Climate models

Scientists have studied global warming with computer models of the climate. These models are based on physical principles of fluid dynamics, radiative transfer, and other processes, with simplifications being necessary because of limitations in computer power and the complexity of the climate system. All modern climate models include an atmospheric model that is coupled to an ocean model and models for ice cover on land and sea. Some models also include treatments of chemical and biological processes.These models predict that the effect of adding greenhouse gases is to produce a warmer climate. However, even when the same assumptions of future greenhouse gas levels are used, there still remains a considerable range of climate sensitivity.
Current climate models produce a good match to observations of global temperature changes over the last century, but do not simulate all aspects of climate. These models do not unambiguously attribute the warming that occurred from approximately 1910 to 1945 to either natural variation or human effects; however, they suggest that the warming since 1975 is dominated by man-made greenhouse gas emissions.

Global climate model projections of future climate are forced by imposed greenhouse gas emission scenarios, most often from the IPCC Special Report on Emissions Scenarios (SRES). Less commonly, models may also include a simulation of the carbon cycle; this generally shows a positive feedback, though this response is uncertain (under the A2 SRES scenario, responses vary between an extra 20 and 200 ppm of CO2). Some observational studies also show a positive feedback.
The representation of clouds is one of the main sources of uncertainty in present-generation models, though progress is being made on this problem.

2005 wins for science

A Concerned Scientist looks back at some wins for science and and conservation in the assult by ID activists, and big oil's search for big deposits. Sustainable Energy 2005 Round-up:
2005 saw it's drastic ups and downs in gas and energy prices, with the threat of Peak Oil to our economy looming, our energy infrastructure remaining a troublesome national security issue, and evidence abounding for the acceleration of global warming and climate change. But renewable energy has seen great progress this last year as well, with numerous local and state initiatives proposed and implemented (even if Bush continues to stand in the way), further R on improving energy and transportation technologies, and a nascent community of private companies taking steps towards a sustainable future (e.g. GE, BP).

At the top of the list are Governor Schwarzenegger's (R-CA) Million Solar Roofs Initiative, the Northeast's Regional Greenhouse Gas Initiative, and a series of other regional projects encouraging Kyoto-like emissions reduction targets. Given the threat posed by a collapse following contraction of our petroleum-based economy, expanding alternative fuels and energies is a must. Significant obstacles remain, however: most solar panels still require expensive highly purified silicon; wind farms are objected to as unsightly and threaten migratory birds/bats; biofuels would take more energy to produce than they would supply and don't represent a permanent solution to carbon emissions; hydrogen fuel cells still require expensive platinum and other components, and hydrogen production/distribution schemes remain unsatisfactory; nuclear power has gotten safer in the last 30 years, but still has questions of waste disposal that need addressing; and coal does nothing to address carbon emissions, although mercury and other pollutants have been cleaned up substantially.

Still, we must laud the initiatives and projects that've seen notable progress this year, as we head towards Peak Oil.
I would add the growing realisation that GM seeds have lower yields than unmodified seeds to be a win. Modifying seeds genetically so they can help sell more chemical fertiliser (at the expense of the environment) does not deserve to be a sustainable business.