SA Forum is an invited essay from experts on topical issues in science and technology.

Editor’s Note: As leaders from business, politics and science convene this week at the World Economic Forum conference in Davos, Switzerland, to discuss pressing matters of the day, Scientific American is publishing a series of interviews with leading scientists, produced in conjunction with the forum. This is the first of four interviews for the WEF by Katia Moskvitch.

Evidence is overwhelming that carbon emissions are the biggest single cause of increasing global average temperatures, melting polar ice caps and rising sea levels. Why, then, do so many people deny that climate change is the result of human activity? Mario J. Molina, a co-recipient of the 1995 Nobel Prize in Chemistry for his work on the ozone layer, says that more must be done to help the public understand climate science before atmospheric carbon reaches catastrophic levels.

Molina spoke to us about why public understanding of the impact of climate change is so important, and what efforts are being planned to get this message across.



[An edited transcript of the interview follows.]

You’ve been trying to convey the current state of climate science to the public for many years. Why is it so difficult for some people to accept the situation?

There has been a very well financed public relations campaign by some interest groups to question climate change science. And they have succeeded quite well—in response to these efforts the media very often still communicates the idea that there are two sides to this question, that there are some scientists who think that it’s a serious problem but other scientists think that it’s still debatable whether society has to do anything about it. And it’s a myth: There are surveys that show 97 percent consensus among informed scientists who have published on climate change issues.

The basic science is very well established; it is well understood that global warming is due to greenhouse gases. What is uncertain is projections about specifics in the next few decades, by how much will the climate change. And that’s why we focus on communicating the concept of risk: It is not necessary to have absolute certainty about the dangers that society will face in order to take action.

You wear seatbelts in your car not because you’re certain that you’re going to have a crash but because there’s a possibility. You build houses likely to withstand an earthquake not because you’re certain that there will be an earthquake but because there might be one. These examples involve probabilities that are much smaller than the probabilities that climate change will have very serious impacts. So it’s totally unacceptable for society not to act.

Are there any other myths about the effects of climate change?

Yes. There’s also a myth that climate change is a worry only for future generations. It’s clearly a mistake because climate change is already happening and we already have increased frequency of extreme events—there are many more floods and heat waves. We cannot say that one particular event is caused by climate change but we can say from a scientific perspective that the probability that the increase in intensity of these events is caused by climate change is large.

Another myth is that it would be very costly to do anything about climate change. Very serious economic analyses have shown that we have alternative energy sources and that at a relatively modest cost—about 1 or 2 percent of global GDP [gross domestic product]—we could take measures to decrease the risk very significantly. We don’t have to cut all the emissions in the near future; that would be very costly. But we can agree as a planet to decrease emissions within a certain timetable so that these unacceptable risks are minimized.

One more point is communicating effectively to the public. In a recent report called “What We Know” well-known climate scientists summarize the main scientific findings. What we haven’t done yet—and it is our next step—is to make a public communication campaign so that these findings are well communicated.

You discovered the cause of the hole in the ozone layer of the atmosphere and received a Nobel Prize for your work. Is the ozone depletion linked in any way to climate change?

Climate change and ozone depletion are two global issues that are different but have many connections. In the ozone depletion case we managed to work with decision makers effectively, so that an international agreement called the Montreal Protocol was achieved that essentially solved the ozone depletion problem.

This is an example, unfortunately the only one, of a global environmental issue that has been properly resolved—because the agreement is to no longer manufacture the chemicals that affect the ozone layer.

It was easier to deal with the stratospheric ozone because it was down to five or six very large chemical industries that we could work with early on. But greenhouse gases are mostly of fossil-fuel origin and that is a huge activity in our society, so it’s much harder to deal with.

Unfortunately climate change has become politicized, which is something we avoided with the stratospheric ozone issue.

What is likely to happen in the future if we don’t do anything to minimize the impacts of climate change?

The average surface temperature of the planet will probably increase this century by 4, 5 or more degrees Celcius. We know that the planet has not been that warm for millions of years, but it was that warm at some point in time and it was a very different planet—with crocodiles at the North Pole.

A big worry is that if the temperature increases by that many degrees, we’ll reach tipping points—there might be abrupt climate changes that would be very disruptive for society. Furthermore, the sea level will rise further and many coastal cities will be flooded; island states are likely to disappear. We already know that the sea level is increasing. Heat waves are also occurring more frequently and they have consequences such as increased mortality.

What can an average person do to help manage the effects of climate change?

One action society needs to take is to use energy much more efficiently. Instead of incandescent light bulbs you could switch to LEDs that consume a lot less electricity, for example.

But as important as it is for people to change, the problem cannot be solved just with voluntary personal actions. The most important action that people can take is to press the government so that there is an international agreement. Because only then will the entire planet begin to change.

Society must let governments know that people are worried and expect changes—because no one country can solve the problem. We know it’s feasible—we’ve done it with the stratospheric ozone. We can also do it with climate change, but we must try harder.