What is your big idea?

Our current stalemate over climate policy has important roots in earlier battles over population growth and resource scarcity. Many dire predictions made a generation ago about disastrous food shortages and running out of oil have not come true, at least not yet. This poses a challenge for environmentalists, who are gravely concerned about global warming. Earlier failed prophecies help fuel conservative opposition to current concerns about climate change, even though the science is different and the threat is real.

I argue that we need to probe these earlier clashes between different legitimate viewpoints to better understand how to communicate with each other and to develop successful policy solutions.

What is the “bet” at the heart of your new book?

In 1980, Julian Simon, an iconoclastic economist, and Paul Ehrlich, the celebrated environmentalist and author of the 1968 blockbuster The Population Bomb, bet on whether five metals—chromium, copper, nickel, tin, and tungsten—would go up or down in price over the next 10 years.

Ehrlich, along with two scientist friends who sided with him in the bet, believed that prices would rise. This fit Ehrlich’s theory that population growth and excessive consumption were increasingly causing resource scarcity and would lead to disaster. Simon thought metal prices would fall, and prove that humans could solve any environmental problem and fend off grave disruption.

Simon won their wager. Despite an unprecedented growth in world population from 4.5 to 5.3 billion between 1980 and 1990, the prices of the five metals fell by an average of around 50 percent.

Since then, conservatives and environmentalists have argued about the meaning of the Ehrlich-Simon bet. Conservatives claim that Simon’s victory shows how environmentalists exaggerate environmental problems like global warming; environmentalists counter that a bet on metal prices says little about serious environmental dangers, and that Simon just caught a break. As with many tough issues, there’s truth on both sides, which is what makes the story so interesting. Conservatives rightly point to the immense power of human adaptability and creativity, but environmentalists also correctly show how dramatically we are transforming the planet and how climate change poses a serious challenge to human societies.

Ehrlich and Simon’s lives and ideas fit a historical narrative, from the dawning environmentalism of the 1960s through the pivotal presidential contest between Jimmy Carter and Ronald Reagan and on through the 1990s. The fight between Ehrlich and Simon—between environmental fears and free-market confidence—helped create the gulf separating environmentalists and their critics today.

So how is the bet between Paul Ehrlich and Julian Simon relevant to debates over climate change today?

Paul Ehrlich and Julian Simon offered dramatically different visions of the future that apply to how we think about global warming. Should we count on technology and economic growth to help societies adapt to change (Simon’s view)? Or must we cut emissions immediately, and dramatically reshape our societies (Ehrlich’s view)? Both sides, I think, exaggerate the consequences of their opponents’ position: on the one hand, how expensive and disruptive it would be to shift away from fossil fuels; on the other hand, whether it would be possible for humanity to adapt to a warmer world.

Stark ideological framings of the future, symbolized by Ehrlich and Simon and their bet, make a productive conversation almost impossible. Rather than choose between their competing perspectives, I think we need to wrestle with the tensions and uncertainties they raise. Perhaps humans can continue to thrive in a warming world, as followers of Julian Simon assert, but are the risks and inequalities inherent in this change something we want? We need to reframe our policy debates around social values and political choice.

Julian Simon optimistically contended that fresh challenges generate innovative solutions that, in the end, improve the human condition. I believe that can be true, and human societies can continue to progress, but only if we recognize the real risks of climate change and take action to respond.