Los Angeles Times - Joshua Emerson Smith
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| Climate
scientist Ralph Keeling at UC San Diego's Scripps Institution of
Oceanography stands next to round glass flasks wrapped in tape and
mounted on an analyzer rack that measures air samples for carbon
dioxide. (Hayne Palmour IV / San Diego Union-Tribune) |
The
world’s oceans may be heating up faster than previously thought —
meaning the planet could have even less time to avoid catastrophic
global warming than predicted just weeks ago by the United Nations’
Intergovernmental Panel on Climate Change.
According
to a study published Wednesday in the journal Nature, ocean
temperatures have been warming 60% more than outlined by the IPCC.
“The
ocean warmed more than we thought, and that has serious implications
for future policy,” said Laure Resplandy, a researcher at Princeton
University’s Environmental Institute who coauthored the report. “This is
definitely something that should and will be taken into account in the
next report.”
The
new study, authored by scientists at Princeton University, UC San
Diego’s Scripps Institution of Oceanography and a number of other
research centers around the world, is not the first to suggest oceans
could be warmer than previously thought.
The
report, however, relies on a novel approach that could revolutionize
how scientists measure the ocean’s temperature. The findings would need
to be reproduced in coming years to gain widespread acceptance
throughout the scientific community.
The ocean warmed more than we thought, and that has serious implications for future policy. Laure Resplandy, researcher at Princeton University’s Environmental Institute
According
to the most recent IPCC report, climate emissions need to be cut by 20%
by 2030 and then zeroed out by 2075 to keep warming from exceeding 2
degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels.
The
new report found that emissions levels in coming decades would need to
be 25% lower than laid out by the IPCC to keep warming under that 2
degree cap.
That’s
because, according to climate scientists, even if the world slams the
brakes on greenhouse gases tomorrow, rising ocean temperatures will
continue to drive warming for several more decades. If those warming
impacts are underestimated, humanity could easily skid past its goals
for capping climate change.
“When
you stop the greenhouse gases, the ocean continues to warm for like
another two decades, and so everything continues to warm,” said Ralph
Keeling, climate scientist at Scripps Institution of Oceanography and
coauthor of the report. “Extra warming in the pipeline means it’s harder
to stay below the climate targets.”
Earth
has already warmed by roughly 1 degree Celsius above preindustrial
levels and is on track to warm 3 degrees by the end of the century,
according to the IPCC.
Scientific
consensus has found that the impacts of climate change are being felt
today with stronger storms, drought and wildfire.
Even
if human emissions are reduced to zero, previously emitted greenhouse
gases, such as carbon dioxide, will persist in the atmosphere for
hundreds of years before dissipating — locking in some level of climate
change for generations to come.
With
2 degrees of warming, the impacts to humanity could be catastrophic,
all but wiping out the planet’s coral reefs, triggering severe food
shortages and throwing hundreds of millions of people, especially in
developing countries, into extreme poverty.
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| NOAA Corps scientists deploying an Argo float to capture ocean temperature data. (Associated Press) |
Much of the data on ocean temperatures currently relies on the
Argo array
— robotic devices that float at different depths, surfacing roughly
every 10 days to transmit readings to satellites. There are about 3,800
such pieces of equipment in waters around the globe that provide the
publicly available information.
However,
the program, which started in 2000, has gaps in coverage. Even with
national efforts providing hundreds of new floats a year, some parts of
the ocean have too many while others have too few.
“It’s
not that easy to reliably estimate the whole ocean heat from spot
measurements,” Keeling said. “You have to model what’s happening in the
gaps.”
Still,
the system’s large number of direct measurements means any individual
errors are averaged out, said Pelle Robbins, a researcher with the
Massachusetts-based Woods Hole Oceanographic Institution’s department of
physical oceanography, who works with the Argo program.
“The
power of Argo is that we have so many instruments that we’re not
reliant on any one of them,” he said. “When you average over things, you
beat down the error.”
By
comparison, Resplandy and Keeling calculated heat based on the amount
of oxygen and carbon dioxide rising off the ocean. Filling round glass
flasks with air from research stations in the Canadian Arctic, Tasmania
and La Jolla, San Diego, researchers analyzed the samples to determine
the aggregate temperature of the ocean.
It’s
certainly not the case that this study alone suggests that we have been
systematically under-representing the oceanic warming.
Pelle Robbins, researcher with the Massachusetts-based Woods Hole Oceanographic Institution
Their paper is an extensive effort to prove this new method and ensure the calculations are free of any scientific errors.
Robbins said the new approach is “bold,” but he still believes strongly in the accuracy of the Argo program.
“It’s
an intriguing new clue,” he said, “but it’s certainly not the case that
this study alone suggests that we have been systematically
under-representing the oceanic warming.”
Resplandy
said her discovery is not intended to replace the Argo system but
rather to compliment it. “In science, we want several methods to measure
things, to have several methods that converge.”
Measurements
of ocean temperatures are also used to determine impacts on marine life
and sea-level rise. Oceans have absorbed about 90% of the excess energy
produced by global warming.
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