By Joydeep Gupta, IANS
New Delhi : Climate change caused by humans has reached a point where all governments must make hard choices to reduce greenhouse gas (GHG) emissions even as they prepare to deal with an inevitable global warming, the Intergovernmental Panel on Climate Change (IPCC) says.
UN Secretary General Ban Ki-moon will deliver this message as the IPCC — a UN body that shared this year’s Nobel Peace Prize — releases Saturday the synthesis of its fourth assessment report at Valencia, Spain.
The report provides the reasons for climate change, its effects and possible ways to tackle it. The report says that global warming is likely to affect the health of millions, particularly those with low capacity to adapt.
This would lead to increased malnutrition; deaths, disease and injury due to heat waves, floods, storms, fires and droughts; diarrhoeal diseases; cardio-respiratory diseases due to higher concentrations of ground-level ozone; and increased range of vectors such as the mosquito carrying malaria and dengue.
From 1900 to 2005, rainfall has come down significantly in the Sahel, the Mediterranean, southern Africa and parts of South Asia while increasing in parts of North and South America as well as parts of Europe and Central Asia.
The IPCC predicts that hot extremes, heat waves and heavy rainfall events will become more frequent. It is likely that future tropical storms will become more intense, with larger peak wind speeds and more rainfall due to rise in tropical sea surface temperatures.
By the middle of the 21st century, annual average river runoff and water availability are projected to decrease by 10-30 percent over some dry regions at mid-latitudes and in the dry tropics, and to increase by 10-40 percent at high latitudes and in some wet tropical areas.
Water supplies from glaciers and melting snow cover are projected to decline, reducing water availability in regions supplied by melt water from major mountain ranges such as the Himalayas, home to more than one-sixth of the world population.
Approximately 20-30 percent of plant and animal species assessed are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5-2.5 degrees Celsius.
At lower latitudes, especially seasonally dry and tropical regions, crop productivity is projected to decrease. This would increase the risk of hunger.
Many millions are projected to be flooded every year due to sea level rise by the 2080s. The densely populated and low-lying areas where peoples’ capacity to adapt is relatively low and which already face other challenges such as tropical storms or local coastal subsidence are especially at risk.
The numbers affected will be largest in the mega-deltas of Asia and Africa while small islands are especially vulnerable.
The report says that for the next two decades, a warming of about 0.2 degrees Celsius per decade is projected for a range of emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been constant at 2000 levels, a further warming of about 0.1 degrees per decade would be expected.
Continued GHG emissions at or above current rates would cause further warming and induce many changes in the global climate system in the 21st century.
The best estimate of global warming by 2100 for the low emission scenario is 1.8 degrees Celsius (likely range 1.1-2.9), and for the high emission scenario four degrees Celsius (likely range 2.4-6.4).
The report says even the most stringent mitigation efforts cannot avoid further impacts of climate change in the next few decades, which makes adaptation essential. Unmitigated climate change would in the long term be likely to exceed the capacity of natural, managed and human systems to adapt.
The IPCC suggests a mix of strategies that include mitigation and adaptation. It recommends that governments combine regulations with incentive-based approaches to cap GHG emissions.