Most climate impacts are like repeatedly shooting ourselves in the foot: we keep emitting greenhouse gases, the planet warms and more heatwaves happen, and wildfires, and flooding, and drought. Science tells us that this is mechanistic: pull the trigger and you will get hurt.
But in some cases, large uncertainty remains. One particular concern is the Atlantic Meridional Overturning Circulation (AMOC), the system of currents that transport a tremendous amount of heat from the Gulf of Mexico to Europe. As ever more icebergs and meltwater from Greenland rush into the north Atlantic, the AMOC is thought to be slowing down. Eventually it could even collapse, bringing 鈥渋ce age鈥� winters to Europe, raising sea levels in North America and disrupting vital monsoons in Africa and Asia.
Will that happen? We don鈥檛 know. Some research says the AMOC could cross a tipping point in centuries, some says decades and some says it has crossed it already. If we start reducing emissions, it may not happen at all. Scientists have long described it as low probability but high impact. You might think of it as climate Russian roulette.
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Scientists have long described the AMOC鈥檚 collapse as low probability but high impact
To tackle this uncertainty, scientists are trying to build an early warning system to alert us that the AMOC is going to cross a tipping point. It is unclear whether that warning would give us enough time to avoid this, or merely to prepare for the impacts, but both are better than doing nothing, which is what we are doing now. We may not know the probability of the AMOC collapsing, but we know it is increasing.
So far, the uncertainty around it has been an excuse to ignore it, or treat it as a distant problem. In fact, the uncertainty makes it even more important for policy-makers to take action now, in the same way we fund militaries for wars we hope will never come. Whether we decide to invest in mitigation or adaptation, we won鈥檛 regret it, since all of it will help with our bigger climate problem. Stop emissions, take the gun away and no one needs to get hurt.
