New research published in the journal Nature on May 14 has revealed that human-caused climate change has elevated summer temperatures in the Northern Hemisphere to their highest level in the past 2,000 years. This finding comes as experts estimate global temperatures dating back to the 1st century using tree ring data from the Northern Hemisphere.
According to lead author Jan Esper, a climate professor at Germany’s Johannes Gutenberg University, the findings are not surprising given the ongoing release of greenhouse gases that contribute to global warming. Trees serve as a historical record of past climate conditions due to their sensitivity to changes in rainfall and temperature, which is reflected in their growth rings. By examining tree-ring data from various locations across the Northern Hemisphere, the research team was able to estimate global temperatures from the 1st century to 1850.
Their conservative estimates suggest that the summer of 2023 is at least 0.5 degrees Celsius hotter than the hottest summer in the Northern Hemisphere during that period. The team also noted that 25 of the past 28 years have exceeded the highest temperature experienced in the summer of 246. The impact of volcanic activity on past temperatures was also explored, with the coolest summer in the past 2,000 years being nearly 4 degrees Celsius lower than the summer temperatures in 2023 in the Northern Hemisphere following a major volcanic eruption.
However, while volcanic eruptions can temporarily bring cooler conditions, it is human emissions of greenhouse gases that are ultimately responsible for trapping heat in the atmosphere. Delaying action will only make it more difficult and costly to curb rising temperatures and combat climate change and its devastating effects on our planet.