Pacific region climate change
Due to the pervasive effect of El Niño-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 El Niño 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 Niño conditions and the decadal timescale observed anomaly pattern. The model results suggest that future droughts in the Australasian region, already associated with naturally-occurring El Niño 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.
Available from: Kristie L Ebi
- "(ENSO) cycle, with the eastern tropical Pacific projected to warm more than the western tropical Pacific (Meehl 1997; Nurse et al. 2001). This would shift rainfall eastward and could cause drought conditions over Australasia. "
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ABSTRACT: Small island states are likely the countries most vulnerable to climate variability and longterm climate change. Climate models suggest that small island states will experience warmer temperatures and changes in rainfall, soil moisture budgets, prevailing winds (speed and direction), and patterns of wave action. El Niño events likely will strengthen shortterm and interannual climate variations. In addition, global mean sea level is projected to increase by 0.09-0.88 m by 2100, with variable effects on regional and local sea level. To better understand the potential human health consequences of these projected changes, a series of workshops and a conference organized by the World Health Organization, in partnership with the World Meteorological Organization and the United Nations Environment Programme, addressed the following issues: the current distribution and burden of climate-sensitive diseases in small island states, the potential future health impacts of climate variability and change, the interventions currently used to reduce the burden of climate-sensitive diseases, additional interventions that are needed to adapt to current and future health impacts, and the health implications of climate variability and change in other sectors. Information on these issues is synthesized and key recommendations are identified for improving the capacity of the health sector to anticipate and prepare for climate variability and change in small island states.
Environmental Health Perspectives 01/2007; 114(12):1957-63. DOI:10.1289/ehp.8429 · 7.98 Impact Factor
Available from: Richard Kleeman
- "Thus, although the warming trend in the tropical Pacific is somewhat reminiscent of the conditions observed during El Niño (Fig. 6b), the associated changes in the atmosphere do not support the picture that the trend pattern looks like a ''giant'' El Niño. If the observed SST trends reflect greenhouse warming, our results contradict the model results of Meehl and Washington (1996), who argue that greenhouse warming in the tropical Pacific will look like present-day El Nin ˜os. "
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ABSTRACT: The dominant variability modes in the Tropics are investigated and contrasted with the anomalous situation observed during the last few years. The prime quantity analyzed is anomalous sea surface temperature (SST) in the region 30°S-60°N. Additionally, observed tropical surface wind stress fields were investigated. Further tropical atmospheric information was derived from a multidecadal run with an atmospheric general circulation model that was forced by the same SSTs. The tropical SST variability can be characterized by three modes: an interannual mode [the El Niño-Southern Oscillation (ENSO)], a decadal mode, and a trend or unresolved ultra-low-frequency variability. The dominant mode of SST variability is the ENSO mode. It is strongest in the eastern equatorial Pacific, but influences also the SSTs in other regions through atmospheric teleconnections, such as the Indian and North Pacific Oceans. The ENSO mode was strong during the 1980s, but it existed with very weak amplitude and short period after 1991. The second most energetic mode is characterized by considerable decadal variability. This decadal mode is connected with SST anomalies of the same sign in all three tropical oceans. The tropical Pacific signature of the decadal mode resembles closely that observed during the last few years and can be characterized by a horseshoe pattern, with strongest SST anomalies in the western equatorial Pacific, extending to the northeast and southeast into the subtropics. It is distinct from the ENSO mode, since it is not connected with any significant SST anomalies in the eastern equatorial Pacific, which is the ENSO key region. However, the impact of the decadal mode on the tropical climate resembles in many respects that of ENSO. In particular, the decadal mode is strongly linked to decadal rainfull fluctuations over northeastern Australia in the observations. It is shown that the anomalous 1990s were dominated by the decadal mode. Considerable SST variability can be attributed also to a linear trend or unresolved ultra-low-frequency variability. This trend that might be related to greenhouse warming is rather strong and positive in the Indian Ocean and western equatorial Pacific where it accounts for up to 30% of the total SST variability. Consistent with the increase of SST in the warm pool region, the trends over the tropical Pacific derived from both the observations and the model indicate a strengthening of the trade winds. This is inconsistent with the conditions observed during the 1990s. If the wind trends reflect greenhouse warming, it must be concluded that the anomalous 1990s are not caused by greenhouse warming. Finally, hybrid coupled ocean-atmosphere model experiments were conducted in order to investigate the sensistivity of ENSO to the low-frequency changes induced by the decadal mode and the trend. The results indicate that ENSO is rather sensitive to these changes in the background conditions.
Journal of Climate 09/1997; 10:2221-2239. DOI:10.1175/1520-0442(1997)010<2221:GWDVOE>2.0.CO;2 · 4.44 Impact Factor
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