A man cools off with water in São Paulo on Sept. 20 due to the heat wave in Brazil. Record warmth is to be expected as greenhouse gases heat up the planet. But a spike in global temperatures observed in September was so much more dramatic than past extremes that some climate scientists said it defies a simple explanation.
Some stressed that, while the sudden surge in temperatures is alarming, it shouldn’t be used to assert any broader statements about how climates are changing around the globe. The arrival of the infamous El Niño climate pattern in June spurred predictions of a record-warm year — in 2024. An ongoing upswing in the sun’s normal cycle of activity means there is even more solar radiation than normal to be trapped in the atmosphere.