Exactly how much carbon is being released into the atmosphere and by how much must it be reduced if we are to survive?
Currently, we are producing some 50 billion tonnes of carbon dioxide and releasing it into the atmosphere. If this continues, then the world’s average temperature will increase by 4 degrees centigrade by about the year 2040 and, if that happens, the extent of change will be so enormous it is possible that human society will no longer be recognizable afterwards.
In order to prevent this from happening, it will be necessary to reduce the amount of carbon emissions. About the most change that can be managed without completely changing the way we live is an average increase of 2 degrees centigrade and even that will be highly problematic. To keep the probability of an average temperature to a 2 degrees rise to a 50% chance, the amount of emissions must be decreased to 35 billion tonnes by 2025 and further to 20 billion tonnes by 2040. This means a decrease of 60% from today’s usage.
However, there is more to it than that – given that we can expect something like a 2.5% annual increase in global output in the foreseeable future, by the time 2040 comes there will be three times the level of output than there is now (much of this will come from China, India and other rapidly industrializing countries). That level of increase in output will require an increase in energy use. Altogether, therefore, in order to reduce carbon emissions to the extent required while dealing with growth, it will be necessary to increase energy efficiency to eight times what it now is. Since it is unlikely that the demand for energy can be reduced that much, it will be necessary to increase the efficiency of use by that amount.
To make the investments necessary to deal with these changes, governments will need to set aside approximately 1-2% of total GDP. This is a large amount of money but it is a manageable amount of money. Investment is not the same as a cost, of course, since investment will unlock improvements and reduce costs in the future. However, the length of time over which the investment is going to be assessed is such that a fair amount of the investment concerned will appear to be a cost on the present generation.
Currently, many countries around the world are making plans to reduce emissions and make the changes necessary. Industry and universities are also contributing research and knowledge-sharing to new initiatives and projects. There are reasons to be cautiously optimistic about the possibility of surviving this crisis but it is far from certain at the moment.
For more information, see the work of Lord Nick Stern, the chair of the Stern Report on Climate Change and subsequent updates.