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Observational records and climate projections provide abundant evidence that freshwater resources are vulnerable and have the potential to be strongly impacted by climate change, with wide-ranging consequences for human societies and ecosystems. Observed warming over several decades has been linked to changes in the large-scale hydrological cycle such as: increasing atmospheric water vapour content; changing precipitation patterns, intensity and extremes; reduced snow cover and widespread melting of ice; and changes in soil moisture and runoff. Precipitation changes show substantial spatial and inter-decadal variability. Over the 20th century, precipitation has mostly increased over land in high northern latitudes, while decreases have dominated from 10°S to 30°N since the 1970s. The frequency of heavy precipitation events (or proportion of total rainfall from heavy falls) has increased over most areas (likely). Globally, the area of land classified as very dry has more than doubled since the 1970s (likely). There have been significant decreases in water storage in mountain glaciers and Northern Hemisphere snow cover. Shifts in the amplitude and timing of runoff in glacier- and snowmelt-fed rivers, and in ice-related phenomena in rivers and lakes, have been observed (high confidence).

Coastal and marine ecosystems are in decline worldwide. Overfishing, runoff of nutrients and other land-based pollutants, habitat degradation and the increasing impacts of climate change are leading to ecosystem collapse in all the major coastal and ocean regions of the world (Wilkinson 2004; Hughes et al. 2005).

Several urban areas and popular tourist destinations have suffered from pollution from the land, significant fishing pressure, recreational overuse, and alien species. Despite these pressures, many coral reefs in Hawai'i remain in fair to good condition, especially remote reefs; Most MPAs have proven to be highly effective in conserving biodiversity and fisheries resources. MPA size, habitat quality, and level of protection are the most important success factors, but several MPAs are too small to have significant effects outside their boundaries; Community-based management has been effective at several locations in Hawai'i and expansion of these efforts is being encouraged; Continued invasion and degradation of new habitats by alien species remains one of the most pressing threats to reefs in Hawai'i; The Papahanaumokuakea Marine National Monument (PMNM) is the largest fully protected marine conservation area in the world, with a unique predator-dominated trophic structure, many endemic species, and many threatened and endangered species. This is an important global biodiversity 'hot spot'; Global impacts such as climate change (sea level rise, ocean warming and acidification) and marine debris threaten the unique ecosystem of the PMNM, and rapid international action is needed.

Mangrove ecosystems are threatened by climate change. We review the state of knowledge of mangrove vulnerability and responses to predicted climate change and consider adaptation options. Based on available evidence, of all the climate change outcomes, relative sea-level rise may be the greatest threat to mangroves. Most mangrove sediment surface elevations are not keeping pace with sea-level rise, although longer term studies from a larger number of regions are needed. Rising sea-level will have the greatest impact on mangroves experiencing net lowering in sediment elevation, where there is limited area for landward migration. The Pacific Islands mangroves have been demonstrated to be at high risk of substantial reductions. There is less certainty over other climate change outcomes and mangrove responses. More research is needed on assessment methods and standard indicators of change in response to effects from climate change, while regional monitoring networks are needed to observe these responses to enable educated adaptation. Adaptation measures can offset anticipated mangrove losses and improve resistance and resilience to climate change. Coastal planning can adapt to facilitate mangrove migration with sea-level rise. Management of activities within the catchment that affect long-term trends in the mangrove sediment elevation, better management of other stressors on mangroves, rehabilitation of degraded mangrove areas, and increases in systems of strategically designed protected area networks that include mangroves and functionally linked ecosystems through representation, replication and refugia, are additional adaptation options.