Dr. John R. Christy (Ph.D., Meteorology), Distinguished Professor of Atmospheric Science, Alabama State Climatologist, Director of the Earth System Science Center at The University of Alabama in Huntsville, former Lead Author, Contributing Author, and Reviewer of United Nations Intergovernmental Panel on Climate Change assessments, recipient of NASA’s Medal for Exceptional Scientific Achievement, and a Fellow of the American Meteorological Society (all that just to shame the climate alarmists who insist that no serious climate scientist questions the “overwhelming consensus” for CAGW) told the U.S. House of Representatives Committee on Science, Space & Technology on February 2 a little bit about global temperature monitoring. Well, maybe a little more than a little bit. It was an education, too thorough to repeat here. (But you can read his whole written testimony here.)
But here are some fairly simple takeaways:
It’s difficult. There are competing methods. They yield conflicting results. Some methods are better than others. The best are satellite remote sensing and weather balloons because they’re more globally representative (especially satellites) and not subject to urban heat island contamination and improper siting and operation. Perhaps the worst are seawater sampling from ships’ intake valves, which are spatially unrepresentative and subject to many variations in how they’re obtained.
And the infamous NOAA study last year that purported to demolish “the Pause” in global warming? The main (heavily massaged) data that led to its Pause-questioning conclusions were those ship samples.
But no matter. Pretty much all the datasets—including that NOAA one—show the climate models, which are the sole grounds for fears about dangerous anthropogenic warming, predict much more warming than actually observed. Compared with the satellite and balloon data: from 2.5 to 3 times as much.
Along the way Christy refuted charges that the satellite data aren’t all that reliable. Some of that part of the paper I reproduce here:
Because this result challenges the current theory of greenhouse warming in relatively straightforward fashion, there have been several well-funded attacks on those of us who build and use such datasets and on the datasets themselves. As a climate scientist I’ve found myself, along with fellow like-minded colleagues, tossed into a world more closely associated with character assassination and misdirection, found in Washington politics for example, rather than objective, dispassionate discourse commonly assumed for the scientific endeavor. Investigations of us by congress and the media are spurred by the idea that anyone who disagrees with the climate establishment’s view of dangerous climate change must be on the payroll of scurrilous organizations or otherwise mentally deficient. Also thrust into this milieu is promotional material, i.e., propaganda, attempting to discredit these data (and researchers) with claims that amount to nothing.
Several of these allegations against the data appeared a few weeks ago in the form of a well-made video. I shall address the main assertions with the following material, which in similar form has appeared in the peer-reviewed literature through the years.
The video of interest was promoted by a climate change pressure group (Yale Climate Connections, http://www.yaleclimateconnections.org/2016/01/over-reliance-on-satellitedata-alone-criticized/) in which well-known scientists make claims that are mostly meaningless or completely wrong relative to the evidence in Fig. 1. I wish to make four points regarding the video and demonstrate the misdirection for which such agendized videos, along with a happily mimicking media, are so famous.
First, the claim is made the satellites do not measure temperature. In reality, the sensors on satellites measure temperature by emitted radiation – the same method that a physician uses to measure your body temperature to high precision using an ear probe. Atmospheric oxygen emits microwaves, the intensity of which is directly proportional to the temperature of the oxygen, and thus the atmosphere. That the satellites measure temperature is evident by the following chart which compares our UAH satellite data with temperatures calculated from balloon thermistors. As an aside, most surface temperature measurements are indirect, using electronic resistance.
Secondly, the scientists claim that the vertical drop (orbital decay) of the satellites due to atmospheric friction causes spurious cooling through time. This vertical fall has an immeasurable impact on the layer (MT) used here and so is a meaningless claim. In much earlier versions of another layer product (LT or Lower Troposphere), this was a problem, but was easily corrected almost 20 years ago. Thus, bringing up issues that affected a different variable that, in any case, was fixed many years ago is a clear misdirection that, in my view, demonstrates the weakness of their position.
Thirdly, the scientists speak of the spurious temperature changes that occur as the satellites drift in the east-west direction, the so-called diurnal drift problem (which was first detected and accounted for by us). They speak of a sign error in the correction procedure that changed the trend. Again, this error was not a factor in the MT layer in Fig. 1, but for the different LT layer. And, again, this issue was dealt with for LT 10 years ago.
Finally, though not specifically mentioned in this video, some of these scientists claim Fig. 1 above is somehow manipulated to hide their belief in the prowess and validity of the climate models. To this, on the contrary, I say that we have displayed the data in its most meaningful way. The issue here is the rate of warming of the bulk atmosphere, i.e., the trend. This metric tells us how rapidly heat is accumulating in the atmosphere – the fundamental metric of global warming. To depict this visually, I have adjusted all of the datasets so that they have a common origin. Think of this analogy: I have run over 500 races in the past 25 years, and in each one all of the runners start at the same place at the same time for the simple purpose of determining who is fastest and by how much at the finish line. Obviously, the overall relative speed of the runners is most clearly determined by their placement as they cross the finish line – but they must all start together.
In the same way I constructed the chart so that the trend line of all of the temperature time series starts at the same point in magnitude and time (zero value at 1979) so the viewer may see how wide the spread is at the finish line (2015). One way to look at this is seen in Fig. 3 where I provide what is seen in Fig. 1 except this is only the trend line without the variations that occur from year due to volcanoes and such. This is analogous to plotting the overall average speed of a runner along the course even though they likely ran slower on an uphill, and faster on a downhill.
This image indicates the models, on average, warm this global layer about 2.5 times faster than the observations indicate. This is a significant difference that has not been explained and indicates the theory of greenhouse impact on atmospheric temperature is not sufficiently known to even reproduce what has already happened. We are not talking about 10 or 15 years here, but 37 years – well over a third of a century. That two very independent types of measuring systems (balloons and satellites) constructed by a variety of institutions (government, university, private) all showing the much slower rate of warming gives high confidence in its result. Thus, the evidence here strongly suggests the theory, as embodied in models, goes much too far in forcing the atmosphere to retain heat when in reality the atmosphere has a means to relinquish that heat and thus warms at a much slower rate.
I’ve shown here that for the global bulk atmosphere, the models overwarm the atmosphere by a factor of about 2.5. As a further note, if one focuses on the tropics, the models show an even stronger greenhouse warming in this layer. However, a similar calculation with observations as shown in Fig. 3 indicates the models over-warm the tropical atmosphere by a factor of approximately 3, (Models +0.265, Satellites +0.095, Balloons +0.073 °C/decade) again indicating the current theory is at odds with the facts. (again, see section 2.)
It is a bold strategy in my view to actively promote the output of theoretical climate models while attacking the multiple lines of evidence from observations. Note that none of the observational datasets are perfect and continued scrutiny is healthy, but when multiple, independent groups generate the datasets and then when the results for two completely independent systems (balloons and satellites) agree closely with each other and disagree with the model output, one is left scratching one’s head at the decision to launch an offensive against the data. This doesn’t make scientific sense to me.
The whole testimony is a rewarding read for anyone who wants to get beyond the sound bites and slapdash that substitute for most journalistic reporting, and social media commenting, and even a good deal of scientific discourse by scientists on this subject.
Featured image courtesy of John R. Christy.