Thank God!

We can all relax, and forget about the global warming problem.

John Shimkus, Republican congressman from Illinois, assures us that the planet won’t be destroyed by global warming. Why is he so sure? Because God promised Noah.

http://www.dailymail.co.uk/news/article-1328366/John-Shimkus-Global-warming-wont-destroy-planet-God-promised-Noah.html

Extreme Heat

Climate Central has an interesting post about the extreme heat wave in Moscow this last July. They point out that if we assume the data are normally distributed, then the July 2010 average temperature anomaly value was more than 4 standard deviations above the July mean (and they have a lovely graph to emphasize it):

How Likely?

I had a good question the other day:

Now, my question is, if you know the answer: How high is the probability that arctic change is caused by AGW versus that is just natural variation of some kind (confidence level) ?

Good question. I’m not aware of any “official” estimate of the probability, but here’s mine.

First I’ll note that if AGW (anthroppogenic global warming) is basically sound science, then it’s overwhelmingly likely to be the cause of arctic change. Although it’s possible that AGW is sound science but something else has caused recent arctic change, I consider that to be so unlikely that the chance is negligible.

So we’re really trying to decide between two hypotheses. Hypothesis “A” is that AGW is basically sound science, so human activity is altering our climate, pushing it toward significant warming. Hypothesis “B” is that AGW is not basically sound science, that human activity has negligible impact on climate, and any notable changes we’ve observed recently are brought about by natural variation.

The observation “X” will be: arctic changes over the last several decades, namely warming much faster than the globe as a whole, and sea ice showing rapid and unprecedented decline. How likely were such changes (what’s the probability of “X”) if hypothesis “A” is true (AGW is sound), compared to when hypothesis “B” is true (AGW is not)?

Concensus AGW science predicts “X” as a consequence of “A.” But that doesn’t mean it has to happen — it’s still possible that AGW is sound but there something quirky about the Arctic that they missed, or that the changes will happen more slowly than expected, so it won’t warm faster than the globe and/or sea ice won’t decline. Nonetheless, if AGW is sound then the recent Arctic changes were pretty damn likely (seein’ as how they were predicted).

But no known mechanism of natural variation can explain “X”, a drastic change unlike anything in at least a century and probably thousands of years.

So if AGW is sound, then the changes we’ve observed are very likely, if it isn’t then they’re extremely unlikely.

How likely? My estimate: if AGW is sound science there’s at least a 90% chance of such changes as we’ve seen in the Arctic. So the first probability we seek, the probability of seeing “X” if “A” is true, is 90%

.

How unlikely? With no AGW, a change such as hasn’t been seen for thousands of years, for which there’s no known cause, in fact the known sources of natural variation can be ruled out so there must be some entirely natural but unknown cause, is pretty damn unlikely. I don’t believe it’s sane to maintain that there’s more than 5% chance of the recent Arctic changes naturally. In fact I think that’s an overly generous estimate, but let’s say the probability of seeing “X” if “B” is true, is 5%

.

With these conditional probabilities we can make a Bayesian estimate of the probability that AGW is correct.

A Bayesian estimate requires a “prior probability,” i.e., a probability that AGW is correct prior to knowing about the Arctic changes. We’ll call it . Then the probability that AGW is not correct (prior to knowledge of Arctic changes) will be .

The Bayesian estimate of the probabilty that theory is true, given the new information (Arctic changes, i.e., happened), is given by Bayes theorem:

.

If we substitute our estimated values, we get

.

Now we need to estimate the “prior probability,” i.e. the probability that AGW is sound science, without taking into account Arctic changes. In my opinion, the laws of physics all by themselves make AGW more likely than not — by a fair abount. Let’s be conservative and go with a 60/40 split, so we’ll say the prior probability is and . Then the Bayesian posterior probability becomes
.

Like I said: arctic change is very strong evidence of AGW. So strong, in fact, that it increases a naive 60% probability estimate to 96.4%.

And frankly, 60% as a prior probability isn’t right. There’s more to AGW than the laws of physics, there’s a mountain of observed evidence so support it. I’d say a righteous estimate of the prior probability is at least 95%. At least.

And if we use that for the prior probability, the posterior probability becomes 99.7%.

That’s a pretty crude calculation. It’s also not a bad estimate of my belief regarding the question: is AGW sound science or not? Yes 99.7% — being conservative. And yes it’s the cause of recent Arctic change.

Can We Talk?

Recently Walt Meier posted about artic sea ice 2010 on WUWT. Good for Anthony for giving Dr. Meier the podium. Meier emphasized that the state of arctic sea ice has changed dramatically. Referring to predictions of this year’s summer minimum in arctic sea ice extent:

The first thing to point out is that none of the estimates approached the 1979-2000 monthly September average of 7.0 million square kilometers. Even the highest estimates were nearly 20% lower. This is a recognition that conditions have clearly changed since the 1980s and 1990s. It is no longer plausible to prognosticate anything near average levels.

So: things have changed.

History of Arctic (and Antarctic) Sea Ice, Part 1

Nobody in his right mind disputes that since satellite observations began, the extent of sea ice in the arctic has declined dramatically; this year the summer minimum extent was the 3rd-lowest on record. There is also considerable observational evidence that arctic sea ice extent over the last few decades is much lower than it has been for at least a century prior to modern times.

A team of researchers, led by Leonid Polyak of Ohio State University’s Byrd Polar Research Center, has culled the available evidence from hundreds of studies of proxy data for sea ice extent. As reported at Science Daily, in a new paper in Quaternary Science Reviews they report their findings: that the present extent of sea ice in the arctic is at its lowest for at least several thousand years.

Anthony Watts: Pants on Fire

In my last post I made two predictions. The second one was this:

Second: Either Anthony Watts won’t answer my question about why he’s so fond of less than 6 years’ data when we have over 30 (and that’s just from satellites) — or he’ll attack me personally, calling me a coward for blogging under a pseudonym. After all, the best predictor of future behavior is past behavior.

The question was this:

We have over 30 years of satellite data for arctic sea ice. Why do you consistently display the only data source I know of that covers less than 6 years?

Anthony has replied. But just as I predicted, he didn’t answer my question. Instead he told a lie.

Go Ice Go! … Going … Going … Gone!!!

When it comes to up-to-date measures of arctic sea ice, the most popular choice with Anthony Watts and Steve Goddard is the estimated extent from DMI. Others seem to prefer NSIDC data for monthly averages of both sea ice area and sea ice extent, or JAXA for daily data on sea ice extent, or daily sea ice area data from Cryosphere Today. So there are several satellite-based data sets to choose from, but Watts seems to prefer, and Goddard seems to love, the DMI data.

Wonder why?

The great conspiracy to destroy freedom, sabotage the USA, increase taxes, undermine the economy, institute world government based on socialism with Al Gore as dictator, and of course … drive us all back to the stone age

It’s all a conspiracy of lies, deceit, greed for money and power, and hatred of all the USA stands for. It’s nothing but an attempt to destroy our freedom!

Because if fossil-fuel industry profits aren’t safe, then we aren’t safe.

And one of the most important conspirators is NASA. Specifically, the evildoers at GISS: the Goddard Institute for Space Studies. The folks at GISS have been fudging the numbers, and I’ve uncovered their dirty little secret. They apply “adjustments” to the raw data (which they get from a number of sources, but mainly the Global Historical Climate Network) which they’ve cleverly manipulated to make the global temperature trend — if there even is such a thing! — seem different than what the plain old data say.

Vindication?

Craig Loehle has contributed a post to WUWT claiming that a new temperature reconstruction by Ljungqvist (2010, A new reconstruction of temperature variability in the extra-tropical northern hemisphere during the last two millenia, Geografiska Annaler 92A(3):339-351) somehow “vindicates” his own work (Loehle 2007, A 2000 Year Global Temperature Reconstruction based on Non-Treering Proxy Data, Energy & Environment 18:1049-1058).

I got lucky

As most of you are aware, I had predicted that the 2010 minimum of arctic sea ice extent as measured by JAXA would be 4.78 million km^2. This turned out to be a remarkably close prediction, because the minimum (so far, which is probably but not certainly this year’s actual minimum) was 4.813594 million km^2. I was off by less than 1 percent.