The World - Greenhouse gas carbon dioxide (CO₂)
Atmosphere and climate change
978-3-14-100890-6 | Page 21 | Ill. 5
Overview
The Earth's atmosphere has the property of reducing the heat radiation of the Earth's surface and of the layers of air near the ground into space. Without this natural greenhouse effect, global mean temperatures would be more than 30°C lower than they are today, making life on earth impossible.
Human activities have led to a significant accumulation of greenhouse gases in the atmosphere, threatening serious changes in the world's climate.
CO2 emissions of states and world regions
The increased emission of greenhouse gases since the beginning of industrialisation is particularly noticeable. The result is a warming of the global climate, also known as the anthropogenic greenhouse effect. The most important greenhouse gas is carbon dioxide (CO2). It accounts for three quarters of anthropogenic greenhouse gas emissions. CO2 is mostly released by the combustion of fossil fuels and industrial processes (65% of the anthropogenic greenhouse effect), and secondly by agriculture and other land uses (11%).
The map shows serious contrasts in the absolute quantities of CO2 emissions between the industrialised and newly industrialising countries on the one hand and the developing countries on the other. The highest absolute emissions are recorded for the USA, Russia, India, China and Japan (coloured dots). However, this statement must be put into perspective by reference to population size. While the USA and Russia are also among the countries with the highest per capita values, India records low values (area colours). Although countries like Kuwait, Saudi Arabia, Australia or Canada are far behind India or China in terms of absolute emissions, they belong to the group of countries with the highest per capita values. Power generation worldwide is currently dominated by the burning of fossil energy resources. This is one of the main reasons for the explanation of CO2 emissions.
Only in South America - with a high share of hydropower - and Europe more than half of the electricity is generated from other energy sources. Concerning the share of renewable energy (excluding hydropower), Europe is in the lead. Electricity generation in Asia and the Middle East has particularly strong effects on CO2 emissions. On the one hand, it increased strongly between 1995 and 2011 (2.6 times), and on the other hand, the share of fossil energy raw materials in electricity generation is the largest worldwide. (Only in Africa, which is quantitatively insignificant, this share is similarly high).
Greenhouse gases and global warming
The increased emission of greenhouse gases since the beginning of industrialisation is the main cause of global warming. The most important greenhouse gas is carbon dioxide (CO2), which is produced by burning the fossil fuels coal, oil and natural gas. Around 1860, about 340 million tonnes of CO2 were released annually; today the figure is more than a hundred times higher. In the Kyoto Protocol, the first major climate protection agreement, more than 170 countries committed themselves to drastically reducing their CO2 emissions. Nevertheless, according to the Intergovernmental Panel on Climate Change (IPCC), they have continued to rise and will reach new record levels this decade.
The most important causes of rising greenhouse gas emissions are population and economic growth. The energy sector (35%) is primarily responsible, followed by agriculture and forestry (24%), industry (21%), transport (14%) and buildings (6%).
With a moderate increase in climate-impacting greenhouse gases, there will be a rise in temperature in the polar regions of the northern hemisphere. By the year 2100, an increase of over 7°C is predicted there in some cases, not least because of the shorter average duration of snow cover and melting ice. The snow- and ice-free ground surfaces will warm up even more due to their lower albedo, their reduced reflectivity (positive feedback). In the Antarctic, a smaller temperature increase than in the Arctic is expected. Here, the isolated location and the thick inland ice masses contribute to a significantly lower temperature increase. Another positive feedback process occurs in areas where permafrost is currently widespread. There, as temperatures rise and the ground thaws, large quantities of methane, a gas that affects the climate, are released. Once released into the atmosphere, it intensifies the greenhouse effect there.
