Home > Evidence of Abrupt Climate Change

Researchers first became intrigued by abrupt climate change when they discovered striking evidence of large, abrupt, and widespread changes preserved in paleoclimatic archives - the history of Earth's climate recorded in tree rings, ice cores, sediments, and other sources. For example, tree rings show the frequency of droughts, sediments reveal the number and type of organisms present, and gas bubbles trapped in ice cores indicate past atmospheric conditions. With such techniques, researchers have discovered repeated instances of large and abrupt climate changes over the last 100,000 years during the slide into and climb out of the most recent ice age - local warmings as great as 28°F (16°C) occurred repeatedly, sometimes in the mere span of a decade.

Some of the best known and most well studied widespread abrupt climate changes started and ended the Younger Dryas cold interval, a near global event that began abruptly about 12,800 years ago and ended even more suddenly about 11,600 years ago (see Figure 1). Climate records show that much of the northern hemisphere was affected by extraordinary cold, dry, windy conditions; dust and other wind-blown materials were more abundant in Greenland by a factor of 3 to 7, and methane concentrations were lower indicating loss of wetland areas, among other evidence. The 110,000-year-long ice-core records from central Greenland, and many other climate records, indicate that the Younger Dryas was one in a long string of abrupt climate changes.

More recently, less dramatic though still rapid climate changes have continued to occur. For example, a multidecadal drought is implicated in the collapse of the classic Mayan civilization in the ninth century. Paleoclimatic records from the last 10,000 years include apparent abrupt shifts in hurricane frequency, flood regimes, and droughts. Examples of abrupt change in the past century alone include the rapid warming of the North Atlantic from 1920 to 1930 and the Dust Bowl drought of the 1930s.