Energy efficiency can reduce CO2 emissions at a net profit
Most people are familiar with compact fluorescent lightbulbs (CFL’s), which use one-third or less of the electricity of a conventional incandescent bulb of the same brightness. Although a CFL costs more to buy, it lasts longer; that, combined with the electricity savings, actually make it cheaper in the long run. The electricity savings means CFL’s also reduce the need to burn fossil fuels and thus the carbon emissions that are making global temperatures rise.
A recent report lists a wide variety of other efficiencies, including improvements to heating and cooling systems, vehicles and appliances, as well as industry, that could similarly save money (or cost very little) and reduce emissions.[[McKinsey & Company. “Pathways to a Low-Carbon Economy : Version 2 of the Global Greenhouse Gas Abatement Cost Curve.” 2009.]] According to this study, such measures could produce about 30% of the emissions reductions needed by 2030 to keep global temperature rise to no more than 2°F above today's levels , an increase scientists and governments widely regard as dangerous to exceed. Other studies have found similar results.[[S.Nadel, A. Shipley, R.N. Elliott, “The Technical, Economic and Achievable Potential for Energy-Efficiency in the U.S. – A Meta-Analysis of Recent Studies,” (PDF) Proceedings of the 2004 ACEEE Summer Study on Energy Efficiency in Buildings.]]
Impacts that already have been observed range from sea level rise to heat waves to drought and more, and scientists project effects will multiply and intensify with continued temperature increases, especially above this threshold.