New Computer Fund

Saturday, September 7, 2013

Land Modification Impact on Global Climate

For those of you that like to play amateur climate scientist at home while waiting on some serious college football action to begin, here is a neat little "global" analysis you can do in a few minutes during commercials.  Using the ERSSTv3 data you can compare the northern and southern hemispheres with and without land.  LO is the Land and Oceans monthly data and O is the Oceans only monthly data.  N and S are the hemispheres north and south using the 0 to 90 data sets that are easily download.  If there is no land modification impact, there would be no significant change in the LO-O for Land and Ocean (LO) temperature imbalance or differential between hemispheres and O, Ocean only temperature differential during the instrumental period.  On the right axis scale, the differential increases from approximately -0.2 in late 1800s and near 1960 to approximately 0.1 C during 2000 to 2010.  There is an approximately 0.3 C impact which would produce between 0.15C and 0.3C "Global" impact depending on choice of data set, smoothing and start-end dates.  There is no way to separate out glacial melt from UHI to agriculture, but there is a significant impact due to some modification of land area.

When I was playing around with the Houghton Land-use carbon estimate which I had inverted just for grins, I noticed the odd shape of the curve in the above chart.  The "Green Revolution" started in roughly 1960,

"Green Revolution refers to a series of research, development, and technology transfer initiatives, occurring between the 1940s and the late 1960s, that increased agriculture production worldwide, particularly in the developing world, beginning most markedly in the late 1960s.[1] The initiatives, led by Norman Borlaug, the "Father of the Green Revolution" credited with saving over a billion people from starvation, involved the development of high-yielding varieties of cereal grains, expansion of irrigation infrastructure, modernization of management techniques, distribution of hybridized seeds, synthetic fertilizers, and pesticides to farmers."

The correlation between the green revolution and the land modification impact on global climate is at least interesting except for the most devoted minions of the Great and Powerful Carbon.  The is other land use data available, but the data is very coarse, just decade averages in most cases.  I may see if I can add some of that during half time.

UPDATE:  Since many seem to be in love with the Berkley Earth Surface Temperature data here is a comparison of the BEST NH land only with the ERSST3 Northern Oceans 20N-90N which shows more variation than the full hemisphere data.

As you can see the land temperatures started gaining on the SST during the "cooling" or flat period that was supposedly due to northern hemisphere aerosol forcing.  The dust and black carbon portion of the aerosols plus the expansion of farm lands, massive airport build outs and hydro projects would have had some impact on land temperatures with less on ocean temperatures. 

Just to show how baseline dependent BEST is, this chart uses Tmax and Tmin with the 2000-2012 baseline and produces a new Tave.

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