The Climate Science Weblog has documented the following conclusions:
The needed focus for the study of climate change and variability is on the regional and local scales. Global and zonally-averaged climate metrics would only be important to the extent that they provide useful information on these space scales.
Global and zonally-averaged surface temperature trend assessments, besides having major difficulties in terms of how this metric is diagnosed and analyzed, do not provide significant information on climate change and variability on the regional and local scales.
Global warming is not equivalent to climate change. Significant, societally important climate change, due to both natural- and human- climate forcings, can occur without any global warming or cooling.
The spatial pattern of ocean heat content change is the appropriate metric to assess climate system heat changes including global warming.
In terms of climate change and variability on the regional and local scale, the IPCC Reports, the CCSP Report on surface and tropospheric temperature trends, and the U.S. National Assessment have overstated the role of the radiative effect of the anthropogenic increase of CO2 relative to the role of the diversity of other human climate climate forcing on global warming, and more generally, on climate variability and change.
Global and regional climate models have not demonstrated skill at predicting regional and local climate change and variability on multi-decadal time scales.
Attempts to significantly influence regional and local-scale climate based on controlling CO2 emissions alone is an inadequate policy for this purpose.
A vulnerability pespective, focused on regional and local societal and environmental resources of importance, is a more inclusive, useful, and scientifically robust framework to interact with policymakers, than is the focus on global multi-decadal climate predictions which are downscaled to the regional and local scales. The vulnerability paradigm permits the evaluation of the entire spectrum of risks associated with different social and environmental threats, including climate variability and change.
Humans are significantly altering the global climate, but in a variety of diverse ways beyond the radiative effect of carbon dioxide. The IPCC assessments have been too conservative in recognizing the importance of these human climate forcings as they alter regional and global climate. These assessments have also not communicated the inability of the models to accurately forecast the spread of possibilities of future climate. The forecasts, therefore, do not provide any skill in quantifying the impact of different mitigation strategies on the actual climate response
that would occur.
With the legal decision in the United States to define CO2 as a pollutant (see), the important question on how to include this climate forcing in the assessment of emssion controls with respect to the traditional primarily health related pollutants need to be considered. For example, should the climate forcing of CO2, which is claimed will result in major changes in the environment, be a more important consideration than the health effects of pollutants such as produced by fuels that are intended to reduce the emission of CO2.
Biofuels have received considerable attention as at least a partial replacement for fossil fuels. However, there are already issues raised by its use [e.g. see (and thanks to Laure M Montandon for alerting me to this article). A major concern are the possible carcinogens and other toxic gases and particles that would be part of the emissions from vehicles or other combustion sources that use this fuel.
There is a summary available entitled “Biodiesel Emissions Compared to Other Fuels
Fuel Types” which provides some insight into this issue. The values in the table presented in this summary are the difference with respect to diesel, whose emissions are a well known health hazard as identified by the American Lung Association, where they write,
“Diesel exhaust is a mixture containing over 450 different components, including vapors and fine particles. Over 40 chemicals in diesel exhaust are considered toxic air contaminants by the State of California. Exposure to this mixture may result in cancer, exacerbation of asthma, and other health problems.
For the same load and engine conditions, diesel engines spew out 100 times more sooty particles than gasoline engines. As a result, diesel engines account for an estimated 26 percent of the total hazardous particulate pollution (PM10) from fuel combustion sources in our air, and 66 percent of the particulate pollution from on-road sources. Diesel engines also produce nearly 20 percent of the total nitrogen oxides (NOx) in outdoor air and 26 percent of the total NOx from on-road sources. Nitrogen oxides are a major contributor to ozone production and smog….
Diesel exhaust has been linked in numerous scientific studies to cancer, the exacerbation of asthma and other respiratory diseases. A draft report released by the US EPA in February 1998 indicated that exposure to even low levels of diesel exhaust is likely to pose a risk of lung cancer and respiratory impairment. And in August 1998, the State of California decided that there was enough evidence to list the particulate matter in diesel exhaust as a toxic air contaminant - a probable carcinogen requiring action to reduce public exposure and risk.”
While biofuels including biodiesel may improve on traditional diesel, health concerns regarding its use will exist. In any regulation on CO2, if it results in increased emssions of gases and aerosols with health issues, then the climate concerns of human inputs of CO2 will have trumped the health effects of the replacement fuels.