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Three Decades of Vegetation Change in Northeastern Brazil

Paper Reviewed
Erasmi, S., Schucknecht, A., Barbosa, M.P. and Matschullat, J. 2014. Vegetation greenness in northeastern Brazil and its relation to ENSO warm events. Remote Sensing 6: 3041-3058.

In prefacing their work, Erasmi et al. (2014) write that "one of the key indicators to evaluate the existence of alterations in vegetation productivity is the trend in long-term vegetation greenness," and they state that "against the widespread assumption from fieldwork and modelling," several studies have "explicitly reported a 'greening' of semi-arid regions worldwide." Focusing on northeastern Brazil (approximately 34-39°W, 1-19°S), a region characterized by a semi-arid climate and considered to be "at risk of desertification processes and loss of biodiversity," Erasmi et al. set out to determine whether or not a similar unexpected greening has occurred there recently. In order to accomplish this objective, the team of researchers analyzed 29 years of Normalized Difference Vegetation Index (NDVI) data from Advanced Very High Resolution Radiometers on-board orbiting satellites. Specifically, they set out to answer the question "of whether land degradation (browning) or rather greening can be observed for the period 1982 to 2010 and [to] further investigate if such vegetation trends can be explained by long-term climate trends."

Long-term inter-annual statistical analyses of annual summed NDVI values revealed both increasing and decreasing regions, yet "browning is the inferior process, covering only 18% of the area," whereas "the remaining 82% show long-term vegetation greening." With respect to the cause of the trends, the authors report they can only "partly be explained by climatological drivers" and that "land-use and land-cover change remain key drivers for small-scale degradation in the study area."

Two potential contributing factors to the observed greening trend that were not mentioned are the aerial fertilization effect and the transpiration-reducing effect of the 8% increase in the air's CO2 concentration that was experienced over the study period. Whatever the cause, however, one thing is for sure, against the widespread assumption of climate alarmists, the vegetative productivity in northeastern Brazil has increased notwithstanding increasing concentrations of atmospheric CO2 and global warming, the "twin evils" of the extreme environmental movement. How could they get things so backwards?

Posted 31 December 2014