Test your Comment

I don’t yet know how to enable a Post Preview feature for blog commenters. Also, I haven’t found HTML documentation for users.
This thread is intended as a quick fix: If you’re unsure, test a comment here before you post it at the intended thread. Comments here will be deleted regularly.


9 Responses to Test your Comment

  1. Testing the target=”_blank” thingy:
    test link

  2. Florifulgurator says:

    Four Nuclear Myths: A Commentary on Stewart Brand’s Whole Earth Discipline and on Similar Writings

  3. John Baez says:

    I don’t think there’s a way to preview comments on the free WordPress blogs like yours and mine. If you discover one, let me know!

  4. It’s only after having been convinced that kinetic energy should be positive and -\nabla^2 means ‘energy’ that all these minus signs seem like good ideas.

    Plus, -div being the adjoint of grad, so “\-nabla^2= \nabla^\ast\nabla being the right thing in Hilbert space.

  5. In the third IPCC report, models predicted that by 2050, plants will be drawing down 6 gigatonnes more carbon per year than they do now! The fourth IPCC report was similar.

    That would be a 10% increase! (According to this, global terrestial NPP is 48-69Gt.)

    Currently it looks we can completely forget about this:

    From satellite observations, Zhao & Running (2010) estimate a 0.55 Gt (ca. 1%) decline in global terrestrial NPP from 2000 to 2009. Between 1982 and 1999 the increase was up to 6%.

    Other observations:

    Shilong Piao, Xuhui Wang, Philitppe Ciais, Biao Zhuz, Tao Wang, and Jiu Liu, Changes in satellite-derived vegetation growth trend in temperate and boreal Eurasia from 1982 to 2006, Global Change Biology preview 31 March 2011:

    Abstract (…) although a statistically significant positive trend of average growing season NDVI is observed (0.5 × 10−3 year−1, P= 0.03) during the entire study period, there are two distinct periods with opposite trends in growing season NDVI. Growing season NDVI has first significantly increased from 1982 to 1997 (1.8 × 10−3 year−1, P < 0.001), and then decreased from 1997 to 2006 (−1.3 × 10−3 year−1, P= 0.055). (…)

    MASA Earth Observatory,April 22, 2006: Northern Forest Affected by Global Warming.

    [pretty image] For parts of the region, growth has not changed (gray), but in interior Alaska and a wide swath of Canada, growth has declined (brown). Only in the far north, regions of tundra, has growth increased (green).

    reporting on

    Scott J. Goetz, Andrew G. Bunn, Gregory J. Fiske, R. A. Houghton, Satellite-observed photosynthetic trends across boreal North America associated with climate and fire disturbance, PNAS September 20, 2005 vol. 102

    and in Europe:

    Jofre Carnicera, Marta Colla, Miquel Ninyerolac, Xavier Ponsd, Gerardo Sáncheze, Josep Peñuelasa, Widespread crown condition decline, food web disruption, and amplified tree mortality with increased climate change-type drought, PNAS January 25, 2011 vol. 108

    Abstract. Climate change is progressively increasing severe drought events in the Northern Hemisphere, causing regional tree die-off events and contributing to the global reduction of the carbon sink efficiency of forests. (…) Here we report a generalized increase in crown defoliation in southern European forests occurring during 1987–2007. Forest tree species have consistently and significantly altered their crown leaf structures, with increased percentages of defoliation in the drier parts of their distributions in response to increased water deficit. We assessed (…) Our results reveal a complex geographical mosaic of species-specific responses to climate change–driven drought pressures on the Iberian Peninsula, with an overwhelmingly predominant trend toward increased drought damage.

  6. glacial maximum

    Is climate sensitivity independent of ice albedo etc.? I’d guess it’s smaller during glaciation than without ice caps.

  7. Arrow asks:

    can you prove (…) that the 1000 year record is inconsistent with the hypothesis that 20 century warming was mostly a repeat of MWP

    Proof by reductio ad absurdum: Consider the northernmost commercial vineyards today:

    Eventyrvin and Lerkekåsa Vineyard, Telemark county, Norway. 59°40′N 09°19′E

    L’Esprit d’Edvard Munch, Vestfold county, Norway. 59°25′N 10°25′E

    Blaxsta Vineyard, Södermanland County, Sweden. 59°03′N 16°35′E

    Scholium: 59°N is north of Scotland (Orkney Islands).

    Compare with MWP vineyards. Q.E.D.

  8. As for the vineyards any arguments based on them first have to establish that we are talking about the same grape varieties.

    Usually this subtle detail gets overlooked in the “debate”. I should have added the following 2nd scholium:
    The medieval motivation to produce wine at northern latitudes was its necessity for catholic eucharist where it transubstantiates into the blood of Christ (and not just consubstantiate as in Lutheranism). For this act of metaphysical cannibalism the wine’s taste is unimportant. Today the motivation is pure hedonism and the taste needs to be sufficient to compete with cheap southern imports.

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