Premium
vertical patterns of free and forced climate variations
Author(s) -
Vinnikov Konstantin Ya.,
Robock Alan,
Stouffer Ronald J.,
Manabe Syukuro
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl01736
Subject(s) - troposphere , stratosphere , environmental science , atmospheric sciences , climatology , atmosphere (unit) , climate model , greenhouse gas , forcing (mathematics) , climate change , meteorology , geology , geography , oceanography
Observations of the vertical structure of atmospheric temperature changes over the past three decades show that while the global‐average lower atmosphere has warmed, the upper troposphere and lower stratosphere have cooled. While these changes may be due to observed anthropogenic increases of greenhouse gases, decreases of lower stratospheric ozone, and increases of tropospheric aerosols, the changes may also have been caused by natural unforced internal fluctuations of the climate system. Here we use the results of a 1000‐year simulation from a mathematical model of the coupled ocean‐atmosphere‐land system performed without any changes in external forcing, so that we may consider its variations as a surrogate for free, internally‐generated, natural fluctuations of the climate system. When the global mean surface air temperature is warm in the model, the lower troposphere, upper troposphere and lower stratosphere are also warm over most of the Earth, in contrast to the observations of the last three decades and to model simulations of the forced climate response due to increased greenhouse gases. The observed temperature change of the past three decades is therefore unlikely to have been caused solely by natural internal variations of the climate system, thereby strengthening the argument that these changes can at least partly be attributed to anthropogenic activities.