Old trees show how hot the summer is

A summer marked by deadly heatwaves across Asia, Europe and North America last year turned out to be the hottest in the Northern Hemisphere in at least 2,000 years, according to a new study. Stady Published in the magazine nature.

officiallyThe year 2023 has been recorded in the history books as the hottest year on record for the planet, but those records only began in 1850. To find out how radically the climate has changed over thousands of years, the authors of the new paper studied ancient tree rings to measure temperature fluctuations. . Over the years.

The results show us just how harsh the weather can be. Although temperatures have reached unprecedented levels, they also represent a warning of what is to come unless policymakers do more to turn down the heat.

“I personally am not surprised, but I am concerned,” Jan Esper, lead author of the study and professor of climatology at Johannes Gutenberg University, said in a press conference. “The longer we wait, the more expensive it becomes and the more difficult it is to mitigate or even stop [global warming]”.

In this study, Esper and his colleagues were limited to the data they could collect from the Northern Hemisphere outside the tropics. Most of the older weather stations, dating from the mid-to-late 19th century, are located in the Northern Hemisphere. Of these, 45 out of 58 are in Europe. To look back in time and across a wider area, they relied on tree rings from archaeologists’ wooden archives.

The cross section of a tree can tell us about its life and the world in which it lives. Many trees add a layer of light-colored “earlywood” each spring and a layer of darker “latewood” each summer. Count the rings Shows the age of the tree. The rings may be thick Indicates a warmer year In trees whose growing seasons coincide with temperature changes.

This is a treasure trove of data on cold climates with specific seasons. But unfortunately, again, most of them are found in the Northern Hemisphere. there These data are scarce in the drier and more tropical regions of the Southern Hemispherewhere there may be fewer trees or trees that do not share the same growth patterns.

Using their findings, the researchers found that land temperatures in the summer of 2023 in the Northern Hemisphere were 2.2 degrees Celsius higher than average temperatures between the years 1890-1. On paper, this may seem like a small difference. When it comes to life on Earth, this is a big shift.

It is a greater rise in temperatures than the target set in the landmark Paris Agreement, which seeks to prevent global temperatures from rising by more than 1.5 to 2 degrees Celsius above what they were before the industrial revolution.

Two degrees Celsius of global warming would be enough for the shift 13 percent Earth’s ecosystems into a new biome, according to Intergovernmental Panel on Climate Change. a lot of The Amazon rainforest is in danger of turning into savannah, For example. Coral reefs would decline by 99 percent, and nearly 40 percent of the world’s population could experience extreme heatwaves at least once every five years.

We saw a deadly taste of that already last year, with record heatwaves across Europe, North America and China, which could have been ‘deadly’.Extremely rare or even impossible Without human-caused temperature increases,” according to an international collaboration of researchers called World Weather Attribution.

It’s been a particularly hot year, partly due to an El Niño climate pattern that has delivered a double whammy on top of climate change in 2023. El Niño isn’t over yet, so that combo is already expected to make this another scorching summer. Achieving the goals of the Paris Agreement It would stop climate change in its tracksHowever, if countries around the world can transition to clean energy by 2050.

“I’m not worried about myself because I’m old, but I have two children and there are many other children. And for them [global warming is] “Really dangerous,” Esper said. “So we must do as much as possible as soon as possible.”