Eight years and eight new record average temperatures since the 2015 Paris climate accords, it can seem as if the world is already fated to pass the 1.5C warming limit agreed then. Not so. That limit will have been officially reached when the 30-year rolling average global temperature is 1.5C above its pre-industrial level. Global warming by that measure is currently at 1.15C. But the number ticks steadily up and for the first time the World Meteorological Organization has said it’s “more likely than not” the 1.5C threshold will be breached within the next five years. Even then, radical emissions cuts could prevent 1.5C of long-term warming on the 30-year measure, but homo sapiens, polar bears and the rest of the biosphere will get a sense of what really dangerous heat feels like. Its worst effect may be to dry out the Amazon.
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