There is an article in the March 2012 issue of the IGBP Newletter
Fragkias, F. and K.C. Seto, 2012: The rise and rise of urban expansion Urban land area has expanded globally during the past few decades – a trend that looks set to continue in the foreseeable future. IGBP Newsletter, 78. March 2012
that documents the dynamic character of urbanization. This land use change not only affects local and regional climate, but also results in a time varying effect on surface temperatures that have been used by the IPCC and others as the iconic metric of global warming. As we reported on in
Montandon, L.M., S. Fall, R.A. Pielke Sr., and D. Niyogi, 2011: Distribution of landscape types in the Global Historical Climatology Network. Earth Interactions, 15:6, doi: 10.1175/2010EI371
GHCNv.2 station locations are biased toward urban and cropland (>50% stations versus 18.4% of the world’s land) and past century reclaimed cropland areas (35% stations versus 3.4% land).
This bias is only going to increase in coming years as urban areas continue to expand.
The press release on the article has the title
Cities expand by area equal to France, Germany and Spain combined in less than 20 years
Text in the press release includes [highlight added]
Unless development patterns change, by 2030 humanity’s urban footprint will occupy an additional 1.5 million square kilometres – comparable to the combined territories of France, Germany and Spain, say experts at a major international science meeting underway in London.
UN estimates show human population growing from 7 billion today to 9 billion by 2050, translating into some 1 million more people expected on average each week for the next 38 years, with most of that increase anticipated in urban centres. And ongoing migration from rural to urban living could see world cities receive yet another 1 billion additional people. Total forecast urban population in 2050: 6.3 billion (up from 3.5 billion today).
Fragkias [Dr. Michail Fragkias of Arizona State University] notes that while there were fewer than 20 cities of 1 million or more a century ago, there are 450 today. While urban areas cover less than five per cent of Earth’s land surface, “the enlarged urban footprint forecast is far more significant proportionally when vast uninhabitable polar, desert and mountain regions, the world breadbasket plains and other prime agricultural land and protected areas are subtracted from the calculation.”
This article provides support for a statement in an earlier chapter of this IGBP Newsletter
Syvitski, J. 2012: An epoch of our makng. IGBP Newletter. 78. March 2012.
which highlights that with respect to the human role on the environment (including climate ) that
“….the Anthropocene isn’t as well known as global warming, which two out of three people had heard of by 2008, according to a Gallop Poll (http://www.gallup.com/ poll/117772/Awareness-Opinions-Global-Warming-Vary-Worldwide.aspx). But the former is a more effective paradigm in describing the cumulative impact of civilisation, making global warming and its consequences but one of many ways in which humans have modified the Earth. Narrow focus on global warming might suggest that we simply need to stop emitting greenhouse gases and use renewable energy to abate the planet’s pressures. The human footprint is much larger than that.
This is the viewpoint that we presented in our article
Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell, W. Rossow, J. Schaake, J. Smith, S. Sorooshian, and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union.
The new IPCC reprts should heed this growing call for a broader, more complete assessment of threats to the enviroment and society, rather than their scientifically flawed focus on the radiative effects of CO2 and a few other greenhouse gases.
Climate Science: Roger Pielke Sr. 
