How much ‘global warming’ isn’t global? Vijay Jayaraj and E Calvin Beisner debate two aspects of climate change: what caused the increase from the 1970s to the 1990s, and why has there been a slowdown since then There would be no climate sceptics if climate science were settled (like the science of gravity) and we knew the precise causes of planetary warming. But neither is the case. The two most debated aspects of the climate change observed in the past five decades are, first, what caused the increase in the global average of temperature measurements that prevailed from the 1970s through 1990s, and, second what caused the apparent slowdown in that increase since then. Like his fellow students in climate science, Vijay learned from his professors—at the University of East Anglia, home of the infamous Climategate scandal, which happened while he was there—that carbon dioxide emissions caused the first. But then the increase in the global average of temperature measurements did something strange. For all intents and purposes, it flat-lined. That wouldn’t have been so strange if CO2 emissions had flat-lined, too. But they didn’t. They continued rising as fast as before. The result? Well, if Vijay’s professors were right about what caused the increase in the global average of temperature measurements pre-2000, the result post-2000 was a cause without an effect: increasing emissions without correspondingly increasing global average of temperature measurements. A crucial distinction You might wonder why we’re writing of “increase in the global average of temperature measurements.” Why not simply “global warming” or, a phrase that means the same thing, “increase in global average temperature.” It’s because increase in the global average of temperature measurements (IGATM) could happen entirely without global warming (GW), that is, increase in global average temperature (IGAT). IGATM puts the focus on measurements. GW and IGAT put the focus on temperature. They assume that measurements accurately reflect what’s happening with temperature, and not just temperature here and there but temperature at the global scale. That assumption has led to widespread and persistent confusion and error. It has blinded researchers to the possibility that something other than, or in addition to, changes in temperature at the global scale, could have contributed to increase in the global average of temperature measurements. But the essential flat-lining of IGATM since around 2000—which researchers first began to suspect around 2008 and became so obvious as to be nearly undeniable by 2016—should have alerted them that their explanation of the earlier IGATM was suspect. If the apparent cause (increasing atmospheric CO2 concentration) continued, but the apparent effect (IGATM) didn’t, it should have followed that other causes were involved. What could those have been? What else might have caused significant IGATM before 2000 but far less after 2000? It’s not that nobody’s ever noticed the mismatch between continued cause and absent effect before. Climate scientists have discussed the ‘pause’ or ‘hiatus’ in GW (or IGAT) for over a decade. The pause: now you see it, now you don’t The first standard response was that the pause was too short to matter. When it stretched to about six years, advocates of the standard theory—that CO2 emissions drove the earlier warming—first told us it wouldn’t pose a problem until it lasted about eight years. As that milestone neared, they revised it to twelve years, then fifteen. When it stretched to eighteen years, that excuse fell out of favour. When observations conflicted with theory, honest, objective, self-critical scientists would have reconsidered. Instead, some tried to prove that the pause was an illusion. They did so by ‘adjusting’ temperature data in ways that minimized or even eliminated the pause. The problem isn’t with data adjustment per se. Use of different instruments, deterioration of instruments over time, changes in the environment surrounding instruments, changes in location of instruments and even of the people reading the same instruments in the same places (after all, some people are more careful than others)—all of these and more can necessitate adjustments to make readings from one time and place properly comparable with readings from another. But adjustments driven solely by those factors would tend to be random over time. Instead, an extraordinary thing happened. Data keepers at NASA, NOAA, and similar agencies in other countries ‘adjusted’ temperature data in strange ways that consistently raised later numbers and lowered earlier ones. And without apparent justification. The result? The pause seemed to disappear. Until close scrutiny by a variety of scientists exposed the shenanigans. And now even leading proponents of the theory that CO2 emissions drove dangerous warming through the last two decades of the last century admit that the pause—or at least the slowdown—in IGATM has been real, and major. So the question remains: why did the cause (rising atmospheric CO2 concentration) continue unabated while the effect (IGATM) didn’t? One set of possible reasons is that factors other than atmospheric CO2 concentration significantly affect global average temperature (GAT). These would include cyclical changes in the sun and major ocean cycles. Such changes are widely recognized. But as solutions to the challenge posed by the pause they aren’t very promising—at least not for those who are determined to cling to the theory that CO2 has been the primary cause of recent GW. If they could have caused the post-2000 pause, it follows that they could have contributed to the pre-2000 warming, too. And that then calls the whole theory into doubt. So is there another possible explanation—not necessarily instead of, but in addition to? As it happens, yes. And it’s been lurking in the background for over a decade. Warming from Urban Infrastructure (UHI) As human settlements—from small villages to mid-sized towns to giant cities—develop, they both generate heat of their own and retain heat from the sun. They become ‘heat islands’, pockets with higher temperatures than surrounding areas. Their excess heat comes from construction materials, roads, transportation, loss of vegetation, and other surfaces that retain heat. This artificial warming of urban areas is known as the Urban Heat Island (UHI) effect. As a result of UHI, temperatures measured inside villages, towns, and cities are usually higher than those taken in rural locations. The bigger the settlement, the bigger the difference. It is theoretically possible, by carefully comparing measurements taken inside cities with those taken outside them, to adjust for UHI. In practice, though, so many factors could contribute to the difference that it is impossible to quantify, with great certainty, the difference between natural warming and UHI inside any specific city. But independent studies using different data and methods, two (in 2004 and 2006) by Jos de Laat and Ahilleas Maurellis, and one by Ross McKitrick and Patrick Michaels, both concluded that UHI likely accounts for about half of warming measured over land since 1980. It follows that if we want to measure only truly global warming, not including UHI effect, we should use only measurements from rural sites. Unfortunately, we haven’t done that. As a result, UHI effect remains the elephant in the room. It has been neither resolved nor accounted for adequately by corrections. According to University of Alabama climate scientist Dr Roy W Spencer, “because UHI warming looks like global warming, it is difficult to remove from the data. In fact, NOAA’s efforts to make UHI-contaminated data look like rural data seems [sic] to have had the opposite effect.” All cities in India (where Vijay lives) display UHI effect, and the gradual increase in temperatures in them during the past three decades is no surprise. European cities also are well known for UHI. Recently, NASA’s ECOSTRESS released pictures of the UHI effect in Europe. NASA, in its July statement, highlighted the growing effect of UHI: “heat from previous days was stored by surfaces with high heat capacity (such as asphalt, concrete and water bodies) and unable to dissipate before the next day. The trapped heat resulted in even higher midday temperatures.” Likewise, UHI is well known in the United States, where Calvin lives. For example, “From 1997 to 2000, the average daily low temperature was almost 10° F higher at the Sky Harbor weather station [in Phoenix, AZ] than at a companion station 60 miles to the west ….” More broadly, for the country as a whole, the US Environmental Protection Agency “describes heat islands as urban areas, populated with over a million people, where the average air temperature is 1.8 to 5.4° F warmer than surrounding areas (and 22 degrees warmer at night).” Thermometer locations exaggerate apparent warming Thermometers may appear harmless players in the climate drama. Instead, they are a major hurdle to our efforts to make accurate measurement of global average temperature. Because of UHI effect and the improbability of separating natural warming from it, the thermometer readings from urban sites do not help, but may actually hinder, the effort to assess the actual increase in global temperatures. Despite this, scientists continue using thermometer readings from urban sites as actual indicators of global warming. Even worse, most of the thermometers are situated in cities, and the global average temperature calculated from these readings is bound to show warming, even if there were none at global scale. Spencer says the solution would be to use measurements from sites that are free from the UHI effect. “The best strategy would be to simply use only the best (most rural) sited thermometers. This is currently not done.” So, our thermometers not only are sitting at the heart of the UHI effect but also are erroneous. It is no surprise that there is an apparent rise in global temperature when measurements come from UHI-polluted thermometers. These two reasons could also be the cause behind the increasing difference between thermometer measurements and satellite temperature measurements. Unlike thermometers, satellites are free from UHI interference and a more reasonable source for the estimation of global average temperatures. So next time you hear someone blame CO2 emissions for global warming, you can explain that because of the UHI effect, a significant part of apparently global warming isn’t global at all. You can also explain that satellite data—far more accurate and not biased by UHI—show less warming than surface thermometers. If we are to make progress in our assessments of climate and how it is changing, we must acknowledge the glaring errors in our measurement technology and rectify them globally. ABOUT THE AUTHORS Vijay Jayaraj (MSc, Environmental Science, University of East Anglia, England) is Research Contributor for Developing Countries, and E Calvin Beisner, PhD, is Founder and National Spokesman, for the Cornwall Alliance for the Stewardship of Creation.
If we are to make progress in our assessments of climate and how it is changing, we must acknowledge the glaring errors in our measurement technology and rectify them globally