“A friend recently mentioned to me that he was having trouble believing in global warming after the record-setting cold weather this year. This reminded me that I had recently heard news of a record heat wave at the Australian Open tennis match,” writes Dr. Kenneth Hicks, Ohio University Professor of Physics, in the Feb. 9 Columbus Dispatch.
“Both extremes — one in the northern hemisphere and the other in the southern hemisphere — happened at nearly the same time,” Hicks writes, adding, “The key word here is global, meaning it’s essential to take temperature averages over the whole Earth, and even then the data show trends only when averaged over many years. But what data set are we talking about, and how reliable is it?”
Hicks explains that satellites sample the entire Earth and measure infrared light at various wavelengths. “Because the polar orbits are sun-synchronous, they take each measurement on Earth under the same lighting conditions, giving less variation in the data,” notes Hicks.
“Even when temperatures over the entire Earth are averaged for a full year, a year-to-year trend is not visible. A warming trend can be seen only when averaged over decades. And even that is small — about one-tenth of a degree Centigrade per decade, according to a study at the University of Alabama in Huntsville.
“Since the University of Alabama trend is small, most scientists would want to know more about the statistical variance in the result. It turns out that some studies get about half of the Alabama warming trend, and other studies get about twice the warming.
“So there is some uncertainty in how to analyze the satellite data. But most scientists using the satellite data agree that there is a small warming trend,” he writes. Yet even with the “tiny warming trend, … there are good indications that the warming trend is increasing exponentially. So although it might be small now, climate models indicate that the warming rate could increase substantially in future decades. But weather is “insanely difficult to predict,” writes Hicks, noting two variables in the complex climate forecasting models:
- “One of the lessons learned from the satellite data is that every time there is a major volcanic eruption, it is followed by a cooling trend for a few years.”
- “Another variable is the amount of energy put out by the sun each year. This can also be measured by satellites, such as NASA’s Solar Radiation and Climate Experiment mission. These data show a variation in the sun’s energy output by about 0.1 percent over an 11-year cycle. In years when the sun puts out less energy, it has a slight cooling effect on Earth’s average temperature.”
“Although I have no reason to doubt the existing models (these are done by collaborations of expert scientists), I think it’s fair to say that there’s some uncertainty in the forecasts,” concludes Hicks. “If I had to guess, I’d say that Earth will be a warmer place in the future. But the real question is: by how much?” Read the entire article in the Columbus Dispatch.