With regard to what the United States is doing on climate change, the actions we have taken are next to none in the world,

When it comes to global consciousness, the United States is walking the walk. And when it comes to climate change, we are making significant progress, more progress than many of those who have been most critical of us.

The potential consequences of climate change are so sobering that it's difficult to imagine how individual actions can make any impact. We are hopeful that Yahoo!'s Earth Day campaign will illustrate that if we act as a global community, together we can make a difference. We encourage citizens everywhere to embrace our collective responsibility to protect the earth for future generations.

You couldn't necessarily say, 'That hurricane, that storm, that flood only happened because of climate change,' (but) you're starting to see a pattern of extreme weather events.

Bush agreed in Gleneagles that climate change was urgent.

Climate change is, in my view, long term, the single biggest issue that we face,