A new University of Cambridge study indicates that the Northern Hemisphere has already seared past the Paris 2015 red-line of 1.5 degrees increase in temperature over the pre-industrial levels, creating conditions for increasingly severe weather events
If you thought 2023 was the hottest in recorded history, think again. 2024 is likely to be even hotter. But the year gone by was torrid enough with a new University of Cambridge study showing that it was the hottest in 2000 years in the Northern Hemisphere.
As the world reels under relentless heatwaves and catastrophic weather events triggered by climate change, these findings, based on an analysis of tree rings, show that the worst is yet to come. Already, 2023 was a full four degrees hotter than the coldest summer during the last two millennia.
The study, which involved the analysis of tree rings dating back two millennia, has been published in the prestigious journal Nature. Its findings are ominous, revealing that the Northern Hemisphere has already exceeded the 2015 Paris Agreement’s red-line of 1.5C above pre-industrial levels.
The baseline temperature from the 19th century, used to provide context for global warming, has been found to be several tenths of a degree Celsius colder than previously believed. By readjusting this baseline, researchers have determined that summer conditions in the Northern Hemisphere in 2023 were 2.07°C warmer than the average summer temperatures between 1850 and 1900.
Tree rings provide a valuable historical record, preserving yearly data on past summer temperatures. By analysing tree-ring patterns, researchers can gain insights covering thousands of years, free from the uncertainties of early instrumental measurements.
Cooler periods over the past two millennia, such as the Little Ice Age and the Little Antique Ice Age, were often caused by large volcanic eruptions that released significant aerosols. The coldest summer on record occurred in 536 CE.
Conversely, warmer periods, such as the one we are currently experiencing, correlate with El Nino events. These are large-scale ocean-atmosphere climate phenomena that can significantly influence global weather patterns. Interestingly, these events were observed in tree ring data long before fishermen noted them in the 17th century, highlighting the sensitivity of our climate system to even small changes.
However, the current trend of global warming, exacerbated by greenhouse gas emissions, is significantly intensifying El Nino's impact, leading to the amplification of heatwaves and droughts.