For current and future climatological effects of human influences, see global warming. For the study of climate change articles pdf climate change, see paleoclimatology. For temperatures on the longest time scales, see geologic temperature record.
Climate change may refer to a change in average weather conditions, or in the time variation of weather within the context of longer-term average conditions. Climate change is caused by factors such as biotic processes, variations in solar radiation received by Earth, plate tectonics, and volcanic eruptions. Certain human activities have been identified as primary causes of ongoing climate change, often referred to as global warming. Scientists actively work to understand past and future climate by using observations and theoretical models.
A climate record—extending deep into the Earth’s past—has been assembled, and continues to be built up, based on geological evidence from borehole temperature profiles, cores removed from deep accumulations of ice, floral and faunal records, glacial and periglacial processes, stable-isotope and other analyses of sediment layers, and records of past sea levels. More recent data are provided by the instrumental record. General circulation models, based on the physical sciences, are often used in theoretical approaches to match past climate data, make future projections, and link causes and effects in climate change. Accordingly, fluctuations over periods shorter than a few decades, such as El Niño, do not represent climate change.
Anthropogenic climate change is caused by human activity, as opposed to changes in climate that may have resulted as part of Earth’s natural processes. In this sense, especially in the context of environmental policy, the term climate change has become synonymous with anthropogenic global warming. Within scientific journals, global warming refers to surface temperature increases while climate change includes global warming and everything else that increasing greenhouse gas levels affect.
A related term is “climatic change”. 10 years, regardless of cause. When it was realized that human activities had a potential to drastically alter the climate, the term climate change replaced climatic change as the dominant term to reflect an anthropogenic cause. Climate change, used as a noun, became an issue rather than the technical description of changing weather.
On the broadest scale, the rate at which energy is received from the Sun and the rate at which it is lost to space determine the equilibrium temperature and climate of Earth. This energy is distributed around the globe by winds, ocean currents, and other mechanisms to affect the climates of different regions.
Factors that can shape climate are called climate forcings or “forcing mechanisms”. These include processes such as variations in solar radiation, variations in the Earth’s orbit, variations in the albedo or reflectivity of the continents, atmosphere, and oceans, mountain-building and continental drift and changes in greenhouse gas concentrations.