New research underscores the catastrophic cost of not rapidly cutting carbon emissions, as the collapse of a key ocean current is more likely than previously believed.
The Atlantic meridional overturning circulation (Amoc) is one of our planet’s largest heat transport systems, cycling the equivalent of 50 times the human energy use, and a new study – reported in the Guardian – shows that the tipping point that will make its collapse inevitable is likely to be passed within the next few decades.
Scientists have long warned that Amoc collapse must be avoided “at all costs.” Losing it would shift rainfall patterns in the tropics, drastically transform Europe’s climate, add 50 centimetres to our rising seas, and exacerbate climate change by reducing the ocean’s ability to absorb carbon.
Scientists once believed the likelihood of collapse to be quite low. “Now even in a low-emission scenario, sticking to the Paris agreement, it looks like it may be more like 25 percent,” Professor Stefan Rahmstorf, at the Potsdam Institute for Climate Impact Research in Germany, who was part of the study team, told the Guardian.
[See more: Around 40 percent of the world’s glaciers will melt, even without further warming: study]
Published in the journal Environmental Research Letters, the study analysed the standard models used by the Intergovernmental Panel on Climate Change (IPCC), running to 2100, 2300 and 2500.
They found while the tipping point will likely be passed within decades, the collapse may take 50 to 100 years to hit. More emissions increase the likelihood of collapse, ranging from 70 percent if emissions continue to rise to a low of 25 percent if we are able to keep temperature rise at 1.5°C.
“These numbers are not very certain, but we are talking about a matter of risk assessment where even a 10 percent chance of an Amoc collapse would be far too high,” Rahmstorf said.
When the Amoc collapsed at the end of the last ice age, Rahmstorf told the Guardian last October, it took around 1,000 years to recover and that was without the massive carbon emissions we’re putting out. “CO2 is already higher [now] than at any time in 15 million years,” he said.
