04/14/2014 05:57 pm ET Updated Jun 14, 2014

Is Global Warming Real? A 30-Second Answer

It's been a common frustration for environmentalists: how to give a brief, persuasive answer to the question "Is global warming real?" My colleague, Dr. Ilissa Ocko, recently wrote about facing this challenge. In her case, the question came from the dentist as he tapped around on her molars, but it can come up any time you identify yourself as someone who wants action to address climate change. In my experience, it's a question that uncles at family gatherings are particularly prone to posing. The challenge is to convey decades of evidence clearly in about thirty seconds.

Ilissa is an atmospheric scientist, so she knows a lot more than me about the actual chemistry of climate change, and her version of the thirty-second answer reflected that. She clearly wants to convince and educate her questioner. Coming from her, this approach has a lot of credibility. But coming from me -- who makes a point of not revealing my high school chemistry grade to my kids -- it wouldn't be the way to go. I think my Uncle Steve would see right through my attempt to explain the science, and lots of uncles out there just wouldn't be interested in the details.

My approach would be to talk about why I believe it. My acceptance of the reality of man-made climate change is not based on data I've gathered or experiments that I've conducted. I have never tested the troposphere, pulled ice core samples in Antarctica, or set up temperature monitoring stations. Instead, I rely on the consensus of people who do those things, on experts. It's the same reason I avoid shaking hands with someone who has the flu, or believe NASA can get a lander to Mars, or accept that my GPS must account for Einstein"s Theory of General Relativity in order to get me to the restaurant. Decades of data, reviewed and questioned by experts, has led those who carefully study these issues to arrive at a general consensus about how the science operates.

It is true that science evolves over time. But it also tends to solidify knowledge in some areas. Flu is caused by a virus, and it spreads from person to person. Probes meant for Mars do not go shooting off towards Venus. My GPS calculates for relativity and it gets me to dinner. Even though we don't see the virus or understand the calculations, generally speaking we accept these things.

On the fundamentals of climate change, virtually all experts agree -- and when they show the basic data, it agrees too. As carbon dioxide levels have risen in the atmosphere, average global temperatures have gone up, too. All of this has been tested and tested and tested again. All the major American scientific organizations say it is happening, as do the national science academies of all the major nations. There is either a decades-long conspiracy involving tens of thousands of scientists who have imbedded false formulas into the basic physics and chemistry textbooks, or climate change is real.

How I answer the question:

"Yes, climate change is real. Every major American scientific organization has said it is real, based on decades of data and experiments. Average global temperatures have been rising right along with increases in climate pollution. There will always be someone on the Internet to question anything, using questionable sources for support, but the actual climate scientists and the expert-reviewed data all agree. Besides, it's common sense: You can't pour billions of tons of pollution into the atmosphere and expect it won't have any effect. It would be like dumping chemicals in a river and expecting the fish to be fine. It's a hard problem, but unfortunately it's real."

What's your version?

This post originally appeared on EDF Voices.