Media release

From: Springer Nature

Climate: Summer of 2023 warmest in 2,000 years

The summer of 2023 was the warmest in the Northern Hemisphere extra-tropical regions in the past 2,000 years, according to a study published in Nature.

Jan Esper and colleagues employed a combination of observational data and proxy-based reconstructions to analyse June–August surface air temperatures across the Northern Hemisphere's extra-tropical regions (30–90 degrees north, which covers areas including Europe) over the past 2,000 years. By combining measurements from thousands of meteorological stations, the authors found that land temperatures in this section of the Northern Hemisphere were 2.07 °C higher in the summer of 2023 than instrumental averages between 1850 and 1900 CE.

To investigate trends over the past 2,000 years, the authors used a community ensemble reconstruction of Northern Hemisphere extra-tropical summer temperatures combined with the 9 longest temperature-sensitive tree chronologies available. They found that the summer of 2023 exceeded pre-instrumental average temperatures for the years 1–1890 CE by 2.20 °C. In comparison to the coldest reconstructed summer during this period — 536 CE, where temperatures were influenced by a volcanic eruption — 2023 was 3.93 °C warmer.

The authors note that the warming reported in this study cannot be applied on a global scale. However, they argue that the estimates demonstrate the unparalleled nature of present-day warming and the need for urgent action to reduce carbon emissions. 

***