projections by the Intergovernmental Panel on Climate Change
to a report by the UN’s Intergovernmental Panel on Climate Change(IPCC),
30% of animal and plant species will be vulnerable to extinction if
global temperatures rose by 1.5 to 2.5 degrees Celsius. It says the
world’s have-nots would be worst hit by climate change, predicting
greenhouse gases would change rainfall patterns, intensify tropical
storms, accelerate the melting of Arctic ice and mountain glaciers,
and amplify the risk of drought, flooding and water stress.
holds that Asia faces a heightened risk of flooding, severe water
shortages, infectious disease and hunger from global warming this
century. The region is confronted by a 90% likelihood that more than
a billion of its people will be “adversely affected” by
the impacts of global warming by the 2050s.
estimates say the magnitude of climate-change effects will vary according
to the size of the world’s population, energy use and the level
of greenhouse gases in the atmosphere. But under any scenario, the
world’s most populous region will be badly hit.
on Global Warming by IPCC ( New York Times)
notes that using the term “very likely” indicates a likelihood
of more than 90%. This is how the the statements about the evidence
have evolved and become stronger.
unequivocal detection of the enhanced greenhouse effect
from observations is not likely for a decade
balance of evidence suggests a discernable
human influence on global climate”
is new and stronger evidence that most
of the warming observed over the last 50 years is attributable
to human activities.”
of the observed increase in globally averaged temperatures
since the mid-20th century is very likely due
to the observed increase in anthropogenic greenhouse gas
findings from the 4th Assessment Report regarding projected impacts
as well as vulnerability and adaptation
water demand and climate change
120 million to 1.2 billion people in Asia will experience increased
water stress by 2020 and 185 to 981 million by 2050.
Per capita water availability
in India will drop from around 1900 cubic metre currently to 1,000
cu-metres by 2025.
By mid-century, annual average
river runoff and water availability are projected to increase by 10-40%
at high latitudes and in some wet tropical areas, and decrease by
10-30% over some dry regions at mid-latitudes and in the dry tropics,
some of which are presently water stressed areas.
In the course of the century,
water supplies stored in glaciers and snow cover are projected to
decline, reducing water availability in regions supplied by meltwater
from major mountain ranges, where more than one-sixth of the world
population currently lives.
Adaptation procedures and risk management practices for the water
sector are being developed in some countries and regions that have
recognized projected hydrological changes with related uncertainities.
of Indian agriculture to climate change
Cereal yields in South Asia could drop in some areas by up to 30%
Crop productivity is projected
to increase slightly at mid-to high latitudes for local mean temperature
increases of up to 1-3 degrees Celcius depending on the crop, and
then decrease beyond that in some regions.
At lower latitudes, especially
seasonally dry and tropical regions, crop productivity is projected
to decrease for even small local temperature increases (1-2 degrees
Celsius), which would increase risk of hunger.
Globally, the potential
for food production is projected to increase with increases in local
average temperature over a range of 1-3 degrees Celsius, but above
this it is projected to decrease.
Increases in the frequency
of droughts and floods are projected to affect local crop production
negatively, especially in subsistence sectors at low latitudes.
hazards due to climate change
Even modest rises in sea levels will cause flooding and economic disruption
in densly-populated mega-deltas, such as the mouths of the Yangtze
in China, the Red River in China and Vietnam, and the Ganges-Brahmaputra
delta in low-lying Bangladesh.
Coasts are projected to
be exposed to increasing risks, including coastal erosion, due to
climate change and sea-level rise. The effect will be exacerbated
by increasing human-induced pressures on coastal areas.
Many millions more people
are projected to be flooded every year due to sea level rise by the
2080s. Those densly populated and low-lying areas where adaptive capacity
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.
Adaptation for coasts will
be more challenging in developing countries than in developed countries,
due to constraints on adaptive capacity.
The most vulnerable industries, settlements and societies are generally
those in coastal and river flood plains, those whose economies are
closely linked with climate-sensitive resources, and those in areas
prone to extreme weather events, especially where rapid urbanization
is occurring. Poor communities can be especially vulnerable, in particular
those concentrated in high-risk areas. They tend to have more limited
adaptive capacities, and are more dependent on climate-sensitive resources
such as local water and food supplies.
Projected climate change-related exposures are likely to affect the
health status of millions of people, particularly those with low adaptive
a. increases in malnutrition and consequent disorders, with implications
for child growth and development;
b. increased deaths, disease and injury due to heat waves, floods,
storms, fires and droughts;
c. the increased burden of diarrhoeal disease;
d. the increased frequency of cardio-respiratory diseases due to higher
concentrations of ground level ozone related to climate change; and,
e. the altered spatial distribution of some infectious disease vectors.
Cholera and malaria could
increase due to flooding and a wider habitat range for mosquitoes.
Climate change is expected
to have some mixed effects, such as the decrease or increase of the
range and transmission potential of malaria in Africa.
Studies in temperate areas(mainly
in industrialized countries) have shown that climate change is projected
to bring some benefits, such as fewer deaths from cold exposure. Overall
it is expected that these benefits will be outweighed by the negative
health effects of rising temperatures world-wide, especially in developing
on ecosystem structure and function
The resilience of many ecosystems is likely to be exceeded this century
by an unprecedented combination of climate change, associated disturbances
(e.g., flooding, drought, wildfire, insects, ocean acidification),
and other global drivers(e.g., land use change, pollution, over-exploitation
Some 30 per cent of Asian
coral reefs, which sustain a large percentage of marine life, are
expected to be lost in the next 30 years, although this will occur
as a result of multiple stresses.
Over the course of this
century, net carbon uptake by terrestrial ecosystems is likely to
peak before mid-century and then weaken or even reverse, thus amplifying
Approximately 20-30% of
plant and animal species assessed so far are likely to be at increased
risk of extinction if increases in global average temperature exceed
1.5-2.5 degrees Celsius.
The progressive acidification
of oceans due to increasing atmospheric carbon dioxide is expected
to have negative impacts on marine shell forming organisms (e.g.,corals)
and their dependent species.
Regional changes in the
distribution and production of particular fish species are expected
due to continued warming, with adverse effects projected for aquaculture
Corals are vulnerable to
thermal stress and have low adaptive capacity. Increases in sea surface
temperature of about 1-3 degrees Celsius are projected to result in
more frequent coral bleaching events and widespread mortality, unless
there is thermal adaptation or acclimatization by corals.
Coastal wetlands including
salt marshes and mangroves are projected to be negatively affected
by sea-level rise especially where they are constrained on their landward
side, or starved of sediment.
events in terms of intensity and frequency
In the Himalayas, glaciers less than four kilometers long will disappear
entirely if average global temperatures rise by 3 degrees Celsius.
This will initially cause increased flooding and mudslides followed
by an eventual decrease in flow in rivers that are glacier-fed.
Drought-affected areas will
likely increase in extent. Heavy precipitation events, which are very
likely to increase in frequency, will augment flood risk.
While extreme weather events become more intense and more frequent,
the economic and social costs of those events will increase, and these
increases will be substantial in the areas most directly affected.
Climate change impacts spread from directly impacted areas and sectors
to other areas and sectors through extensive and complex linkages.