AMOC climate tipping point is now at higher risk than we first thought

44 leading scientists from around the world have warned that the Intergovernmental Panel on Climate Change (IPCC) has “underestimated” the risk of a “catastrophic” key climate tipping point happening in the near future. It concern the so-called AMOC.

Triggered by inaction on the manmade climate crisis, tipping points can set off a domino effect in the climate, with one event leading to another, eventually causing irreversible heating and a collapse in the earth’s ecosystem.

Warning of destabilisation of earth’s ‘central heating system’

One such tipping point is the potentially looming fall of the Atlantic Meridional Overturning Circulation (AMOC). Ocean currents work as a system of regulation for global temperatures, transporting heat around the planet. And AMOC is a major one of these systems.

It’s the main reason for the difference in temperature between the Northern and Southern hemispheres and moves heat at a rate of one petawatt, or 50 times the energy use of all humankind.

AMOC, our planetary ‘central heating system’, is at risk of collapse.

As well as temperature, how salty the water is for AMOC, is a key factor in its maintenance. The heat transfer works by water sinking below into the depths. The less salty the water is the less it sinks, because it’s less dense. Manmade climate change isn’t just impacting temperatures, it’s also making the water less salty through an increase in the level of freshwater.

The saltiness of the water works as a self-sustaining feedback loop for AMOC, so it’s critical the saltiness remains stable. If we don’t stop emissions, the end of this loop will mean the end of AMOC.

The potential collapse of AMOC has long been building. A landmark study in 2010 found that AMOC “has been weakening since the late 1930s and that the North Atlantic overturning cell suffered an abrupt shift around 1970”.

Scientists think a ‘cold blob’ in the subpolar North Atlantic is a major sign of AMOC collapsing, because the area is where AMOC delivers its heat, yet it’s cooling despite the entire globe heating.

The science that AMOC is weakening and that there is a tipping point is well-known. The question is when it could happen.

The impact of an AMOC collapse

The letter warns that “recent research” suggests that the tipping point is a “serious possibility already in the next few decades”.

The consequences “would be catastrophic” and impact “the entire world for centuries to come”, the scientists write. They note the fall of AMOC would mean

a shift in tropical rainfall belts, reduced oceanic carbon dioxide uptake (and thus faster atmospheric increase) as well as major additional sea-level rise particularly along the American Atlantic coast, and an upheaval of marine ecosystems and fisheries

The climate academics further put that it would “threaten the viability of agriculture in northwestern Europe”.

They argue these extreme risks should mean a prioritisation of decarbonisation in “governance and policy”. Yet in the UK, prime minister Keir Starmer has dropped his pledge for a £28bn investment in green energy. Instead, he’s issuing £22bn for fossil fuel companies to conduct vanity carbon capture and storage projects that don’t even work.

This is worse than a ‘head in the sand’ approach.

Featured image via PBS Terra – YouTube