Two University of Chicago scientists last week appeared at EPA hearings in Rosemont, Ill., to offer support for proposed new regulations on carbon-dioxide emissions from large power plants.

The comments of David Archer, Professor in Geophysical Sciences, and Pamela Martin, Assistant Professor in Geophysical Sciences, came Nov. 19 at hearings on the EPA’s proposed “Tailoring Rule,” which would require industrial facilities that emit at least 25,000 tons of greenhouse-gas pollution annually to obtain permits covering their emissions.

Permit recipients would have to demonstrate their use of the best-available control technologies and energy-efficiency measures to minimize emissions when facilities are built or significantly modified.

The complete statements of Archer and Martin appear below.

David Archer’s statement:

My name is David Archer, and I am a professor at the University of Chicago in the Department of the Geophysical Sciences. I’ve published 80-some peer-reviewed papers and five books on the carbon cycle of the Earth and its interaction with global climate.

I teach a class as part of our core science curriculum about the physics and chemistry of the global warming forecast. It has become the most popular class on campus, even bigger than the class about pirates, which shows the concern that young people have about what business-as-usual is doing to their futures.

One of the books I have the students read is called Six Degrees, Our Future on a Warmer Planet, by Mark Lynas.

The first chapter describes potential impacts of one-degree centigrade average global warming, all the results taken from the mainstream, peer-reviewed climate impacts literature.

Chapter 2 is about two degrees, and so on up to six degrees, the high end of the Intergovernmental Panel on Climate Change projection range for the year 2100. It’s a good book, well-researched and clear.

The Earth today is already deep in Chapter 1, one degree. In my opinion, the most profound climate impact of global warming in this country is the ongoing drought in the Southwest.

The climate impacts in later chapters of the book get truly horrific, including droughts and desertification that make the Dust Bowl seem mild. Nebraska used to be a dune field in a warmer climate a few thousand years ago; now we grow wheat there, but it could go back to how it was.

You can imagine mass migration of people, and wars about water and other resources, and failed states. The population of the Earth depends on the infrastructure of our complex society, and if this breaks down, the carrying capacity of the Earth could collapse.

This happened to the Mayans, the most advanced civilization of their day, as a result of extended droughts during the medieval warm time. How many of us would survive if there were no food in the grocery stores?

I come away from the book thinking that ultimately, humankind is better than this. Humans have done amazing things, and this challenge, technologically, isn’t even really all that hard. Coal is by far the most abundant fossil fuel, and the future of climate depends on what we decide to do with the coal.

If hypothetically there were no more coal in the ground, we wouldn’t be going back to the Stone Age, we’d figure out another way to keep things running, no problem. And if the climate starts to bite harder in the future, humankind will figure out ultimately how to leave the coal in the ground.

Since dangerous climate changes are already under way, really fixing the climate means preventing the Earth from getting any warmer than it already has. Our understanding of the physics of Earth’s climate tells us that to do this would require an atmospheric CO2 concentration of 350 parts per million.

The atmosphere already has more CO2 than this, 387 ppm. Even if the CO2 concentration in the atmosphere stopped rising, the Earth would continue to warm for a few decades as the oceans warm up.

This is what they call committed warming. Avoiding that committed warming is where the target CO2 concentration of 350 ppm comes from.

My optimistic opinion is that ultimately, humankind, in the coming decades, will begin to actively scrub CO2 from the atmosphere, as part of an effort to get back to 350 ppm.

Someday someone will clean up the mess. In the larger scheme of things, this wouldn’t be that hard to do. But if this is the ultimate tide of history, there is an easier way to get there, and a harder way.

As with many environmental messes, it would be much cheaper in the long run to avoid emitting so much CO2 to the atmosphere in the first place.

Climate change is more difficult than other challenges humans have faced, only in that it is global, and the tragedy of the commons effect is particularly strong. The people who benefit from using coal are not the same people as pay the price, mostly people in the future and in the developing world.

Will humankind plan intelligently for our collective good, or are we just another out-of-control weed species like so many others in Earth history, doomed to bloom and collapse? This is the decision you’re making.

Pamela Martin’s statement:

My name is Pamela Martin. I am an assistant professor at the University of Chicago. I teach classes in past climate change ― “paleoclimatology” ― chemical oceanography and the science of sustainability.

Looking back into the paleorecords, the records of past climate change, we see abrupt changes, tipping points, changes we can’t fully explain or don’t fully understand. We must look back millions and millions of years to find carbon dioxide levels as high as we have today.

This past fall I have been participating in a seminar with other scientists such as David Archer, who is here today and one of the top experts on the carbon cycle, climate dynamicists who study interactions among components of the climate system, atmospheric chemists and biologists who study the nitty-gritty of photosynthesis.

We have been studying the details of the fate of carbon dioxide that we have emitted into the atmosphere, looking for the natural “sinks” of the CO2 that has cycled through the air. One of the clear sinks for this carbon dioxide is in the oceans, where carbon dioxide acts as an acid and lowers the pH. Some of the other sinks and effects of elevated CO2 are not so clear.

While understanding the sinks of carbon dioxide requires detailed sleuthing, understanding the anthropogenic sources, the major emissions sources, does not. A relatively small number of polluters emit over half of the point-source greenhouse-gas pollution.

And, by starting with the biggest polluters, the EPA is taking an important first step inaddressing greenhouse-gas pollution under the Clean Air Act.

I commend the EPA’s commitment to hold the big polluters responsible first, but I also urge the EPA to work quickly to address the emissions from facilities that emit less than 25,000 tons per year.

I urge the EPA to shorten the proposed timescales of five and six years to address the sources under 25,000 tons.

The longer we wait to take action, the more we are committing to future warming and the more it will cost to address the problem.