Monday, January 19, 2015

The Probability of Global Warming

Forbes magazine has become a real dreg of climate change denialism, bringing in paid shills to write up the standard nonsense put out by the fossil fuel industry. Which means I have to spend a lot of time reading it. The reward is they will, on occasion, bring in someone to write about the science. These articles are frequently written by noted climate scientists and can be excellent sources of information.

Today, I read one that really caught my attention - The End of the Partisan Divide Over Climate Change. The article was hopeful and that part was nice. The author, Tom Zeller Jr., wrote about how polls show even Republicans are starting to agree CO2 needs to be regulated as a pollutant. But, that wasn't the part I found most interesting. It was the last paragraph that really got my attention. Referring to the fact that 2014 was the hottest year ever recorded, he said:
After all, a record-setting year every now and again is no big deal. Anomalies happen. But the fact is that all 15 years since the year 2000 have been among the top 20 warmest years ever recorded. The odds of this happening randomly, or as a part of natural variability? About 1.5 quadrillion to one.
This is a very different way to look at it and is very persuasive. If correct, these figures show there can be no doubt about the reality of global warming. That figure is devastating to any claim global warming is not real.

The calculations were performed by a team of university statisticians and I am confident in their accuracy.  But, let's look at the figures for ourselves and see if we get something close to the same number.

The way to imagine this is to suppose we have a bag filled with tokens numbered from 1 to 135. That is the number of years in the recorded temperature record. Number 1 would be for the hottest year on record, number 2 for the second hottest and so on. Now, we are going to reach into the bag and blindly draw out a token for the year 2014. The chances of that token being between 1 and 20 (inclusive) is 20/135 = .148148. That is a 14.81% chance, or one chance in 6.75 tries. Now, we do it again for 2013, but we took out a token already and we know the token was in the top 20 (that is the situation we are calculating the odds for), so there are only 134 tokens remaining and 19 of the top 20. The odds of 2013 being randomly one of those top 19 years is 19/134 = .141791. That is a 14.18% chance, or 1 chance in 7.05 tries. We can continue this process for all fifteen years since 2000 and the odds would be 18/133 for 2012; 17/132 for 2011, 16/131 for 2010, etc.

Those are the odds for each year individually. But, we want to know the odds for all of them at once. To get that figure we multiply the individual probabilities together. For the fifteen years in question, that would be (20/135) * (19/134) * (18/133) * (17/132) * ......

When I do that, I get 5.0409 x 10^(-16). That is percentage of .00000000000000504%, or one chance in 1,983,770,000,000,000.

Or 1 chance in about 2 quadrillion tries, very close to what the article quoted.

In other words, there is positively no way it could be a random occurrence. Global warming is most definitely real.

I never doubted the professors were right, I just wanted to make sure no one else did, either.


  1. The laws are correct, but that doesn't me you are applying them correctly. I didn't even bother with them because your premise of no greenhouse effect is a false one. You're right about one thing, the numbers don't lie. We can calculate what the planetary temperature would be without any greenhouse effect and we can compare that to the measured value. We find the planet is about 35 C warmer with an atmosphere than it would be without.

  2. The greenhouse theory claims that heat is somehow being trapped, and building up over time. Didn't it also used to be called the "runaway greenhouse effect"? It is warmer at the surface of the earth than it would otherwise be because there is an atmosphere, and enough atmospheric pressure to raise the temperature. But there is no mechanism to trap that heat over time. The comparison to Venus and Titan makes that obvious.

  3. The greenhouse theory says certain molecules will absorb and reemit infrared radiation, thus slowing the movement of IR radiation from the surface to space. CO2 is a major greenhouse gas, as is water vapor, methane and many others.

    The runaway greenhouse effect is the idea that greenhouse gases will lead to an increase in temperature, which will lead to greenhouse gases being released into the atmosphere, which leads to higher temperatures and so on until it becomes catastrophic. There have been some claims we risk creating such a scenario here, but most climate scientists believe we will reach a stable temperature, albeit, one much higher than is good for us and the environment.

    Like I said, I didn't examine your numbers because I already know they are wrong. The greenhouse effect is real and been proven with extensive experimental evidence. You might was well produce numbers that say gravity isn't real.

  4. That is the difference between the greenhouse gas theory and an actual greenhouse. It may slow down infrared radiation, but CO2 can do nothing to slow heat transfer by convection. The theory was actually proven wrong over a hundred years ago by Robert W. Wood in 1909. You may want to look that up.

  5. You are mixing up two different things. The term "greenhouse effect" is a misnomer and comes from the old idea that sunlight went into a greenhouse, heated up the surface and the glass windows kept the IR light from going back out. That, as it turns out, is not really how greenhouses work (although there is some of that going on). Be that as it may, the greenhouse effect is real - even if it is a misnomer.

  6. The issue about the data sets was settled by Berkeley Earth. They made the same complaint and established an entirely different data set to challenge the main groups. They came up with almost exactly the same results.

    We can't even keep NSA secrets (REAL secrets) from becoming public. How can anyone thing NASA and NOAA can do a better job of it?

    The natural cycle is great. They've been telling everyone we are going into a new ice age. Now, they want to say the heat is all natural? The strange part is they are closer to the truth with the new ice age claim. The natural cycle we're currently in is a cooling one. Maybe not a new ice, but certainly not one leading to record warming.

  7. Being in my late 20's, I've spent a lot of time on the internet, and seen a lot of crazy things.

    This may be the best of all of them.

    You cannot accuse someone of cherry picking statistics because they refuse to cherry pick the single position that effectively misrepresents a trend, when all others are valid.

  8. Rexx Vernon SheltonFebruary 23, 2015 at 2:25 PM

    Who accuse anyone of cherry picking statistics?