For a long time, I have been skeptical of the catastrophic anthropogenic global warming theory, which I think is utterly refuted by the evidence. But I have been willing to assume that in recent decades, the Earth has in fact gotten slightly warmer, consistent with the natural fluctuations that have been going on for millions of years.
At Watts Up With That, Dr. Fred Singer suggests that this assumption may be unfounded. The balance of evidence, he argues, shows that the Earth has not warmed perceptibly during the time when alarmists claim to see the effects of CO2 emissions.
Dr. Singer begins with the graph that purports to show 20th century warming, which you probably have seen many times. He compares it with the standard U.S. temperature record over the same period, which shows relatively little recent warming:
Dr. Singer explains:
Although these two trends look similar, they are really quite different: the initial warming is genuine, but the later warming is not. What a surprise! I wouldn’t exactly call it ‘fake,’ but it just does not exist; I try to demonstrate this difference as an artifact of the data-gathering process, by comparing with several independent data sets covering similar time intervals.
The later warming is contradicted by every available dataset, as follows:
** the surface record for the ‘lower 48’ [US] shows a much lower trend; [see fig 1, bottom]; presumably there is better control over the placement of weather-stations and their thermometers…
Probably true, although inspections have shown that most American weather stations do not comply with official standards, in ways that generally would cause them to record higher temperatures (e.g., being located next to heat discharge vents).
Other data sources do not show the generally assumed warming trend:
** the trend of global sea surface temp [SST] is much less; with 1995 temp values nearly equal to those of 1942 [acc to Gouretski and Kennedy, as published in Geophysical Research Letters in 2012];
** likewise, the trend of night-time marine air-temperatures [NMAT], measured with thermometers on ship decks, according to data from J Kennedy, Hadley Centre, UK
** atmospheric temperature trends are uniformly much lower and close to zero (during 1979-1997), whether measured with balloon-borne radiosondes or with microwave sounding units [MSU] aboard weather satellites [see fig 8 in ref 2].
** compatible data on solar activity that show nothing unusual happening [Interestingly, the solar data had been assembled for a quite different purpose – namely, to disprove the connection between cosmic rays and climate change [see here fig 14 of ref 2], assuming that the late-century warming was real. In the absence of such warming, as I argue here, this attempted critique of the cosmic-ray–climate connection collapses.]
** proxy data also show near-zero trends, whether from tree rings or ice cores, as noted about 20 years ago [see fig 16 in ref 1 and figs 2 and 3 of ref 2; plus those that may have been withheld by Michael Mann]. [If you look carefully at Mann’s original 1998 paper in Nature or subsequent copies, you will note that his proxy temps cease suddenly in 1979 and are replaced by temps from thermometers from CRU-EAU, the Climate Research Unit of East Anglia University. This substitution not only supplies the ‘blade’ of Mann’s ‘hockey-stick’ but enables the claim of IPCC-AR3  that the 20th century was the warmest in the past 1000 years, surpassing even the high temps of the Medieval Warm Period. In Climategate e-mails this substitution was referred to as “Mike’s Nature trick. I can’t help wondering if Mann’s original post-1979 proxy data showed warming at all; perhaps that has some bearing on why Mann has withheld these data; it could have killed the blade and spoiled the IPCC claim.]
Ocean temperatures allegedly have risen a bit during recent decades. But is that related to the fact that they are now being measured differently?
We first look at Ocean data: as seen from fig 2, there was a great shift in the way Sea Surface Temperatures [SSTs] were measured:
This is rather stunning: ocean temperatures have gone from being measured by buckets to being measured by buoys:
Data from floating buoys increased from zero to 60% between 1980 and 2000. But such buoys are heated directly by the sun, as indicated in the cartoon of fig 3, showing a floating buoy in the solar-heated top layer and unheated engine inlet water in lower ocean layers; this combination leads to a spurious rise in SST when the data are mixed together.
Most people naturally assume that the weather stations that are now reporting higher temperatures, on average, are the same as the weather stations that reported lower temperatures decades ago. Unfortunately, this is not true. A large majority of the weather stations that existed in 1970 have gone out of business, and those that remain are almost all at airports:
The land data have problems of their own. During the same decades, quite independently, there was a severe reduction in ‘superfluous’ (mostly) rural stations [fig 12 in ref 2] — unless they were located at airports. As seen from fig 4, the number of stations decreased drastically in the 1990’s:
The weather stations that have been deleted from the temperature record are overwhelmingly rural. They record lower temperatures than urban stations because of the urban heat island effect, which, although it is universally acknowledged (“chance of frost in outlying areas”) is nowhere accounted for in the alarmists’ models.
These are not the only reasons to suspect that the claimed temperature increases of the last few decades may be spurious. There is a huge problem, which Dr. Singer does not address in this post, with the surface temperature record. Pretty much all temperature records are under the control of global warming alarmists, and the alarmists constantly “adjust” temperatures that were recorded historically by thermometers by making the past cooler and the present warmer. We have written about this many times. A large portion of the warming that is alleged to have occurred in the late 20th century is attributable to these after-the-fact “adjustments.”
The bottom line is obvious: global warming doesn’t prove catastrophic anthropogenic global warming, any more than the cooling a few decades back proved catastrophic anthropogenic global cooling. The Earth gets warmer and cooler without any help from us. But if there is no global warming in recent decades, then obviously there is no catastrophic anthropogenic global warming, and the alarmists’ models, already discredited, are even farther from reality.