Friday, October 11, 2013

129.6 - Global warming

Global warming

So we've recently seen the release of the latest climate assessment by the Intergovernmental Panel on Climate Change, the IPCC. What do we learn there?

Well, for one thing, scientists are 90% sure that 1981-2010 was the warmest such span in the last 800 years and there's a 2/3 chance that it was the warmest 30-year period in the last 1,400 years. There hasn't been a below-average temperature month in over 28 years. Each of the last three decades has set a new record for the warmest decade since 1850, which was about when reliable records of actual temperature observations began.

More: There is increasing evidence that ice sheets are losing mass, glaciers are shrinking, Arctic sea ice cover is diminishing, snow cover is decreasing, and permafrost is thawing in the Northern Hemisphere, so much so that over 180 native communities in Alaska may have to be abandoned due to flooding and land loss. Tide gauges and satellite data make it "unequivocal" that the world's mean sea level is on the upswing and could rise as much as over two and a-half feet by the end of the century.

And while it remains impossible to blame any particular weather event on global warming, there is increasing evidence that global warming is connected to an observed overall increase in severe weather, with more storms here, more droughts there, and more floods somewhere else.

With the release of this report, scientists can now say it is "extremely likely," that is, can be said with 95% confidence, that human activity is the dominant and perhaps the only significant cause of the warming of the global climate since the 1950s. To really understand the significance of that, you have to realize that 95% confidence is virtually always as far as scientists will go in matters where they can't actually do controlled laboratory experiments. It's as close to certainty as we're going to get.

Humans are screwing with the climate to their own detriment. Period. Worst-case predictions are that by 2100, temperatures could increase by as much as 3.7 degrees Celsius (6.6 degrees Fahrenheit). That, I have to tell you, would be utterly disastrous. That is a worst case scenario, yes, but it still means it's within the realm of possibility unless we as a species stop being so damn stupid about the environment.

One of the ways we are so stupid, at least in this country, is the unwarranted and utterly bizarre attention and credence we give to a tiny handful of nanny-nanny naysayers who for whatever reason will twist, distort, nitpick at, and where necessary simply ignore the ever-growing mountain of scientific and observational evidence that we are digging our own climate grave.

I have never, ever, not once, gotten into a dispute with someone claiming that global climate change is anything from "uncertain" to "over-hyped" to an outright "hoax" in which I have not been faced with the same, hoary, long-since disproven claims originated by the professional naysayers more interested in keeping the funding from the fossil fuel industry flowing than in either facts or the future.

I loved the line at the website SkepticalScience that "arguing with some climate change contrarians is similar to attempting debate with a well-trained parrot [that] has memorised some twenty statements that it can squawk out at random." That is an excellent description of the experience.

But I have to admit there are two relatively new nanny-nanny naysayer claims I've seen rather often of late of which you might have heard, so I'll deal with those quickly. First is the relatively new claim of a "pause" in global warming over the past 15 years, a "pause" climatologists are, it's claimed, "unable to explain" - which of course then means, the argument goes, that the entire notion of global climate change has to be tossed aside and it's Woo-Hoo! coal-fired power plants for everyone!

Let's start with a simple fact: There is no pause in global warming. Atmospheric warming - and remember, the atmosphere is not the only place heat can go, there is also the land, which is not very efficient as a heat sink, and the oceans, which are outstanding as a heat sink and where most of the heat energy is actually stored - but atmospheric warming has not increased as fast over the past 15 years as it had in the years previously. But it's still going up. Just not as fast. Calling that a "pause" is exactly like saying that a car that was going 45 mph that has slowed to 25 mph is no longer moving forward.

The claim of a "pause" is based entirely on deliberate statistical deception. It's done by comparing 1998 temperatures with those of 2010. Right off the bat that's improper: Climatologists have long said that because of natural year-to-year variability, to assess climate trends you should look at time frames of at least 30 years.

But no matter: We can even accept the unreasonably short time frame and still put the lie to the claim of a "pause." 1998 was an outlier, a year with an unusually strong El NiƱo, which causes warmer temperatures, a year significantly warmer than those just before or after. Until 2010, it was the warmest single year on record. So using that as a starting point is clearly bogus, clearly cherry-picking data. Simply shift the range a couple of years - say, compare 1996 to 2008 or 2000 to 2012 - and a clear upward trend is visible even over that short term.

The other new claim is that the IPCC's predictions for temperature increases have been consistently too high so that (weak version) the danger is overblown or (strong version) the computer models used to make the predictions are trash so the whole idea of climate change is as well. The naysayers do this primarily by looking at predictions made in 1990, 23 years ago, when the models were much less sophisticated and the computers that produced them far less powerful than now.

Even so, unfortunately for the naysayers and their trained parrots, the claim is simply not true. This is a bit subtle, so follow this. When the models are run and these predictions are made, they are made in the form of a range. That is, "We think temps will go up at least this much in this time frame but no more than this much and the actual increase will probably be around the middle of that range." What's happened, and the basis for the argument, is that the actual increases have overall run below that midpoint - but they have still been well within the predicted range. Which means the models - even the less sophisticated 1990 models - have held up quite well.

Face reality, people: If we want our children and even more our grandchildren to grow up in a healthy world, we are going to have to make some dramatic changes and fast.

Will that mean cutting back some, doing with a little less? Yes. But do this: Think back to the 1980s, to the way you lived, the amount of stuff you had, the level of technological convenience you had - heck, if you're as old as I am, think back to the '60s - and ask yourself if the way you lived then was so terrible that you would be willing to sacrifice a world rather than live that way again. And if the answer is, as I expect it would be for most of us, "no," then let's get to it. We know the why, let's focus on the how.


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