EL NINO-LIKE CLIMATE-CHANGE IN A MODEL WITH INCREASED ATMOSPHERIC CO2CONCENTRATIONS

SEA surface temperatures in the tropical Pacific Ocean increased on av erage by serveral tenths of a degree during the 1980s and early 1990s( 1-4), contributing to the observed global warming during this period(5 ), Here we investigate the possible causes of this Pacific warming, us ing a global coupled ocean-atmosphere general circulation model incorp orating increasing concentrations of atmospheric carbon dioxide, In th e model, cloud cover and cloud albedo feedbacks contribute to tropical Pacific sea surface temperature increases that are greater east of 18 0 degrees longitude, with attendant shifts in large-scale precipitatio n patterns and mid-latitude circulation anomalies in the north Pacific , These anomalies resemble some aspects of El Nino events, as well as features associated with recent observed Pacific-region climate anomal ies. The resemblance to El Nino complicates the problem of detection a nd attribution of climate change, and suggests that depletion of fresh water resources(6) may be an additional hazard of greenhouse warming f or populations in the western Pacific region.