It’s been almost a week since the publication of Michael L. Mann’s new climate study and everyone has missed the only notable part of it.
Published in the Proceedings of the National Academy of Sciences, the study blames the last 10 years of no-warming on Chinese coal burning. While we don’t know whether that claim has any merit, it is notable that Michael L. Mann and his co-authors began the study’s conclusion as follows:
The finding that the recent hiatus in warming is driven largely by natural factors does not contradict the hypothesis: “most of the observed increase in global average temperature since the mid 20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations (14).”
Note that Michael L. Mann et al. downgraded anthropogenic global warming to a mere “hypothesis.” Further, the footnote for Michael L. Mann’s assertion is as follows:
Houghton J-T, Jenkins G-J, Ephraums J-J, eds. (1990) Climate Change—The IPCC Scientific Assessment. WG1 (Cambridge Univ. Press, Cambridge).
If you don’t recall the IPCC’s First Assessment Report (FAR), it’s the one that presented the below graphs of historical climate showing that any ongoing climate change is not out of the range of natural variability:
Not only did Michael L. Mann opt to cite a document with the graphs above, as opposed to Michael E. Mann’s infamous “hockey stick” study/graph, Michael L. Mann’s downgrading of climate alarmism to a “hypothesis” contrasts sharply with Michael E. Mann’s views as expressed in the Washington Post in October 2010:
Overloading the atmosphere with carbon dioxide from burning fossil fuels is heating the planet, shrinking the Arctic ice cap, melting glaciers and raising sea levels. It is leading to more widespread drought, more frequent heat waves and more powerful hurricanes. Even without my work, or that of the entire sub-field of studying past climates, scientists are in broad agreement on the reality of these changes and their near-certain link to human activity.
That paragraph is, shall we say, inconsistent with “hypothesis.”
No, Boston University’s Michael L. Mann is not the same person as Climategate’s Michael E. Mann. But as long as some “Michael Mann” has taken the debate back to its 1990 status, have another look at those graphs from the FAR. What exactly are we debating anyway?