A New Paper On The Role Of Agriculture Within The Climate System

One of the several excellent papers in the special issue of Global and Planetary Change on land use/land cover change and impact on climate is

Navin Ramankutty, Christine Delire and Peter Snyder, 2006: “Feedbacks between agriculture and climate: An illustration of the potential unintended consequences of human land use activities”. Global and Planetary Change – Land-use/land-cover change and its impact on climate, 79-93

The abstract reads,

“Agriculture has significantly transformed the face of the planet. In particular, croplands have replaced natural vegetation over large areas of the global land surface, covering around 18 million km2 of the land surface today. To grow crops, humans have taken advantage of the resource provided by climate — optimum temperature and precipitation. However, the clearing of land for establishing croplands might have resulted in an inadvertent change in the climate. This feedback might, in turn, have altered the suitability of land for growing crops. In this sensitivity study, we used a combination of land cover data sets, numerical models, and cropland suitability analysis, to estimate the degree to which the replacement of natural vegetation by croplands might have altered the land suitability for cultivation. We found that the global changes in cropland suitability are likely to have been fairly small, however large regional changes in cropland suitability might have occurred. Our theoretical study showed that major changes in suitability occurred in Canada, Eastern Europe, the Former Soviet Union, northern India, and China. Although the magnitude, sign, and spatial patterns of change indicated by this study may be an artifact of our particular model and experimental design, our study is illustrative of the potential inadvertent consequences of human activities on the land. Moreover, it offers a methodology for evaluating how climate changes due to human activities on the land may alter the multiple services offered by ecosystems to human beings.”

The paper concludes that,

“This study also provides a different perspective for evaluating climate change. Traditionally, climate and climate change has been viewed froma purely biophysical perspective, i.e., variables such as temperature, precipitation, humidity, wind speeds, etc., and many derived diagnostic thereof (Houghton et al., 2001). However, evaluating climate and its change, as relevant to human societies, needs to be critically tied to the concept of the “ecosystem servicesâ€? (Daily et al., 1997). In this study, we offer the concept of “land suitability for cultivationâ€? as one such measure of climate, as it is relevant to the global food production system. We have used change in this suitability index, rather than climatic variables such as temperature and precipitation, to measure how human modifications of the landscape, mediated through climate– vegetation interactions, may potentially affect human food production capacities.”

This paper illustrates further why landscape change and vegetation dynamics must be included in any assessment of the role of human- and natural caused climate variability and change.

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Filed under Climate Change Forcings & Feedbacks, Vulnerability Paradigm

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