The droughts that have plagued central Europe in recent years are worse than any that have happened in the region in recorded history — at least 2,100 years — according to a new report from researchers at Cambridge University.
The team looked at carbon and oxygen isotopes in 147 living and dead European oak trees, which allowed them to better understand water and photosynthetic conditions across two millennia. They found that while prolonged dry periods have happened over this period, Europe has been getting significantly drier.
Researchers also found that a series of devastating droughts that began in 2015 are without precedent, a worrying sign that points to climate change.
"We're all aware of the cluster of exceptionally hot and dry summers we've had over the past few years, but we needed precise reconstructions of historical conditions to see how these recent extremes compare to previous years," said Ulf Büntgen, professor in Cambridge's Department of Geography and a lead author of the report, in a statement.
"Our results show that what we have experienced over the past five summers is extraordinary for central Europe, in terms of how dry it has been consecutively," he said.
The new study, published in the science journal Nature Geoscience, further shows how climate change impacts our day-to-day lives. In 2015, severe drought and heat waves spread across Europe causing agricultural output to decline, wildfires to intensify, sources of freshwater to diminish, and hundreds of premature deaths. Over the past 15 years, Europe has had five summers so extreme they would have only occurred once every 500 years had climate change not been a factor.
The authors said that changing jet streams are affecting weather and climate patterns worldwide. As ice sheets and glaciers melt in Greenland and the Arctic, for example, huge amounts of cold air and water are being poured into the atmosphere, destabilizing the Gulf Stream over the Atlantic Ocean, according to the New York Times.
Greenhouse gas emissions, meanwhile, are trapping an exponential amount of heat in the atmosphere, causing mean temperatures to rise across the globe, and melting the polar regions.
"Climate change does not mean that it will get drier everywhere: Some places may get wetter or colder, but extreme conditions will become more frequent, which could be devastating for agriculture, ecosystems, and societies as a whole," Büntgen said.
The study's authors warned that worsening droughts threaten trees that anchor ecosystems by providing food, shelter, and myriad forms of support. If trees don’t get enough water, they become more susceptible to pests, disease, and fires, and struggle to grow, a phenomena that is well underway in Europe.
"We've seen a sharp drop following centuries of a slow, significant decline, which is particularly alarming for agriculture and forestry," said co-author Professor Mirek Trnka, from the CzechGlobe Research Center, in a statement. "Unprecedented forest dieback across much of central Europe corroborates our results."