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New research provides an improved understanding of the causes of historical changes in climate and increases confidence in model simulations of continued global warming over the 21st century.
Satellite observations and computer simulations are important tools for understanding past changes in Earth's climate and for projecting future changes.
However,
satellite observations consistently show less warming than climate model simulations from 1979 to the present, especially in the tropical troposphere (the lowest ~15km of Earth's atmosphere). This difference has raised concerns that
models may overstate future temperature changes.
Rather than being an indicator of fundamental model errors, the model-satellite difference can largely be explained by natural fluctuations in Earth's climate and imperfections in climate-model forcing agents, according to new research by
Lawrence Livermore National Laboratory (LLNL) scientists.
"Natural climate variability appears to have partly masked warming over the satellite era," said Stephen Po-Chedley, a LLNL climate scientist and lead author of a paper appearing in the
Proceedings of the National Academy of Sciences.
The results of the study provide an improved understanding of the causes of historical changes in climate and increase confidence in model simulations of continued global warming over the 21st century.
"Although the Earth is warming as a result of human emissions of carbon dioxide, natural variations in the Earth's climate can temporarily accelerate or diminish this overall warming trend," noted Zachary Labe, a co-author from Princeton University and the National Oceanic and Atmospheric Administration's
Geophysical Fluid Dynamics Laboratory. In addition to modulating the rate of warming, natural fluctuations in climate such as the Interdecadal Pacific Oscillation also produce unique patterns of regional surface temperature change.
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