Climate Change Issues

While the phrase "climate change" only refers to differences that continue for a longer length of time, generally decades or more, climate variability covers all fluctuations in the climate that last longer than individual weather occurrences. Although the word "climate change" can relate to any period in Earth's history, it is currently most often used to refer to current climate change. The impact of human activity on the climate has increased since the Industrial Revolution. The sun supplies almost all of the energy that the climate system needs, and it also radiates energy into space. Earth's energy budget is determined by the equilibrium of incoming and outgoing energy as well as the flow of energy through the climate system. Earth's energy budget is balanced when incoming energy exceeds outgoing energy. If more energy is lost, Earth cools and the energy budget is negative. Weather is a manifestation of the energy flowing through the Earth's climate system, and it varies through time and space. A region's climate is made up of its long-term averages and weather variability. When natural processes intrinsic to the many components of the climate system modify the distribution of energy, this is known as "internal variability," and it can cause such shifts. The Pacific decadal oscillation and the Atlantic multidecadal oscillation are two examples of variability in ocean basins. External forcing, or changes in the climate system caused by factors outside the system's components, can also cause climate variability. Volcanism and variations in solar output are two examples.