Oct 15, 2024 05:02 PM
https://www.sciencefocus.com/comment/atl...t-collapse
EXCERPTS: Icy winds howl across a frozen Thames, ice floes block shipping in the Mersey docks, and crops fail across the UK. Meanwhile, the US east coast has been inundated by rising seas and there’s ecological chaos in the Amazon as the wet and dry season have switched around… The world has been upended. What’s going on?
While these scenes sound like something from a Hollywood disaster movie, a new scientific study investigating a key element of Earth’s climate system – the Atlantic Meridional Overturning Circulation (AMOC) – says this could occur for real as soon as 2050.
[...] Direct instrumental measurements of the strength of the AMOC only began in 2004, when the RAPID array was installed across the Atlantic. After nearly 20 years of continuous measurements, the data show a 10-per-cent decrease in its strength, but because the observations show such a lot of change from year to year, we can’t be sure that this is a meaningful, long-term decline.
To look further back in time beyond 2004, we have to rely on indirect measurements of AMOC strength. Sea surface temperature data from the south of Greenland reveal a cooling trend over the past several decades, which is unusual given the general global warming pattern.
At the same time, salty water, which is normally transported into the North Atlantic as part of the AMOC, has been building up in the South Atlantic. These two patterns are thought to be a result of the reduced heat and salt transport by the weakening system.
Palaeoclimatologists have also used ocean sediment cores containing mud and the shells of once-living organisms that settled in layers on the seafloor over millennia, to study changes further back in time. Results suggest the current weakening is unprecedented in the last 1,600 years.
These lines of evidence indicate that the system may have already weakened by about 15 per cent. The indirect nature of this evidence means we’re not certain if there has been a substantial decrease in the AMOC, however... (MORE - missing details)
EXCERPTS: Icy winds howl across a frozen Thames, ice floes block shipping in the Mersey docks, and crops fail across the UK. Meanwhile, the US east coast has been inundated by rising seas and there’s ecological chaos in the Amazon as the wet and dry season have switched around… The world has been upended. What’s going on?
While these scenes sound like something from a Hollywood disaster movie, a new scientific study investigating a key element of Earth’s climate system – the Atlantic Meridional Overturning Circulation (AMOC) – says this could occur for real as soon as 2050.
[...] Direct instrumental measurements of the strength of the AMOC only began in 2004, when the RAPID array was installed across the Atlantic. After nearly 20 years of continuous measurements, the data show a 10-per-cent decrease in its strength, but because the observations show such a lot of change from year to year, we can’t be sure that this is a meaningful, long-term decline.
To look further back in time beyond 2004, we have to rely on indirect measurements of AMOC strength. Sea surface temperature data from the south of Greenland reveal a cooling trend over the past several decades, which is unusual given the general global warming pattern.
At the same time, salty water, which is normally transported into the North Atlantic as part of the AMOC, has been building up in the South Atlantic. These two patterns are thought to be a result of the reduced heat and salt transport by the weakening system.
Palaeoclimatologists have also used ocean sediment cores containing mud and the shells of once-living organisms that settled in layers on the seafloor over millennia, to study changes further back in time. Results suggest the current weakening is unprecedented in the last 1,600 years.
These lines of evidence indicate that the system may have already weakened by about 15 per cent. The indirect nature of this evidence means we’re not certain if there has been a substantial decrease in the AMOC, however... (MORE - missing details)
