8. El Nino

2005

1 December 2005. Alarm over dramatic weakening of Gulf Stream. Ian Sample, science correspondent, The Guardian Excerpt: Slowing of current by a third in 12 years could bring more extreme weather. Temperatures in Britain likely to drop by one degree in next decade. The powerful ocean current that bathes Britain and northern Europe in warm waters from the tropics has weakened dramatically in recent years, a consequence of global warming that could trigger more severe winters and cooler summers across the region, scientists warn today. Researchers on a scientific expedition in the Atlantic Ocean measured the strength of the current between Africa and the east coast of America and found that the circulation has slowed by 30% since a previous expedition 12 years ago. The current, which drives the Gulf Stream, delivers the equivalent of 1m power stations-worth of energy to northern Europe, propping up temperatures by 10C in some regions. ... Previous expeditions to check the current flow in 1957, 1981 and 1992 found only minor changes in its strength, although a slowing was picked up in a further expedition in 1998.... If the current remains as weak as it is, temperatures in Britain are likely to drop by an average of 1C in the next decade, according to Harry Bryden at the National Oceanography Centre in Southampton who led the study. ...The current is essentially a huge oceanic conveyor belt that transports heat from equatorial regions towards the Arctic circle. Warm surface water coming up from the tropics gives off heat as it moves north until eventually, it cools so much in northern waters that it sinks and circulates back to the south. There it warms again, rises and heads back north. The constant sinking in the north and rising in the south drives the conveyor. Global warming weakens the circulation because increased meltwater from Greenland and the Arctic icesheets along with greater river run-off from Russia pour into the northern Atlantic and make it less saline which in turn makes it harder for the cooler water to sink, in effect slowing down the engine that drives the current....

2004

1 December 2004. NASA SATELLITES WITNESSED EL NIÑO CREEP IN FROM THE INDIAN OCEAN. NASA Earth Observatory News. El Niño has fascinated people for centuries, and continues to interest people around the world, because it changes global weather patterns....Just in time for this Christmas, an index created to see the development of El Niño events received the approval of the scientific community. Scott Curtis, a NASA-funded scientist from East Carolina University in Greenville, N.C. and colleagues, created an index using satellite data of rain and winds in the eastern Indian Ocean that accurately predicted the arrival of the 2002-2003 El Niño. ... Curtis ... and Robert Adler, George Huffman and Guojun Gu, all of NASA's Goddard Space Flight Center, Greenbelt, Md. used NASA's Tropical Rainfall Measuring Mission (TRMM) and QuikScat satellite data ranging from November 2001 to March 2002. ...The researchers developed the El Niño Onset Index (EOI) using the rainfall data alone. "Because the rainfall data has been a consistent indicator of an on-coming El Niño, as compared to the wind data, only the rainfall data was used to construct the EOI,"

8 November 2004. NASA RELEASE: 04-369. TRMM Satellite Proves El Niño Holds the Reins on Global Rains. NASA scientists recently found the El Niño Southern Oscillation (ENSO) is the main driver of the change in rain patterns all around the world. The NASA and Japan Aerospace Exploration Agency (JAXA) Tropical Rainfall Measuring Mission (TRMM) satellite has enabled scientists to look around the globe and determine where the year-to-year changes in rainfall are greatest. By studying the rain patterns in these areas over the past 50 years, with rain gauge data prior to 1998, they established the main component of this change in global rainfall is directly correlated with the El Niño Southern Oscillation. The study appeared in a recent issue of the Journal of Geophysical Research-Atmospheres.

15 April 2004. NASA RELEASE: 04-130. SATELLITES RECORD WEAKENING NORTH ATLANTIC CURRENT. A North Atlantic Ocean circulation system weakened considerably in the late 1990s, compared to the 1970s and 1980s, according to a NASA study. Sirpa Hakkinen, lead author and researcher at NASA's Goddard Space Flight Center, Greenbelt, Md. and co-author Peter Rhines, an oceanographer at the University of Washington, Seattle, believe slowing of this ocean current is an indication of dramatic changes in the North Atlantic Ocean climate. The study's results about the system that moves water in a counterclockwise pattern from Ireland to Labrador were published on the Internet by the journal Science on the Science Express Web site at: http://www.sciencexpress.org. The current, known as the sub polar gyre, has weakened in the past in connection with certain phases of a large-scale atmospheric pressure system known as the North Atlantic Oscillation (NAO).

8 March 2004. From science@NASA -- A Chilling Possibility. By disturbing a massive ocean current, melting Arctic sea ice might trigger colder weather in Europe and North America.

5 January 2004. NASA RELEASE: 04-007. EL NINO-RELATED FIRES INCREASE GREENHOUSE GAS EMISSIONS. Year-to-year changes in concentration of carbon dioxide and methane, two important greenhouse gases in the atmosphere, can be linked to fire activity associated with the El Nino-La Nina cycle, according to a study conducted by a team of NASA scientists and other researchers.... Scientists today are trying to understand the relationship between the carbon cycle and the climate system. The carbon cycle is the movement of carbon, in its many forms, among the biosphere, atmosphere, oceans and the geosphere. The cycling of carbon affects the amount of carbon-based greenhouse gases in the atmosphere and thus the Earth's climate. This study shows carbon loss in the biosphere over the next several centuries may be sensitive to the intensity and variability of El Nino-induced droughts.