Wednesday, February 25, 2009

Cold winter doesn't buck global warming trend


Temperatures sink to record lows while snow depths are twice the normal level - is Switzerland's seemingly abnormal winter another indicator of climate change?

Bern University climatologist Heinz Wanner tells swissinfo that although the current winter season may appear colder and snowier than usual the larger historical picture shows it isn't as severe as it seems.

The head of the Climatology and Meteorology Research Group (Klimet), Wanner has for three decades been studying the climate to reconstruct conditions as they were up to 10,000 years ago. He's also working to understand the influence humans have had on weather patterns.

Wanner explains that the deep cold and record snow has to do largely with changes in the air pressure thousands of kilometres away between the Azores and Iceland. Conditions there influence Europe's wind patterns, which this year have sent storm after storm barrelling across Switzerland.

It's a natural cycle, he says, but that doesn't mean humans aren't influencing those events.

swissinfo: Another storm just rolled through this week. With conditions like these some find it hard to believe that global warming is happening. Is it?

Heinz Wanner: First of all, it's important if we really want to diagnose whether the influences are anthropogenic or natural, we need to look at data over a very long time and a very large area. Normally, if it's warming in a certain area, it's cooling at another site. The only answer, the important answer, can be given if we look at a global scale. On a regional scale or at a single site, there is much more natural variability.

swissinfo: So what is happening on a global scale versus a regional one here in Switzerland?

H.W.: The global trend for the last three decades has been temperatures increasing on average about 0.2 degrees per decade. In Switzerland it's actually higher, at about 0.3 degrees.

swissinfo: But we seem to be having record cold with lots of snow.

H.W.: It's a cold anomaly in southwest and central Europe. I can imagine that in certain sites in the Alps and in the plains, the length of the period of snow cover will be quite high and a record at some sites, but it's local. It's clear that almost every day you'll have a record in some part of the world but we have to study it over a long time and on a global scale.

Article Continues:

No comments:


"Manufactured Landscapes" SEE THIS BRILLIANT MOVIE! You'll never have the same shopping experience again.