Ocean warming over last 135 years twice as great as over last 50 years

This new paper just reinforces my view that man-made carbon dioxide is insignificant with regard to climate. But I wonder how this finding is somehow going to be attributed to anthropogenic carbon dioxide.

Painting of HMS Challenger (1858)

Painting of Challenger by William Frederick Mitchell - Wikipedia

A new study combining data from the HMS Challenger (1872 – 1876) with the the modern data set of the Argo Programme shows that ocean warming 135 years ago was significantly faster than that in the last 50 years.

“… the magnitude of the temperature change since the 1870s is twice that observed over the past 50 years. …. This implies that the time scale for the warming of the ocean is not just the last 50 years but at least the last 100 years.”

… the 100-year timescale of ocean warming implies that Earth’s climate system as a whole has been gaining heat for at least that long.

Dean Roemmich, W. John Gould, John Gilson. 135 years of global ocean warming between the Challenger expedition and the Argo ProgrammeNature Climate Change, 2012; DOI: 10.1038/nclimate1461

Summary: The ocean’s dominant role over the atmosphere, land, or cryosphere comes from its high heat capacity and ability to remove heat from the sea surface by currents and mixing. The longest interval over which instrumental records of subsurface global-scale temperature can be compared is the 135 years between the voyage of HMS Challenger (1872–1876) and the modern data set of the Argo Programme(2004–2010). Argo’s unprecedented global coverage permits its comparison with any earlier measurements. This, the first global-scale comparison ofChallenger and modern data, shows spatial mean warming at the surface of 0.59 °C±0.12, consistent with previous estimates of globally averaged sea surface temperature increase. Below the surface the mean warming decreases to 0.39 °C±0.18 at 366 m (200 fathoms) and 0.12 °C±0.07 at 914 m (500 fathoms). The 0.33 °C±0.14 average temperature difference from 0 to 700 m is twice the value observed globally in that depth range over the past 50 years, implying a centennial timescale for the present rate of global warming. Warming in the Atlantic Ocean is stronger than in the Pacific. Systematic errors in the Challenger data mean that these temperature changes are a lower bound on the actual values. This study underlines the scientific significance of the Challenger expedition and the modern Argo Programme and indicates that globally the oceans have been warming at least since the late-nineteenth or early-twentieth century.

And if warming in the last 50 years was just half the rate of warming over the last 100 years it follows that warming in the first 50 years was 3 times greater than the rate in the second 50.


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