= The Goldilocks Planet =
== The four billion year story of earth's climate ==
=== Jan Zalasiewicz & Mark Williams, Central, 551.609 Z22G 2012 ===
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Skimmed.

I looked more closely at the discussion of the Maunder (sunspot) Minimum ( p220-223 ) and "The early Anthropocene hypothesis" ( p232-237 ).  What evidence is available to estimate past climate, particularly temperature?  And where and when?   Calibrated thermometers did not appear until the 1750s, and systematic records until the 1850s in western Europe and the east-coast United States; a very small slice of time and space.

The [[ https://en.wikipedia.org/wiki/Maunder_Minimum | Maunder Minimum ]] from 1645 to 1715 correlates with the ''middle'' of the [[ https://en.wikipedia.org/wiki/Little_Ice_Age | Little Ice Age ]] starting in 1300 to 1550 (disagreement on labeling) and ending around 1850.

The book claims (p221) that increased sunspot activity strengthens the earth's magnetic shield (huh?) which blocks cosmic rays.  Cosmic rays can nucleate water droplets and make clouds ... no sunspots, more clouds.  

 . Or ... more clouds, fewer opportunities to observe and record sunspots?

 . Matthes, K. (2011) [[ http://fulltext.calis.edu.cn/nature/ngeo/4/11/ngeo1298.pdf | Solar cycle and climate predictions. ]] ''Nature Geoscience'' '''4''', 735-6.

 . Ruddiman, W.F. 2003 [[ http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.651.2119&rep=rep1&type=pdf | The anthropogenic Greenhouse Era began thousands of years ago. ]] ''Climate Change'' 61, 261-293. 
 . Ruddiman, W.F. 2007 [[ http://www.whoi.edu/cms/files/ruddiman07revg_69184.pdf | The early anthropogenic hypothesis: challenges and responses. ]] ''Reviews of Geophysics'' 45, RG4001, 1-37.
 . Ruddiman and Ellis, E.C. 2009 [[ http://kbe.prf.jcu.cz/sites/default/files/prednasky/kbe/bgc-uk/esej-9.pdf | Effect of per-capita land-use changes on Holocene forest cleance and CO2 emissions. ]] ''Quaternary Science Reviews'' 28, 3011-15.
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==== Later References ====
 . Stocker, T. (2009) [[ http://epic.awi.de/20641/1/Els2009b.pdf | Stable isotope constraints on Holocene carbon cycle changes from an Antarctic ice core ]] ''Nature'' '''461''' .
 . ... + Ruddiman, W.F. 2013 [[ https://doi.org/10.1146/annurev-earth-050212-123944 | The Anthropocene ]]
 . ... + Ruddiman, W.F. 2011 [[ http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.997.500&rep=rep1&type=pdf | Holocene carbon emissions as a result of anthropogenic land cover change ]]
 . ... + Ruddiman, W.F. 2011 [[ http://www.theorie-de-tout.fr/wp-content/uploads/2017/02/Ruddiman.pdf | Can natural or anthropogenic explanations of late-Holocene CO2 and CH4 increases be falsified? ]]
 . ... + Ruddiman, W.F. 2016 [[ https://ir.library.oregonstate.edu/downloads/td96k7119 | Late Holocene climate: Natural or anthropogenic? ]]
 . ... + Ruddiman, W.F. 2017 [[ https://doi.org/10.1016/j.ancene.2017.11.003 | Geographic evidence of the early anthropogenic hypothesis ]] Anthropocene