With al the major presidential candidates talking about change this year, it should be no surprise that “climate change” has become part of the political discourse. Hillary Clinton, Barack Obama, John McCain and Ralph Nader all have developed positions on how to protect the environment, as have the Edison Electric Institute and the National Petrochemical and Refiners Association, among others. The candidates' websites include full details of their environmental-policy positions, including their voting records on environmental legislation.

Here is a summary of the candidates' positions on some of the environmental issues in the news. You'll find a full list of their positions compiled by contributing editor Daniel Gottlieb on Purchasing.com.

Greenhouse gases On greenhouses gases, the Democrats want mandatory rules. All candidates want to apply different versions of the “cap-and-trade” concept that awards emissions credits to companies that produce those gases below a ceiling the government would set. Obama and Clinton want to auction all of the credits. McCain says the ceiling should be rational and have timetables. He wants the Environmental Protection Agency administrator to set gradually declining ceilings and by 2012 require companies buy and submit to the government emission credits for each metric ton of greenhouses gases they produce.

Fossil fuels For control of the use of fossil fuels, everyone wants to cut dependence on foreign oil, particularly in light of the major increase in the price of crude oil on the futures markets. Senators Clinton and Obama want to develop clean coal technology and promote biofuels as well as continue tax incentives for renewable energy. Senator McCain favors nuclear power as a clean technology to replace oil. He also supports market-based ethanol promotion, but doesn't want to subsidize it. Ralph Nader wants to add a carbon tax and an emphasis on solar power.

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For more on Green procurement, see Green Buying: How procurement is managing environmental demands