In essence, their reconstruction appears to tell us about past changes in climate with a resolution of about 400 years. (dotearth.blogs.nytimes.com)
In the video, he explains how scientists look to various forcings and responses in past changes in climate. (climatechangenationalforum.org)
Society's knowledge of current and future climate change has been established through decades of scientific research into the natural causes of past changes in climate, the buildup of anthropogenic greenhouse gases in the atmosphere, and the linked behavior of the oceans, atmosphere, ice, land, and biosphere. (environmentalresearchweb.org)