Climate change and how we respond to it is the defining challenge of our generation. Greenhouse gases are the major cause of the Earth's warming and of climate change. Carbon dioxide CO2 is the most common and the most significant of the greenhouse gases generated by humans.

The amount of CO2 in the atmosphere rose from around 275 parts per million to 300 ppm with the industrial revolution, is now at 385 ppm and is currently increasing at about 2 ppm annually. If we can get it back to 350 ppm, where it was in 1988, then we can probably expect to have a climate resembling our own and avert catastrophe. Some scientists are aiming for even lower concentrations.

How do we immediately and dramatically reduce CO2 emissions? Turn off the coal plants. Approximately 50 percent of the power — but 81 percent of the CO2 generated by the production of electrical energy — comes from coal-fired plants. We must immediately stop construction of all new conventional coal plants and phase out all existing plants by 2030. (Current "clean" coal plants capture particulates, but do not reduce CO2.)

The two sides of the strategy that can be employed to deal with this reduction in energy production are:

1) replace the production with other means (e.g. solar, wind, tri-generation) and,

2) use less energy.

A lot of debate is raging around the former, recently defined by Al Gore, but let's consider the latter.

How do we best address using less energy? Because 76 percent of all electricity generated by power plants is used to operate buildings, energy efficiency in buildings is a very good way to offset this decrease in electrical production. In response to this, a local architect, Ed Mazria, has issued the 2030 Challenge. The 2030 Challenge calls for all new buildings to be built to use half the fossil-fuel energy that that building type would typically consume, starting immediately. It also calls for an equal amount of existing building area to be renovated annually to cut its individual fossil fuel usage in half.

The fossil fuel reduction in new and renovated buildings is then to be increased to
60 percent in 2010; 70 percent in 2015; 80 percent in 2020; 90 percent in 2025; and they are to be "carbon neutral" in 2030. The 2030 Challenge allows the use of renewable energy technologies for up to 20 percent, the rest being achieved through design. At our current rate of construction and renovation, this country's building stock will be 75 percent new or remodeled between now and 2030.

The reductions in energy use can be achieved largely through building shape, orientation and insulation, using natural heating, cooling, daylighting and ventilation — all straightforward design strategies that are being successfully implemented in cutting edge buildings today.

The city of Santa Fe is reviewing a new energy code, co-authored by the Santa Fe Area Homebuilders Association, that should be in place by the end of the year. It will require a Home Energy Rating System (HERS) score of 70, which is within 3 percent of meeting the 2030 Challenge's 50 percent reduction. It will make our city one of the top leaders in the country in moving decisively to get the atmosphere's CO2 concentration back to 350 ppm.

This is a very exciting time to be alive, to try and understand how we as a species are contributing to climate change, and to learn how to all work together to meet this challenge.

The 2030 Challenge is presented in great detail at www.architecture2030.org.

Danny Buck is a local green builder, a SFAHBA board member and a trustee on its Green Building Council.