Mike McPhaden--El Niño & La Niña John Lyman--Global Warming Dick Feely--Ocean Acidification The Ocean’s Role in Climate Variability and Change NOAA/Pacific Marine Environmental Laboratory Seattle, Washington

Mike McPhaden NOAA/Pacific Marine Environmental Laboratory Seattle, Washington El Niño and La Niña: Causes and Global Consequences

Seattle Snow Saturday, 23 Dec 2008 Seattle refuses to use salt; roads "snow packed" by design “ To hear the city's spin, Seattle's road crews are making ‘great progress’ in clearing the ice- caked streets.”

El and La El Niño is often followed by or preceded by La Niña: an unusual cooling of the tropical Pacific Upwelling zonesWestern Pacific “warm pool” El Niño happens roughly every 2-7 years, lasts ~12 months, and peaks at the end of the calendar year Tradewinds

El Nino/Normal Every few years, the trade winds weaken…

Global Atmospheric Circulation Changes During El Niño Heavy Rain & Atmospheric Heating Changes in tropical rainfall patterns affect the global atmospheric circulation via long range “teleconnections”

El Niño & La Niña Impacts on Patterns of Weather Variability El Niño and La Niña shift the probability for droughts, floods, heat waves, extreme weather events around the globe El Niño La Niña

El Niño & La Niña Index NINO-3.4 NINO3.4 ≥ 0.5°C for 5 months= El Niño NINO3.4 ≤ -0.5°C for 5 months= La Niña

El Niño: Global Impacts Fatalities: 23,000 Economic Losses: US$ 36 Billion

TAO/TRITON ATLAS Mooring TAO/TRITON: A U.S./Japan collaboration

Conditions in January

Current Conditions

 El Niño & La Niña Forecast system development motivated by socio- economic impacts.  First successful El Niño prediction in 1986  Models are not perfect but are reasonably accurate out to 6-9 month lead times El Niño and La Niña are Predictable “ I can predict El Ni ñ o--by checking the NOAA web page every month! ”

Current El Niño/La Niña Advisory NOAA/Climate Prediction Center 8 May 2009 “Neutral conditions are expected to continue into the Northern Hemisphere Summer.” “During April 2009, the equatorial Pacific Ocean transitioned from La Niña to neutral conditions, ending the La Niña… A majority of model forecasts for the Niño-3.4 region show that neutral conditions will continue through the remainder of 2009.”

Will they change because of global warming? El Niño and La Niña are examples of “natural climate variability”--they are not caused by human activity…

The Climate is Changing… “Warming of the climate system is unequivocal…” IPCC, 2007 Indicators Rising air temperatures Rising sea level Melting glaciers Disappearing Arctic sea ice More heat waves & extreme rainfall events El Niño & La Niña?? The Intergovernmental Panel on Climate Change (IPCC) is sponsored by the United Nations Environmental Program and the World Meteorological Organization to provide objective scientific assessments of human induced climate change.

“Typical” El Niño Impacts Are Always Observed NO!  Not all El Ni ñ os are “ typical ”  Large chaotic day-to-day weather variations may swamp the El Ni ñ o signal.  There are other climate signals that can obscure El Ni ñ o impacts. ENSO shifts the probability of occurrence for particular seasonal climatic conditions in different parts of the globe, but does not guarantee those conditions will be realized in every case.