Earth to deniers — global warming is caused by human emissions, not solar activity.
The Naval Research Laboratory and NASA report that, “if anything,” the sun contributed “a very slight overall cooling in the past 25 years.” D’oh! The study, “How natural and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006,” finds:
Empirical models that combine natural and anthropogenic influences (at appropriate lags) capture 76% of the variance in the monthly global surface temperature record, suggesting that much of the variability arises from processes that can be identified and their impact on the global surface temperature quantified by direct linear association with the observations.
Natural influences produce as much as 0.2 K warming during major ENSO events, near 0.3 K cooling following large volcanic eruptions and 0.1 K warming near maxima of recent solar cycles. To properly quantify their amplitudes, the natural and anthropogenic changes must be accounted for simultaneously when analyzing the surface temperature anomalies, since neglecting the influence of one can overestimate the influence of another. For this reason, we suggest that estimated solar cycle changes of 0.2 K and Pinatubo cooling of 0.4 K are too large.
None of the natural processes can account for the overall warming trend in global surface temperatures. In the 100 years from 1905 to 2005, the temperature trends produce by all three natural influences are at least an order of magnitude smaller than the observed surface temperature trend reported by IPCC [2007]. According to this analysis, solar forcing contributed negligible long-term warming in the past 25 years and 10% of the warming in the past 100 years…
Here are some excellent visual “reconstructions of the contributions to monthly mean global surface temperatures by individual natural and anthropogenic influences (at appropriate lags) are shown”:
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