What to Say to a Climate Change Skeptic

What should you say to a climate change skeptic?

Sabrina Stierwalt, PhD
7-minute read
Episode #216

Misconception #3: Global warming can't be a serious issue because it's still really cold too.

Many of us have heard the argument, including from our own president-elect, that global warming can’t possibly be real because in my neck of the woods, it is currently freezing/snowing/cold. Last year a senator from Oklahoma brought a snowball to the Senate floor as supposed “proof” that global warming cannot be a real problem. Can the Earth be warming if some places are still experiencing very cold winters?

The answer, of course, is yes. The global warming predictions from scientists suggest that on average across the globe, temperatures are rising, and this is undeniably the case. However, this is an average. While parts of the US are experiencing cold temperatures, people are cooking eggs on the sidewalk thanks to heat waves in Australia. Even given the winter storms in the US, many day-to-day heat records were still set in 2014 and 2015 in other US locations.

Extreme weather of any kind is also a predicted outcome from climate models along with global warming. More heat and thus moisture in the air can affect not just heat waves and droughts but also storms, even winter ones.

Misconception #4: Humans aren’t causing global warming so there is nothing we can do.Image courtesy of nasa.gov

Even among those who do not deny the clear trends that the Earth is warming, some dispute the cause. Volcanoes, for example, produce carbon dioxide emissions although at an estimated rate more than 130 times less than human activity, according to the US Geological Survey. When combined, natural sources do indeed dominate the production of greenhouse gases in the atmosphere. However, over the Earth’s 4.5 billion year history, natural sources and sinks of greenhouse gases like forests and oceans have settled into a balance that has kept the level of carbon dioxide in the atmosphere relatively stable for thousands of years. We know this to be true because scientists can measure historic levels of CO2 directly from tree rings and ice cores in the Antarctic.

That stability has begun to falter since the Industrial Revolution. In other words, even though the human contribution to greenhouse gas emissions through fossil-fuel burning and deforestation is a small fraction compared to the entirety of nature’s additions, nature provides appropriate mechanisms for absorbing and thus balancing its emissions. Humans do not. The result has been a dramatic 35% rise in CO2 levels since 1832.

Some skeptics point out that since carbon dioxide makes up only an extremely small percentage of the Earth’s atmosphere, curbing those emissions won’t really make a dent. Others further suggest that water vapor may be a bigger culprit so the focus on carbon dioxide is again misplaced.

Water vapor has been proven to be a major contributor to global warming, but its main role is in amplifying the effects of increasing levels of carbon dioxide. While the amount of CO2 in the atmosphere can drive temperatures to rise and rise and rise because CO2 serves as an effective heat trap, the amount of water vapor the Earth’s atmosphere can hold is ultimately limited by the ambient temperature. Thus, while in a given location in the atmosphere, water vapor may directly raise the temperature more than the CO2 that is present, water vapor cannot drive a continued rise in temperatures the same way that CO2 can.

Astronomical sources, like variations in the sun’s output or cosmic rays, are also logical places to look for an explanation for the observed increase in global temperatures. After all, solar variations are predicted to have been a main reason for the planet’s ice ages. Thus, climate scientists do take these sources into account in their atmospheric models, but so far, convincing evidence has not been found to suggest that solar-related phenomena outweigh human contributions.

Even if the models underestimate the contribution from variations in the solar cycle, the fact remains that human CO2 production works to amplify the existing ambient temperature. Thus, any contribution from human activity in a time of peak solar warming would warrant our attention.

Even if we want to dispute the predicted impact or even causes of global warming, a more important question may be whether or not any differences in opinion change how we decide to react. As a country we spend trillions of dollars in military spending to guard against potential threats. Is it not reasonable to spend a fraction of that cost to protect against the possible threat of rising global temperatures?

If your holiday discussion does turn to climate science, remember to start from a place of common ground. Do you both have a favorite sea shore spot that could be lost to rising sea levels? What about a favorite food that may be subject to shortages should the worst of climate predictions prove true? Investing in climate change requires sacrifices in the short term for long term gains which can be a hard sell so we need everyone we can get on board.

For more detailed explanations of some of the topics discussed in this episode, you can check out the frequently asked questions guide written by the Intergovernmental Panel on Climate Change.

Until next time, this is Sabrina Stierwalt with Ask Science’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Ask Science on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com

Earth image courtesy of shutterstock. Rising CO2 plot courtesy of nasa.gov


Please note that archive episodes of this podcast may include references to Ask Science. Rights of Albert Einstein are used with permission of The Hebrew University of Jerusalem. Represented exclusively by Greenlight.

About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.