Newswise — Overpopulation is the world's top environmental issue, followed closely by climate change and the need to develop renewable energy resources to replace fossil fuels, according to a survey of the faculty at the SUNY College of Environmental Science and Forestry (ESF).

Just in time for Earth Day (April 22) the faculty at the college, at which environmental issues are the sole focus, was asked to help prioritize the planet's most pressing environmental problems.

Overpopulation came out on top, with several professors pointing out its ties to other problems that rank high on the list.

"Overpopulation is the only problem," said Dr. Charles A. Hall, a systems ecologist. "If we had 100 million people on Earth — or better, 10 million — no others would be a problem." (Current estimates put the planet's population at more than six billion.)

Dr. Allan P. Drew, a forest ecologist, put it this way: "Overpopulation means that we are putting more carbon dioxide into the atmosphere than we should, just because more people are doing it and this is related to overconsumption by people in general, especially in the 'developed' world."

"But, whether developed or developing," said Dr. Susan Senecah, who teaches the history of the American environmental movement, "everyone is encouraged to 'want' and perceive that they 'need' to consume beyond the planet's ability to provide."

The ESF faculty pointed to climate change as the second most-pressing issue, with the need to develop renewable energy resources to replace fossil fuels coming in third.

"Experimenting with the earth's climate and chemistry has great risks," said Dr. Thomas E. Amidon, who invented a process for removing energy-rich sugars from wood and fermenting those sugars into ethanol. "This is a driver in climate change and loss of biodiversity and is a fundamental problem underlying our need to strive for sustainability."

Rounding out the top 10 issues on the ESF list are overconsumption, the need for more sustainable practices worldwide, the growing need for energy conservation, the need for humans to see themselves as part of the global ecosystem, overall carbon dioxide emissions, the need to develop ways to produce consumer products from renewable resources, and dwindling fresh water resources.