Although each method has some uncertainties, they all suggest a similar story - that the Earth has warmed dramatically over the last 140 years and that the Earth is now warmer than it has been in the last 600 years.
Some scientists look to satellites to reveal something about the Earth's changing climate.
The paleoclimatic record not only allows us to look at global temperature fluctuations over the last several centuries, it also permits scientists to examine past climate even further back in time. This perspective is an important capability in our quest to understand the possible causes of the 20th century global warming. So far, paleoclimatologists have been unable to find any natural climatic explanations for our present-day warming.