Scientists predict more European heatwaves

LONDON - Summer temperatures in Europe will become more variable in the future and could cause more heatwaves similar to that of 2003, Swiss scientists said today.

They used computer models of the impact of greenhouse gases on climate to determine why summer heatwaves could become more common.

"We identified the main mechanism to explain the enhancement of summer temperature variability in central and eastern Europe," said Sonia Seneviratne, of the Swiss Federal Institute of Technology in Zurich.

"By the end of the century, climate models suggest that every two or three summers could be as warm or warmer than 2003," she told Reuters.

The findings, reported in the journal Nature, show that variations between very extreme and relatively mild summers, which increase the likelihood of heatwaves, are due to the land-atmosphere interaction, or the exchange of energy between the two systems.

Water is stored in the soil from where it evaporates. Higher air temperatures increase the evaporation rate and at some stage it reaches a point when plants can no longer extract water from the soil.

At that point, Seneviratne said, the energy on the surface increases the air temperature further.

"Once you get to this threshold, you get extremely high temperatures. The year when you have a heatwave is when you have reached the threshold," she added.

Seneviratne and her colleagues suggest that land-atmosphere interaction increases climate variability in central and eastern Europe where rising temperatures are expected to lead to a northwards shift of climate zones.

She added that the findings highlight the crucial role of land-atmosphere interaction in future climate change.

"It is very consistent across models that you have an increase of temperature variability which then increases the probability of heatwaves," she added.

- REUTERS