Pursuant to the story on sugarcane cooling the local climate, here are two posts from Dr. Roger Pielke Senior that show the effects of land use change in other venues.
There is an excellent powerpoint presentation by Dev Niyogi of Purdue University at the 15th Annual LCLUC Science Team Meeting, March 28-30th 2011 at the University of Maryland. It is
The question he poses is
“Is there a detectable relation between LULCC as a driver for weather and climate change – and what is needed to understand this further?
The entire set of viewgraphs is a valuable addition to our understanding of the role of land cover/land use change [LCLUC] within the climate system. Dev’s insightful conclusions from his talk are:
- LULCC has a profound impact on the regional‐scale surface energy and water balance and where it has been intensive.
- Growing detectable evidence about weather and climatic feedbacks and possible teleconnections associated with LULCC.
- The LULCC impact is likely on a par with other major global forcings but unlike warming seen from GHG emissions , LULCC forcing is multi directional and can warm/ cool, cause positive/negative feedbacks depending on the region and timing.
- The fact that the impact of LULCC is small with respect to the global average radiative forcing, with the exception of emissions of CO2, is, however, not a relevant metric as the essential resources of food, water, energy, human health and ecosystem function respond to regional and local climate not to a global average.
Without a complete assessment of the role of LULCC on climate, an incomplete understanding of the of humans in the climate system will persist.”
The abstract reads [boldface added]
“Albedo is an important factor affecting global climate, but uncertainty in the sources and magnitudes of albedo change has led to simplistic treatments of albedo in climate models. Here, the authors examine nine years (2000–08) of historical 1-km Moderate Resolution Imaging Spectroradiometer (MODIS) albedo estimates across South America to advance understanding of the magnitude and sources of large-scale albedo changes. The authors use the magnitude of albedo change from the arc of deforestation along the southeastern edge of the Brazilian Amazon (+2.8%) as a benchmark for comparison. Large albedo increases (>+2.8%) were 2.2 times more prevalent than similar decreases throughout South America. Changes in surface water drove most large albedo changes that were not caused by vegetative cover change. Decreased surface water in the Santa Fe and Buenos Aires regions of Argentina was responsible for albedo increases exceeding that of the arc of deforestation in magnitude and extent. Although variations in the natural flooding regimes were likely the dominant mechanism driving changes in surface water, it is possible that human manipulations through dams and other agriculture infrastructure contributed. This study demonstrates the substantial role that land-cover and surface water change can play in continental-scale albedo trends and suggests ways to better incorporate these processes into global climate models.”
This study supports our findings of a significant human effect on weather and climate through land use change in South America in our paper
Beltran-Przekurat, A., R.A. Pielke Sr., J.L. Eastman, and M.B. Coughenour, 2011: Modeling the effects of land-use/land-cover changes on the near-surface atmosphere in southern South America. Int. J. Climatol., accepted.
The abstract reads
GEMRAMS, a coupled atmospheric-biospheric model comprised of the Regional Atmospheric Modeling System and the General Energy and Mass Transport Model, was used to evaluate potential effects of land-use/land-cover changes (LULCC) on near-surface atmosphere over a southern South American domain. Several spring-early summer simulations were conducted using different land-cover scenarios representing current, natural, and afforestation conditions for this region for three periods, associated with El Niño- Southern Oscillation (ENSO) conditions. Changes in surface fluxes and the associated effects on near-surface temperature were spatially heterogeneous: different vegetation changes led to different effects. These changes were also associated with the seasonality of the vegetation. Conversion from grass to agriculture led to cooler, wetter near-surface atmospheric conditions. Warmer temperatures resulted from the conversion ofwooded grasslands or forest to agriculture. Afforestation resulted overall in cooler temperatures. For both LULCC scenarios the direction of the energy fluxes and temperature changes remained in general the same in two extreme ENSO years, although for some vegetation conversions the signal reversed direction. Overall, the impacts were enhanced during a dry year, i.e., 1999-2000, but the response also depended on the vegetation types involved in the conversion. The effects on precipitation were insignificant in the agriculture-conversion scenario. In simulated austral summer precipitation, the afforested scenario generated average increases of 1 mm day−1. The impacts were relatively higher for a “dry year”.
The Loarie et al 2011 study also provides support for the importance of dams and their effect on evaporation and transpiration from adjacent landscapes on local and regional climate that we reported on in
Hossain, F., I. Jeyachandran, and R.A. Pielke Sr., 2010: Dam safety effects due to human alteration of extreme precipitation. Water Resources Research, 46, W03301, doi:10.1029/2009WR007704.
Degu, A. M., F. Hossain, D. Niyogi, R. Pielke Sr., J. M. Shepherd, N. Voisin, and T. Chronis, 2011: The influence of large dams on surrounding climate and precipitation patterns. Geophys. Res. Lett., 38, L04405, doi:10.1029/2010GL046482.
The Loarie et al paper is also interesting as one of the authors, Chris Field, is a Co-Chair of Working Group II of the current IPCC assessment. In this position, he should be introducing the need for a broader perspective on the role of humans within the climate system. Unfortunately, however, this perspective needs to be also in Working Group I’s report since that is the foundation for the other IPCC reports.