Humans Have Pushed Oceans to Their Absolute Limit, Warns Report
The effect of climate change on the world's oceans has been understudied, a recent report from the International Union for the Conservation of Nature (IUCN) finds, and it is far worse than many scientists and politicians had previously thought.
"We all know the oceans sustain
this planet," said Inger
Andersen, IUCN's director general, to National
Geographic, "yet we are making the oceans sick."
The oceans have been shielding us from the worst effects of climate change, according to "Explaining ocean warming: causes, scale, effects and consequences" (pdf), by absorbing 93 percent of the excess heat produced by human activity and trapped in the atmosphere by the greenhouse effect since the 1970s—and humans have produced so much extra heat that without the oceans, surface temperatures worldwide would have risen by 36° Celsius since the 1970s.
Instead, thanks to the oceans'
capacity to absorb so much CO2, global temperatures have only risen about 0.5°
since the 1970s, according to
the National Oceanic and Atmospheric Administration (NOAA).
"Without this oceanic buffer,
global temperature rises would have gone much, much speedier," Andersen
said.
However, the massive amount of CO2
absorbed by the oceans has sent the water temperatures soaring, the report
finds, rapidly depleting the biodiversity of marine and coastal species—from
microbes to whales—and changing weather patterns worldwide.
"Up to now, the ocean has
shielded us from the worst impacts of climate change," the report's
preface notes. "The costs is that its chemistry has been altered as it
absorbed significant amounts of the extra carbon dioxide we put into the
atmosphere, but it has also warmed at an alarming rate in recent decades."
And the oceans can't take much more:
the alarming, rapid rise in sea temperatures indicate that they have reached
capacity and will soon release that extra carbon dioxide back into the
atmosphere in what the IUCN report characterizes as a "positive feedback
loop."
Coastal regions whose economies rely
heavily on fisheries are already feeling
the effects of a rapidly warming ocean, while coastal cities
are greatly
threatened by sea level rise from melting polar ice caps.
The report also predicts that ocean
temperatures will rise by an additional 1° to 4° Celsius by 2100, with the most
warming occurring in the Southern Hemisphere. The polar regions are predicted
to warm even more than the rest of the world's oceans.
"Ocean warming is one of this
generation's greatest hidden challenges—and one for which we are completely
unprepared," Andersen said, according to
the Independent.
"The only way to preserve the
rich diversity of marine life, and to safeguard the protection and resources
the ocean provides us with, is to cut greenhouse gas emissions rapidly and
substantially," Andersen added.