Human activities are releasing greenhouse gases into the
atmosphere. Carbon dioxide is produced when fossil fuels are
used to generate energy and when forests are cut down and burned.
Methane and nitrous oxide are emitted from agricultural activities,
changes in land use, and other sources. CFCs and other gases are
released by industrial processes, while ozone in the lower atmosphere
is generated indirectly by automobile exhaust fumes.
Rising levels of greenhouse gases are expected to cause
climate change. By absorbing infrared radiation, these gases
control the flow of natural energy through the climate system.
The climate must somehow adjust to the "thickening blanket"
of greenhouse gases in order to maintain the balance between energy
arriving from the sun and energy escaping back into space.
Climate models predict that the global temperature will
rise by about 13.5oC by the
year 2100. This projected change is larger than any climate
change experienced over the last 10,000 years. It is based on
current emissions trends and assumes that no efforts are made
to limit greenhouse gas emissions. There are many uncertainties
about the scale and impacts of climate change, particularly at
the regional level. Because of the delaying effect of the oceans,
surface temperatures do not respond immediately to greenhouse
gas emissions, so climate change will continue for many decades
after atmospheric concentrations have stabilized. Meanwhile, the
balance of the evidence suggests a discernable human influence
on the global climate.
Climate change is likely to have a significant impact on
the global environment. In general, the faster the climate
changes, the greater will be the risk of damage. The mean sea
level is expected to rise 1595 cm by the year 2100, causing
flooding of low-lying areas and other damage. Climatic zones (and
thus ecosystems and agricultural zones) could shift towards the
poles by 150550 km in the mid-latitude regions. Forests,
deserts, rangelands, and other unmanaged ecosystems would face
new climatic stresses. As a result, many will decline or fragment,
and individual species will become extinct.
Human society will face new risks and pressures. Food
security is unlikely to be threatened at the global level, but
some regions are likely to experience food shortages and hunger.
Water resources will be affected as precipitation and evaporation
patterns change around the world. Physical infrastructure may
be damaged, particularly by sea-level rise and by extreme weather
events. Economic activities, human settlements, and human health
will experience many direct and indirect effects. The poor and
disadvantaged are the most vulnerable to the negative consequences
of climate change.
People and ecosystems will need to adapt to future climatic
regimes. Past and current emissions have already committed
the earth to some degree of climate change in the 21st century.
Adapting to these effects will require a good understanding of
socio-economic and natural systems, their sensitivity to climate
change, and their inherent ability to adapt. Many strategies are
available for adapting to the expected effects of climate change.
Stabilizing atmospheric concentrations of greenhouse gases
will demand a major effort. Based on current trends, the total
climatic impact of rising greenhouse gas levels will be equal
to that caused by a doubling of pre-industrial CO2
concentrations by 2030, and a trebling or more by 2100. Freezing
global CO2 emissions at their current
levels would postpone CO2doubling
to 2100. Emissions would eventually have to fall to about 30%
of their current levels for concentrations to stabilize at doubledCO2
levels sometime in the future. Given an expanding world economy
and growing populations, this would require dramatic improvements
in energy efficiency and fundamental changes in other economic
The international community is tackling this challenge
through the Climate Change Convention. Adopted in 1992, the
Convention seeks to stabilize atmospheric concentrations of greenhouse
gases at safe levels. Some 165 countries have become Parties.
Developed countries are committed to taking measures aimed at
returning their emissions to 1990 levels by the year 2000; they
will commit themselves to making further emissions cuts after
the year 2000 in a new agreement to be finalized by the end of
1997. Developed countries are also committed to promoting financial
and technological transfers to developing countries to help them
address climate change. Meanwhile, all Parties are gathering information
on their national emissions and developing strategies for adapting
to and minimizing climate change.
Many options for limiting emissions are available in the
short- and medium-term. Policymakers can encourage energy
efficiency and other climate-friendly trends in both the supply
and consumption of energy. Key consumers of energy include industries,
homes, offices, vehicles, and farms. Efficiency can be improved
in large part by providing an appropriate economic and regulatory
framework for consumers and investors. This framework should promote
cost-effective actions, the best current and future technologies,
and "no regrets" solutions that make economic and environmental
sense irrespective of climate change. Taxes, regulatory standards,
tradable emissions permits, information programmes, voluntary
programmes, and the phase-out of counterproductive subsidies can
all play a role. Changes in practices and lifestyles, from better
urban transport planning to personal habits such as turning out
the lights, are also important.
Energy efficiency gains of 1030% above baseline trends
can be realized over the next 2030 years at no net cost.
Some researchers believe that much greater gains are also feasible
during this period and beyond. Improvements over the baseline
can be achieved in all major economic sectors with current knowledge
and with today's best technologies. In the longer term, it will
be possible to move close to a zero-emissions industrial economy
- with the innumerable environmental and economic benefits that
Reducing uncertainties about climate change, its impacts,
and the costs of various response options is vital. In the
meantime, it will be necessary to balance concerns about risks
and damages with concerns about economic development. The prudent
response to climate change, therefore, is to adopt a portfolio
of actions aimed at controlling emissions, adapting to impacts,
and encouraging scientific, technological, and socio-economic
Source: Climate Change Information Kit, UNFCCC