Global Warming debunked?

[jshore]

Oh yeah…Another point to remember is that a competing hypothesis for climate change not only has to explain the warming that is occurring now, it also has to explain why the known perturbation on climate due to rising greenhouse gas levels is not producing significant warming. And since the radiative forcing due to rising greenhouse gas levels is known quite accurately and estimates of climate sensitivity to a particular radiative forcing can be estimated, for example, by looking at ice age - interglacial cycles (or the response of the climate to the Mt. Pinatubo eruption), it has to somehow explain what huge forcing we are have neglected was operating back then…or why the same “radiative forcing” due to different mechanisms can have very different effects or something.

The point is that once a theory has become as well-established as AGW has, there are a lot of things for a competing hypothesis to have to explain and a lot of generally accepted climate science that would have to be radically rethought.

[Kimstu]

@jshore

An analogy might be to a bathtub with an open drain where I carefully adjust the faucet so that the water is coming in at the same rate as it is going out the drain so the level is constant right near the top of the tub. Then, if you came along and started dumping more water in and the tub started overflowing, you might try to argue it is not your fault since the amount of water you are putting in is not as much as the amount coming out of the faucet. Of course, this analogy is not perfect because, for example, in the real world we can’t adjust “the faucet”…In fact, it might be a better analogy if the faucet was being supplied by a pump that just pumped back up all the water that went out the drain.

Better yet, make it a recirculating fountain in a garden pond, where the fountain just keeps on reusing the same pond water over and over. Then the situation is analogous to somebody letting a hose pour additional water into the pond, and blaming the fountain when the pond starts to overflow.

[Intravenus_De_Milo]

@jshore

It is also worth noting that the field regarding observations in changes in tropical cyclone activity (particularly intensity) has been undergoing rapid change, so while Trenberth’s statements arguably may have been outside the mainstream on the basis of the last IPCC report in 2001, they are now supported by a number of papers (although I would say that the opposing viewpoint that Landsea holds is also still within the mainstream in this particular area that remains in a state of flux).

The problem that Landsea had with Trenbreth’s statements (and I can sort of understand this) was that Trenbreth apparently linked the above-average 2004 Atlantic hurricane season directly with the effects of global warming. This doesn’t exactly sound like the sort of line of thinking (attributing a single season’s activity to global warming) that a prominent climate scientist would endorse, hence the fallout. Even Dr. Kerry Emanuel’s recent paper (2005) on the observed increase in Atlantic hurricane intensity and its possible causes has drawn considerable controversy, since even though it takes into account 30 seasons of hurricane data, the beginning point for this 30 years (1970) was an observed low point in Atlantic hurricane activity, thus making his data set look a teensy bit like cherry-picking to some.

For his part, Landsea does not appear to be an all-out denier of AGW effects on hurricane intensity, as Dr. Bill Gray has seemed to be. From his Wikipedia page:

In an interview on PBS, Christopher Landsea said “we certainly see substantial warming in the ocean and atmosphere over the last several decades on the order of a degree Fahrenheit, and I have no doubt a portion of that, at least, is due to greenhouse warming. The question is whether we’re seeing any real increases in the hurricane activity.” He went on to say "with the Atlantic hurricanes in particular, they’re due to changes both in the ocean as well as the atmosphere. Just changing the ocean where it’s a little bit warmer isn’t sufficient. " As for climate change affecting Hurricane strength, Landsea said that global warming theories and numerical modeling suggest only that “hurricanes like Katrina and Rita may have been stronger due to global warming but maybe by one or two miles per hour.” [6]

So he doesn’t flat-out disagree that AGW MAY affect hurricanes at some point; he’s just skeptical as to how much this is happening now.

A final point is that I agree with you that no particular weather event can be definitively attributed to global warming. What can be said, however, is that it is making certain events more likely. So, if the anthropogenic contribution to hurricane intensity trends turns out to be real, the sort of analogy that is often made is to rolling a die that has been weighted so it has, say, twice the normal chance of rolling a six. Then, any particular time that you role a six, you cannot conclude for sure that this is the result of having weighted the die…However, the long term, you will see a six roled about twice as many times as you would have had you not weighted the die.

Well, I agree that with AGW we are likely to see certain events happen more frequently in the future; the concern is about how exactly this message is being trickled down to the public. The “irresponsibility” that I mentioned previously is being perpetrated mostly by the media and not by established scientists. I actually heard a few news outlets raise the question of whether the deadly tornadoes in Florida in February were related to global warming, when in fact no one, not even the IPCC, even mentions the possibility of stronger or more numerous tornadoes as a definitively possible affect of AGW. Current climate modeling technology is nowhere near refined enough to make predictions about the frequency or intensity of such small-scale events over time periods in the decades, even if there were suspicion that higher average temperatures MIGHT lead to more or stronger tornadoes (with tornadoes, it’s a lot more complicated than temperature alone).

It has become a habit of the media to sensationalize every single major weather event as something perpetrated by global warming, whether that event was seasonally expected or not (tornadoes in February in the Deep South are not as rare as some news outlets would have people believe). The danger here is that the death and destruction that is predicted on the TV news will for one reason or another NOT play out as horribly as expected (say, for instance, that the observed multi-decadal cycle in hurricane activity swings the other way in the next decade or so), thus turning people off to the concept of global warming as a legitimate concern. Linking a 1 C rise in sea-surface temperatures to AGW (which is a well-consented link among many scientists) usually does not provide as high ratings as asking the question, “Did Global Warming Cause Katrina?”, even if it’s pretty clear that numerous other factors could just as easily be blamed for that storm. What scientists can and need to do is to stress that climatology is about looking at the big picture, and that the sort of predictions that climatologists currently make are of trends, not of whether a Category 5 hurricane will hit Myrtle Beach next year. Of course, this is the sort of challenge that meteorologists have always faced - that their predictions deal heavily in probability and not with crystal balls - but with AGW it is even more important to stress the correct reasons why people should concern themselves with it, since it is people who can choose to lessen their impact on the environment if they are adequately persuaded.