Observed Global Impacts.
Global warming has brought changes in the hydrological cycle including:
- Increased atmospheric water vapour content
- Changing precipitation patterns
- Reduced snow cover and massive ice melting
- Changes in soil moisture and runoff
Observed Impacts on Asia
- Crop yield in Asian countries has declined due to rising temperatures and adverse weather events.
- There have been extraordinary glacier retreat and permafrost in the continent because of continued warming.
- Climate-induced diseases and heat stress increased.
- Changes in terrestrial and marine systems have been more obvious.
Projected Global Impact
- Temperature is projected to increase by 0.2oC per decade or 0.1oC per decade if the concentration of greenhouse gases were kept constant.
- Heavy precipitation will increase the occurrence of floods, while the proportion of land surface in extreme drought is expected to increase. Hot extremes and heat waves will be more frequent, while tropical cyclones will be more intense.
- The melting of the ice caps will likely reduce water availability during warm, dry periods through a seasonal shift in stream flow, an increase in the ratio of winter to annual flows, and reductions in low flows in regions supplied by melt water. By mid-century, annual river runoff are forecasted to increase by 10-40% at high latitudes, and decrease by 10-30% over some dry regions at mid-latitudes and in dry tropics.
- The average global sea level is forecasted to rise by 0.19-0.59 meters between 1990 and 2100 because of thermal expansion and the melting of ice caps and glaciers. This will extend areas of salinization, which will decrease freshwater availability.
Projected Impact on Agriculture and Water Availability
- A 2.5-10% drop in crop yield is expected in 2020. By 2050, crop yield may decline by 5-30%.
- Freshwater availability in Asia will significantly decline due to climate change. This may affect more than one billion people by 2050.
- An additional 49 million Asian people could be at risk of hunger[1] due to water stress and scarcity in 2020[2].
Projected Impact on Health
- There are expected increases in endemic morbidity and mortality due to diarrheal diseases in South and South-East Asia.
- In South Asia, higher coastal water temperature is seen to aggravate the abundance and toxicity of cholera.
- Natural habitats of water-borne and vector-borne diseases are expected to increase in North Asia.
Philippine Climate Change Scenario
- Observed Climate Changes. Annual temperatures increased by around 0.14oC from 1971 to 2000. Annual mean rainfall and the number of rainy days are now higher. The inter-annual variability of onset of rainfall increased.
- Observed Extreme Events. Heat waves and droughts occur more often, while intense rains, cycles, and tropical storms flood the country during the rainy season.
- Projected Temperature Changes. Mean temperature is expected to rise by about 0.9oC to 1.4oC for 2020 and 1.7oC to 2.4oC by 2050. There will be widespread warming in the country, but the southern regions will be generally warmer.
- Projected Changes in Rainfall. The March-May dry season will become drier, while the July-August wet season will be wetter and will extend to November. The monsoon season will be more active and stronger.
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