Observing & Predicting

Uncommon atmospheric circumstances spawned a pair of tropical cyclones in the western Pacific—one on either side the equator, at nearly the same longitude, at nearly the same time. Why are twin cyclones more common during El Niño?

Saturday, August 1, 2009

  • Temperatures measured on land and at sea for more than a century show that Earth's globally averaged surface temperature is experiencing a long-term warming trend.

  • Human activities, mainly burning fossil fuels, are increasing the concentration of carbon dioxide in our atmosphere, amplifying the natural greenhouse effect.

  • Minimum sea ice extent observed by satellites each September has decreased by 13.7 percent per decade since the late 1970s. The seven lowest extents all occurred since 2007.

  • El Niño and La Niña conditions occur when abnormally warm or cool waters accumulate in tropical latitudes of the central and eastern Pacific Ocean. The Oceanic Nino Index is the tool NOAA scienitsts use to watch for these temperature changes.