New Paper on the Role of Land Use on Climate

A July 2006 Geophysical Research Letters (GRL) paper has appeared entitled “Changes in moisture and energy fluxes due to agricultural land use and irrigation in the Indian Monsoon Belt” by Douglas, Ellen M.; Niyogi, Dev; Frolking, S.; Yeluripati, J. B.; Pielke, Roger A., Sr.; Niyogi, Nivedita; Vörösmarty, C. J.; Mohanty, U. C.

The abstract reads,

“We present a conceptual synthesis of the impact that agricultural activity in India can have on land-atmosphere interactions through irrigation. We illustrate a “bottom upâ€? approach to evaluate the effects of land use change on both physical processes and human vulnerability. We compared vapor fluxes (estimated evaporation and transpiration) from a pre-agricultural and a contemporary land cover and found that mean annual vapor fluxes have increased by 17% (340 km3) with a 7% increase (117 km3) in the wet season and a 55% increase (223 km3) in the dry season. Two thirds of this increase was attributed to irrigation, with groundwater-based irrigation contributing 14% and 35% of the vapor fluxes in the wet and dry seasons, respectively. The area averaged change in latent heat flux across India was estimated to be 9 Wm−2. The largest increases occurred where both cropland and irrigated lands were the predominant contemporary land uses. ”

In the conclusion we state,

” The potential implications of flux changes reported in this study are consistent with the interpretation from similar work in other regions of the world [e.g., Marshall et al., 2004; Adegoke et al., 2003]. In addition to alterations in the surface heat and moisture fluxes due to regional land-scape change, the spatial heterogeneity of such a change also influences rainfall patterns [e.g., Segal et al., 1989; Lohar and Pal, 1995; Pielke, 2001]. These flux and rainfall alterations, when they cover a large enough area, can result in teleconnection effects which influence monsoon and global circulations [e.g., Fu et al., 2004; Chase et al., 2003].

Following the vulnerability paradigm used to assess risks associated with environmental/societal resources [Kabat et al., 2004; Pielke et al., 2006], we identified linkages and interactions with economic, societal and water resource factors that need to be investigated in more detail in future work. With this ‘‘bottom up’’ approach, the threats to a resource are identified such that procedures can be developed to reduce the risk to both natural and human systems that depend on them.”

The previous IPCC reports did not adequately address this issue in the past. Climate Science recommends that they include this perspective as a starting point in the IPCC report that is under development.

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Filed under Climate Change Forcings & Feedbacks, Vulnerability Paradigm

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