The Guardian has reported that the US response to a draft of the UN report on climate change prepared by the Intergovernmental Panel on Climate Change (IPCC) which will be released in three parts beginning on February 2nd says that a statement advocating research on the development of technology to block sunlight as a way of stopping global warming if other measures fail should be included. Schemes to block sunlight that have been suggested so far include giant space mirrors, sulphate droplets scattered into the atmosphere, and distributing into the atmosphere tiny shiny balloons. According to the Guardian the US wants the following statement placed in the policymakers statement at beginning of each report:
“Modifying solar radiance may be an important strategy if mitigation of emissions fails. Doing the R&D to estimate the consequences of applying such a strategy is important insurance that should be taken out. This is a very important possibility that should be considered.”
The IPCC draft said that sunlight blocking schemes were “speculative, uncosted and with potential side-effects.”
Although these ideas to block sunlight as a way to combat global warming are often considered as wacko, and in most cases the US position seems counterproductive to stopping global warming, in this instance I have to say that I agree with the US. If the goal as is often stated is to limit global warming to a 2°C increase above preindustrial levels and to achieve this requires that atmospheric carbon dioxide levels can not rise above 450 parts per million and this would require a worldwide reduction of carbon dioxide emissions in the order of 70% to 80% by the year 2050 then I think we have to face the fact that although this is probably theoretically possible the political obstacles make it an almost impossible goal to reach. The list of political hurdles to overcome seem nearly endless. A large majority of the US population would have to be convinced that global warming is linked to human activities. A carbon tax or the equivalent would have to accepted around the world. People in developed countries would have to accept limitations on lifestyle. China and India would have to agree to reduce emissions and Western countries would probably have to pay for their implementation of renewable energy and energy efficiency measures to make this possible. Tremendous investments would have to be made for research on new energy technologies. The ability of the oil and coal industries to successfully fight change would have to be overcome. Etc, etc, etc.
Sunlight blocking schemes at best can only buy time and might cause unexpected adverse consequences. However, we are now at point of time where I think we need a Plan B.