Long-Term Climate Change Mitigation
Gaskill reviewed the physics behind the long-term climate change problem. [An error in slide 5 giving the solar radiation wavelength range has been corrected. The correct range is 0.3 to 2.5 micrometers]. Shortwave solar radiation is absorbed by the Earth (atmosphere, surface) and the Earth in turn re-emits this radiation as longwave infrared radiation (IR) that is absorbed by trace gases in the atmosphere, e.g. water vapor and carbon dioxide known as greenhouse gases (GHGs) that in turn re-emit IR back to the surface where it is absorbed and re-emitted again.
The addition of man-made GHGs to the atmosphere from fossil fuel use and food production is increasing the amount of infrared radiation in the atmosphere, enhancing the natural greenhouse effect, causing a global warming and leading to significant global climate change. The Intergovernmental Panel on Climate Change believes that unless GHG levels in the atmosphere can be stabilized by 2050, there will be irreversible climate change with droughts, floods, famines, deadly heat waves, loss of millions of species, significant sea level rise and other consequences.
For this reason, governments have decided to reduce GHG emissions through treaties and legislation and by supporting technological innovation. Gaskill said his group had concluded that neither approach was going to be successful in stabilizing GHG levels by 2050. He cited the failure of the Kyoto Protocol to go into effect and the lack of progress by European Union (EU) nations and Japan in meeting their assigned targets. He said most view the U.S. Clear Skies program as a business as usual (BAU) hybrid, with most of the projected emissions reduction heavily back-loaded. He also said pending legislation in the U.S. Congress, although well intentioned, is years away from enactment and that the U.S. would eventually rejoin the international treaty process.
He gave three reasons why technology changes would not occur in time to solve the long-term global climate change problem. The first was that emissions are spread across too many sources (transportation, power generation, heating, food production, landfills, pipeline leaks, deforestation, non-transportation halocarbons) to expect changes to be made easily and rapidly. [An error in slide 17 showing the apportionment of GHG emissions contribution to global warming by sector has also been corrected. Food production, landfills and pipeline leaks contribution is 25%, not 20%. The percentages refer to the radiative forcing caused by the emissions, not the raw emissions in GtC].
The second reason is that replacement technologies are either immature or non-existent. Gaskill cited the 2004 National Academy of Engineering report that said hydrogen/fuel cell use would not be significant before 2030. In general, Gaskill said that replacement technologies are 20-40 years away from the beginnings of widespread use. He also cited the long capital lifetimes of vehicles, power stations and heating systems as contributing to the lag time in deployment of replacement technologies until well past 2050.
Gaskill concluded that for all of these reasons, GHG emissions couldn’t be reduced in time to prevent a global climate catastrophe. He said that what was needed was more time, a way to delay the anticipated warming as long as possible. He proposed geoengineering or deliberate modification of the Earth’s climate as a delaying tactic. He described various geoengineering schemes that have been proposed, noting most of them are presented as alternatives to reducing emissions, not as delaying tactics.
