Monday, March 21, 2011

Freddy Schenk zum "Hot Summer of 2010: Redrawing the Temperature Record Map of Europe"

A guest contribution by Freddy Schenk

A new study has recently been published dealing with the heat wave of 2010 in E-Europe:

"The summer of 2010 was exceptionally warm in eastern Europe and large parts of Russia. We provide evidence that the anomalous 2010 warmth that caused adverse impacts exceeded the amplitude and spatial extent of the previous hottest summer of 2003. "Mega-heatwaves" such as the 2003 and 2010 events broke the 500-year-long seasonal temperature records over approximately 50% of Europe. According to regional multi-model experiments, the probability of a summer experiencing "mega-heatwaves" will increase by a factor of 5 to 10 within the next 40 years. However, the magnitude of the 2010 event was so extreme that despite this increase, the occurrence of an analogue over the same region remains fairly unlikely until the second half of the 21st century."

D. Barriopedro, E. M. Fischer, J. Luterbacher, R. M. Trigo, R. García-Herrera, The hot summer of 2010: redrawing the temperature record map of Europe, Science, (2011), 10.1126/science.1201224

Spiegel (German):
Science Daily (English):
ETH Zürich (German): reads as:
„Aus Einzelereignissen, wie sie die Hitzewellen von 2003 oder 2010 darstellen, lassen sich keine direkten Aussagen über den Klimawandel ableiten“, betont Luterbacher. „Dass diese zwei Rekordsommer und drei weitere sehr heiße Sommer in den letzten 10 Jahren stattfanden, ist jedoch bemerkenswert und die Häufung dieser Phänomene stimmt uns nachdenklich.“

E. Zorita, T. Stocker and H. von Storch. How unusual is the recent series of warm years? Geophysical Research Letters 35, L24706 doi:10.1029/GL036228 (2008).

The speed this study was made and got published in Science is as remarkable as the summer 2010. The heat wave seems to continue the recent series of warm years like examined by Zorita et al. above. To only address the recent heatwave 2010 and not including all the other "strange" weather events in the last two years looks somewhat biased to the Global Warming debate:
At least the last two years are showing weak zonal flow / strong meridional anomalies and strong + more frequent atmospheric blockings over the Northern Hemisphere giving raise to (regionally) severe winters, heat waves, extreme rainfalls (i.e. also the famous Vb-pattern over E-Europe incl. flooding), strongly negative NAO incl. inversals etc. This seems to be even more remarkable than only the heat wave in E-Europe 2010 as a small piece of the whole puzzle. Part of this puzzle (or the weak zonal flow) has also recently been attributed to "Global Warming makes winters cooler". I'm meanwhile very confused about weather, climate and the attribution to Global Warming by this kind of publications... If we tend to attribute these extremes to Global Warming, shouldn't we stay consequent here as well: Global Warming = more atmospheric blocking / weaker zonal flow. I don't see any indication of this being simulated by Global Climate Models for future projections. The rejection of this hypothesis would be what? Low sun activity? Or recent extremes are most likely not caused by Global Warming? Or we don't know?

In addition, is it really possible to estimate the magnitudes of historical heat waves e.g. 400 to 500 years ago to end up with the conclusion made in the article - hottest summer since 500 years? Can we mix reconstructed summer temperatures since 1500 with observations into one probability distribution (fig. 1)?

Fig. 1: Hot summers (JJA) of 2003 and 2010 at the very right side are strongly differing from other years.
(Bild: ETH Zürich), source: ETH Zürich


Anonymous said...

@ Hans von Storch

"I'm meanwhile very confused about weather, climate and the attribution to Global Warming by this kind of publications... "

You are not alone.
Here's what NOAA scienstists tell us on the subject ...

"Despite this strong evidence for a warming planet, greenhouse gas forcing fails to explain the 2010 heat wave over western Russia"

"We conclude that the intense 2010 Russian heat wave was mainly due to natural internal atmospheric variability"


Freddy Schenk said...

The article correctly attributes the heat waves 2003 and 2010 to the typical Omega pattern - this time more shifted and extended to the east. The combination of this Omega type and already dry soil (early snow melt, little rain) have caused the heat wave.

Freddy Schenk said...

I got a little confused by what the article said and what articles about the articles wrote. The synoptical Analysis (Omega type etc.) was onlye shortly noted in press, not in the paper itself.

I got quite personal insultations on my short questions here. I have to admit that I don't like the way I wrote it and want to apologize for that (see rule 4 of the blog, heat of the moment after reading the press about the topic).

However I still would like to hear the oppinion of others if they agree on mixing proxy-reconstructions with measurements when searching for T2m records for the last 500 years(see also Figure S9 in the Supplement to the paper).

Like Ralph posted already, synoptical analysis might lead to more natural causes of the singularity of 2010. Also the Supplement includes interesting results from projections till 2100 with respect to (not too much) changing statistics related to the kind of similar weather types.