Global Warming over a Century

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• National Climate Data Center

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This time it is globally averaged, but only for one month (AugustGlobal Warming over a Century

). The trend rises very convincingly above the year to year variations, particularly for the ocean. This is because the year to year variations are substantially smaller, about +/- 0.2 °C or +/- 0.4 °F . This global trend is undoubtedly real. However, legitimate questions are

(1) is this the signature of human activities, or is it a natural fluctuation similar to what presumably happened over land between 1940 and 1970?

(2) if this is human induced global warming, is it large enough compared to the year to year fluctuations in particular regions to matter significantly?