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.

There are several gases that exist naturally in the atmosphere and contribute to the warming of the Earth's surface by trapping heat from the sun, also known as the greenhouse effect. However, burning fossil fuels also contributes to the concentration of greenhouse gases, including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), among others. Additionally, clearing forested land through burning or logging trees 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 has coincided with an increase in the average global temperature of 0.74 [±0.18]°C / 1.33 [± 0.32]°F between 1906 and 2005. Furthermore, the IPCC stated that there is very high confidence (or 90 percent certainty) that human activities since 1750 have had a global average net effect of warming the planet. In 2009, the World Meteorological Organization (WMO) released its analysis that projects the decade spanning from 2000 to 2009 to be the warmest on record.

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.

Fortunately, there are ways to reduce our use of fossil fuels. 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. 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.

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