Pacific region climate change

Due to the pervasive effect of El Nino-related climate anomalies on societies over broad regions of the Indian and Pacific Ocean regions, climate model simulations can provide valuable information concerning possible future climate change that could have a similar signature in those regions. Average climate change in the Pacific region from increased carbon dioxide (CO2) in a global coupled ocean-atmosphere general circulation model is characterized by greater warming of the ocean surface in the eastern tropical Pacific than in the western tropical Pacific. This pattern resembles EI Nino conditions as well as the decadal timescale climate anomalies observed during the 1980s. As a consequence, average increases in precipitation in the central equatorial Pacific in the model with increased CO2 are accompanied by precipitation decreases in the northern and southern tropical Pacific, Australasia and eastern Indian Ocean regions. A deepened Aleutian low pressure center in the North Pacific is also associated with mean climate changes due to increased CO2 in the model and is similar to El Nino conditions and the decadal timescale observed anomaly pattern. The model results suggest that future droughts in the Australasian region, already associated with naturally-occurring EI Nino events, would increase in intensity due to the juxtaposition of climate anomalies of the same sign from increasing CO2 in the atmosphere. This result has implications for the management of fresh water resources in these regions. (C) 1998 Elsevier Science Ltd. All rights reserved.