Coming as no surprise to the millions who sweltered through a Northern Hemisphere summer, the season that has just passed was Earth’s hottest since records began in 1880, according NASA scientists.

The announcement from researchers at the Goddard Institute of Space Studies (GISS) in New York, follows consecutive months of record temperatures.

June, July, and August, together, were 0.41 °F (0.23 °C) warmer than in NASA’s record books, and 2.1 °F (1.2 °C) warmer than the average summer between 1951 and 1980. August was 2.2 °F (1.2 °C) warmer than the average.

And it may come as no surprise that June, July and August all broke individual records for their hottest months so far. July beat its 2019 best by (0.43 °F) 0.24 °C, and the top five hottest Julys on record have been in the last five years.

“Summer 2023’s record-setting temperatures aren’t just a set of numbers – they result in dire real-world consequences,” said NASA administrator Bill Nelson. “From sweltering temperatures in Arizona and across the country, to wildfires across Canada, and extreme flooding in Europe and Asia, extreme weather is threatening lives and livelihoods around the world.”

GISTEMP, NASA’s temperature records, stem from surface air temperature data provided by tens of thousands of meteorological stations, and sea surface temperature data from ships and buoys. The raw data is analyzed, taking into consideration the spacing of temperature stations around the planet and the effect of urban heating.

“Exceptionally high sea surface temperatures, fueled in part by the return of El Niño, were largely responsible for the summer’s record warmth,” said Josh Willis, climate scientist and oceanographer at NASA’s Jet Propulsion Laboratory in Southern California.

The Southern Hemisphere is now bracing itself for El Niño Southern Oscillation (ENSO), with the World Meteorological Organization (WMO) forecasting a 90% probability of “moderate strength” El Niño arriving in spring 2023.

“The onset of El Niño will greatly increase the likelihood of breaking temperature records and triggering more extreme heat in many parts of the world and in the ocean,” said WMO Secretary-General Professor Petteri Taalas in the July statement.

The naturally occurring El Niño, which usually occurs every two to seven years, stems from an upwelling of warm water to the surface in the central and eastern tropical Pacific Ocean. This has a huge influence on seasonal weather, intensifying events such as heatwaves and floods.

As the US heads into winter, it may be a temporary reprieve. Decades of data collected by NASA, National Oceanic and Atmospheric Administration (NOAA), and others show that El Niño events are exacerbated by human-driven global warming.

“With background warming and marine heat waves that have been creeping up on us for decades, this El Niño shot us over the hump for setting all kinds of records,” Willis said. “The heatwaves that we experience now are longer, they’re hotter, and they’re more punishing. The atmosphere can also hold more water now, and when it’s hot and humid, it’s even harder for the human body to regulate its temperature.”

Earlier this year, the United Nations’ Intergovernmental Panel on Climate Change (IPCC) found that the global temperature was likely to increase 2.7 °F (1.5 °C) by the early 2030s. It’s shifted the timeline forward from earlier predictions set at 2050.

As well as more summer records to break, this increase also brings with it many other serious issues including growing prevalence of novel zoonotic diseases, extinctions that cripple the international agreement on biodiversity targets, and food and water security concerns.

“Unfortunately, climate change is happening,” said Gavin Schmidt, climate scientist and director of GISS. “Things that we said would come to pass are coming to pass. And it will get worse if we continue to emit carbon dioxide and other greenhouse gases into our atmosphere.”

Source: NASA