Source: https://www.ndtv.com/world-news/2023-summer-was-hottest-in-2-000-years-but-2024-could-top-it-5666492
Researchers discovered that 2023 was the hottest summer in the Northern Hemisphere in the last two thousand years, about four degrees warmer than the coldest summer during the same time span. A recent analysis published in the journal Nature compares 2023 to a longer temperature record throughout the majority of the Northern Hemisphere. The study uses data from tree rings to date back to before the invention of thermometers and weather stations, to the year A.D. 1.
“That gives us the full picture of natural climate variability,” said Jan Esper, climatologist at Johannes Gutenberg University in Mainz, Germany, and the paper’s lead author. The El Niño climatic pattern, also known as the El Niño-Southern Oscillation (ENSO), accounts for the majority of the warmer periods observed in tree ring data. El Niño weakens trade winds in the Pacific Ocean, causing warmer summers in the Northern Hemisphere.
According to the researchers’ tree ring data, the average temperature from June to August 2023 was 2.20 degrees Celsius higher than the average summer temperature between 1 and 1890.
And last summer was 2.07 degrees Celsius warmer than the average summer temperature between 1850 and 1900, which is widely regarded as the baseline for the time preceding human-caused climate change. The new study implies that Earth’s normal temperature was lower than this baseline, which is commonly utilized by scientists and politicians when debating climate targets such as limiting global warming to 1.5 degrees Celsius over pre industrial levels.