Predictions of the human cost of climate change

Guzman has studied intractable economic problems, such as poverty, recessions, and trade wars. But, in recent years, one problem loomed larger than all the rest: climate change. It became impossible to fathom the economic impact of state actions without including global warming in the equation.

"Climate change is the most important problem facing the international community in the 21st century," Guzman said. "It's a problem that no country alone can solve, but a solution is imperative."

Countless books exist on the scientific aspects of climate change, but not one on why people should care, said Guzman. So he decided to write for a popular audience, to engage them, to capture their imaginations in a way that would communicate the depth of the problem.

Guzman adopted the predictions of scientists who expect a minimum warming of two degrees Celcius. But even such a modest calculation will mean unprecedented migrations, flooding, famine, and war. It will decimate infrastructures we take for granted, crippling roadways, sewers, and irrigation systems. Social services we rely on (sanitation, transportation, heath care) will cease working normally, and humans will find themselves competing for ever more scarce resources.

"Climate change is going to damage the very foundations upon which we've built our civilization. I don't think people understand how pervasive this problem is," Guzman said.

Examples of the impact of climate change include:

• Flooding and forced migration will push citizens to crowded cities or refugee camps, creating ripe conditions for the spread of infectious diseases. It could lead to a global pandemic similar to the 1918 Spanish Flu that killed 3 percent of the world's population. In the U.S. today, that would mean nine-ten million deaths.

• California's Sierra Snowpack, its most important water source, will have shrunk by a third by 2050. No plan exists for how the state will find enough water for its projected 50 million residents.

• Rising seas will displace populations, ruin farmland, and destroy infrastructure. Bangladesh alone will lose 17 percent of its land mass, the equivalent of the U.S. losing Alabama, Tennessee, Kentucky, Ohio, and every inch of land to the East.

• Rainfall-dependent crop production in Nigeria may fall by 50 percent. Social chaos and the fight over dwindling oil resources could lead to the creation of a terrorist breeding ground.

• Water flow to the Indus River could drop off by 35 percent, as glaciers melt. India and Pakistan, which have had 4 wars since the 1940s, will have to share this shrinking resource. At issue is life and death for tens of millions on both sides of the border -- and both countries have nuclear weapons.

Guzman acknowledges that it is tempting to ignore the problem or deny its very existence. The harsh reality, however, is that we have to do something now to stem a full-blown disaster in our lifetime. One of the biggest hurdles: political opposition.

"Solving this problem is not going to be free. But as long as politicians are punished for imposing economic costs now in exchange for larger economic gains later, it will be an impossible problem to solve," he said.

In fact, the world's largest emitters of the greenhouse gases (GHG) that cause global warming -- the U.S., the E.U., China, India, and Brazil -- have failed to come to a substantive agreement to reduce carbon output. Carbon dioxide is one of the most damaging of the GHG emissions. Guzman is convinced that U.S. will balk at signing any international accord until its people demand it.

"People have to accept the fact that, as with social security, public education, or military expenditures, we have to pay now for benefits later," he said.

As an economist, Guzman suggests a simple policy solution for the United States: a carbon tax. Taxing carbon up the supply chain as far as possible would raise the price of fossil fuels -- and encourage the development of alternative energy.

Guzman isn't promoting one particular solution; he says a Cap-and-Trade program to regulate GHG emissions could be just as viable. Most important is that we take action. Raise the price of carbon sufficiently to keep the planet from overheating and "prevent human tragedy on a scale the world has never seen." It's a scenario that haunts him daily.

"I'm terrified for my children -- for everybody's children," he said. "The world they are going to inhabit when they're my age in 2050 is not a pretty place. If I have grandchildren, it'll be even worse. One of the features of this problem, which is chilling, is that if you just decide to live with it, it doesn't stabilize. It gets worse and worse with every passing year or decade that we fail to act."