Climate Change
In the News

A planet's climate is decided by its mass, its distance from the sun and the composition of its atmosphere. Mars is too small to keep a thick atmosphere. Its atmosphere consists mainly of carbon dioxide, but the atmosphere is very thin. The atmosphere of the Earth is a hundred times thicker.

Over the last 400,000 years the Earth's climate has been unstable, with very significant temperature changes, going from a warm climate to an ice age in as rapidly as a few decades. These rapid changes suggest that climate may be quite sensitive to internal or external climate forcings and feedbacks.

The Earth has a natural temperature control system. Certain atmospheric gases are critical to this system and are known as greenhouse gases.

Radiative forcing is the change in the balance between radiation coming into the atmosphere and radiation going out.

The table lists some of the main greenhouse gases and their concentrations in pre-industrial times and in 1994; atmospheric lifetimes; anthropogenic sources; and Global Warming Potential.

Atmospheric CO₂ has increased from a pre-industrial concentration of about 280 ppmv to about 367 ppmv at present (ppmv= parts per million by volume).

This map depicts the unequal distribution of industry in the world. The significant part of carbon dioxide emissions comes from energy production, industrial processes and transport.

The rich countries of the world historically has emitted most of the anthropogenic greenhouse gases since the start of the industrial revolution in the latter half of the 1700s. Per capita, the significant emissions still are produced by the OECD countries

The global carbon cycle shows the carbon reservoirs in GtC (gigatonne= one thousand million tonnes) and fluxes in GtC/year.

The amount of aerosols in the air has direct effect on the amount of solar radiation hitting the Earth's surface. Aerosols may have significant local or regional impact on temperature.

The United Nations Framework Convention on Climate Convention is the foundation of global efforts to combat global warming.

In 1988, UNEP and WMO jointly established the Intergovernmental Panel on Climate Change (IPCC) as concern over climate change became a political issue. The purpose of the IPCC was to assess the state of knowledge on the various aspects of climate change including science, environmental and socio-economic impacts and response strategies.

The mean global surface temperature has increased by about 0.3 to 0.6?C since the late 19th century and by about 0.2 to 0.3?C over the last 40 years.

Precipitation has increased over land at high latitudes of the Northern Hemisphere, especially during the cold season. Decrease in precipitation occurred in steps after the 1960s over the subtropics and the tropics from Africa to Indonesia.

Over the last 100 years, the global sea level has risen by about 10 to 25 cm.

If greenhouse gas concentrations keep rising, climatic changes are likely to result. Those changes will potentially have wide-ranging effects on the environment and socio-economic sectors.

The projection of future climate change depends partly on the assumptions made about future emissions of greenhouse gases and aerosol precursors and the proportion of emissions remaining in the atmosphere.

Projected anthropogenic CO₂ emissions from fossil fuel use, deforestation and cement production for the six IPCC emission scenarios.

Climate models calculate that the global mean surface temperature could rise by about 1 to 4.5 centigrade by 2100.

Models project an increase in global mean sea level of between 13 and 94 cm by the year 2100.

The potential impacts of climate change on the environment and socio-economic systems can be understood in terms of sensitivity, adaptability and vulnerability of the system.