Editor’s note: This is the first in a two-part series regarding climate change.

Editor’s note: This is the first in a two-part series regarding climate change.

What is a responsible citizen to make of the issue of climate change? The topic is complicated. Practically any opinion, from "warm winter weather is nice" to "the sky is falling" to "it’s just a bunch of corrupt scientists" can quickly be found in a web search. If the climate is getting warmer how can this winter be so cold? How strong is the evidence that the climate is changing? Why do experts think humans are causing the change? Couldn’t a warmer climate be a good thing?

We understand the confusion. We don’t do research on climate change or receive funding to work on this issue, but our courses require us to cover the topic, and despite being able to devote work time to the subject, we find it difficult to keep up with the latest developments. Here are our thoughts on a few common questions. Next week will explore the topic a bit further.

What is the difference between weather and climate? Weather refers to short-term variation. Climate refers to long-term norms. The weather can fluctuate wildly while the climate doesn’t change at all. Or both can change. A bout of strange weather is not, by itself, evidence for or against climate change, but we have met local senior citizens who reported that they routinely walked or skated on frozen lakes around Sherman when they were kids. Skating on a lake around here takes more than a cold spell. We have lived in Sherman for decades and have never seen a time when it was cold enough to safely walk on a pond. If kids owned skates, sustained winter cold must have been predictable — the climate must have been different. Who would have bought skates otherwise? But that is just one place at one time — anecdotal evidence. We will summarize all of the evidence next week.

What is the greenhouse effect? Various gases in the atmosphere let light waves from the sun in, but trap the heat given off by the earth’s surface on the way back out. This is how glass windows warm a greenhouse — they let light in but don’t let much of the resulting infrared radiation back out. A car parked in the sun with the windows closed does the same thing. The greenhouse effect should probably be called the parked-car effect since that is more familiar. Some of this is a good thing. Just like a car that gets warm in the sun on a cold winter day, the normal amount of greenhouse effect is a good thing — we are suited to it. Without it the water on the planet would be frozen and neither we nor anything else would be alive here. But just like a car parked in the sun with the windows up in August, too much greenhouse effect would be a bad thing.

What difference could a couple of degrees make? Small amounts of change in today’s temperature are trivial but small amounts of change in the average global temperature have monumental effects. Evidence from the last ice age about 20,000 years ago shows that when the average global temperature was about 9 degrees colder than today — just 9 degrees — the site where Chicago now exists was covered with ice that reached all the way from the North Pole and was over a mile thick in some locations. To us that says Texas isn’t the only thing that shouldn’t be messed with. Neither should the average global temperature.

Next week we will discuss whether "climate change" is a better description than "global warming," what happened to the global cooling concerns of the 1970s, why we are confident that human actions are causing the climate to change, and why we think climate change is undesirable.

At 6 p.m. Feb. 10, the authors will attempt to answer questions about climate change in a "stump the chumps" type format at 903 Brewers, 1718 S. Elm St., Sherman. All ages welcome.

PETER SCHULZE is a professor of biology &environmental science. He be reached at pschulze@austincollege.edu. KEITH KISSELLE is an associate professor of biology and environmental science. He can be reached at kkisselle@austincollege.edu. GEORGE DIGGS is a professor of biology. He can be reached at gdiggs@austincollege.edu. All three teach at Austin College.