Archive for February, 2010

Global Drought

February 24, 2010

You’ll recall in my last post I noted that the US shows no evidence of increasing drought. It is fair to suggest that the story may be different elsewhere (although not relevant for the EPA for instance). It just so happens that a study that examined global soil moisture was recently published. Here is the reference:

Sheffield, J., K.M. Andreadis, E.F. Wood, and D.P. Lettenmaier. 2009. Global and Continental Drought in the Second Half of the Twentieth Century: Severity–Area–Duration Analysis and Temporal Variability of Large-Scale Events. Journal of Climate, 22, 1962-1981.

This has just gotten noticed at WCR. As you can see, the last fifty years have not seen more drought.

I’m also trying to download the paper but for some reason the pdf is not opening…

Testing Claims of Climate Impacts

February 24, 2010

Beyond arguments for warming themselves, warming advocates usually add a laundry list of horrible terrible things that will occur because of this. I think this is the most important thing to analyze. With out impacts, there is no logical justification for climate regulations or legislation-and naturally if they are present this will be used as justification even if those policies actually cause more damage than they avert.

So I’ve looked into several of the more common claims. Particularly relevant for the EPA regs are claims which affect the public health and welfare of the people of the United States. Among these are claims that heat related mortality will increase-this is not borne out in the data, and beyond that neglects the fact that a large reduction in cold related mortality could also occur due to strong (and it is generally stronger than summer) winter warming. Claims of more flooding aren’t supported by the data either, which show changes mostly in the minimum to median streamflow, not flood flows,and no significant change in normalized flood damages. This supports assertions that the tendency for more rain has mainly beneficial effects, rather than negative as activists often claim. The opposite claim of increasing drought neither comports with the widespread trends toward more water available nor drought trends themselves. Warming has not induced pollution problems, since air quality continues to improve. And it will in the future, too. Hurricanes are not increasing in the frequency with which they hit the US nor in their normalized damages. Major tornadoes are not more frequent. Studies don’t support claims of accelerating sea level rise and the rates so far observed (less than a foot a century) related to  are swamped by subsidence and uplift.

Can anyone think of any catastrophes that I haven’t mentioned?

Two Foggy Hypotheses

February 17, 2010

So Global Warming is making San Francisco less foggy. Or maybe more foggy. Or maybe both. Maybe neither. Hm….

Seems like a job for Hypothesis Testing! So which is it? Anyone know of actual data on San Francisco foggy-ness?

Maybe Smuggyness?

Warming is what we expect, snow is what we get?

February 13, 2010

In the same breath as activist promoters of global warming concern denounce anyone who mocks them due to the recent snow storms in the Mid-Atlantic-“Weather is NOT climate!” they whine-they contradict themselves-“This weather is just proof of climate change!”.

Huh. That’s pretty amusing in and of itself. But is an increase in snow what we really expect from global warming?

The answer is a qualified no. The qualifier is that in places like Antarctica, we would expect more snow, because while the increased global evaporation from globally increased surface temperatures must lead to a global increase in precipitation, only in places which are sufficiently cold are snowfalls constrained by atmospheric moisture as opposed to atmospheric temperature. When it gets sufficiently warm, the moisture falls as rain instead.

According to a study by RE Davis et al, the relationship between temperature and snow switches sign at a fairly high latitude in North America-in Canada, in fact. This basically rules out atmospheric warming over Virginia leading to more snow.

In fact, the relationship in Virginia is distinctly negative, not positive.

The Return Of Global Warming? Not Just Yet…

February 6, 2010

Many of you may be wondering whether the recent announcement by Roy Spencer of January’s temperature anomaly from UAH’s LT time series might effect the major conclusion here at Hypothesis testing that there has been more than twelve years without warming. Ordinarily I don’t update such a story more than annually or so, but the anomaly was so strikingly large that it was worth asking whether it has brought global warming back. Now, even though I am a denier, I believe in AGW, so I expect that warming will return eventually. But I won’t declare the return of warming until there is real evidence that it has returned. I have crunched the numbers and the previous finding of no warming for 151 months should now be 149 months. Yes, a full three months later than before. I will let other people see if they can disagree-the data is widely available, after all.

Of course, It is possible that when John Christy posts the final values, they may be a little different. However, in my experience this doesn’t seem to happen.