Warming Arctic blamed for worsening summer heatwaves

[GliderGuider]

Warming Arctic blamed for worsening summer heatwaves

Dim Coumou and colleagues at the Potsdam Institute for Climate Impact Research in Germany studied atmospheric circulation in the northern hemisphere from 1979 to 2013. They found longer and more frequent hot spells in mid-latitudes that, they say, are likely to have been triggered by a reduction in the temperature difference between the Arctic, which is warming quickly, and mid-latitudes, where average warming is slower.

Climatologists believe that this temperature difference drives the general west-to-east movement of mid-latitude weather systems, such as the depressions that bring storms and the high-pressure systems that bring hot dry weather in summer and intense cold in winter. A smaller temperature difference slows these systems down, so their associated weather persists for longer.

Coumou's team found that the frequency of stalled weather systems in summer has doubled since the onset of rapid Arctic warming around 2000. In many cases, they stop moving for weeks at a time. That can mean long spells of hot weather that dry out soils, kill crops, empty rivers, trigger forest fires – and strain the body, with consequences for our health. So even though average weather is not changing much at mid-latitudes, the incidence of heatwaves is increasing fast.

The resulting stalled weather systems have been blamed - alongside the changing polar vortex - for the present long cold winter in the eastern US and the one immediately before this. But Coumou says that the summer effects are just as strong.

[daleanime]

1. kick, kick, kick.....

[pscot]

2. Yes, there really is a Dim Coumou

For those, like myself, who believed he was a character in a Dr. Who episode.



Dim Coumou: A geophysicist by training, Dim Coumou worked for a while as marine geophysicist in the offshore industry, before starting PhD research at ETH in Zurich. In Zurich, I worked on the development of efficient multiphase fluid flow transport schemes which I used to study hydrothermal systems. More on my PhD work can be found here and here. In 2008, I joined Potsdam Institute for Climate Impact Research (PIK) and currently I am working on development of the atmospheric component of the next-generation Earth System model CLIMBER-3 (as part of PIK´s flagship project NEXT). This novel atmosphere model, Aeolus 1.0, treats the dynamical equations in a statistical way, which makes the model computationally very efficient compared to the more common general circulation type models. We can therefore study the sensitivity of atmospheric circulation to global mean temperature and other key parameters. Next, this newly developed model (a so-called Earth System Model of Intermediate Complexity - EMIC) should pave the way to efficiently study tipping elements in the Earth climate system, of which some could potentially cross a tipping point in the coming century due to anthopogenic forcings. My recent work focused on the link between extreme weather events and global warming, which got some popular-media attention in e.g. WIRED and FOCUS (in german). My scientific interests include climate dynamics, extreme events, global warming, complex earth system, hydrothermal and geothermal systems. Technical interests include parallel programming, C++, object-oriented design, etc, etc, etc...