In zerocarbonbritain2030 there is a 90% reduction in all greenhouse gas emissions including carbon dioxide, methane and nitrous oxide. The remaining residual emissions are balanced by indigenous natural sequestration, bringing net greenhouse gas emissions to zero.
The warming effects of all greenhouse gases can be converted to "carbon dioxide equivalent" based on the warming that they cause relative to carbon dioxide. It is in this carbon dioxide equivalent sense that zerocarbonbritain2030 is "zero carbon".
In the first Zero Carbon Britain report the phrase “zero carbon” was used in a more limited sense, referring to “an economy where there are no carbon dioxide emissions from the use of fossil fuels”, but in this report we have broadened the focus.
The world is now about 0.8 degrees Centigrade hotter than it was in pre-industrial times. Future warming has been estimated using many different methods. These include scientific understanding of physical systems and feedbacks and the study of past temperature changes.
The Intergovernmental Panel on Climate Change (IPCC) reviewed the different scientific estimates in their last assessment report and gave an overall estimate of between 1.1 and 6.4°C over pre-industrial temperatures for the coming century, depending on how much we emit, exactly how sensitive the climate is to greenhouse gases and how the natural carbon cycle responds to the increasing CO2 and temperatures.
The lower end of this range would require emissions trajectories much lower than those that we have been following so far. The top end of the range is similar to the difference between our current climate and the depths of an ice age.
No this is not correct, although sadly there has been a lot of misinformation on this subject circulated recently in the UK. To find really good answers to the misinformation we recommend the following websites:
Skeptical Science: provides point-by-point text answers to the common sceptic talking points, with links to original scientific papers.
Climate Denial Crock of the Week: provides short youtube videos on climate sceptic topics.
A useful thing to understand is that if temperatures are to be stabilised at any temperature emissions from the whole world must tend towards zero at some point, because of the long life term of CO2 in the atmosphere. Otherwise we will just keep on getting hotter. The question is not, "how much must we decarbonise?" the question is, "how fast must we decarbonise?".
In the climate science chapter we argue that there is a good case for very rapid decarbonisation in the UK. This allows poorer countries longer to decarbonise (considered fair as they have less historical responsibility for climate change, fewer resources to invest in low-carbon technologies, and they produce a great deal of manufacturing emissions on our behalf) while still giving the world a good chance of avoiding 2°C of warming over pre-industrial temperatures - the target to which the UK and all other signatories of the Copenhagen accord are pledged.