Study: Recent droughts and heatwaves most severe in more than 2,000 years

Photo: klimkin, Pixabay / CC0

The series of severe droughts and heatwaves that hit central Europe in recent years have been the most severe in the past two millennia, suggests a study carried out by an international team of scientists, including researchers from the Czech Republic. The study analysed tree rings dating back to the Roman Empire, creating the longest such record to date.

I discussed the outcome of the study with one of its authors, Miroslav Trnka from the Czech Academy of Sciences:

“The research was based on using tree rings from about 150 oaks that span over 2100 years. We don’t really have living oaks that would be so old. What we have are oaks that come from forests but mostly from building sites, from archaeological remains, but also from riverbanks.

“Our colleagues collected tree rings and we then cut the individual rings and analysed them for the content of stable isotope of carbon and oxygen.

Miroslav Trnka,  photo: Czech Television

“It was a very laborious long-term process that required individual cutting of 13,500 tree rings and over 27, 000 analyses. And based on that, because stable isotopes are very good fingerprints of climate, we could reconstruct how the trees did since Julius Caesar’s childhood until 2018.”

What is the cause of the recent rise in extreme heat?

“What we have found is a drying trend for central Europe that spans from Roman times till the present. That’s the first finding. But the drying trend intensified greatly after 1850. Especially in the last 50 years.

“When you compare the drying we have witnessed in the past decades with the overall trend, the current drying is over 40 times faster than it used to be.

“So that I think is a very critical finding, one of the most important results of the study, which says: yes, the climate is changing, it’s superimposed over the natural changes that would be happening anyway, but we make it much faster.”

What are the biggest consequences of the heatwaves here in the Czech Republic?

Photo: archive of Radio Prague International

“In our region, we use rain as one of the critical sources of water. Being on the continental divide, we don’t have any substantial influx of water from anywhere else. So we have to be very economical with our water already now, and we will have to be even more in the future. So that’s one of the consequences.

“We have been spared the heatwaves that hit Europe for example in 2003 and Russia in 2010, but we are afraid it’s coming. So far it has only presented discomfort for people.

“But we expect that more heat could really put strain on the infrastructure, both on the people, on hospitals for example, but also on the energy system, because of the extreme demand for example on cooling in the future.

“The other thing is that heat increases the risk of wildfires. It is of course not a major problem in the Czech Republic at the moment. But in the future, again, that’s one of the risks associated with climate change and the shifting of the climate regime.”