What made July 2023 the hottest month ever recorded?

July 2023 was the most well liked month on report, the European Centre for Medium-Range Weather Forecasts confirmed on 8 August. More broadly, this yr’s total international common temperature is shaping as much as be the most well liked ever measured.

The major purpose for these extremes is the long-term impact of people releasing ever extra greenhouse gases into the environment, plus the shift to a heat El Niño sample within the Pacific Ocean, says Michael McPhaden on the US National Oceanic and Atmospheric Administration.

He says El Niño’s impact is very putting after a number of cooler years within the Pacific “masked” a gentle rise within the atmospheric focus of carbon dioxide – a rise of about 4 per cent for the reason that final large El Niño in 2016.

The warmth was additionally boosted by a wavy jet stream sample (in yellow, above) that fashioned simultaneous “heat domes” of trapped scorching air in North America, Europe and China. Whether local weather change makes such warmth domes themselves extra possible is an lively space of analysis.

While this explains the lion’s share of the warmth, pure variability and different elements might also be behind native extremes. For occasion, a pure heat section within the North Atlantic Ocean has contributed to report sea floor temperatures there. Other elements, from a deficit of reflective sand blown off the Sahara desert to a drop in sulphur emissions from ships following new rules in 2020, might also be at play. Water vapour injected into the stratosphere by the 2022 eruption of Hunga-Tonga Hunga Ha’apai in Tonga might even have had a marginal international warming impact.

But, typically, local weather researchers aren’t shocked. “Nothing in the physical climate side that is happening now is unexpected,” says Andrew Dessler at Texas A&M University. With El Niño prone to strengthen and emissions rising, don’t anticipate 2023 to carry on to its information for lengthy.

This story is a part of a sequence by which we discover essentially the most urgent questions on local weather change. Read the opposite articles under: 

The risks of local weather doom | Is local weather change actually accelerating? | The tempo of the renewable power revolution | Can people adapt to warmth?