Regional Climate Drivers, Trends and Forecast Change

Hydroclimatology across the Pacific depends on the rain-generating South Pacific Convergence Zone and Intertropical Convergence Zone. These convergence zones move northward and southward over time (described by the El Niño Southern Oscillation index), which results in naturally high variability in rainfall, wind, tropical cyclone risk, and sea level. Future changes in convergence zone dynamics will be important for Pacific Island populations but known climate model deficiencies make projections uncertain. Extreme rainfall will probably increase, potentially enhancing flood risk, but drought risk is likely to decline in most countries. Average temperatures will be warmer in the future and marine heatwaves, together with ocean acidification, could threaten important coral reefs and fisheries. Sea level rise presents a key threat to small island nations due to saline intrusion and flooding. Global greenhouse gas emissions must be urgently reduced to avoid the worst impacts on Pacific Island nations. Local communities often have a deep understanding of their surroundings built over many generations and they are highly resilient to variable conditions. Therefore, adaptation strategies should respect and leverage traditional knowledge to maximise their effectiveness.