"Heat waves are on the rise": PIK statement

24/06/2019 - Germany likely faces a heat wave this week. In which way is this releated to human-caused climate change?
"Heat waves are on the rise": PIK statement
Wind speed map indicating planetary wave behavior. Image: PIK/Petri

Stefan Rahmstorf, co-chair of Earth System Analysis at the Potsdam Institute for Climate Impact Research (PIK) and Professor at Potsdam University, Germany:

"Weather data show that heat waves and other weather extremes are on the rise in recent decades. The hottest summers in Europe since the year 1500 AD all occurred since the last turn of the century: 2018, 2010, 2003, 2016, 2002. Monthly heat records all over the globe occur five times as often today as they would in a stable climate. This increase in heat extremes is just as predicted by climate science as a consequence of global warming caused by the increasing greenhouse gases from burning coal, oil and gas."

Also on this issue Dim Coumou, IVM, Vrije Universiteit Amsterdam and PIK:

"On top of this worrying trend, the atmospheric circulation is also changing. Data analysis shows that the normally eastward travelling summer circulation of the Northern Hemisphere mid-latitudes has slowed down, including the jet stream. This favors the build-up of hot and dry conditions over the continent, sometimes turning a few sunny days into dangerous heat waves. We melt sea ice in the Arctic which contributes to the disproportionally strong warming in the northernmost regions of our planet, which in turn can disturb the natural jet stream patterns. A strong atmospheric planetary wave with wave number 7 has likely played an important part in the current heat extreme (see image below). This was shown to be the case in the extreme weather events of last summer as well."

Stefan Rahmstorf concludes:

"While in Europe we worry about reaching 40 °Celsius this week, India has seen temperature records above 50° Celsius recently. Heat waves can heavily impact societies by leading to additional deaths in vulnerable groups such as old people and children, and the combination of hot and dry conditions can lead to water shortages and harvest failures. Only rapidly reducing fossil fuel use and hence CO2 emissions can prevent a disastrous further increase of weather extremes linked to global heating."

Contact to scientists working on the issue:
Stefan Rahmstorf, Potsdam Institute for Climate Impact Research (PIK)
Dim Coumou, IVM, Vrije Universiteit Amsterdam (and PIK)
Kai Kornhuber, Earth Institute, Columbia University, New York (and PIK)

For further information please contact the PIK PR Office:
Jonas Viering, Sarah Messina, Marie Luise Kimbel, Thorsten Greb
Phone: +49 331 288 25 07
E-Mail: press@pik-potsdam.de

Further reading:
  • Kai Kornhuber, Scott Osprey, Dim Coumou, Stefan Petri, Vladimir Petoukhov, Stefan Rahmstorf, Lesley Gray (2019): Extreme weather events in early summer 2018 connected by a recurrent hemispheric wave-7 pattern. Environmental Research Letters, Volume 14, Number 5. [DOI: 10.1088/1748-9326/ab13bf] (here's our press release)
  • Michael E. Mann, Stefan Rahmstorf, Kai Kornhuber, Byron A. Steinman, Sonya K. Miller, Stefan Petri, Dim Coumou (2018): Projected changes in persistent extreme summer weather events: The role of quasi-resonant amplification. Science Advances, Vol. 4, no. 10  [DOI: 10.1126/sciadv.aat3272] (here's our press release)
  • Dim Coumou, Giorgia Di Capua, Steven Vavrus, L. Wang, S. Wang (2018): The influence of Arctic amplification on mid-latitude summer circulation. Nature Communications [DOI:10.1038/s41467-018-05256-8] (here's our press release)
  • Dim Coumou, Jascha Lehmann, Johanna Beckmann (2015): The weakening summer circulation in the Northern Hemisphere mid-latitudes. Science (Express). [DOI: 10.1126/science.1261768] (here's our press release)
  • Dim Coumou, Alexander Robinson, Stefan Rahmstorf (2013): Global increase in record-breaking monthly-mean temperatures. Climatic Change [doi:10.1007/s10584-012-0668-1] (here's our press release)