Well, you can’t win for losing, if this study reported by the BBC has any truth to it:
Research presented at a major European science meeting adds to other evidence that cleaner air is letting more solar energy through to the Earth’s surface.
The decline in Soviet industry and clean air laws in western countries apparently reduced concentrations of aerosols, tiny particles, in the atmosphere.
These aerosols may block solar radiation directly, or help clouds to form which in turn constitute a barrier; or both effects may occur.
So there you have it: If we increase pollution, we cause global warming — and if we decrease pollution we also cause global warming. And as I’ve pointed out before, higher temperatures are evidence of global warming, and lower temperatures are also evidence of global warming. This is how we know that global warming is not really a scientific theory — a scientific theory has to be subject to evidence. That is, it need to make “falsifiable predictions” — predictions that, if contradicted, would be regarded as evidence against the theory. If any possible outcome can be viewed as consistent with the theory, then it’s not really a theory since it doesn’t explain anything.
The BBC article also had the following interesting tidbit:
Between the 1950s and 1980s, the amount of solar energy penetrating through the atmosphere to the Earth’s surface appeared to be declining, by about 2% per decade.
This trend received some publicity under the term “global dimming.”
It was also called “the New Ice Age.” I’m just old enough to remember reading in the mid-1970s in elementary school — in the Weekly Reader distributed in over 90% of American elementary schools — that the burning of fossil fuels was causing pollution that would eventually block out enough of the sun’s rays to cause a “New Ice Age.”
In retrospect, this must have come about from the research of Dr. Murray Mitchell, and reported in the famous article Peter Gwynne wrote in Newsweek in 1975 â€“ i â€œThe Cooling Worldâ€ (excerpted here):
The central fact is that after three quarters of a century of extraordinarily mild conditions, the earth’s climate seems to be cooling down. Meteorologists disagree about the cause and extent of the cooling trend, as well as over its specific impact on local weather conditions. But they are almost unanimous in the view that the trend will reduce agricultural productivity for the rest of the century. If the climatic change is as profound as some of the pessimists fear, the resulting famines could be catastrophic. “A major climatic change would force economic and social adjustments on a worldwide scale,” warns a recent report by the National Academy of Sciences, “because the global patterns of food production and population that have evolved are implicitly dependent on the climate of the present century.”
A survey completed last year by Dr. Murray Mitchell of the National Oceanic and Atmospheric Administration reveals a drop of half a degree in average ground temperatures in the Northern Hemisphere between 1945 and 1968. According to George Kukla of Columbia University, satellite photos indicated a sudden, large increase in Northern Hemisphere snow cover in the winter of 1971-72. And a study released last month by two NOAA scientists notes that the amount of sunshine reaching the ground in the continental U.S. diminished by 1.3% between 1964 and 1972.
The BBC article on the more recent research quotes the lead author as follows:
The reversal of “global dimming” has been proposed in some circles as an alternative explanation for climatic change, removing the need to invoke human emissions of greenhouse gases.
Dr[. Martin] Wild dismissed this picture. [We can't have anything contradicting the theory of human-caused global warming, now, can we? --DR] His analysis suggests that “global dimming” and the man-made greenhouse effect may have cancelled each other out until the early 1980s, but now “global brightening” is adding to the impact of human greenhouse emissions.
So if I understand this correctly: we used to have high levels of pollution, which caused both a decrease in sunlight penetrating the atmosphere (“global dimming”), and an increase in heat retained in the atmosphere (“global warming”). These two effects cancelled each other out. Now, however, we have lower levels of pollution, so there is more global warming than global dimming.
This doesn’t make any sense, unless the theory is that low levels of pollution cause only warming, but high levels cause both warming and dimming. I’m not sure what sort of theory would predict that, but if that’s the theory, then emission-reduction programs like the Kyoto treaty will increase global warming — and I kind of doubt that’s what Dr. Wild meant. It would also mean that before the industrial revolution, when fossil fuel emmissions were (presumably) lower, that the temperature should have been higher. I think the opposite is actually true — the “Little Ice Age” ended around 1850 — and it’s certainly the opposite of that the global warming crowd claims.
I’m going to give Dr. Wild the benefit of the doubt here and assume the BBC mangled the quote or took it out of context. That happens all the time to scientists. Unfortunately, there wasn’t enough information in the article to allow me to find Dr. Wild’s paper yet, so I can’t see what it really says.