Climate Change 2007 Update

7. What are the current trends in greenhouse gas emissions?

Since pre-industrial times, increasing emissions of greenhouse gases due to human activities have led to a marked increase in the concentration of greenhouse gases in the atmosphere. Between 1970 and 2004, global emissions have increased by 70%. Over this period, emissions from the energy and transport sectors have more than doubled.

Global greenhouse gas emissions include carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and fluorinated greenhouse gases (HFCs, PFCs and SF6). The gases are each weighted by their global warming potential and the total is expressed in Gigatonnes of carbon dioxide equivalents (GtCO₂-eq). In 2004, total greenhouse gas emissions due to human activities reached 49 Gigatonnes of carbon dioxide equivalents (GtCO₂-eq) and CO₂ alone represented 77% of the total.

Although since the 1970s less and less energy is needed to generate a given amount of GDP, this decrease has been offset by the global economic and population growth. Emission reduction policies have been put in place in some countries that have been effective in reducing emissions in those countries to a certain degree, but not sufficiently to counteract the global growth in emissions.

With current mitigation policies and sustainable development practices alone, global greenhouse gas emissions will continue to grow. Indeed, in the absence of additional mitigation measures, emission scenarios project an increase of 25 to 90% in greenhouse gas emissions in 2030 compared to 2000. (See The Emission Scenarios of the IPCC)

Fossil fuels are expected to maintain their dominant position in the global energy mix beyond 2030. Hence between 2000 and 2030, CO₂ emissions from energy use are projected to grow 45 to 110% over that period, particularly in developing regions (non-Annex I regions). CO₂ emissions per capita are expected to remain substantially higher in developped countries compared to the rest of the world (Annex I regions). However, developed countries are expected to use less energy per unit of GDP than developing countries. More...