In response to a request from Congress, Surface Temperature Reconstructions for the Last 2,000 Years assesses the state of scientific efforts to reconstruct sur

There is little dispute within the scientific community that humans are changing Earth's climate on a decadal to century time-scale. By the end of this century,

The climate record for the past 100,000 years clearly indicates that the climate system has undergone periodic-and often extreme-shifts, sometimes in as little

Many factors contribute to variability in Earth's climate on a range of timescales, from seasons to decades. Natural climate variability arises from two differe

Climate change poses many challenges that affect society and the natural world. With these challenges, however, come opportunities to respond. By taking steps t