Backgrounder: Emission intensity, emission density and per capita emission

BEIJING, Dec. 1 (Xinhua) -- Global warming is generally attributed to additional heat being trapped in the atmosphere by a buildup of greenhouse gases, 75 percent of which is carbon dioxide from the burning of fossil fuels.

As the reduction of carbon emissions is a major way to counter climate change, concepts such as emission intensity, emission density and per capita emission have been developed.

Generally speaking, emission intensity is the average emission rate of a given pollutant from a given source relative to the intensity of a specific activity.

China announced last week its goal of reducing the intensity of carbon dioxide emissions per unit of GDP in 2020 by 40 to 45 percent compared with the level of 2005. Carbon intensity here refers to the amount of carbon dioxide emitted for each unit of GDP over a certain period.

People sometimes confuse emission intensity with energy intensity, which means the amount of energy used to produce each unit of economic output over a given period of time, including both fossil fuels that produce carbon dioxide and clean energy sources such as wind and nuclear power.

Emission density and per capita emission refer to the average emission rates of the total amount of greenhouse gas emissions in a country or a region divided by its area and population, respectively.

According to the principle of "common but differentiated responsibilities" stipulated in the United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol, developed countries are required to set clear targets for emissions reductions.

Developing countries do not have any binding obligations to cap emissions. Instead, they should counter climate change in accordance with their national conditions, with financing and technological transfer provided by developed nations