As the Northern Hemisphere enters the summer season and natural global warming occurs, it’s a good time to consider the concept of global temperature — perhaps the most talked about, but least understood, component of the global warming controversy.
Since 1988 when National Aeronautics and Space Administration (NASA) researcher James Hansen launched global warming alarmism with his congressional testimony that manmade emissions of greenhouse gases were warming the Earth’s atmosphere, global warming has been a hot topic. The controversy only heightened with the advent of the so-called “hockey stick” graph that purports to show a dramatic rise in global temperature during the 20th century.
At JunkScience.com, we’re trying to shed light on the problem of relying on global temperature as an indicator of global warming by developing and displaying the world’s first (almost) real-time global thermometer.
We gather temperature readings from about 1,000 surface-based temperature stations around the globe, calculating an average temperature, which we call the “global mean temperature” (GMT).
We use “raw” temperature data that isn’t statistically massaged to account for seasonal variation or for the urban heat island effect — the phenomenon caused by the heat-retaining properties of concrete and asphalt in urban areas that is known to artificially increase local temperatures. We display the current GMT and maintain old GMTs to track weekly, monthly and, eventually, annual trends.
From what we can tell, our data track pretty well with the temperature estimates published by other climate researchers, which are available only weeks to months after the data are collected.
At the time of this column, the GMT — according to our calculations — is roughly 62 degrees Fahrenheit. So what does that mean exactly?
We’re not really sure. First, global temperature is a contrived concept. There is no magical point in the Earth’s atmosphere to place a thermometer and take the planet’s temperature. Moreover, if you live in a polar or tropical region (or almost anywhere for that matter), a GMT of 62 degrees F is patently meaningless — what matters is what’s going on outside where you are.
Our GMT is based on surface records. But if you look at a map of weather stations around the globe, you’ll readily see the built-in bias of temperature readings from surface-based weather stations.
The overwhelming majority of surface-based weather stations are land-based — relatively few temperature readings come from ocean-based facilities, resulting in a major upward bias in available temperature data since about 75 percent of the Earth’s surface is water.
An additional bias arises from the fact that there is more land mass and, therefore, more surface temperature stations in the Northern Hemisphere than in the Southern Hemisphere.
There’s an even further bias introduced by the tendency of land-based weather stations to be located in more heavily populated areas, which are subject to the urban heat island effect. Relatively speaking, not many temperature readings come from the wilds of northern and central Asia or eastern Africa, for example.
There are alternatives to the JunkScience.com-calculated GMT — none, however, are available in real-time.
The National Climactic Data Center collects temperature data from about 3,000 surface-based weather stations. But researchers often try to statistically adjust these data to account for the urban heat island effect, which produces results that are more statistical mysteries than true averages of global surface temperature readings.
Other researchers calculate GMTs from data collected by satellites and weather balloons. These data measure atmospheric temperatures from all around the Earth and don’t suffer from the same biases as the surface temperature data. It’s important to note that without the upward bias inherent to the surface temperature data, the satellite/balloon temperature measurements show no significant increase since data collection began 30 years ago. Global warming alarmism is largely based on the notion that global temperatures have increased since the 19th century industrial revolution due to manmade emissions of greenhouse gases, primarily carbon dioxide. The infamous hockey stick graph tries to dramatize the alleged increase in temperature by going back 1,000 years.
But the pre-20th century GMTs in the hockey stick graph for the most part don’t come from thermometer readings. Instead they are guesstimates of GMTS based on geographically and temporally scattered data scavenged from tree rings, ice cores and other dubious proxies for thermometers.
Whether calculated in real-time or two months after-the-fact, surface-based calculations of GMT are inherently and impossibly biased. In this light, the hockey stick’s GMTs over the last 1,000 years are near worthless — yet it is this very data that are being used to drive global warming hysteria.
We hope that the JunkScience.com global thermometer will help demystify the flawed science that has led to the present state of climate clamoring. Remember, just 30 years ago, early climate alarmists were actually fretting about global cooling.
It’s shocking that our government may commit us to potentially harmful energy and policies — like the international global warming treaty known as the Kyoto Protocol or the legislation introduced in the U.S. Senate by Sen. John McCain, R-Ariz., and Sen. Joe Lieberman, D-Conn., — based on such an elusive, if not meaningless, concept as global temperature.
Steven Milloy publishes JunkScience.com and CSRwatch.com, is adjunct scholar at the Competitive Enterprise Institute, and is the author of Junk Science Judo: Self-defense Against Health Scares and Scams (Cato Institute, 2001).