BREAKING NEWS
Scientists say the world’s oceans are heating up faster than previously
thought, a finding with dire implications for climate change.
Thursday, January 10, 2019
2:05 PM EST
2:05 PM EST
A new analysis, published Thursday in the journal Science, found that
the oceans are heating up 40 percent faster than the United Nations
estimated five years ago. The escalating water temperatures are already
killing off marine ecosystems, raising sea levels and making hurricanes
more destructive.
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Ocean Warming Is Accelerating Faster Than Thought, New Research Finds
by Kendra Pierre-Louis
January. 10, 2019
New York Times
by Kendra Pierre-Louis
January. 10, 2019
New York Times
Rising ocean temperatures can
bleach corals, like these off of Papua New Guinea. Credit Jurgen
Freund/Minden Pictures
Scientists say the warming of the world’s oceans is accelerating more
quickly than previously thought, a finding with dire implications for
climate change given that the vast majority of the heat trapped by
greenhouse gases ends up stored there.
A new analysis, published
Thursday in the journal Science, found that the oceans are heating up 40
percent faster on average than a United Nations panel estimated five
years ago. The researchers also concluded that ocean temperatures have
broken records for several straight years.
“2018 is going to be
the warmest year on record for the Earth’s oceans,” said Zeke
Hausfather, an energy systems analyst at the independent climate
research group Berkeley Earth and an author of the study. “As 2017 was
the warmest year, and 2016 was the warmest year.”
As the planet
has warmed, the oceans have provided a critical buffer, slowing the
effects of climate change by absorbing 93 percent of the heat trapped by
human greenhouse gas emissions. But the escalating water temperatures
are already killing off marine ecosystems, raising sea levels and making
hurricanes more destructive.
As the oceans continue to heat up,
those effects will become more catastrophic. Coral reefs, whose fish
provide key sources of protein to millions of people, will come under
increasing stress; a fifth of them have already died in the last three
years. Rainier, more powerful storms like Hurricane Harvey in 2017 and
Hurricane Florence in 2018 will become more common, and coastlines
around the world will flood more frequently.
Because they play
such a critical role in global warming, oceans are one of the most
important areas of research for climate scientists. Average ocean
temperatures are also a consistent way to track the effects of
greenhouse gas emissions because they are not influenced much by
short-term weather patterns, Mr. Hausfather said.
“Oceans are really the best thermometer we have for changes in the Earth,” he said.
But, historically, understanding ocean temperatures has also been
difficult. An authoritative United Nations report, issued in 2014 by the
Intergovernmental Panel on Climate Change, presented five different
estimates of ocean heat, but they all showed less warming than the
levels projected by computer climate models — suggesting that either the
ocean heat measurements or the climate models were inaccurate.
Since the early 2000s, scientists have measured ocean heat using a
network of drifting floats called Argo, named after Jason’s ship in
Greek mythology. The floats measure the temperature and saltiness of the
upper 6,500 feet of the ocean and upload the data via satellites.
PHOTO: An ocean sensor deployed by the French research ship Pourquoi
Pas? as part of the Argo project.CreditOlivier Dugornay/IFremer/Argo
Program
But before Argo, researchers relied on expendable
bathythermographs, a sort of temperature sensor that ships lowered into
the ocean with a copper wire. The wire transferred data from the sensor
onto the ship for recording, until the wire broke and the sensor drifted
away.
That method was subject to uncertainties, especially
around measurement depth, that hamper today’s scientists as they stitch
together temperature records into a global picture.
In the new
analysis, Mr. Hausfather and his colleagues assessed three recent
studies that better accounted for instrument biases in the historical
record. The results converged at an estimate of ocean warming that was
higher than the I.P.C.C. predicted and more in line with the climate
models.
The researchers also reviewed a fourth study that had
used a novel method to estimate ocean temperatures over time and had
also found that the world’s oceans were heating faster than the I.P.C.C.
prediction. But that study contained an error that caused its authors
to revise their estimates downward, suggesting that ocean warming was
less of a problem than they originally reported.
As it turned
out, the downward revision brought that study’s estimates much closer to
the new consensus. “The correction made it agree a lot better with the
other new observational records,” Mr. Hausfather said. “Previously it
showed significantly more warming than anyone, and that was potentially
worrisome because it meant our observational estimates might be
problematic. Now their best estimate is pretty much dead-on with the
other three recent studies.”
The scientists who published the
four studies were not trying to make their results align, Mr. Hausfather
said. “The groups who were working on ocean heat observations, they’re
not climate modelers,” he said. “They’re not particularly concerned with
whether or not their observations agree or disagree with climate
models.”
PHOTO: A dead coral reef in waters off Indonesia.CreditEthan Daniels/Stocktrek Images, via Science Source
Laure Zanna, an associate professor of climate physics at the
University of Oxford who was not involved in the study, said the new
research was “a very nice summary of what we know of the ocean and how
far the new estimates have come together.”
Dr. Zanna was an
author of a recent study that used existing data to estimate ocean
temperatures dating back to 1871. The goal was to figure out places
where sea level rise might happen even faster than expected because of
the way ocean currents redistribute heat, allowing regions that are
especially at risk to better plan for those changes.
As the
oceans warm, sea levels rise because warmer water takes up more space
than colder water. In fact, most of the sea level rise observed to date
is because of this thermal expansion, not melting ice caps.
“We
are warming the planet but the ocean is not warming evenly, so different
places warm more than others,” said Dr. Zanna. “And so the first
consequence will be that sea level will be different in different places
depending on the warming.”
Though the new findings provide a
grim forecast for the future of the oceans, Mr. Hausfather said that
efforts to mitigate global warming, including the 2015 Paris climate
agreement, would help. “I think there’s some reason for confidence that
we’ll avoid the worst-case outcomes,” he said, “even if we’re not on
track for the outcomes we want.”
For more news on climate and the environment, follow @NYTClimate on Twitter.
ABOUT THE AUTHOR:
Kendra Pierre-Louis is a reporter on the climate team. Before joining
The Times in 2017, she covered science and the environment for Popular
Science. @kendrawrites
