among the model runs, only one (dashed purple line) shows oscillation with a period of about 70 years, but without significant maximum near year 2000. In other model runs there is no distinct oscillation with a period of 60–70 years but a period of 20–40 years prevails. As a result none of the seven model trajectories reproduces the behavior of the observed AMO index after year 1950 (including its warm phase at the turn of the 20th and 21st centuries).

One can conclude that anthropogenic forcing is unable to produce any significant impact on the AMO dynamics as its index averaged over seven realization stays around zero within one sigma interval (0.08). Consequently, the AMO dynamics are controlled by the internal variability of the climate system and cannot be predicted in historic experiments. On the other hand, the model can correctly predict GMST changes in 1980–2014 having the wrong phase of the AMO (blue, yellow, orange lines in Figs. 1 and 4).

esd-9-1235-2018-f01

Figure 1 The 5-year mean GMST (K) anomaly with respect to 1850–1899 for HadCRUTv4 (thick solid black); model mean (thick solid red). Dashed thin lines represent data from individual model runs: 1 – purple, 2 – dark blue, 3 – blue, 4 – green, 5 – yellow, 6 – orange, 7 – magenta. In this and the next figures numbers on the time axis indicate the first year of the 5-year mean.

The Bottom Line

Since the models incorporate AGW in the form of CO2 sensitivity, they are unable to replicate Atlantic Multidecadal Variability.  Thus, the logical conclusion is that variability of North Atlantic SSTs is an internal, natural climate factor.

The-Elephant-in-the-RoomOMC