2003 and 2010 European heat waves set 500-year records, but could be the norm by the end of the century.
An international team of researchers has settled the debate over whether the 2003 European heatwave was worse than the 2010 heatwave, and found that the most recent heatwave across Eastern Europe and Russia was unprecedented in every respect. On top of that, the researchers found that Europe has not experienced temperature anomalies so large in the last 500 years.
“The reason we felt 2003 was more extreme is that Western Europe was more affected by the 2003 heatwave and it stayed warm for a long period of time,” explains Erich Fischer, a postdoctoral student at the Institute for Atmospheric and Climate Science at ETH Zurich.
The 2010 heatwave rocked all the records for the region, both in terms of the deviation from the average temperatures expected as well as the size of the region it impacted.
- The temperatures were between 6.7°C and 13.3°C above the average, depending on the time period
- The heatwave affected a region approximately 2 million kilometres squared, a space fifty times the size of Switzerland for comparison
- On average, the summer of 2010 was 0.2°C warmer across the whole of Europe than it was in 2003
- Daytime temperatures in Moscow reached 38.2°C, and didn’t cool much at night
- Fires caused by the dry conditions covered 1 million hectares
- Fires caused crop failures of around 25%
- The total damage ran to approximately $15 Billion
Persistent High-Pressure System
Both heatwaves were caused by a large and persistent high-pressure system (blocking) associated by areas of low pressure in the east and west. The 2010 system centred over Russia, and the low pressure system to the east was partly responsible for the devastating Pakistani floods. On top of the blocking was minimal rainfall and an early snow melt, both of which dried out the soil and aggravated the extreme conditions.
“Such prolonged blockings in the summertime are rare, but they may occur through natural variability. Therefore, it’s interesting for us to put the two heatwaves in a wider temporal perspective,” explains Fischer.
The researchers compared the data from the last two heatwaves with data dating back as far as 1871 using average daily temperatures, and farther back using seasonal reconstructions derived from tree rings, ice cores and historical documents.
What they found was extraordinary. Both the 2003 and 2010 summers broke 500-year-old records across half of Europe.
However, Erich Fischer stresses that “you can’t attribute isolated events like the heatwaves of 2003 or 2010 to climate change. That said, it’s remarkable that these two record summers and three more very hot ones all happened in the last decade. The clustering of record heatwaves within a single decade does make you stop and think.”
A Hot European Future
Continuing their research, the international team of researchers analysed regional scenarios for the periods 2020-2049 and 2070-2099 based on eleven high-resolution climate models and came up with two projections:
- The 2010 heatwave was so extreme that there will not be another one like it within the next few decades. However, by the end of the century, we can expect 2010-like heatwaves every eight years or so.
- By the end of the century, 2003-like heatwaves will essentially be the norm, meaning that they could take place every two years.
In the end, the exact changes in frequency depend very much on the exact outcome of the future climate, but all the simulations suggest that the heatwaves we have seen over the past decade will become more frequent, more intense, and will last longer.
Source: ETH Zürich