Have read....explains your lovely grapg from the epa.
So let’s look at global warming. We start with the summary for policymakers, which is what everybody reads. We will go into more detail in a minute, but for now, we assume the summary has all the important stuff, and turning to page three we find what are arguably the two most important graphs in climate science in 2001.
The top graph is taken from the Hadley Center in England, and shows global surface warming. The bottom graph is from an American research team headed by Mann and shows temperature for the last thousand years.
Of these two graphs, one is entirely discredited and the other is seriously disputed. Let’s begin with the top graph.
I have redrawn the graph in Excel, and it looks like this.
Now the first thing to say is that there is some uncertainty about how much warming has really occurred. The IPCC says the 20th century temperatures increase is between .4 and .8 degrees. The Goddard Institute says it is between .5 and .75 degrees. That’s a fair degree of uncertainty about how much warming has already occurred.
But let’s take the graph as given. It shows a warming of .4 degrees until 1940, which precedes major industrialization and so may or may not be a largely natural process. Then from 1940 to 1970, temperatures fell. That was the reason for the global cooling scare, and the fears that it was never going to get warm again. Since then, temperatures have gone up, as you see here. They have risen in association with carbon dioxide levels. And the core of the claim of CO2 driven warming is based on this thirty-five year record.
But we must remember that this graph really shows annual variations in the average surface temperature of the earth over time. That total average temperature is ballpark sixteen degrees. So if we graph the entire average fluctuation, it looks like this:
So all the interest is in this little fluttering on the surface. Let’s be clear that I am graphing the data in a way that minimizes it. But the earlier graph maximizes it. If you put a ball bearing under a microscope it will look like the surface of the moon. But it is smooth to the touch. Both things are true. Question is which is important.
Since I think the evidence is weak, I urge you to bear this second graph in mind.
Now the question is, is this twentieth-century temperature rise extraordinary? For that we must turn to the second graph by Michael Mann, which is known as the “hockey stick.”
This graph shows the results of a study of 112 so-called proxy studies: tree rings, isotopes in ice, and other markers of relative temperature. Obviously there were no thermometers back in the year 1000, so proxies are needed to get some idea of past warmth. Mann’s findings were a centerpiece of the last UN study, and they were the basis for the claim that the twentieth century showed the steepest temperature rise of the last thousand years. That was said in 2001. No one would say it now. Mann’s work has come under attack from several laboratories around the world. Two Canadian investigators, McKitrick and McIntyre, re-did the study using Mann’s data and methods, and found dozens of errors, including two data series with exactly the same data for a number of years. Not surprisingly, when they corrected all the errors, they came up with sharply differing results.
But still this increase is steep and unusual, isn’t it? Well, no, because actually you can’t trust it. It turns out that Mann and his associates used a non-standard formula to analyze his data, and this particular formula will turn anything into a hockey stick---including trendless data generated by computer.
Physicist Richard Muller called this result “a shocker…” and he is right. Hans von Storch calls Mann’s study “rubbish.” Both men are staunch advocates of global warming. But Mann’s mistakes are considerable. But he will get tenure soon anyway.
But the disrepute into which his study has fallen leaves us wondering just how much variation in climate is normal. Let’s look at a couple of stations.
Here you see that the current temperature rise, while distinctive, is far from unique. Paris was hotter in the 1750s and 1830s than today.
Similarly, if you look at Stuttgart from 1950 to present, it looks dramatic. If you look at the whole record, it is put into an entirely different perspective. And again, it was warmer in the 1800s than now.
Now, these are graphs taken from the GISS website at the time I did my research for the book. For those of you think the science is all aboveboard, you might contemplate this. The data have been changed.
I have no comment on why the Goddard Institute changed the data on their website. But it clearly makes the temperature record look more consistently upward-trending and more fearsome than it did a few months ago.
All right. With the second graph demolished, it is time to return to the first. Now we must ask, if surface temperatures have gone up in the twentieth century, what has caused the rise? Most people have been taught that the increase is caused by carbon dioxide, but that is by no means clear.
