One of the things that yanks your humble Devil's pointy little beard is when those talking about climate change, anthropogenic or otherwise, keep burbling on about how they studied this science or that science and if you are not a scientist then you have no right to discuss the subject whatsoever.
As I attempted to intimate in this post, the only science at the heart of the climate change debate is that of data-gathering.
And, though the scientific community will no doubt be shocked by this assertion, you do not actually need shedloads of scientific training to be able to design and set up a reliable data-gathering exercise. Yes, some scientific training can be of use, but only because a stable foundation of said training is—or certainly used to be—practical experiment design.
Equally, you do not need to be a scientist to spot when a data-gathering exercise is fundamentally flawed. Let us take, for instance, the whole "global temperature" idea, shall we?
How does one measure global temperature? It's a bit tricky, wouldn't you say? After all, the Earth does not have one temperature across its entirety at any one time. As such, you need to measure the temperature in a particular spot over a reasonably long period in order to be able to gain an average temperature for that spot.
Given that the Earth has been in existence for about 4.5 billion years, you then need to ask yourself how you define "a reasonably long time"? NASA's Goddard Institute of Space Studies (GISS)—James Hansen's crew—uses a network of land temperature stations, some of which have been in place (roughly speaking) since 1880. That is to say, those stations have been recording measurements for just 128 years out of 4.5 billion, or 0.00000284% of the time that Earth has been in existence.
Of course, one could say that we are really interested in how temperatures react to man's activities, and vaguely civilised man at that. So, let's say that we have records of civilisation going back about 2,500 years. OK, so, these stations have been around for about 5.12% of the time that we want to examine. Is that long enough? Who knows?—it will just have to do.
So, having determined that 128 years is long enough, we need to set these stations up all over the surface of the globe, in order to get representative results. Well, the Earth has a surface area of some 510,072,000 km²: what density of measurement stations would be representative? And remember that you have an added problem: only 29.2% of that is land—the other 361,132,000 km² is water.
But you can't simply measure the surface: we are looking for a global temperature, so you need to place stations in the atmosphere too. Now, the Earth has a mean radius of 6,371.0 km and the volume of a sphere is calculated thus: v = (4/3) x pi x radius3. This gives us a rough volume of 1.3333 x 3.14159 x 258,596,602,811 = 1,083,205,999,191.998 km3.
But we want the volume, not of the whole sphere, but of the atmosphere that we can measure. So, we'll be generous and use only the three quarters of the atmosphere that is underneath the troposphere; the troposphere is at an average of roughly 12 km above the surface of the Earth. So, the volume, including the troposphere, is about 1.3333 x 3.14159 x 260,060,583,887 = 1,089,338,303,588.998 km3.
Now, to get the volume that we need to install our temperature stations in, we simply take the first total from the second: 1,089,338,303,588.068 - 1,083,205,999,191.998 = 6,132,304,396.07 km3. Which is a pretty large volume to measure, is it not?
Plus, of course, we haven't actually taken account of the depth of the seas in that calculation—after all, the Pacific Ocean alone adds another 161,000,000 cubic miles to the total).
NASA GISS relies on only a few thousand surface-only temperature stations, the oldest of which has been established for less than 130 years (and all of these are in the USA). Furthermore, as the now 67% complete surfacestations.org project has shown, the measurements from many of these stations have been contaminated by the spread of urban heat islands and other localised man-made factors.
And we haven't even delved into the problems of advancing technology (are thermometers more sensitive now than they were in 1880. Yep), incomplete records, human error and other such issues yet.
But in spite of all of this, the IPCC—which relies heavily on the NASA GISS data (though there are other sources too)—believes that it can tell us what an average global temperature should be. They cannot. Using the NASA GISS resources, they might be able to tell us what the temperature for one particular spot was, but only to a maximum of 128 years ago.
What to do? Well, our earth is old and so are many of the beings on it and we can try to use some of these as proxies to measure temperatures further back than our instruments or records can go. But these provide their own problems, as Michael Mann (amongst others) found with bristle-cone pines. And, Al Gore, famously and inconveniently, found that his proxy—ice cores—contradicted his thesis that CO2 caused temperature rises when it was discovered that the data showed that a CO2 rise lagged behind a temperature rise by an average of 800 years.
Anyway, in trying to illustrate the problems inherent in the climate change data-gathering exercise, I have turned this post into something of an essay (when it was meant to be a swift point) so maybe I should summarise: we don't really know what temperatures global temperatures are now, let alone what they have been to a reasonable past timescale—and we certainly do not know to the fractions of a degree Centigrade that are required for determining the current supposed rate of warming. We simply do not have enough reliable data to decide whether or not there is anything to explain, let alone postulate an explanation.
So, lengthy though this post has become, the point that I was trying to make is a pretty simple one: if we manage, somehow, to get some data that shows a trend that we need to explain, then we can start calling on the scientists who can then come up with hypotheses and properly test them.
But until we have some reliable data, there is no point in wittering on about your PhD.