Republican presidential candidate John McCain revealed this week his plan to fight global warming, promising to increase funding for alternative fuel vehicles and power generation as well as introduce a market-based cap on greenhouse gas emissions. Under his plan, McCain predicts by 2012 greenhouse gas emissions would return to 2005 levels and by 2020 they would reach 1990 levels – the same levels mandated by the Kyoto Protocol for 2012.

Rival candidate Hillary Clinton has described McCain’s proposals as not going far enough, claiming they need to be backed by a science-based plan instead of halfway measures. Barack Obama, meanwhile, has supported the market-based cap system and hopes to reduce carbon emissions 80% below 1990 levels by 2050. By contrast, President George W. Bush national goal released last month only sets out to stop the growth of greenhouse emissions in 2025.

Under McCain's plan, companies would need to make their own greenhouse gas reductions or pay a penalty once a certain cap is met. Money generated from the penalties could be used to support the development of advanced green technologies, reports The Detroit News.

All three candidates are also in favor of the move by California and 17 other states to impose their own 30% reduction in vehicle tailpipe emissions by 2016. Carmakers, who are opposed to the move, are planning to meet with California Governor Arnold Schwarzenegger to warn of the effects of the tougher standards on jobs and the economy.