Sunday, February 28, 2010
It's the Sun: Watt's favorite suspect. But if we look first at temperatures:
And then at solar irradiance (using sunspots as a proxy):
. . . we can see that is the past 50 years temperatures have gone way up, while the intensity of the sun is currently at a low ebb, and has never over that period been particularly intense, relative to historic conditions.
And that's about it.
2. It's the water: There are a real dearth of multi-decade climate cycles to try and pin thirty years of dramatic warming on, but "skeptics" point to the Pacific decadal oscillation as a potential cause of recent warming. This fails to make sense for a lot of reasons, but the quickest way to refute it is to look at ocean heat content: if the dramatic warming of the air were due to heat emerging from the oceans, the amount of heat in the oceans (the heat content) would have to decline: if the globe is not warming overall, heat leaving the oceans means less heat in the oceans overall. Yet the oceans' heat content is increasing along with the rest of the globe:
3. It's cosmic rays.
It's not cosmic rays. That's an idiotic idea. I don't even want to explain how that one is supposed to work. Just compare cosmic rays to temperature:
Notice the cosmic rays go down, and the temperature goes up. So much for that.
This may all seem too easy. It is, in fact, really easy, if you come to the thing with an open mind. If you come to it determined to pull for your "side," and find fault with the science, if you surrender to what the psychologists call confirmation bias, then nothing is ever simple unless it proves you right. Hence denialists spend a lot of their time arguing that the temperature records are faked, or the sunspot counts are unreliable, or whatever. They attack the data. When they can't attack the data any more, they attack the people: Mann, Hansen, Gavin Schmidt, Al Gore. Anyone and everyone presenting evidence that people are changing the climate in dangerous ways. I'll delve into some of those ad hominem attacks in a future post.
The year was 1824. Jean Baptiste Fourier sat stooped over in his study, when he felt a thrill of fear at the approach of a rasping, metal-on-metal sound. All too soon, the Grand Wizard appeared before him.
"Sir Newton" Fourier asked with a slight shiver of fear, wondering if he would ever get used to the unnatural steam-powered apparatus that prolonged the life of Isaac, the greatest of the European Illuminata. "How may your humble servant assist you?"
"Fourier, we need you to fabricate something called a "greenhouse effect" saying that CO2 warms the planet."
"CO2!" Fourier was shocked. "But it's a harmless trace gas!"
"I know, Fourier, and of course, all clear-thinking minds know intuitively that a large and important effect cannot proceed from a small cause. To maintain this deception, we will have the falsify vast amount of scientific data for the next two centuries. But we must convince the ignorant that this is so."
"But my master, why?"
"Wheels within wheels, my son. Wheels within wheels."
Flash forward to 1989. James Hansen is in his lab, working on Vensuvian climatology. Steven Hawking enters, making use, far from the prying eyes of the public, of the cybernetic body suit designed for him by Robert Noyce in Atlantis.
"It's time, James. All our work with Fourier, Tyndall, Arrhenius and thousands of lesser scientists in about to bear fruit. You – you will have the honor of unveiling to the public the theory of anthropogenic global warming!"
"I still don't understand, Hawk. Why must we go forward with this deception? What will it achieve?"
"Don't you understand yet, James? All our preparations and planning has been for this – to give the world no choice but to raise taxes!"
"To destroy the Earth! After which I will return to the use of my family name, Darvos, and be free to design a race of pitiless cyborgs to enslave the galaxy! EXTERMINATE! EXTERMINATE! EX-TER-MIN-ATE! "
Give these rather ambitious requirements, it is reasonable to ask what we may expect of the skeptics. What are their obligations?
Many skeptics deny having any obligations. "I am a skeptic; I don't have to prove anything" is a common refrain. And they take this seriously, especially when their luminaries prove neither reliable, nor honest, nor consistent in their demands or in their reasoning. But is it true that all the responsibility in science flows one way, and that by rashly articulating what they think is happening in the world, scientists have transformed themselves into the sharecroppers of the skeptics, obligated to prove and prove, and never be rewarded which the wages of proof, which are agreement?
Fortunately, that is not the way science works. Scientific theories are falsified not by there being things they cannot explain (for the universe is large, and no theory explains everything) but by facts that directly conflict with what they predict, usually by facts backed up by a better theory.
Skeptics tend to idealize "consensus-busting" scientists like Galileo and Copernicus, but they invariably ignore a key aspect of those rebels' fight: they were proponents of scientific theories, not merely enemies of ones they did not like. They had another way of accounting for the observations that had been made; that's why they won out in the end. Einstein did not change our ideas about physics by hanging around the patent office complaining that inertia was a leftist plot for world government.
Skeptics do not want to provide an alternative theory for the observations. Being skeptical, they believe, means never having to provide an explanation of your own. "Natural variation" is the mantra, but "natural variation" is not an explanation.
There are a couple things one can mean by "natural variation." You can be talking about a standard distribution, which is the universally observed fact that measurable phenomena tend to cluster around the average value: if you take a thousand people, only a few of them will be 6'6 or 4'10', but a lot of them will be 5'8'. The number that are 6'2' or 5'4' will be less than the number in the middle but more than the number at the extremes.
So one form of "natural variation" is just the oscillation you see in things around the average value. For example, you might see a couple of 6'10' people walking down the street. Does that mean people are getting taller on average? Not necessarily. It may just be chance. If by chance you get a lot of large or small values in a row, you may think there is a trend, upwards or downwards, when in reality the result is just luck.
Figuring out this kind of "natural variability" is simplicity itself; we just work out the chance a pattern could have occurred by the luck of the draw. If that chance is extremely small (typically, >5%) we say that there's a trend in the data.
You can do this with temperatures very easily. Go to http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts.txt. The numbers on the table are the difference from the average temperature that month, with the "average" defined as the average from 1951-1980.
If on average it hasn't been warmer in the last ten years than it was from 1951 to 1980, we would expect half the numbers to be positive, and half negative. That is, if the average hasn't changed, half the time we should be above it, and half the time we should be below it (ignoring the rare times when the anomaly is exactly zero.)
So what's the chance the first number will be positive by chance? 50%. The first and the second number? 25% (0.5 * 0.5 = 0.25). And so on. So, what is the probability that things seem warmer these days, but it's all chance? Let's look at the numbers:
[Pause while you follow the link. Hmm, I should learn more about table formatting.]
Positive. One hundred and twenty times in a row. I'll tell you the odds, but you can work it out; it's the odds against flipping a coin and having it come up heads a hundred and twenty times in a row. Not likely.* The world is warmer than it used to be.
The second kind of "natural variability" the skeptics could be talking about is a natural cycle making the world warmer: perhaps the sun has grown brighter, or the earth's orbit has changed. That is certainly worthy of consideration; just because we know something is happening, doesn't mean we know why.
But here's the hitch: none of the sources of natural variability we know about seem to work. The sun' energy varies slightly, but it has been very low in 2008 and 2009, and temperatures continued to be very high. The earth's orbit hasn't changed. Our albedo (the amount of light the surface of the earth reflects back up towards space) has slightly increased, which should make the world cooler.
Skeptics will typically fudge this question. It hasn't always been so: as we saw in the last post, in 2006, Anthony Watts said forthrightly: " Chances are, we’ll see another dramatic dip in sunspots by 2015 through 2022 and global cooling will set in again as it did in the 1970’s." He later elaborated: "Now if I’m wrong, and I see compelling and undisputable evidence (not models or projections) that man made CO2 is the culprit and nothing else,
I’ll be happy to stand up in the middle of city plaza and announce "I was
wrong".I expect I’ll know the answer by about January to March 2018, when its expected that solar cycle 24 will be over, and temperatures on earth are postulated to drop."
As we saw, 2007-2009 gave us a long and deep solar minimum, without anything like a "cooling." 2009 was tied in the GISS data as the second-warmest year on record.
Most skeptics, including Watts these days, do not define the source of the "natural variability" to which they attribute the warming. They reject the idea that they should provide an alternate explanation of what is going on, that that explanation should be testable and falsifiable.
The odds are 1 in 1,329,227,995,784,900,000,000,000,000,000,000,000.
Despite this, there are those who refuse to look beyond the dog-whistle politics of the issue -- who insist on viewing this real-world problem purely as an ideological football. Because there is no way to address global warming without collective international action, because only governments can take the necessary action, because global warming is a problem which unites us as a species in the firing line, admitting of only very imperfect prospects of shielding ourselves with wealth and technology, people on the right have identified global warming as a threat to their political viewpoint and, by extension, themselves.
Along the way, the usual themes of elitism and "socialist" leanings have cropped up. And in the middle of it all sits Anthony Watts, whose denialist blog is sitting on two million hits a month -- the kind of internet numbers usually reserved for fluffy kittens or hardcore pornography.
Watts uses this ample stage to promote anything and everything that calls into question (or can be made to seem to call into question) the theory of anthropogenic global warming. He may, at the outset, have had some glimmer of intellectual honesty in how he went about his work, but those days are long gone.
To understand Watts today, look at Watts in the very beginning, 2006:
" Chances are, we’ll see another dramatic dip in sunspots by 2015 through 2022 and global cooling will set in again as it did in the 1970’s." (http://www.norcalblogs.com/watts/2006/12/scientists_predict_big_solar_c_1.html) He later elaborated: "Now if I’m wrong, and I see compelling and undisputable evidence (not models or projections) that man made CO2 is the culprit and nothing else, I’ll be happy to stand up in the middle of city plaza and announce "I was wrong".I expect I’ll know the answer by about January to March 2018, when its expected that solar cycle 24 will be over, and temperatures on earth are postulated to drop."
That seems pretty straightforward: Mr Watts thinks "it's the sun." When sunspots (a proxy for solar radiation) dip dramatically, Mr. Watts posultulated the earth would cool. If it didn't, he would " stand up in the middle of city plaza and announce "I was wrong." (http://www.norcalblogs.com/watts/2007/03/)
Mr. Watts made that rash promise in one of his first posts. He is much more cautious today. He is right to be. Because we did see that dramatic drop in sunspot activity: but in 2007, 2008, and 2009, not in 2015 or later. In 2009 there were 260 days with no sunspots at all. That's unprecedented in living memory. Did we see "global cooling" as predicted?
No. Not even close. 2009 was the second-warmest year on record. Mr. Watts has never, so far as I know, alluded to his promise which, while perhaps being naïve about solar physics, was truly scientific in its formulation: "My hypothesis is that the warming observed is caused by the sun. If the sun becomes quiet, but the world does not cool, I am wrong, and I will say so."
He has moved on since then to other, increasingly far-fetched theories, his favorite right now being that the measurements of temperature are all corrupted and the recording warming is all an illusion. We can consider that idiocy in a future post. For now, take a look at a time when Watts didn't doubt the world was warming, but only why. It's a reminder to non-idiots that what separates a scientists from a charlatan is not that one is right and the other is wrong: it's how they react to being proven wrong.