NOAA: Scientists Find 20 Years of Deep Water Warming Leading to Sea Level Rise
Sea-level rise has the potential to reshape the coastal environment. Credit: NOAA)
Scientists analyzing measurements taken in the deep ocean around the globe over the past two decades find a warming trend that contributes to sea level rise, especially around Antarctica.
Greenhouse gases in the atmosphere, such as carbon dioxide, cause heating of the Earth. Over the past few decades, at least 80 percent of this heat energy has gone into the ocean, warming it in the process.
“Previous studies have shown that the upper ocean is warming, but our analysis determines how much additional heat the deep ocean is storing from warming observed all the way to the ocean floor,” said Sarah Purkey, an oceanographer at the University of Washington and lead author of the study.
This study shows that the deep ocean – below about 3,300 feet – is taking up about 16 percent of what the upper ocean is absorbing. The authors note that there are several possible causes for this deep warming: a shift in Southern Ocean winds, a change in the density of what is called Antarctic Bottom Water, or how quickly that bottom water is formed near the Antarctic, where it sinks to fill the deepest, coldest portions of the ocean around much of the globe.
The scientists found the strongest deep warming around Antarctica, weakening with distance from its source as it spreads around the globe. While the temperature increases are small (about 0.03°C per decade in the deep Southern Ocean, less elsewhere), the large volume of the ocean over which they are found and the high capacity of water to absorb heat means that this warming accounts for a huge amount of energy storage. If this deep ocean heating were going into the atmosphere instead – a physical impossibility – it would be warming at a rate of about 3°C (over 5°F) per decade.
“A warming Earth causes sea level rise in two ways,” said Gregory Johnson, a NOAA oceanographer at the Pacific Marine Environmental Laboratory in Seattle, and the study’s co-author. “The warming heats the ocean, causing it to expand, and melts continental ice, adding water to the ocean. The expansion and added water both cause the sea to encroach on the land.”
Sea level has been rising at around 3 mm (1/8 of a inch) per year on average since 1993, with about half of that caused by ocean thermal expansion and the other half because of additional water added to the ocean, mostly from melting continental ice. Purkey and Johnson note that deep warming of the Southern Ocean accounts for about 1.2 mm (about 1/20th of an inch) per year of the sea level rise around Antarctica in the past few decades.
The highly accurate deep-ocean temperature observations used in this study come from ship-based instruments that measure conductivity through salinity, temperature and depth. These measurements were taken on a series of hydrographic surveys of the global ocean in the 1990s through the World Ocean Circulation Experiment and in the 2000s in support of the Climate Variability program. These surveys are now coordinated by the international Global Ship-based Hydrographic Investigations Program.
The study, “Warming of Global Abyssal and Deep Southern Ocean Waters between the 1990s and 2000s: Contributions to Global Heat and Sea Level Rise Budgets,” authored by Sarah G. Purkey and Gregory C. Johnson, will be published in an upcoming edition of the Journal of Climate.
NOAA’s mission is to understand and predict changes in the Earth’s environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Find us on Facebook.
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Here is the abstract:
2 NOAA/Pacific Marine Environmental Laboratory, Seattle WA 98115, USA
| Abstract |
|---|
We quantify abyssal global and deep Southern Ocean temperature trends between the 1990s and 2000s to assess the role of recent warming of these regions in global heat and sea level budgets. We compute warming rates with uncertainties along 28 full-depth, high-quality, hydrographic sections that have been occupied two or more times between 1980 and 2010. We divide the global ocean into 32 basins defined by the topography and climatological ocean bottom temperatures and estimate temperature trends in the 24 sampled basins. The three southernmost basins show a strong statistically significant abyssal warming trend, with that warming signal weakening to the north in the central Pacific, western Atlantic, and eastern Indian Oceans. Eastern Atlantic and western Indian Ocean basins show statistically insignificant abyssal cooling trends. Excepting the Arctic Ocean and Nordic seas, the rate of abyssal (below 4000 m) global ocean heat content change in the 1990s and 2000s is equivalent to a heat flux of 0.027 (±0.009) W m−2 applied over the entire surface of the Earth. Deep (1000–4000 m) warming south of the Sub-Antarctic Front of the Antarctic Circumpolar Current adds 0.068 (±0.062) W m−2. The abyssal warming produces a 0.053 (±0.017) mm yr−1 increase in global average sea level and the deep warming south of the Sub-Antarctic Front adds another 0.093 (±0.081) mm yr−1. Thus warming in these regions, ventilated primarily by Antarctic Bottom Water, accounts for a statistically significant fraction of the present global energy and sea level budgets.
Received: February 16, 2010; Revised: July 28, 2010; Revised: August 18, 2010
*Pacific Marine Environmental Laboratory Contribution Number 3524.
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Jeff L says:
September 26, 2010 at 11:38 am
Correct. The oceans drive the atmosphere. The warmth of the atmosphere is an expression of the warmth of the hydrosphere.
http://wattsupwiththat.com/2010/04/06/a-new-and-effective-climate-model/
Gordon Ford asked: “Also how many cubic kilometers of sediment are washed into the oceans each year?”
20 billion tons at 120 #/ft3. If my decimal places are correct, that amounts to 0.03mm average depth.
HockyShtick, hmmm…. infra-red radiation also is emitted by the sun.
It is that infra-red (heat) that is absorbed by the solar ponds. Typically, those ponds are around 10 feet (3 meters) deep.
Are you saying that the IR from atmospheric CO2 emissions is different in kind from solar IR? Different in wavelength, or amplitude?
Trenberth’s missing heat is very likely just a miscalibration of the 3000 Argo floats that came online exactly when he noticed that his heat was disappearing. I don’t know where these authors are going with their Southern Ocean temperatures. If you have to look at the ocean bottom to find global warming you are in bad shape. But evidently the idea brought grant money so here we are with another paper that goes nowhere. Expect more of the same with seven billion dollars to spend on climate research and propaganda.
Warming at deeper levels of the ocean could explain how the atmosphere is increasing CO2 with a lower abundance of 14C. There are at least two natural sources of CO2 where a temperature increase could shift the equilibrium between ocean and air. There seems to be an insufficient quantity of bicarbonate in the ocean to explain the CO2 rise, but the conversion of methane to CO2 may be a better explanation.
Accumulated methane clathrates on the sea floor depend on pressure and temperature to remain stable. These methane/water ices outgas at standard temperature and pressure, and can burn. At the margins of stability, a small change in temperature could cause the release of a large volume of methane over time. Methanothophs are bacteria that consume methane and release CO2. This CO2 would be old, and would be depleted in 14C. Similarly, ancient sediments rich in organic matter are digested by methanogens, releasing methane in the process. These bacteria produce methane more efficiently at higher temperature. As the deeper waters warm, marginal areas become more hospitable to methanogens and their rate of methane production rises. Ancient sediments can similarly be depleted, or at least reduced in 14C. The falling concentration of [14C]O2 in the atmosphere is not the smoking gun of AGW, where it is claimed the only source of 14C-depleted CO2 is burning fossil fuels.
As warmer waters reach more abundant sources of methane, the production of CO2 could accelerate. An acceleration of CO2 accumulation in the atmosphere has been observed since 1900.
As Siegenthaler and others observed in ice cores, CO2 changes follow temperature changes by 500 to 1200 years. What was happening roughly in the range of 400 to 1100 years ago? The Medieval Warm Period. Are we then surprised by an increasing temperature of deep ocean waters? Deep ocean currents might explain the time delay. Along with physical chemistry / thermodynamics, we should also consider a biological component in models of temperature change resulting in a delayed CO2 response.
Stephen Wilde wrote: The article said: “The scientists found the strongest deep warming around Antarctica, weakening with distance from its source as it spreads around the globe.”
So you are saying that warming surface water over the southern hemisphere causes it to expand and flow south where it is cooled and drops to great depth where it is still warmer than the water it displaces?
Which of these currents accomplishes that?
http://www.geology.iastate.edu/gccourse/ocean/images/image2.jpg
http://tinyurl.com/265d4t6
max says:
September 26, 2010 at 11:17 am
“Dirk
both can be right, it has to do with the time scales. On the time scale from 1989-2010 there has been warming, even though in the period from 2005-2008 there was cooling. One step forward and two steps back or something.”
I had the same idea; i just wanted to provide the link for others.
anna v says:
September 26, 2010 at 11:27 am
“I can comment on the statistics
0.027 (±0.009) W m−2 applied over the entire surface of the Earth.
This is according to them a 3 sigma effect. Possibly interesting, but could disappear as noise
Deep (1000–4000 m) warming south of the Sub-Antarctic Front of the Antarctic Circumpolar Current adds 0.068 (±0.062) W m−2.
This is barely 1 sigma, definitely noise.
The abyssal warming produces a 0.053 (±0.017) mm yr−1 increase in global average sea level and the deep warming south of the Sub-Antarctic Front adds another 0.093 (±0.081)
Adding noise to a weak 3 sigma putative signal , to more than double it, is not only a scientific misstep, it also betrays the authors as working on an agenda.
”
I had such a suspicion when i read “The three southernmost basins show a strong statistically significant abyssal warming trend”
– strong – statistically – significant – immediately made me think of Dr. Mann…
i think that kills it. It’ll be gone from the newspapers in no time, say…
6 months from now.
EFS_Junior says:
September 26, 2010 at 11:57 am
Well the article is behind a pay wall.
‘But wait, Underdog to the rescue, the author’s copy can be found here;
http://www.pmel.noaa.gov/people/gjohnson/Recent_AABW_Warming_v3.pdf‘
Thank you for the link. Much appreciated.
Dominic
DirkH says:
“[…]i think that kills it. It’ll be gone from the newspapers in no time, say…
6 months from now.”
…and it’s 3 months to Cancun. IOW, this is the time to publish the right kind of paper… The kind that is easily debunked but the debunking will be published *after* Cancun is over…
I aologise for not having read all comments before posting this – as always I am short of time.
In summary:
– they have found warming in the Antarctic equivalent to less than 0.1mm/yr sea level rise.
– avg rate of sea-level rise over the last 21k yrs is 5.7mm/yr (IPCC).
– they have no mechanism for the Antarctic acquiring the heat. Somehow it must have travelled there from the tropical troposphere (where AGW occurs – IPCC).
– they don’t rule out volcanoes as the source. Thx Verity Jones, and Ian W for posting link (which I haven’t read yet!)
http://www.sciencedaily.com/releases/2004/05/040527235943.htm
I would add that there is a lot of movement in the S ocean, with what appears to be multiple upwellings of warmer water, and much sinking of cooler water too of course. It is simply not possible for one or a small number of ships taking spot readings to determine overall heat content or trend in same.
See the warm patches (which I think show upwellings) around the S ocean here:
http://www.ldeo.columbia.edu/res/pi/CO2/carbondioxide/pages/air_sea_flux_2000.html
In haste, or I would look for references to S ocean upwellings.
Reply to Roger Sowell says: September 26, 2010 at 1:28 pm
yes about 45% of incoming solar radiation is IR – there is a chart of the solar spectrum in this post:
http://hockeyschtick.blogspot.com/2010/08/is-greenhouse-effect-is-based-on-cool.html
The IR causes skin evaporation only (and skin cooling which uptakes more CO2 as a negative feedback on CO2 levels)
But the more energetic solar UV and visible can penetrate & heat the oceans & solar ponds
http://hockeyschtick.blogspot.com/2010/08/why-greenhouse-gases-wont-heat-oceans.html
simpleseekeraftertruth says: at 11:16 am & W^L+ @ur momisugly 12:10
“Sea-level is a local phenomena?”
See the second paragraph under “Description”
http://en.wikipedia.org/wiki/Geoid
DCC said:
“So you are saying that warming surface water over the southern hemisphere causes it to expand and flow south where it is cooled and drops to great depth where it is still warmer than the water it displaces? ”
No,no,no.
The paper starts with a discussion of unexpected warmth at lower levels which got there from an unknown mechanism. We are not discussing surface waters at all.
Solar shortwave penetrates the ocean surface to a couple of hundred metres and they describe a finding whereby it has somehow gone even deeper. It is that deeper warmed water which is implicated in thermohaline circulation movements.
here is something more based on proper science:
Satellite altimetry and sea surface height analysis have recently revealed a previously unknown feature of the Antarctic Circumpolar Current, the Antarctic Circumpolar Wave. This wave propagates westward against the current but ultimately ends up traveling eastward, due to the massive size of the ACC, at a slower rate than the mean flow. The wave circles the earth every eight to nine years (White and Peterson, 1996). It has a long wavelength (wavenumber=2) resulting in two crests and two troughs at any given time. The crests and troughs are associated with massive patches or pools of warm water and cold water respectively. The areas can be thousands of kilometers long. The warm patches are 2 to 3°C warmer than the mean sea surface temperature (SST) and the cold patches are 2 to 3°C cooler than the mean SST (White and Peterson, 1996). Though it is not yet clear how these waves are triggered or maintained, they directly influence the temperature of the overlying atmosphere. While the Wave’s effects on climate are just beginning to be studied, the phase (warm pool vs. cold pool) correlates well with four to five year rainfall cycles found over areas of southern Australia and New Zealand (White and Cherry, 1998). Some scientists believe that the Antarctic Circumpolar Wave may be more important than El Niño in governing rainfall over these regions.
http://oceancurrents.rsmas.miami.edu/southern/antarctic-cp.html
anna v says:
September 26, 2010 at 11:27 am
I can comment on the statistics
0.027 (±0.009) W m−2 applied over the entire surface of the Earth.
– This is according to them a 3 sigma effect. Possibly interesting, but could disappear as noise
Deep (1000–4000 m) warming south of the Sub-Antarctic Front of the Antarctic Circumpolar Current adds 0.068 (±0.062) W m−2.
– This is barely 1 sigma, definitely noise.
The abyssal warming produces a 0.053 (±0.017) mm yr−1 increase in global average sea level and the deep warming south of the Sub-Antarctic Front adds another 0.093 (±0.081)
– Adding noise to a weak 3 sigma putative signal , to more than double it, is not only a scientific misstep, it also betrays the authors as working on an agenda.
What sort of peer reviews are these that do not catch so elementary scientific errors ?
====
It hasn’t been published yet, “… will be published in an upcoming edition of the Journal of Climate.”
Its possible the Study hasn’t been Peer Reviewed but its been revised a couple of times.
DCC,
Some helpful material from vuk there.
And even from your link the warm current from the Pacific circles Antarctica before heading north so one would expect an accumulation of energy around Antarctica.
Their panic will probably be unfounded soon as they discover volcanic and mantle heating as a cause for deep ocean temps. Silly buggers.. 😉
Verity Jones says:
September 26, 2010 at 10:41 am
John said at 10:07 am
evanmjones said at 9:23 am
I have done several ‘back of envelope’ calculations on volcanic heating of water (a while back) and come up with quite small numbers which may actually be worth revisiting in the light of this.
I’ve always considered the role of volcanoes not to be significant in the amount of heat they generate, but rather in the fact they set up convection columns which distribute the heat much more effectively than normal.
It’s a bit like the heat from the fan in a fan-assisted oven doesn’t really help the cooking times – but the cooking times improve out of all proportion anyway.
(The morning after a wild drunkered party)
New discovery: After detecting lipstick marks with the use of small handheld mirror, evidence was found to indicate he could kiss himself on the back of the head, with only the use of alkohol.
In the same way, CO2 produced by man’s emissions is the most likely explanation for fractional changes to deep ocean temperatures, say the experts. Hmmmm^*(&$.
Maybe its all one and the same thing: the effect of alkohol?
“The highly accurate deep-ocean temperature observations used in this study come from ship-based instruments that measure conductivity through salinity, temperature and depth” results in “about 0.03°C per decade in the deep Southern Ocean, less elsewhere”.
1.Ship-based instruments: How accurate were these instruments?
2. What was the margin of error? The report does not specify this.
3.How can one write “about 0.03C”?
4.How can one continue with: “less elswhere”, how much less is “less” and how big is “elswhere”?
I always suspected that someday someone would ‘discover’ Trenberth’s elusive temperature rise. Now comes a magician and finds 0.03C per decade, that is 0.003C per year but not everywhere, but somewhere, with less elswhere. LOL.
Its worse than I thought.
The oceans act as a capacitor for storing heat energy with minimal global temperature rises during (natural) global warming times, and releasing that energy during (natural) global cooling periods, thus flattening the sinusoidal temperature curve along the centuries and thankfully saving us from climate extremes. With much smaller oceans, this planet would be hell during warmings and freezing during coolings. As it is, this is a perfectly designed planet, but the alarmists want to redesign it according to their own needs. Stay off please. I like the planet as it is.
I’ve referenced this paper in comments here a number of times, but it has been a while
http://www.ocean-sci.net/5/203/2009/os-5-203-2009.pdf
Geothermal heating, diapycnal mixing and the abyssal circulation
J. Emile-Geay1 and G. Madec2,*
The essential finding of this work is that geothermal heating at abyssal depths has been seriously underestimated and it likely is most influential at high latitudes in the North Pacific and most pertinent to this paper in the AABW circulation.
“– In that sense, it is directly analogous to diapycnal mixing, both qualitatively and quantitatively. It has a similar effect on bottom water, eroding extrema of the global T- S diagram and depositing a comparable amount of heat in the abyss. On a global scale, it is in fact equivalent toa diapycnal mixing coefficient of ∼1.2×10−4 m2 s−1 at
3500 m, i.e. the canonical value of (Munk, 1966).”
“– A remarkable finding is that the increase in ocean heat transport was nearly constant across experiments, despite the broad range of thermal and circulation changes they encompass. The presence of a geothermal heatflow, whether spatially variable or not, means that the ocean must evacuate an additional 0.03 PW, which it does in all cases by enhancing poleward heat transport in the Southern Hemisphere, by about 10% near 50◦ S.”
“The case is hereby made that geothermal heating is an important actor of abyssal dynamics. We recommend its inclusion in every model dealing with the long-term ocean circulation, for it substantially alters bottom water mass characteristics and generates a non-negligible circulation in the present-day climate.”
I haven’t had time to peruse all of the paper referenced in this post, but given the relatively infinitesimal variations of ocean heat they seem to be citing, if they haven’t dealt with the geothermal component in the light of Emile-Geay and Madec’s work, they are probably overstating even the small changes they are suggesting.
I am starting to realize that these ultra-microfocused studies lack an honest scientific integrator to tie them into verifiable theories or they (ultra-microfocused studies) are just not providing actually any real differentiation for the integrator to objectively deal with.
John
@ur momisugly Richard111 : September 26, 2010 at 10:13 am
Good catch Richard. What it does tend to indicate is that there was a decadal upward SW irradiance trend over this same long period and you seem right, it is the SW that has buried this deep. You also seem right that they cannot dance with the logic that this was surface LW from the top 1 mm or the air temperature, everyone in their dance would be steping all over the others!
Davidmhoffer writes:
“With no physical mechanism to move the heat content from CO2 to the depths of the oceans, all they have reported is some interesting data that has no more to do with warming from GHG than it does with the sinking of the Titanic.”
Something tells me that Trenberth has a homey-reviewed paper titled “Down Radiation From CO2 At Sea Surface” which explains how massive amounts of CO2 collect just at the sea surface, catch radiation escaping from the water, and hurl it down into the depths of the ocean.