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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).

All over the world Indigenous Peoples are affected by the impacts of climate change. They often live close to the land and depend on its physical resources and richness for their livelihoods and well-being. Their environments are increasingly threatened by, for example, desertification, sea level rise, extreme weather events, and changes in wildlife health, migration patterns and abundance. At the same time, there is evidence that some current attempts to tackle climate change may also have disastrous effects on indigenous groups and communities.

The goal of Article II of the United Nations Framework Convention on Climate Change (UNFCCC) is to ensure stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent "dangerous anthropogenic interference with the climate system".

The human drama of climate change will largely be played out in Asia, where over 60 per cent of the world's population, around four billion people, live. Over half of those live near the coast, making them directly vulnerable to sea-level rise. Disruption to the region's water cycle caused by climate change also threatens the security and productivity of the food systems upon which they depend. In acknowledgement, both of the key meetings in 2007 and 2008 to secure a global climate agreement will be in Asia.

Mangrove systems occur extensively on low gradient tropical shorelines, where sedimentation enables resilience during sea-level rise (SLR). Within mangroves, inundation frequencies across the intertidal slope cause zonation of different species with elevation. This tight sea-level control of the seaward margin and zones within mangroves has been demonstrated by precise EDM survey. Hence species zones in mangroves are definitive indicators of sea-level position, and pollen distributions record the locations of different zones in the sedimentary record. Pollen stratigraphic records can be used to reconstruct Holocene sea-levels and show mangrove response to change. Mangrove response to sea-level rise has been investigated in Bermuda, the Cayman Islands, Tonga and southern New Guinea. Radiocarbon dating of stratigraphy determined a sediment accretion rate of 1 mm a1for the low island locations, and up to 1.5 mm a"1 in two estuaries of southern New Guinea. The IPCC SLR projections of 9-88 cm by 2100 equate to a rate of 0.9-8.8 mm a"1. Mangrove recession events and replacement by lagoon environments are shown to occur during more rapid sea-level rise. In Bermuda rates of SLR exceed 2 mm a1and the largest mangrove area having existed for the last 2000 years lost 26% area in retreat of its seaward edge during the last century. In Tonga, a large mangrove swamp persisted 7000-5500 yr BP during SLR of 1.2 mm a1, then retreated when the rate increased. In Cayman 20 km of mangroves died back between 4080 and 3230 yr BP, during SLR of 2.8-3.3 mm a1, to become a lagoon. In extensive swamps of southern New Guinea gradual Late Holocene retreat of mangrove zones occurred with SLR of 0.67 mm a1. Hence while low island mangroves are likely to be the most sensitive to projected SLR, continental margin mangroves will also suffer disruption and retreat.

Plants, birds, insects, mammals, amphibians and fishes are rapidly responding to the observed changes in climate everywhere on the planet. Extreme high temperatures immediately result in hefty responses. The responses, however, significantly differ from species to species and from year to year, which complicates a clear attribution of causes. The ecological impacts are nowadays visible everywhere through changes in the timing of life cycle events and the geographic distributions of species. Plants have advanced flowering by up to 30 days and are now doing so at dates never documented in the last two centuries. Some species show a dramatic increase in range area, disrupting ecosystems like, for example, the rapid spread over millions of hectares of the Mountain Pine Beetle in North America and the northward expansion of the Oak Processionary caterpillar in The Netherlands. Also fires have increased catastrophically in tropical wet forests during the severe droughts of the El Niño years in the nineties. Other species show a dramatic decrease in distribution or population sizes, illustrated by bleaching corals and disappearing amphibians worldwide. Warm winters, hot summers, excessive precipitation and extended droughts are weather events that trigger these responses