Catastrophic climate 'doom loops' could start in just 15 years, new study warns Because it is so close and so significant that we have to take immediate action now." In some sense it's not fruitful," Peter Ditlevsen, a professor of physics and climate science at the Niels Bohr Institute in Copenhagen, told Live Science. The model's results alarmed the researchers - yet they say that checking them only reinforced their findings: The window for the system's collapse could begin as early as 2025, and it grows more likely as the 21st century continues. If it were to turn off, temperatures in Europe and North America could drop by as much as 9 F (5 C) in the same amount of time.ĭirect data on the AMOC's strength has only been recorded since 2004, so to analyze changes to the current over longer timescales, the researchers turned to surface temperature readings of the subpolar gyre between the years of 18, a system which they argue provides a 'fingerprint' for the strength of AMOC’s circulation.īy feeding this information into a statistical model, the researchers gauged the diminishing strength and resilience of the ocean current by its growing year-on-year fluctuations. The last time the AMOC switched modes during the most recent ice age, the climate near Greenland increased by 18 to 27 degrees Fahrenheit (10 to 15 degrees Celsius) within a decade. The region near Greenland where the southerly waters sink (known as the North Atlantic subpolar gyre) borders a patch that is hitting record low temperatures, while the surrounding seas climb to all-time highs, forming an ever-expanding 'blob' of cold water. (Image credit: NASA/Goddard Space Flight Center Scientific Visualization Studio) Fresh water from melting ice sheets has made the water less dense and salty, and recent studies have shown that the current is at its weakest in more than 1,000 years.Ī simplified animation of the global AMOC "conveyor belt," with surface currents shown in red and deep sea currents in blue. Then, once it has sunk beneath the ocean, the water slowly drifts southward, heats up again, and the cycle repeats. Warmer southerly waters, which are saltier and denser, flow north to cool and sink below waters at higher latitudes, releasing heat into the atmosphere. We were actually bewildered." AMOC as a global conveyor beltĪtlantic Ocean currents work like an endless global conveyor belt moving oxygen, nutrients, carbon and heat around the globe. "It was not a result where we said: 'Oh, yeah, here we have it'. "The expected tipping point - given that we continue business as usual with greenhouse gas emissions - is much earlier than we expected," co-author Susanne Ditlevsen, a professor of statistics and stochastic models in biology at the University of Copenhagen, told Live Science. But human-caused climate change may push the AMOC to a critical tipping point sooner rather than later, researchers predicted in a new study published Tuesday (July 25) in the journal Nature Communications.
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