High-Resolution Image

The image illustrates the drastic reversal of an increasing trend in biomass burning in just one year, due to a combination of human effort for change and meteorological factors.

The upper left panel shows the slopes of linear fits through six years of seasonal mean aerosol optical depth (AOD) as observed by the Terra-MODIS satellite sensor. The regressions were calculated independently for each 1 degree square. The biomass burning season is defined as August - November. The time series spans 2000-2005. We see that smoke increased over the entire Amazon Basin during this period. These trends are as high as 0.05 to 0.1 AOD per year, which represents an increase in AOD of 0.30 to 0.60 over the six year period.

Then suddenly in 2006 there was much less smoke. The lower left panel shows the difference in the seasonal mean Terra MODIS AOD between 2006 and 2005. Blues indicate that 2006 had less smoke. The panel on the right shows the interannual variability in MODIS AOD averaged over the entire northern part of South America and also the total number of fire counts summed over the season as observed by AVHRR. We note the tight correlation between total number of fires and seasonal/regional mean AOD. We also note the tightly increasing trends upwards in both data sets until observations in 2006 reverse the trend.

Because the smoke was so terrible in 2005 a concerted effort was made by a coalition of governments, scientists and civil authorities in 2006 to monitor burning and mitigate smoke production. Also in 2006 the rains came earlier. The result was dramatic. Smoke from biomass burning is a serious environmental hazard, but unlike earthquakes and severe weather, effective policy can mitigate the severity of the danger to human health, the well-being of the rain forest and the whole climate system.

For more information: Koren, I., L.A. Remer, K. Longo, 2007: Reversal of trend of biomass burning in the Amazon. Geophys. Res. Lett., in press.

(submitted by Lorraine Remer)