The effects of climate change are well-documented and clearly visible in Glacier National Park and yet the United States refuses to fulfil its obligations under the World Heritage Convention to reduce greenhouse gas emissions.

The lagging performance of the United States on environmental issues -- particularly on energy and climate change -- signals trouble not only for the American people, but for the whole world. Perhaps this ranking will serve as a wake-up call to the American public and particularly to leaders in Washington.

The measurements show long-term trends. Glaciers react to climate change, and warmer temperatures in the Alps are reflected in the results.

If we let climate change run its course, this could be a fairly typical winter 30 or 40 years from now.

We're vulnerable to begin with, and climate change exacerbates the vulnerability.

The hurricanes we are seeing are indeed a direct result of climate change and it's no longer something we'll see in the future, it's happening now.