IT鈥橲 not often that global news is garnered from a sponge. But that is what we find ourselves debating this week.
Researchers studying long-lived sea sponges to track the average global surface temperature over 300 years have made a startling discovery: when delegates at the Paris climate conference in 2015 agreed to aim to limit warming to 1.5掳C above pre-industrial levels, it may have already been too late. According to data from the sponges, the world was already more than 1.5掳C hotter as a result of the burning of fossil fuels.
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This conclusion is controversial. A key issue is that this species of sponge lives only in the Caribbean. Even if its skeleton does accurately record past temperature changes, extrapolating globally from one region is questionable. However, the idea that fossil fuels have warmed the planet somewhat more than the official figures suggest is plausible.
But debates about whether we have passed 1.5掳C distract from the bigger picture. What really matters is that the current level of global warming is already dangerously high, and that further warming will be even more disastrous.
We are already seeing ever more extreme weather events around the world, with record-breaking heatwaves, floods and droughts. These extremes are causing increasingly serious knock-on effects.
They are reducing productivity, damaging crops, and creating political instability. They are destroying homes and . They are also disrupting trade, with low water levels in Europe and the Panama Canal affecting shipping (see 鈥淒rought has hit the Panama Canal hard 鈥� can it survive climate change?鈥�).
To prevent things from getting much worse, we need to stop the world warming further. Achieving this will require global greenhouse gas emissions to reach net zero. All the focus should therefore be on reducing emissions, not on discussing rather arbitrary temperature limits.
And with global emissions still rising, we have an awful lot of work to do.
