Glossary of Climate Change

Adaptation - in the climate change context, adaptation implies an adjustment in natural or human systems in response to a changing/changed climate.
Additionality - in the context of a project funded by carbon offsets, the additionality is the reduction in greenhouse gas emissions that is in addition to what would have resulted in the absence of the carbon offset funding.
Albedo - An index of the "reflectiveness" - a way of quantifying how much radiation is reflected back, as opposed to that absorbed. Low albedo ~0 absorb most of the radiation and high ~1 reflect it.
Anoxic event - a period when the Earth's oceans are free of oxygen below the surface layer.
Antarctic oscillation (AAO) - a low-frequency mode of atmospheric variability of the southern hemisphere.
Anthropogenic - literally, man-made.
Anthropogenic climate change - climate change with the presumption of human influence, usually warming.
Anthropogenic global warming (AGW) – global warming with the presumption of human influence.
Anti-greenhouse effect - the cooling effect an atmosphere has on the ambient temperature of the planet.
Arctic amplification - The effect of sea ice melting replace high albedo ice with low albedo sea that absorb the radiation from the sun get warmer and melt more ice.
Arctic oscillation (AO) - the dominant pattern of non-seasonal sea-level pressure (SLP) variations north of 20 degrees N, and it is characterized by SLP anomalies of one sign in the Arctic and anomalies of opposite sign centered about 37-45 degrees N. See also NAO.
Arctic shrinkage - the marked decrease in Arctic sea ice and the observed melting of the Greenland Ice Sheet in recent years.
Atlantic Multidecadal Oscillation (AMO) - a hypothesised mode of natural variability occurring in the North Atlantic Ocean and which has its principle expression in the sea surface temperature (SST) field.
Atmospheric sciences - an umbrella term for the study of the atmosphere, its processes, the effects other systems have on the atmosphere, and the effects of the atmosphere on these other systems.
Atmospheric window - refers to those parts of the electromagnetic spectrum that are, with the Earth's atmosphere in its natural state, not absorbed at all.
Attribution of recent climate change - the study of the causes of climate change.