What is it, how well can we predict it, and how will it impact us?
Scientist gave the background and implications of the 2015-2016 El Niño event at a congressional briefing hosted by AGU (American Geophysical Union), AMS (American Meteorological Society), AGI (American Geosciences Institute), GSA (Geological Society of America), WHOI (Woods Hole Oceanographic Institution), US CLIVAR (US Climate Variability and Predictability Program), Consortium for Ocean Leadership, and Alliance for Earth Observations.
“El Niño is the result of the tropical Pacific Ocean being coupled to the atmosphere above it. It doesn’t exist in the ocean by itself, it doesn’t exist in the atmosphere by itself,” according to Dr. Tony Busalacchi (Professor and Director of the Earth System Science Interdisciplinary Center, University of Maryland). A fluctuation in sea surface temperature and the air pressure of the overlying atmosphere every two to seven years is known as the El Niño Southern Oscillation (ENSO). During normal conditions, some of the warmest water of the world’s oceans is west of the International Date Line, north of Australia, east of Indonesia, where the water temperatures are about 30°C (or 86°F). Above the warm water pool, moist air rises and condenses, driving global atmospheric circulation and resulting in rainfall. During El Niño conditions, the warm water pool migrates east of the International Date Line to the central and equatorial Pacific, and with it moves the tropical convection. This has a variety of effects including changes in temperatures, precipitation pattern, and frequency of tropical cyclones.
Dr. David DeWitt (Director of NOAA Climate Prediction Center) discussed the predicted impacts of El Niño in the United States. According to NOAA, El Niño will likely peak during the Northern Hemisphere winter 2015-16, with a transition to ENSO-neutral anticipated during the late spring or early summer 2016. Typically, cooler and wetter than average conditions are observed in the south of the U.S., and warmer and dryer than average conditions are observed in the north of the U.S. during El Niño events. NOAA provides regional El Niño impacts and outlooks assessments. While the above-average precipitation forecast is good news for drought-ridden California, it is unlikely that it will end the drought, which would require almost twice the state’s normal October-May precipitation.
Dr. Lisa Goddard (Director of Columbia University’s International Research Institute for Climate and Society) and David Zierden (Florida state climatologist, Center for Ocean-Atmospheric Prediction Studies) stressed the importance of increasing the prediction accuracy for El Niño to better plan global and regional responses. “The first El Niño forecast was made at the end of 1985 for the 86-87 El Niño. So we made a lot of progress since then… We actually do have some decent skill at predicting El Niño,” Goddard said. However, no two El Niño events are alike, and improving the resolution and time range of forecast is critical. Resolving local and regional impacts and giving more lead-time will allow stakeholders to better plan their responses. In Florida, where the 1997-1998 El Niño had severe impacts, water planners and farmers are preparing responses to expected impacts of this year’s El Niño. As important as regional forecasts are, so is it to understand the global picture of the social and economic developments and outcomes. Many of the places where droughts are expected during an El Niño event are also places that are important for wheat, maize, and rice production. “The implication of many of these regions having droughts at the same time is a serious one… Being able to better prepare in those regions, better prepare globally for what that could mean for our food market and food trade is an important extension,” Goddard stated.
The briefing highlighted the importance of continued investment in data assimilation, model improvement, and communication to stakeholders and decision makers to better predict and prepare for future El Niño events.