The oceans are warming faster than ever. Here’s what could happen next.


The world’s oceans are experiencing generations of warming, a trend that is accelerating and threatening to fuel more extreme storms, destroy marine ecosystems and upend the lives and livelihoods of millions of people, according to a new scientific analysis.

published This week in Nature Reviews, I found that the upper reaches of the oceans — roughly 2,000 meters, or just over a mile — have warmed around the planet since at least the 1950s, with the most stark changes observed in the Atlantic and Southern Oceans.

The review authors, who include scientists from China, France, the United States and Australia, wrote that the data show that heating has accelerated over time and increasingly reached deeper and deeper depths. This warming – which scientists have said will likely be irreversible within the year 2100 – is set to continue, creating new hotspots around the world, especially if humans fail to achieve significance and speed. Reducing greenhouse gas emissions.

The findings underscore the key role oceans have played in helping to compensate anthropogenic emissions The oceans absorb more than 90 percent of the excess heat trapped in the world’s atmosphere — and the effects will also be profound if warming continues unabated. If that happened, the scientists wrote, the areas near the ocean surface could warm two to six times their current temperature.

“Global warming really means a warming ocean” Kevin E. Trenberth, who is a review co-author and a scientist at the National Center for Atmospheric Research, in an interview from New Zealand. “The single best indicator that the planet is warming is the record of ocean warming.”

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This record, made up of thousands of temperature measurements across the globe over decades, shows an “unrelenting” trajectory, he said. “The warming has accelerated, and the fastest warming has been in the last 10 years or so,” he said.

The consequences of ocean warming are already manifesting in several ways.

Scientists attribute about 40 percent of global sea level rise to the effects of thermal expansion in ocean waters. Warmer oceans also speed up the melting of ice sheets, which increases sea level rise. They disrupt traditional weather patterns and exacerbate droughts in some areas. It also fuels more severe cyclones, and it also sets the conditions for more torrential rains and deadly floods.

The authors cite one example from August 2017, when the Gulf of Mexico reached its highest summer temperature on record up to that point. In the same month, Hurricane Harvey swept across the Gulf, erupting from a tropical depression into a major hurricane and dumping catastrophic amounts of rain on Houston and other areas.

“It’s all part of the fact that there’s more energy available” in the oceans, Trenberth said.

In addition, the analysis found that future warming could cause severe declines in some fisheries, causing the loss of livelihoods and food sources. The trend also makes it “inevitable” that marine heat waves will become more extensive and longer-lasting – a fact that can lead to toxic algal blooms and fuel massive mortality events among coral reefs, kelp forests and other marine life.

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While the authors explain that oceans around the world are expected to continue warming over the coming decades, even if humanity begins to become extinct. greenhouse gas emissions, that global warming will not occur evenly across the world. Largely due to circulation patterns, some regions are expected to warm faster than others and are likely to struggle with more severe impacts.

The paper also stresses that while there are still many uncertainties, how this happens is “critical” to the consequences likely to humans, says Jolene Russell, a professor and oceanographer at the University of Arizona.

“Small portion more [mixing] “It will slow our warming, and a smaller fraction of the mixing will accelerate the warming,” said Russell, who was not involved in this week’s analysis. “This is very important for people to understand.”

The latest findings are largely consistent with the growing body of research that has been documented – that the oceans have long stored staggering amounts of energy from the atmosphere and mitigated the effects of greenhouse gas emissions, but that over time profound effects on land and sea are unavoidable.

In its most recent assessment of the state of climate science earlier this year, Intergovernmental panel on climate change He said it’s “almost certain” that the upper ocean has warmed over the past half century, and that human-caused carbon emissions are the main driver.

“Global mean sea level has risen faster since 1900 than in any previous century in at least the past 3,000 years,” the Intergovernmental Panel on Climate Change wrote. “The global ocean temperature has warmed more rapidly over the past century than it has since the end of the last ice movement (about 11,000 years ago).”

However, the researchers say, the amount of future warming depends on what humans do – or don’t do – to curb the greenhouse gases that ultimately warm the oceans. Better measuring, understanding and mitigating the problem must be a global priority.

If the world can head toward a future of this kind of rapidly shrinking emissions conceivable by Paris Climate Agreementthe author of a review this week wrote, is likely to “lead to a detectable and permanent reduction in [the] The rate of ocean warming, with marked decreases in the effects of climate change.”

Russell said the latest findings underscore that it’s “extremely important” that humans reduce emissions as quickly as possible, to reduce ocean warming and ultimately the effects on humans.

“Our oceans do us a profound service,” she said. “As a scientist and mother, I pray for the fact that we need to bend this curve in my life. … It is important that we do that.”

Chris Mooney contributed to this report.

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