On any timescale, global climate can be seen to be continuously varying, never dwelling long at any one value and frequently crossing the mean, thereby further rendering the definition of climate as a long-term mean unworkable when considering the history of changes in the Earth system. However, over some timespans, such as the past million years and over the interval between 80,000 and 10,000 years ago, the variations of climate remain within a "corridor" of values, indicating that the climate system is not completely non-stationary, in the sense of having continuously varying statistical properties. Variations in climate influence many other aspects of the Earth system, including atmospheric composition, the hydrological cycle, and marine and terrestrial biology. Records of these changes are preserved in natural archives; variations in atmospheric composition are recorded by air trapped in bubbles in the slowly accumulating ice sheets, changes in the hydrological cycles are recorded by lake shorelines or fluvial deposits, while changes in vegetation cover are recorded through pollen and plant macrofossils trapped in anoxic lake or bog sediments. Provided that such records can be unambiguously dated, they can be used as "sensors" of climate and environmental change. Since environmental conditions change as climate changes, it is unsurprising that a large number of environmental archives show similar scales and types of variability.
|Title of host publication||The Future of the World's Climate|
|Editors||Ann Henderson, Kendal McGuffie|
|Place of Publication||Amsterdam; Oxford|
|Number of pages||34|
|Publication status||Published - 2012|