The term "climate change" refers to a rise in the average global temperature due to an increase in the concentration of atmospheric greenhouse gases, resulting in numerous climatic shifts and impacts around the globe. The term “global warming” is also used, although it is important to recognize that the increase in temperature is a global average and individual locations will experience varied temperature and precipitation changes.

Several gases, such as carbon dioxide (CO2) and methane (CH4), exist naturally in the atmosphere and contribute to the warming of the Earth's surface by trapping heat from the sun, in what is known as the greenhouse effect. When the proportion of such greenhouse gases in the atmosphere is stable, the effect is beneficial, making surface temperatures warmer and alleviating temperature swings. However, human activity is increasing the concentration of greenhouse gases in the atmosphere, which is already causing average temperatures to rise. Burning fossil fuels in vehicles and power plants emits potent greenhouse gases, including carbon dioxide, methane and nitrous oxide (N2O), among others. In addition, clearing forested land through burning or logging trees also releases CO2 into the atmosphere and contributes to the greenhouse effect.

There is broad scientific consensus that human activities, most notably the burning of fossil fuels for energy, have led to the rapid buildup in atmospheric greenhouse gases. The Intergovernmental Panel on Climate Change (IPCC) stated in 2007 that CO2 levels in the atmosphere rose from a pre-industrial level of 280 parts per million (ppm) to 379 ppm in 2005. This coincided with an increase in the average global temperature of 0.74°C / 1.33°F between 1906 and 2005. In 2013, the U.S. National Oceanic and Atmospheric Administration announced that CO2 levels had hit in 400ppm. That same year, the IPCC concluded, "It is extremely likely [95 percent confidence] that human influence has been the dominant cause of the observed warming since the mid-20th century." In 2012, the World Meteorological Organization (WMO) released its analysis that shows that the decade spanning 2001-2010 was the warmest ever recorded in all continents of the globe.

Impacts from this warming already have been observed and include increases in global average air and ocean temperatures, accelerated melting of snow and sea ice, widespread retreat of glaciers, rising global average sea level, and extensive changes in weather patterns, including changes in precipitation levels and increased storm intensity. And as atmospheric concentrations of CO2 rise, oceans absorb more carbon, causing ocean waters to become acidic. The acidic conditions make it more difficult for calcifying organisms such as corals and crustaceans to form hard shells or skeletons, ultimately affecting the entire marine food chain. Climate change is the greatest environmental threat confronting the world.

There is an urgent need to address climate change, as climate scientists now say that we have a decade or less to begin reducing greenhouse gas emissions to avoid catastrophic changes to the planet. Energy efficiency and renewable energy are the fastest, safest, cleanest, and most cost-effective means of reducing our use of fossil fuels within this diminishing window of time. We can improve the energy efficiency of our buildings, vehicles, communities, and energy generation sector. We can transition to clean renewable energy resources that do not emit new greenhouse gases into the atmosphere. And responsible land management practices can help sequester more carbon in plants and soils. Putting a price on carbon emissions would help promote all of these solutions, by harnessing the power of market forces (private companies and nonprofits would invest in the most cost-effective ways to diminish greenhouse gas emissions).

Ramping up the production and deployment of renewable energy and energy efficiency technologies does not only provide environmental benefits. It will also provide jobs and economic growth while helping to alleviate our nation’s dependence on energy imports, which sends hundreds of billions of dollars out of the country every year.

Although we have already committed ourselves to a certain amount of warming, quick implementation of these solutions will mitigate the impacts of climate change in coming decades.