Ocean temperatures have been rising steadily for decades, with the oceans absorbing much of the excess heat in the atmosphere generated by the constant burning of fossil fuels. But in March 2023, ocean temperatures suddenly spiked, almost overnight. Since then, temperatures have remained well above normal, reaching “hot tub” levels in some places, with worrying implications that suggest marine ecosystems have reached their limits.
The rapid pace of these changes and the severity of the catastrophe they will cause have astounded scientists, as they report “How Climate Change is Pushing the Oceans to the Brink of Catastrophe. But it is also a stark reminder that the effects of climate change will not necessarily be a slow and predictable decline, but sudden knock-on effects with severe consequences, many of which we do not fully understand.
Consider the world’s coral reefs, which suffered their fourth global bleaching event on record this year. Within a few years, a series of marine heatwaves will likely kill most of the world’s corals. The death of corals means catastrophe for marine life and for the people who depend on coral reefs for food, coastal protection, and income.
Warming waters also push the world closer to other tipping points: They coat the edges of melting ice sheets, for example, and slow ocean currents. When these systems collapse, they can’t be reversed.
But we are not heeding the warnings. It is too easy to believe that as greenhouse gas emissions increase gradually, the impacts will be similarly gradual. The past 18 months have demonstrated how quickly systems can break down when exposed to new extreme conditions.
We’ve already been far too slow in our response. Reducing greenhouse gas emissions to net zero as quickly as possible is the only way to restore balance in the long term. You’ve probably heard this before, but when you consider the ongoing crisis in our oceans, it’s hard to imagine more compelling evidence of what we face if we don’t take drastic action.
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