The current drought in the Southwest is not drier or longer-lasting than historic episodes documented in tree rings, but the current dry conditions stand out from the historical record by being hotter, according to Jonathan Overpeck, professor of geosciences at the University of Arizona.

The lead character in the 2011 climate story was La Niña—the cool phase of the El Ni

Spring storms across Europe and the Mediterranean Sea finally swept away a high pressure system that had been fostering increasingly dry conditions over the Horn of Africa in early 2011.

In the mid-1980s, the winter sea ice pack in the Arctic was dominated by multi-year ice—ice that had survived at least one summer melt. Today, less than half of the sea ice at winter maximum has survived at least one summer.

An expert on climate conditions in East Africa describes the climate factors behind the 2011 drought, which has contributed to food insecurity and famine.

Near the Earth’s equator, solar heating is intense year round. Converging trade winds and abundant water vapor all combine to produce a persistent belt of daily showers known as the Intertropical Convergence Zone.

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