Consequence of Climate Change
Higher Temperature, More Risk — In all regions of the world, the faster temperatures rise, the greater the risk of damage. The climate does not respond immediately to emissions, which can last for years or decades in the atmosphere. And because of the delaying effect of the oceans — which absorb and eventually release heat more slowly than the atmosphere — surface temperatures do not immediately respond to greenhouse gas emissions. As a result, climate change will continue for hundreds of years after atmospheric concentrations have stabilized.
Adverse changes in the hydrological cycle — Rising temperatures are already accelerating the hydrological cycle. A warmer atmosphere holds more moisture, becomes less stable and produces more precipitation, particularly in the form of heavy rain bursts. Greater heat also speeds up evaporation. The net effect of these changes in the cycling of water will be a decline in the quantity and quality of freshwater supplies in all major regions. Meanwhile, wind patterns and storm tracks are likely to change. The intensity (but not the frequency) of tropical cyclones are expected to increase, with larger peak wind speeds and heavier rains.
Threats to biodiversity — Wildlife and biological diversity, already threatened by habitat destruction and other human-generated stresses, will face new challenges from climate change. Many ecosystems are already responding to higher temperatures by advancing towards the poles and up mountainsides. Some species will not survive the transition, and 20-30 per cent of species are likely to face an increased risk of extinction. The most vulnerable ecosystems include coral reefs, boreal (sub-arctic) forests, mountain habitats and those dependent on a Mediterranean climate.
Rising sea level — The best estimate for how much further the sea level will rise due to ocean expansion and glacier melt by the end of the 21st century (compared to 1989-1999 levels) is 28-58 cm. This will worsen coastal flooding and erosion.
Larger sea-level increases of up to 1 metre by 2100 cannot be ruled out if ice sheets continue to melt as temperature rises. There is now evidence that the Antarctic and Greenland ice sheets are indeed slowly losing mass and contributing to sea level rise. About 125,000 years ago, when the polar regions were significantly warmer for an extended period than at present, melting polar ice caused the sea level to rise by 4 to 6 metres. Sea-level rise has substantial inertia and will continue for many centuries.
Increased health risks — Climate change will increasingly alter the distribution of malarial mosquitoes and other carriers of infectious diseases, affect the seasonal distribution of some allergy-causing pollen and increase the risks of heat waves. On the other hand there should be fewer deaths due to the cold.
Changes to ocean eco-systems — The oceans will also experience higher temperatures, which have implications for sea life. Over the past four decades, for example, North Atlantic plankton have migrated pole-ward by 10 degrees of latitude. Similarly, the acidification of the oceans as they absorb more carbon dioxide will impair the ability of corals, marine snails and other species to form their shells or skeletons.
Hitting the most vulnerable — The poorest communities will be the most vulnerable to the impacts of climate change as they have fewer resources to invest in preventing and mitigating the effects of climate change. Some of the most at-risk people include subsistence farmers, indigenous peoples and coastal populations.