Applied science workshop: The changing debate on global warming

By Linda Holeman, Associate Editor, The Leading Edge

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Every credible climate scientist recognizes that increases in greenhouse gases promote warming, according to Eric J. Barron, Director of the National Center for Atmospheric Research. The real issues in the debate are:

• How much will it warm–in response to humans adding more greenhouse gases?
• How fast will it warm?
• How significant will be the impact?

Addressing a packed house of delegates and students at SEG’s Applied Science Education Program in Las Vegas, USA, Barron acknowledged that the first two questions will likely remain uncertain for decades. But for decision-makers and concerned citizens, the last question is key. “It is not just a science question,” said Barron, “it’s a human question that depends on how we value things.”

Photograph by Barchfeld Photography

Eric J. Barron, Director, of the National Center for Atmospheric research, delivers his keynote address to the Applied Science Education Program at the SEG Annual Meeting in Las Vegas.

The value is, of course, relevant. As an example, Barron discussed a fictional scenario where all the trees on the west side of a mid-sized city were cut down. An economist may view such an action favorably, asserting that the positive effects on the economy from the sale of the products generated outweigh any negatives. However, an environmentalist may argue that animal habitat, the ecosystem, and aesthetics are too precious to risk, and that conservation should prevail over profit.

Values also change, continued Barron. For example, no one bemoans that the English countryside has been deforested or lacks habitat. They talk about the rolling hills and the pastures and how beautiful it is. That's because they’ve never seen it covered in forest. The deforestation took place a long time ago. Therefore, they can’t place a value on what has been lost because they’ve never seen it. For future generations, it’s essentially out of sight, out of mind.

In other words, will our grandchildren “assign value” to trees?

What do scientists really believe about global warming?

Barron is the first to admit that getting a group of scientists to agree with 100% certainty is difficult, and existing climate models for global warming therefore are varied. “I had the pleasure of chairing a meeting where experts from both camps were put into a one room at one time. We buckled down to work over two days and wrote down a foundation that all climate scientists involved could agree with, and then we took the predictions from climate models and assigned them odds.”

This group broke down the argument about global warming into three broad categories:

• Predictions that are virtually certain: The stratosphere will cool. Every observation shows it, and all the models predict it. But since no one lives in the stratosphere, there is no societal impact and less attention is paid.
• Predictions that are very probable: Surface temperatures will increase 0.5 to 2.0 degrees C by 2050. Global precipitation will increase, sea ice will retreat in the Northern Hemisphere, and Arctic warming will occur. Sea level will rise due to thermal expansion of seawater and melting mountain glaciers. Those two things give you a range for some sea level increase. The fate of the ice caps remains questionable. Skeptics and nonskeptics both agree that solar variability—the change in the amount of solar radiation emitted by the sun—-is at most 10 or 20 percent of the forcing of the greenhouse gases.
• Predictions that remain uncertain: Climate variability changes such as El Nino will be difficult to predict, as will regional climate changes, the frequency and severity of tropical storms, and climate system interactions within the next 25 years.

However, Barron noted, “It is abundantly clear that the climate models are suggesting that this planet is changing and at the same time they’re not capable of providing the information that you need to really connect with the problem, so that you can make informed decisions.”

Photograph by Barchfeld Photography

Barron leads a lively Q&A session with nearly 150 Las Vegas-area students who attended the program.

Barron compared two well-known climate models—the Hadley Model (produced by the U.K.), and the Canadian Model—and discussed some of the potential impacts of each. Both models are studies of the summer and winter seasons in the contiguous U.S. While the Hadley model suggests only moderate climate changes from global warming, the Canadian climate model warns of dramatic changes and societal impact that global warming will wreak on the U.S. in the 21st century.

Values, again

Both the Hadley and the Canadian climate models provide convincing data regarding the impact of global warming on temperature, ecosystems, water supply, human health, and agriculture, and both models provide compelling scenarios addressing each of these impact areas. How we respond to these scenarios depends on our societal values and “risk profile.” For example, the predicted increase in mosquito- and vector-borne diseases will be of higher concern to those in poorer regions (such as Mexico) who lack air conditioning, access to health care, and public mosquito control (and therefore have an increased “risk profile” for diseases like Dengue fever) than for those who live in areas with a strong public health infrastructure and relative wealth, such as the U.S.

To expand the “values” argument, take the predictions for Denver, USA, regarding drought. Both models predict that the western U.S., particularly the Rocky Mountains, will experience moderate-to-severe drought. The reason? Snow pack, on which this region depends for much of its water, will disappear. Creating alternative water collection and storage mechanisms will require a great expenditure of financial and human resources, not to mention time. Will citizens in nonimpacted areas cheerfully agree to higher taxes that remedy a situation that may or may not occur in 20 years?

Concluded Barron, “There is a high level of uncertainty that we’re going to have to live with, and we have to start addressing the societal impact minus any ‘silver bullet’ evidence. It’s up to us as a society to determine what we value and the level of risk we are willing to bear.”