The difficult question is at what level CO2 concentrations in the atmosphere will have to peak – or be stabilized - to prevent 2°C being exceeded?
At ‘Avoiding Dangerous Climate Change’, a 3-day conference in the UK held in early 2004, Malte Meinshausen from ETH Zurich and others presented their assessment of this question.
If CO2 concentrations were to stay below 400ppm (parts per million), staying below 2°C would be likely (probability of exceeding 2°C ranges between 8% and 57%, depending on the model). However, given current energy and power infrastructures, it is very unlikely that we can keep concentrations that low.
A level of 550ppm is very unlikely to keep us below 2°C and could even mean overshooting 4°C. At 475ppm the prospect of staying below 2°C is still rather slim.
If 475ppm was the peak and a rapid decrease followed, by the year 2100, we have at least options to stabilise at a temperature 2°C higher than pre-industrial times.
Note: Current concentrations of CO2 are at over 380 ppm. These measurements include the effect of other greenhouse gases by attributing global warming values equivalent to CO2; greenhouse gas warming capacities are expressed in CO2 equivalents.
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Source:
Meinshausen, M, What does a 2°C target mean for greenhouse gas concentrations? In ‘Avoiding Dangerous Climate Change’, 2006, Cambridge University Press
At ‘Avoiding Dangerous Climate Change’, a 3-day conference in the UK held in early 2004, Malte Meinshausen from ETH Zurich and others presented their assessment of this question.
If CO2 concentrations were to stay below 400ppm (parts per million), staying below 2°C would be likely (probability of exceeding 2°C ranges between 8% and 57%, depending on the model). However, given current energy and power infrastructures, it is very unlikely that we can keep concentrations that low.
A level of 550ppm is very unlikely to keep us below 2°C and could even mean overshooting 4°C. At 475ppm the prospect of staying below 2°C is still rather slim.
If 475ppm was the peak and a rapid decrease followed, by the year 2100, we have at least options to stabilise at a temperature 2°C higher than pre-industrial times.
Note: Current concentrations of CO2 are at over 380 ppm. These measurements include the effect of other greenhouse gases by attributing global warming values equivalent to CO2; greenhouse gas warming capacities are expressed in CO2 equivalents.
- - - -
Source:
Meinshausen, M, What does a 2°C target mean for greenhouse gas concentrations? In ‘Avoiding Dangerous Climate Change’, 2006, Cambridge University Press