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Rising population a big concern

Scientist tells UW crowd ballooning numbers will lead to higher levels of carbon dioxide

A National Center for Atmospheric Research scientist told a crowd at the University of Wisconsin Tuesday population growth is a factor which can affect future carbon dioxide emissions on a global scale, but it is only a piece of the puzzle that will ultimately solve the climate problem.

Brian O’Neill, head of the Program on Population and Climate Change at the International Institute for Applied Systems Analysis in Austria, spoke at the chemistry building.

“Population growth is clearly not a silver bullet in solving the climate change problem, but it is also not a red herring that is distracting us; its effects are significant,” O’Neill said.

O’Neill’s work specifically deals with modeling the several different pathways which population could take in the next 100 years and making projections about global greenhouse gas emissions based on those models.

Associate Director of the Nelson Institute for Environmental Studies Lewis Gilbert, who introduced O’Neill, said current projections have the Earth’s population increasing by 2.5 billion people by the year 2050 to a total of 9.2 billion, with most of those increases coming in undeveloped nations.

Nathan Pinney, a UW graduate student studying materials engineering, questioned O’Neill’s method of analyzing population trends and their relation to GHG emissions.

Pinney is president of the UW Energy Hub, a student organization formed to ignite conversation and action on energy issues.

“I was not impressed by the speaker’s lack of evidence as to what wide range of possible factors were taken into account in his population-emissions model,” Pinney said. “It seemed as though he was connecting models and ideas that were unrelated in making some of his conclusions.”

O’Neill said the study of population, or demography, is more complex than simply growth rates but includes age structure, urbanization, fertility and education rates.

O’Neill’s collaborative team of researchers developed an “integrated assessment model” that projects long-term GHG emissions scenarios based on different established models of population growth with a focus on the effects of an aging population and increasing urbanization.

In answering his overarching question as to whether a study of population has shown that different population projections will have a substantial effect on the climate problem, O’Neill said the difference between his high and medium population scenarios was a carbon emission of around 1.8 billion tons emitted into the atmosphere per year until 2100.

Adding up over that time frame, that is a huge carbon difference, and if legislators enact policies that ensure a medium population scenario, it will be one piece of the pie in the solution to global warming, O’Neill said.

O’Neill spoke as a part of the UW Nelson Institute’s Gaylord Nelson Lecture Series, which honors the legacy of the late Wisconsin governor.