Southern hemisphere clocks warmest month on record

April 2023 was the southern hemisphere’s hottest month on record, beating the previous record set in March 2016 by 0.06°C.

The record passed almost without comment or substantial media coverage, such is the level of desensitisation of a rapidly heating planet.

April also happened to be the fourth hottest April globally since modern recordkeeping began in 1880, measuring at 1.00°C above NASA’s 1951–1980 baseline average. The six hottest Aprils on record have occurred since 2016.

The US National Oceanic and Atmospheric Administration (NOAA) and the European Copernicus Climate Change Service also reported April as being the world’s fourth hottest on record.

Global ocean temperatures experienced their warmest April on record, according to the NOAA. This marked the second-highest monthly ocean temperature for any month on record, just 0.01°C shy of the record-warm ocean temperatures set in January 2016.

May 2023 was the world’s third hottest May since record-keeping began in 1880.

In fact, greenhouse gas emissions have reached an all-time high. Scientists say the world is quickly running out of “carbon budget”, the amount of carbon dioxide that can be released into the atmosphere if we are to stay within the vital threshold of 1.5°C above pre-industrial temperatures. The results and analysis were published in a recent edition of Earth System Science Data.

To avoid the accumulation of CO₂ in the atmosphere that would raise temperatures by 1.5°C, only about 250 billion tonnes of carbon dioxide can now be emitted. Based on the annual rates of greenhouse gas emissions of about 54 billion tonnes a year over the past decade, this tally would be used up well before the end of the 2020s should the pattern continue.

“This is the critical decade for climate change,” says University of Leeds Professor Piers Forster, the paper’s lead author. “Decisions made now will have an impact on how much temperatures will rise and the degree and severity of impacts we will see as a result.”

Prof. Forster called for considerably stronger climate action from the nations of the world.

“We need to change policy and approaches in light of the latest evidence about the state of the climate system,” Prof. Forster says. “Time is no longer on our side.”