To limit the negative impact of climate change, the global temperature must not rise by more than 2°C compared to preindustrial levels. This target is part of the EU’s energy policy.
- A rise of 0.8°C has already taken place and a rise of further 0.5-0.7°C is unavoidable.
The 2°C rise is typically associated with a CO2 concentration of 400-500 ppm (parts per million) by volume. This indicates that out of one million parts in the atmosphere, 400 to 500 are parts of CO2.
- The current (1) level of CO2 alone is around 395,53 ppm by volume, and is rising by 2 ppm annually.
Therefore, CO2 emissions must be reduced quickly and significantly. Thus the current carbon-based economy must change dramatically and as soon as possible, since world economic energy efficiency is improving at only half the world economic growth rate.
- CO2 emissions must be reduced to 50% of 1990 levels by 2050.
Industrialized countries produce most of the CO2 per capita, e.g. 24 tonnes in the US, 10 to 11 tonnes in Germany, as opposed to 4.6 tonnes in China and less than 0.1 tonnes in almost 20 other countries such as Madagascar, Nepal and Tanzania.
- A sustainable amount of human CO2 emission is 3t per capita(2).
If the 2°C target is to be reached, then industrialized countries must not only support developing countries to keep their emissions low, but they must also reduce their own emissions drastically.
Many levers can help to limit global warming to 2°C, e.g. demand reduction for emissions-intensive goods and services, increase of efficiency gains, increased use and development of low-carbon technology, reduction of fossil fuel emissions. Time is crucial in reducing CO2 emissions since it stays in the atmosphere for a very long time(3).
Therefore a mechanism is needed to ensure that the different levers are used as efficiently as possible concerning both time and effectiveness.
Emission trading systems are such a mechanism which caps total emissions and makes all CO2 emitters compete in a common market.
- October 2014 http://scrippsco2.ucsd.edu; this figure is adjusted for the effect of aerosols that are cooling the climate; actual level of CO2 is around 460ppm
- The German WBGU (Wissenschaftlicher Beirat Globale Umweltveränderung) derives an emission limit of 750 billion tons until 2050; divided by the world population of 6.9 billion people in 2010 and spread over 40 years this yields 2.72 t per year and capita
- Climate change which takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop http://www.pnas.org/content/early/2009/01/28/0812721106.abstract