Trimming energy waste could provide a third of the CO2 cuts many experts say are needed by mid-century

 A recent McKinsey & Company study[[McKinsey & Company. “Pathways to a Low-Carbon Economy: Version 2 of the Global Greenhouse Gas Abatement Cost Curve.” 2009]] is just one of many showing how much CO2 emissions could be reduced by improved energy efficiency. By 2030, it says, those improvements could get us about 30% of the way to reductions that would keep temperatures below what many scientists consider the global warming danger threshold — about a 2°F increase from today’s global average. Other studies get different numbers over different time periods — the International Energy Agency, estimates a 36% contribution by 2050.[[ International Energy Agency. “Energy Technology Perspectives 2008, Scenarios and Stratagies, IEA Publications Bookshop.”]] Additionally, emissions reductions that come from improved efficiency often work out to save money on the whole.

Efficiency works to reduce greenhouse pollution by allowing us to get more of what we want (light, heat, transportation, etc.) from each unit of energy consumed, so we can reduce the amount of fossil fuels we burn.  Most of the ongoing increase in atmospheric CO2 comes from burning fossil fuels. Without action to limit emissions, average global temperature is expected to rise about 7°F over pre-industrial levels by the end of the century. Warming has already led to a wide range of impacts, from sea level rise to heat waves to drought and more, and scientists project the effects will multiply with continued temperature increases.