The “hockey stick” graph featured in the 2001 IPCC assessment, showing temperature (departures from the 1961–1990 average) in the Northern Hemisphere during the past 1000 years. (IPCC)
Dutch painter Hendrick Avercamp (1585–1634) was a specialist in winter scenes, especially skaters on frozen rivers, canals, and flood waters. (Hendrick Avercamp [public domain], via Wikimedia Commons)
Scientists take ice core samples in cold, windy, and forbidding environments. (Ted Scambos and Rob Bauer, U.S. National Snow and Ice Data Center)
The Indian subcontinent about to crash into Asia 60 million years ago.
The process involved in undersea volcanism and the surface and atmospheric effects.
An ancient bristlecone pine from the White Mountains of California. (Gnarly/Wikimedia Commons)
Mount Pinatubo erupts on June 12, 1991. (U.S. Geological Survey/Cascades Volcano Observatory)
The Earth, circa 250 million years ago, showing the supercontinent Pangaea.
James Croll. (J.C. Irons/photo courtesy NOAA)