Paper: Record-Setting Ocean Warmth Continued in 2019

[donsutherland1]

Abstract:

uman-emitted greenhouse gases (GHGs) have resulted in a long-term and unequivocal warming of the planet (IPCC, 2019). More than 90% of the excess heat is stored within the world’s oceans, where it accumulates and causes increases in ocean temperature (Rhein et al., 2013; Abram et al., 2019). Because the oceans are the main repository of the Earth’s energy imbalance, measuring ocean heat content (OHC) is one of the best way to quantify the rate of global warming (Trenberth et al., 2016; Von Schuckmann et al., 2016; Cheng et al., 2018). Following reports released in the previous two years (Cheng and Zhu, 2018; Cheng et al., 2019c), this article presents new OHC data for the year 2019. These data reveal that the world’s oceans (especially at upper 2000 m) in 2019 were the warmest in recorded human history. Specifically, the ocean heat anomaly (0−2000 m) in 2019 was 228 Zetta Joules (ZJ, 1 ZJ=1021 Joules) above the 1981−2010 average and 25 ZJ above 2018 (Table 1).

The OHC values (for the upper 2000 m) were obtained from the Institute of Atmospheric Physics (IAP) ocean analysis (see "Data and methods" section, below), which uses a relatively new method to treat data sparseness and updates in the instruments that have been used to measure ocean temperature (Cheng et al., 2017). The evolution of OHC (Fig. 1) shows that the upper 2000 m OHC in 2019 was 228 ± 9 ZJ above the 1981–2010 average. The record-setting ocean warmth is also found in National Oceanic and Atmospheric Administration/National Center for Environmental Information (NOAA/NCEI) data, showing 217± 4 ZJ in 2019 above 1981−2010 average (21 ZJ above 2018) (Table 1) (updated from Levitus et al. 2012). With these newly available IAP data, a ranking of the warmest years since 1950s is now possible (Table 1). The past five years are the top five warmest years in the ocean historically with modern instruments, and the past ten years are also the top ten years on record. The same ranking also applies to NOAA/NCEI data (Table 1).

The full paper can be viewed here: https://link.springer.com/content/pdf/10.1007%2Fs00376-020-9283-7.pdf

[chubbs]

From Lijeng Cheng's twitter - 2019 ended on a high note.

[etudiant]

Powerful stuff! 

Can anyone help put the heat content change into perspective? The increase of roughly 300 Zetta Joules since the 1980s is what percentage of the annual global heat budget?

 

[bdgwx]

So to put that in perspective the change from 1985 to 2019 is about 350e21 joules (eyeballing for now). The average uptake is thus...

350e21 (OHC-joules) / (31.56e6 (seconds in year) * 34 (years))  / 510e12 (Earth area-m^2) = 0.64 W/m^2.

The ocean takes up about 90% of the imbalance so we can probably estimate the average imbalance as 0.64 / 0.9 = +0.7 W/m^2.

That is a pretty large imbalance and is inline with expectations of the net radiative force from all agents subtracted off from what has already equilibriated to raise the global mean temperature.

Over the last 10 years this imbalance actually works out to about +1.0 W/m^2. The implication...even if GHG emissions were to cease instantly there is still a lot of warming waiting in the pipeline that needs to equilibriate.

 

 

[bdgwx]

5 hours ago, etudiant said:

Powerful stuff! 

Can anyone help put the heat content change into perspective? The increase of roughly 300 Zetta Joules since the 1980s is what percentage of the annual global heat budget?

 

Using my +0.7 W/m^2 figure above and dividing by 240 W/m^2 yields = 0.7 / 240 = 0.3% of the surface budget. However, keep in mind that +0.7 W/m^2 is just the imbalance that still needs to equilibriate. The energy imbalance from the past that has caused 1.1C of warming has already equilibriated so is not included in my +0.7 W/m^2 value. This additional energy is probably in the 1.5-2.0 W/m^2 'ish range (just guessing right now). If you include that then we're probably close to 1% of the surface budget.

[etudiant]

7 hours ago, bdgwx said:

Using my +0.7 W/m^2 figure above and dividing by 240 W/m^2 yields = 0.7 / 240 = 0.3% of the surface budget. However, keep in mind that +0.7 W/m^2 is just the imbalance that still needs to equilibriate. The energy imbalance from the past that has caused 1.1C of warming has already equilibriated so is not included in my +0.7 W/m^2 value. This additional energy is probably in the 1.5-2.0 W/m^2 'ish range (just guessing right now). If you include that then we're probably close to 1% of the surface budget.

Thank you! That is both informative and very helpful.

[etudiant]

Trying to translate this measurement into actual temperature impact, I estimate as follows.

The increased heat content since 1990 of 300 or so zettajoules (300x10**21 joules) is spread over perhaps the top one third of the oceanic volume of roughly 1.3 billion cubic kilometers.

That is roughly 400 million cubic kilometers. (400x10**6 cubic kilometers).  A cubic kilometer contains 10**9 cubic meters, each of which contains 10**6 cubic centimeters of water, so the relevant ocean volume is about 400 zettacubic centimeters (10**21 cubic centimeters) of water. Rounding, it means the added heat content is about a joule per cubic centimeter.

It takes about 4 joules to raise the temperature of 1 cubic centimeter of water 1 degree C, so the added heat increases the temperature by about a quarter of a degree C.

At first glance, that does not seem much, but it really highlights how massively important the oceans are to our survival. They buffer the imbalances hugely.

 

 

 

 

 

 

[psv88]

https://www.bbc.com/news/science-environment-51111176

[chubbs]

On 1/15/2020 at 8:24 AM, etudiant said:

Trying to translate this measurement into actual temperature impact, I estimate as follows.

The increased heat content since 1990 of 300 or so zettajoules (300x10**21 joules) is spread over perhaps the top one third of the oceanic volume of roughly 1.3 billion cubic kilometers.

That is roughly 400 million cubic kilometers. (400x10**6 cubic kilometers).  A cubic kilometer contains 10**9 cubic meters, each of which contains 10**6 cubic centimeters of water, so the relevant ocean volume is about 400 zettacubic centimeters (10**21 cubic centimeters) of water. Rounding, it means the added heat content is about a joule per cubic centimeter.

It takes about 4 joules to raise the temperature of 1 cubic centimeter of water 1 degree C, so the added heat increases the temperature by about a quarter of a degree C.

At first glance, that does not seem much, but it really highlights how massively important the oceans are to our survival. They buffer the imbalances hugely.

 

 

 

 

 

 

Here are 0 to 700m ocean temperatures. Your estimate is pretty good. The top 100m have warmed twice as fast.

[bobjohnsonforthehall]

I question the uncertainty range of this study. I seriously doubt that measurements going back to the 1960's regarding the top two kilometers of ocean temperature are accurate within plus or minus .003 degrees celsius. That seems highly problematic. The number of buoys that are currently in use versus the number it would take to truly measure enough of the ocean down to two kilometers is also quite problematic. As is the fact that this buoy system has only been in place since 2005.

 

Finally, even if one assumes their problematic findings are indeed accurate, it will take some 300+ years for the oceans to warn by a single degree. Not exactly alarming. And to say with certainty that the change in temperature is 100% due to human causes as opposed to cloud cover or El Nino frequency, or any number of other slight variances in a highly complex climate system seems to me very definition of arrogance.

[LibertyBell]

On 1/14/2020 at 9:51 AM, etudiant said:

Powerful stuff! 

Can anyone help put the heat content change into perspective? The increase of roughly 300 Zetta Joules since the 1980s is what percentage of the annual global heat budget?

 

the amount of heat being added to the oceans is the equivalent of 5 Hiroshima level atomic bombs EVERY SECOND!  Also read the paper on oceanic heatwaves that was posted earlier, pretty eyeopening....

 

[LibertyBell]

2 hours ago, bobjohnsonforthehall said:

I question the uncertainty range of this study. I seriously doubt that measurements going back to the 1960's regarding the top two kilometers of ocean temperature are accurate within plus or minus .003 degrees celsius. That seems highly problematic. The number of buoys that are currently in use versus the number it would take to truly measure enough of the ocean down to two kilometers is also quite problematic. As is the fact that this buoy system has only been in place since 2005.

 

Finally, even if one assumes their problematic findings are indeed accurate, it will take some 300+ years for the oceans to warn by a single degree. Not exactly alarming. And to say with certainty that the change in temperature is 100% due to human causes as opposed to cloud cover or El Nino frequency, or any number of other slight variances in a highly complex climate system seems to me very definition of arrogance.

increasing severity of el nino has also been connected to AGW.

 

[bobjohnsonforthehall]

25 minutes ago, LibertyBell said:

the amount of heat being added to the oceans is the equivalent of 5 Hiroshima level atomic bombs EVERY SECOND!  Also read the paper on oceanic heatwaves that was posted earlier, pretty eyeopening....

 

And the amount of heat being added to the oceans BY THE SUN is what? A thousand times that? Every second? Yawn.

[bobjohnsonforthehall]

25 minutes ago, LibertyBell said:

increasing severity of el nino has also been connected to AGW.

 

That doesn't do anything to answer my post regarding the sensitivity and accuracy of the math used in the paper.

[LibertyBell]

55 minutes ago, bobjohnsonforthehall said:

And the amount of heat being added to the oceans BY THE SUN is what? A thousand times that? Every second? Yawn.

the sun has existed for 5 billion years and the rate at which it has been adding heat has been fairly constant (note I said "fairly").  If that weren't true, life as we know it would not exist.

 

[bdgwx]

1 hour ago, bobjohnsonforthehall said:

And the amount of heat being added to the oceans BY THE SUN is what? A thousand times that? Every second? Yawn.

Heat is the transfer of thermal energy. For the body being warmed/cooled it requires a net positive/negative flow of energy. If I am to interpret your question in precise terms then it is equivalent to asking...of the Earth Energy Imbalance (EEI) how much does the Sun contribute? The answer is effectively nothing. The reason is because total solar irradiance is not increasing. In fact, if anything it has actually been decreasing, albeit by a small amount, over the last few decades. I'm going to estimate the RF of the Sun over this period at about -0.01 W/m^2 as compared to the EEI of +0.70 W/m^2. In order of magnitude terms you might say it is 1/100th and in the opposite direction. 

Now if the question were...how much energy is being added by the Sun then the answer is about 240 W/m^2. This is the effective solar ingress flux near the surface. It is about 300x the EEI. Don't forget about the near surface egress fluxes though!

[bdgwx]

1 hour ago, bobjohnsonforthehall said:

That doesn't do anything to answer my post regarding the sensitivity and accuracy of the math used in the paper.

You can see in the graph that @chubbs posted that the 2σ (95%) confidence envelope is delineated by the green error bars.

[bdgwx]

4 hours ago, bobjohnsonforthehall said:

Finally, even if one assumes their problematic findings are indeed accurate, it will take some 300+ years for the oceans to warn by a single degree.

Fun with math. The ocean has a mass of about 1.4e21 kg. The specific heat capacity is about 4 kj/kg. This means it would require 5.6e24 joules of energy to increase the mean temperature of the ocean by 1.0C. This would require an EEI of +1.2 W/m^2 to persist for 300 years. A smaller +0.7 W/m^2 imbalance is causing the GMST to increase by about +0.2C/decade. I doubt the relationship would be linear but you can certainly do an order of magnitude estimate on what might happen if we added 5.6 yottajoules of energy to geosphere over a 300 year period. Hint...hothouse Earth might be something worth researching.

4 hours ago, bobjohnsonforthehall said:

And to say with certainty that the change in temperature is 100% due to human causes as opposed to cloud cover or El Nino frequency, or any number of other slight variances in a highly complex climate system seems to me very definition of arrogance.

It's a good thing then that no reputable scientific work claims that climate forcing agents are known with perfect certainty nor is it claimed that anthroprogenically modulated forcing agents are the only contributors to changes in temperature. I highly recommend reading IPCC AR5 WGI chapter 8 on radiative forcings for a brief summary of the agents in play and estimates of their magnitudes and uncertainty. ENSO, clouds, and likely a bunch of stuff that you haven't even thought of are all actively researched. I think what you'll find when looking at the academic literature is that the exact opposite of arrogance is happening in climate science.

 

[bobjohnsonforthehall]

1 hour ago, LibertyBell said:

the sun has existed for 5 billion years and the rate at which it has been adding heat has been fairly constant (note I said "fairly").  If that weren't true, life as we know it would not exist.

 

Correct. Just pointing out that the old "Hiroshima bomb" tripe is used for sensationalism and is not in any sort of context. I am simply giving it context.

[bobjohnsonforthehall]

48 minutes ago, bdgwx said:

Heat is the transfer of thermal energy. For the body being warmed/cooled it requires a net positive/negative flow of energy. If I am to interpret your question in precise terms then it is equivalent to asking...of the Earth Energy Imbalance (EEI) how much does the Sun contribute? The answer is effectively nothing. The reason is because total solar irradiance is not increasing. In fact, if anything it has actually been decreasing, albeit by a small amount, over the last few decades. I'm going to estimate the RF of the Sun over this period at about -0.01 W/m^2 as compared to the EEI of +0.70 W/m^2. In order of magnitude terms you might say it is 1/100th and in the opposite direction. 

Now if the question were...how much energy is being added by the Sun then the answer is about 240 W/m^2. This is the effective solar ingress flux near the surface. It is about 300x the EEI.

Jan 2014 Skeptical Science:
“… in 2013 ocean warming rapidly escalated, rising to a rate in excess of 12 Hiroshima bombs per second”

https://skepticalscience.com/The-Oceans-Warmed-up-Sharply-in-2013-We-are-Going-to-Need-a-Bigger-Graph.html

So I guess we are looking better then? 

Five Hiroshima bombs is the equivilant of 0.6 watts per square meter. Downwelling energy at the surface is about half a kilowatt per square meter. 

Context.

[bobjohnsonforthehall]

47 minutes ago, bdgwx said:

You can see in the graph that @chubbs posted that the 2σ (95%) confidence envelope is delineated by the green error bars.

Argo in situ calibration experiments reveal measurement errors of about ±0.6 C.

Hadfield, et al., (2007), J. Geophys. Res., 112, C01009, doi:10.1029/2006JC003825

False precision is fun.

[bdgwx]

1 hour ago, bobjohnsonforthehall said:

Argo in situ calibration experiments reveal measurement errors of about ±0.6 C.

Hadfield, et al., (2007), J. Geophys. Res., 112, C01009, doi:10.1029/2006JC003825

False precision is fun.

This paper is not relevant to the error for the annual OHC anomaly or annual global temperature. Nor is the quoted 0.6C figure the measurement error that can be expected from an ARGO float which is said to be approximately ±0.002C for individual measurements. The 0.6C figure is the RMS error of ARGO derived hydrographic section temperature fields. These sections are computed even in lieu of being occupied by an ARGO float at each grid cell. Using the WOA (World Ocean Atlas) dimensions we can estimated 75x30 = 2250 grid cells along the cruise line of the hydrographic section used in the paper. If you were to then answer the question...what is the error of computed mean temperature of this hydrographic section then you might expect it to be 0.6/sqrt(2250) = ±0.01C using the standard error of the mean formula. In reality I suspect the actual error to be a bit different for a variety of reasons. I'm just giving you an order of magnitude estimate based on trivial statistical principals using the RMS error of the temperature field on that single hydrographic section mentioned in the publication. Note that this hydrographic section represents but an infinitesimally small part of a much larger 3D volume containing vastly many more grid cells by which to significantly reduce the error in the global mean temperature estimate if such a method were used. I do not see anything in this publication that is inconsistent with Cheng's OHC 2σ envelope. I do see that ARGO reduces the error by a factor 2 relative to the non-ARGO era. Perhaps this is why the 2σ envelope appears to be significantly reduced in later years on Cheng's graph?

[bdgwx]

1 hour ago, bobjohnsonforthehall said:

Downwelling energy at the surface is about half a kilowatt per square meter. 

Context.

Yeah, pretty close. Most estimates I've seen show DWIR to be about 345 W/m^2. The EEI would then be about 0.2% of that. I'm not sure how meaningful that is by itself though. Like you said...context.

[bobjohnsonforthehall]

12 minutes ago, bdgwx said:

This paper is not relevant to the error for the annual OHC anomaly or annual global temperature. Nor is the quoted 0.6C figure the measurement error that can be expected from an ARGO float which is said to be approximately ±0.002C for individual measurements. The 0.6C figure is the RMS error of ARGO derived hydrographic section temperature fields. These sections are computed even in lieu of being occupied by an ARGO float at each grid cell. Using the WOA (World Ocean Atlas) dimensions we can estimated 75x30 = 2250 grid cells along the cruise line of the hydrographic section used in the paper. If you were to then answer the question...what is the error of computed mean temperature of this hydrographic section then you might expect it to be 0.6/sqrt(2250) = ±0.01C using the standard error of the mean formula. In reality I suspect the actual error to be a bit different for a variety of reasons. I'm just giving you an order of magnitude estimate based on trivial statistical principals using the RMS error of the temperature field on that single hydrographic section mentioned in the publication. Note that this hydrographic section represents but an infinitesimally small part of a much larger 3D volume containing vastly many more grid cells by which to significantly reduce the error in the global mean temperature estimate. I do not see anything in this publication that is inconsistent with Cheng's OHC 2σ envelope.

One float covers an area the size of Portugal for goodness sake. And two kilometers deep. Are we to believe that one data point covering the entire country of Portugal is an accurate representation of temperature for the entire country? I should hope not. 

If we want to get within .03 instead of .003 accuracy, we could do so using 1/100th the number of points of measurement. So you are saying that we would be able to get within .03 of the actual temperature of the entire ocean with just 40 data points? I'm gonna say no to that one. Which is why I am saying that getting within .003 using 4000 data points is equally absurd.

[bobjohnsonforthehall]

1 minute ago, bdgwx said:

Yeah, pretty close. Most estimates I've seen show DWIR to be about 345 W/m^2. The EEI would then be about 0.2% of that. I'm not sure how meaningful that is by itself though. Like you said...context.

"Hiroshima bombs" sounds so bad and scary. That's why it is used. Scare the masses.

[bobjohnsonforthehall]

Per Chang et al, the average annual change in ocean heat content is 5.5 zettajoules per year...about 0.1% of the energy entering and leaving the ocean. Yet all we hear like a constant drum beat is that this tiniest of imbalances is due to human causes. We never hear about IPCC or others noting other possible causes. It is always humans. It is always critical. It is always an impending catastrophe, and it always requires a massive restructuring of human activity. When science runs into politics it generally degrades science.

[bdgwx]

34 minutes ago, bobjohnsonforthehall said:

Per Chang et al, the average annual change in ocean heat content is 5.5 zettajoules per year...about 0.1% of the energy entering and leaving the ocean.

Yeah. That's pretty close.

35 minutes ago, bobjohnsonforthehall said:

Yet all we hear like a constant drum beat is that this tiniest of imbalances is due to human causes.

That's because it is. At least post WWII it is. In fact, the anthroprogenic force has been so large during this period that it accounts for nearly 100% of the net force.

38 minutes ago, bobjohnsonforthehall said:

We never hear about IPCC or others noting other possible causes.

The IPCC considers all agents that are modulating the climate. They have to because the energy imbalance is modulated by the net affect of all energy fluxes; not just one of them. I posted a link to IPCC AR5 WGI chapter 8 above that provides a brief summary of the agents that have contributed to the modulation of Earth's energy budget.

39 minutes ago, bobjohnsonforthehall said:

It is always humans.

Not always. Humans either did not exist or were not capable of influencing the climate in the distant past. But here's the cool thing about the laws of physics. They stipulate that the radiative force induced by perturbations in GHGs are invariant of the actor that modulated them. In other words, GHG molecules have the exact same radiative behavior regardless of whether they are emitted by natural agents or by human agents. That's why GHGs are crucial and essential pieces of the puzzle in solving many paleoclimate mysteries like the PETM, glacial cycles, faint young Sun problem, etc.