Sunday, August 9, 2009
Was the heat wave a sign of global warming?
Quite a few have emailed me asking whether last week's heat wave was a sign of global warming. Others have suggested that I have been strangely silent on this issue.
Anything, although I have commented on this subject in my blog and KUOW, let me give you my take on this--and I think the take of most meteorologists.
One heat wave, one storm, one event says nothing about global warming or its effects. That is why those who jumped on Hurricane Katrina as proof of global warming were really off-base.
First, this last hot event was completely localized...while we had record breaking heat, the upper plains and midwest (and parts of the east coast) had record breaking cold. The reason: a persistent ridge of high pressure over the western U.S. and a trough over the central/eastern U.S.-- NOT uniform warming. When I went back east for a meeting, people were complaining about the cold, and those of conservative bent were griping about the global-warming fanatics.
Second, one event does not provide much information on trends, and trends are what count in climate. The atmosphere has a certain amount of natural variability, and there will be records and extremes even if the large-scale situation remains the same. The atmosphere is rarely "normal" and the averages include extremes of both directions.
The media and some climate-action groups are continuously confusing the differences between weather and climate and some of their claims are unsupportable --like the frequently stated prediction that the NW will have more windstorms under global warming. There is NOTHING to support this conjecture. I have even heard some explain the unusual cold/snow wave last December on global warming! (the claim is that global warming will produce more weather variability). And another one is about heavy rain events--that our recent heavy rains/flooding are due to global warming. The truth is that heavy rain events are decreasing in Oregon and increasing over parts of NW Washington (I have a student working on this issue). Why would global warming produce such a dipole effect? (I can speculate on this but won't here).
Don't get me wrong...I am absolutely convinced that global warming is going to happen and will be significant here, but many of the claims about local effects are without support. And because we are downstream of the cool NE Pacific, the Pacific NW may see global warming's effects delayed and weakened.
The bottom line of global warming is that the effects will not be uniform, and that the differences will be profound. And there is much about local effects that we don't know. The whole topic has also gotten too political...with some believing that global warming is some left wing/Gore induced dementia, while others hyping its effects to induce a social/economic transformation or to enhance their political prospects.
I suspect mankind will not act fast enough to reduce fossil fuel use to stop large global warming effects and that we will learn to live with it. But that is another topic...
Posted by Cliff Mass at 10:17 AM