The Gulf Stream *might* be collapsing already.

The Guardian, a British paper, opens itself to the possibility of a near-Arctic future England after looking at some cold, hard facts. The Gulf Stream, scientists warn, is showing some early signs of total collapse:

The research found “an almost complete loss of stability over the last century” of the currents that researchers call the Atlantic Meridional Overturning Circulation (AMOC). The currents are already at their slowest point in at least 1,600 years, but the new analysis shows it may be nearing a shutdown.

[Niklas] Boers [from the Potsdam Institute for Climate Impact Research] and his colleagues reported in May that a significant part of the Greenland ice sheet is on the brink, threatening a big rise in global sea level. Others have shown recently that the Amazon rainforest is now emitting more CO2 than it absorbs, and that the 2020 Siberian heatwave led to worrying releases of methane.

The new research, published in the journal Nature Climate Change, is titled “Observation-based early-warning signals for a collapse of the AMOC”. Ice-core and other data from the last 100,000 years show the AMOC has two states: a fast, strong one, as seen over recent millennia, and a slow, weak one. These data show rising temperatures can make the AMOC switch abruptly between states over one to five decades.

The AMOC is driven by dense, salty seawater sinking into the Arctic ocean. But the melting of freshwater from Greenland’s ice sheet is slowing this down earlier than climate models suggested.

Boers used the analogy of a chair to explain how changes in ocean temperature and salinity can reveal the AMOC’s instability. Pushing a chair alters its position, but does not affect its stability if all four legs remain on the floor. Tilting the chair changes both its position and stability.

Eight independently measured datasets of temperature and salinity, going back up to 150 years, enabled Boers to show that global heating is indeed increasing the instability of the currents, not just changing their flow pattern.