[OANNES Foro] New research finds large buildup of heat in the oceans, suggesting a faster rate of global warming

[Mario Cabrejos]

The findings mean the world might have less time to curb carbon emissions.

Startling new research finds large buildup of heat in the oceans, suggesting
a faster rate of global warming

By  <https://www.washingtonpost.com/people/chris-mooney/> Chris Mooney and
<https://www.washingtonpost.com/people/brady-dennis/> Brady Dennis

October 31, 2018

 
<https://www.washingtonpost.com/energy-environment/2018/10/31/startling-new-
research-finds-large-buildup-heat-oceans-suggesting-faster-rate-global-warmi
ng/?utm_term=.12e974b2db74>
https://www.washingtonpost.com/energy-environment/2018/10/31/startling-new-r
esearch-finds-large-buildup-heat-oceans-suggesting-faster-rate-global-warmin
g/?utm_term=.12e974b2db74

 

The world’s oceans have been soaking up far more excess heat in recent
decades than scientists realized, suggesting that Earth could be set to warm
even faster than predicted in the years ahead, according to new research
published Wednesday.

Over the past quarter-century, Earth’s oceans have retained 60 percent more
heat each year than scientists previously had thought, said Laure Resplandy,
a geoscientist at Princeton University who led
<https://www.nature.com/articles/s41586-018-0651-8> the startling study
published Wednesday in the journal Nature. The difference represents an
enormous amount of additional energy, originating from the sun and trapped
by Earth’s atmosphere — the yearly amount representing more than eight times
the world’s annual energy consumption.

 

In the scientific realm, the new findings help resolve long-running doubts
about the rate of the warming of the oceans before 2007, when reliable
measurements from devices called “
<http://www.argo.ucsd.edu/How_Argo_floats.html> Argo floats” were put to use
worldwide. Before that, differing types of temperature records — and an
overall lack of them — contributed to murkiness about how quickly the oceans
were heating up.

The higher-than-expected amount of heat in the oceans means more heat is
being retained within Earth’s climate system each year, rather than escaping
into space. In essence, more heat in the oceans signals that global warming
is more advanced than scientists thought.

“We thought that we got away with not a lot of warming in both the ocean and
the atmosphere for the amount of CO2 that we emitted,” said Resplandy, who
published the work with experts from the Scripps Institution of Oceanography
and several other institutions in the United States, China, France and
Germany. “But we were wrong. The planet warmed more than we thought. It was
hidden from us just because we didn’t sample it right. But it was there. It
was in the ocean already.”

Wednesday’s study also could have important policy implications. If ocean
temperatures are rising more rapidly than previously calculated, that could
leave nations even less time to dramatically cut the world’s emissions of
carbon dioxide, in the hope of limiting global warming to the ambitious goal
of 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels
by the end of this century.

The world already has warmed one degree Celsius (1.8 degrees Fahrenheit)
since the late 19th century. Scientists backed by the United Nations
<https://www.washingtonpost.com/energy-environment/2018/10/08/world-has-only
-years-get-climate-change-under-control-un-scientists-say/> reported this
month that with warming projected to steadily increase, the world faces a
daunting challenge in trying to limit that warming to only another
half-degree Celsius. The group found that it would take “unprecedented”
action by leaders across the globe over the coming decade to even have a
shot at that goal.

 

Meanwhile, the Trump administration has continued to roll back regulations
aimed at reducing carbon emissions from vehicles, coal plants and other
sources and has said it intends to withdraw from the Paris climate accord.
In one instance, the administration
<https://www.washingtonpost.com/national/health-science/trump-administration
-sees-a-7-degree-rise-in-global-temperatures-by-2100/2018/09/27/b9c6fada-bb4
5-11e8-bdc0-90f81cc58c5d_story.html?utm_term=.fa78b88904a3> relied on an
assumption that the planet will warm a disastrous seven degrees Fahrenheit,
or about four degrees Celsius, by the end of the century in arguing that a
proposal to ease vehicle fuel-efficiency standards would have only minor
climate impacts.

 

The new research underscores the potential consequences of global inaction.
Rapidly warming oceans mean that seas will rise faster and that more heat
will be delivered to critical locations that already are facing the effects
of a warming climate, such as coral reefs in the tropics and the ice sheets
of Greenland and Antarctica.

“In case the larger estimate of ocean heat uptake turns out to be true,
adaptation to — and mitigation of — our changing climate would become more
urgent,” said Pieter Tans, who is the leader of the Carbon Cycle Greenhouse
Gases Group at the National Oceanic and Atmospheric Administration and was
not involved in the study.

The oceans absorb more than 90 percent of the excess energy trapped within
the world’s atmosphere.

The new research does not measure the ocean’s temperature directly. Rather,
it measures the volume of gases, specifically oxygen and carbon dioxide,
that have escaped the ocean in recent decades and headed into the atmosphere
as it heats up. The method offered scientists a reliable indicator of ocean
temperature change because it reflects a fundamental behavior of a liquid
when heated.

“When the ocean warms, it loses some gas to the atmosphere,” Resplandy said.
“That’s an analogy that I make all the time: If you leave your Coke in the
sun, it will lose the gas.”

This approach allowed researchers to recheck the contested
<http://www.argo.ucsd.edu/How_Argo_floats.html> history of ocean
temperatures in a different and novel way. In doing so, they came up with a
higher number for how much warming the oceans have experienced over time.

 

“I feel like this is a triumph of Earth-system science. That we could get
confirmation from atmospheric gases of ocean heat content is extraordinary,”
said Joellen Russell, a professor and oceanographer at the University of
Arizona. “You’ve got the A team here on this paper.”

But Russell said the findings are hardly as uplifting.

The report “does have implications for climate sensitivity, meaning, how
warm does a certain amount of CO2 make us?” Russell said, adding that the
world could have a smaller “carbon budget” than once thought. That budget
refers to the amount of carbon dioxide humans can emit while still being
able to keep warming below dangerous levels.

The scientists calculated that because of the increased heat already stored
in the ocean, the maximum emissions that the world can produce while still
avoiding a warming of two degrees Celsius (3.6 Fahrenheit) would have to be
reduced by 25 percent. That represents a very significant shrinkage of an
already very narrow carbon “budget.”

The U.N. panel of climate scientists said recently that global carbon
emissions must be cut in half by 2030 if the world hopes to remain beneath
1.5 Celsius of warming. But Resplandy said that the evidence of
faster-warming oceans “shifts the probability, making it harder to stay
below the 1.5-degree temperature target."

Understanding what is happening with Earth’s oceans is critical, because
they, far more than the atmosphere, are the mirror of ongoing climate
change.

According to a major climate report  <https://science2017.globalchange.gov/>
released last year by the U.S. government, the world’s oceans have absorbed
about 93 percent of the excess heat caused by greenhouse gases since the
mid-20th century. Scientists have found that ocean heat has increased at all
depths since the 1960s, while surface waters also have warmed. The federal
climate report projected a global increase in average sea surface
temperatures of as much as nearly five degrees Fahrenheit by 2100 if
emissions continue unabated, with even higher levels of warming in some U.S.
coastal regions.

 

The world’s oceans also absorb more than a quarter of the carbon dioxide
emitted annually from human activities — an effect making them more acidic
and threatening fragile ecosystems, federal researchers say. “The rate of
acidification is unparalleled in at least the past 66 million years,” the
government climate report stated.

Paul Durack, a research scientist at the Lawrence Livermore National
Laboratory in California, said Wednesday’s study offers “a really
interesting new insight” and is “quite alarming.”

The warming found in the study is “more than twice the rates of long-term
warming estimates from the 1960s and ’70s to the present,” Durack said,
adding that if these rates are validated by further studies, “it means the
rate of warming and the sensitivity of the Earth’s system to greenhouse
gases is at the upper end.” He said that if scientists have underestimated
the amount of heat taken up by the oceans, “it will mean we need to go back
to the drawing board” on the aggressiveness of mitigation actions the world
needs to take promptly to limit future warming.

Beyond the long-term implications of warmer oceans, Russell added that in
the short term, even small changes in ocean temperatures can affect weather
in specific places. For instance, scientists have said warmer oceans off the
coast of New England have contributed to more-intense winter storms.

“We’re only just now discovering how important ocean warming is to our daily
lives, to our daily weather,” she said.

////////////////////////

 

Nature volume 563, pages 105–108 (2018) 

 <https://www.nature.com/articles/s41586-018-0651-8#article-info> 31 October
2018

 

Quantification of ocean heat uptake from changes in atmospheric O2 and
CO2composition

 <https://www.nature.com/articles/s41586-018-0651-8#auth-1> L. Resplandy,
<https://www.nature.com/articles/s41586-018-0651-8#auth-2> R. F. Keeling,
<https://www.nature.com/articles/s41586-018-0651-8#auth-3> Y. Eddebbar,
<https://www.nature.com/articles/s41586-018-0651-8#auth-4> M. K. Brooks,
<https://www.nature.com/articles/s41586-018-0651-8#auth-5> R. Wang,
<https://www.nature.com/articles/s41586-018-0651-8#auth-6> L. Bopp,
<https://www.nature.com/articles/s41586-018-0651-8#auth-7> M. C. Long,
<https://www.nature.com/articles/s41586-018-0651-8#auth-8> J. P. Dunne,
<https://www.nature.com/articles/s41586-018-0651-8#auth-9> W. Koeve &
<https://www.nature.com/articles/s41586-018-0651-8#auth-10> A. Oschlies 

 

Abstract

 

The ocean is the main source of thermal inertia in the climate system
<https://www.nature.com/articles/s41586-018-0651-8#ref-CR1> 1. During recent
decades, ocean heat uptake has been quantified by using hydrographic
temperature measurements and data from the Argo float program, which
expanded its coverage after 2007
<https://www.nature.com/articles/s41586-018-0651-8#ref-CR2> 2,
<https://www.nature.com/articles/s41586-018-0651-8#ref-CR3> 3. However,
these estimates all use the same imperfect ocean dataset and share
additional uncertainties resulting from sparse coverage, especially before
2007 <https://www.nature.com/articles/s41586-018-0651-8#ref-CR4> 4,
<https://www.nature.com/articles/s41586-018-0651-8#ref-CR5> 5. Here we
provide an independent estimate by using measurements of atmospheric oxygen
(O2) and carbon dioxide (CO2)—levels of which increase as the ocean warms
and releases gases—as a whole-ocean thermometer. We show that the ocean
gained 1.33 ± 0.20  × 1022 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. We also find that the ocean-warming effect that
led to the outgassing of O2 and CO2 can be isolated from the direct effects
of anthropogenic emissions and CO2sinks. Our result—which relies on
high-precision O2 measurements dating back to 1991
<https://www.nature.com/articles/s41586-018-0651-8#ref-CR6> 6—suggests that
ocean warming is at the high end of previous estimates, with implications
for policy-relevant measurements of the Earth response to climate change,
such as climate sensitivity to greenhouse gases
<https://www.nature.com/articles/s41586-018-0651-8#ref-CR7> 7 and the
thermal component of sea-level rise
<https://www.nature.com/articles/s41586-018-0651-8#ref-CR8> 8.

 



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