Climate Scientists and Chelsea Community Connect

Chelsea, MI, November 2, 2013 — Organizing for Action (ofawashtenaw.com) and Clean Water Action (cleanwateraction.org) brought climate scientists to the Chelsea District Library to discuss how climate has changed over time, to project future changes, and consider the impact. The Chelsea community asked about the validity of reconstructions of climate history; impacts of warming on ecosystems; and naturally occurring versus man-made greenhouse gases. Professor Gretchen Keppel-Aleks in broad strokes and with video from NASA defined five things that create climate: atmosphere, oceans, cryosphere (Arctic and Antarctic ice sheets), plants, and the sun. Scientists Derek Posselt , Andrew Gronewold, David Wright, and Samantha Tushaus facilitated breakout sessions.

Discussion of the sun led to explaining the greenhouse effect. Keppel-Aleks emphasized that without it, the earth would be like moon, very cold and devoid of life. Greenhouse gases trap heat and reflect much of it back to earth’s surface, making the planet habitable. A graph of the amount of the greenhouse gases in the atmosphere over the last two thousand years shows a dramatic spike in carbon dioxide, nitrous oxide, and methane over the last century. This increase of greenhouse gases causes the earth’s temperature to rise. Moreover, this increase stems from human activity. Records and measurements indicate that the major contributors are power plants, transportation, industry, commercial and residential, and agriculture. Even routine flooding of rice paddies for harvest makes a difference.

The predicted increase in the average temperature in the United States will impact mountain snow pack, decreasing the flow of important rivers such as the Colorado. As flow of the Colorado River drops, the feasibility of growing crops that depend upon irrigation and the water supply for many cities would be threatened. Michiganders may no longer be able to depend on California spinach or strawberries in December and people of Los Angeles may have to find a new source for water. There would be desertification in some regions of the United States. The Southwest has already experienced severe drought that is consistent with climate change predictions.

For those in audience who were wondering about extreme weather, Keppel-Aleks summed it this way, “Warm air has a greater capacity to hold water than cold air.” She pointed out that we already know this with our humid air in July and chapped skin in February. The problem is that when our seasonal storms, such as Hurricane Sandy or the recent flooding in Colorado come, they will be stronger and last longer.

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