Fig. 4 shows monthly averaged changes in NDVI for the
dominant land cover types (36) separated by regions with net
declines in precipitation (Fig. 4 A–C) and regions where precipitation
remained unchanged or increased (Fig. 4 D–F). Of the
tropical evergreen forest, 69.4% (5.4 million km2) recorded
a net decrease in precipitation of, on average, 16.6% (Fig. 4A),
whereas rainfall remained the same or increased across 30.6%
(2.8 million km2) of the area between 2000 and 2012. The
decrease in precipitation accounted for about 55% of the observed
decline in NDVI. Although the size of this decline was
small (0.8%), the implications could be considerable, because
the trend has been observed over 13 y and across an area of 5.4
million km2. For comparison, the estimated 1 billion tons carbon
released during the 2005 drought (8) corresponds to an 8% reduction
of satellite-observed NDVI below the seasonal mean but
only across an area of 0.32 million km2 (19) (Figs. S4 and S5).
Fig. 4 shows monthly averaged changes in NDVI for the
dominant land cover types (36) separated by regions with net
declines in precipitation (Fig. 4 A–C) and regions where precipitation
remained unchanged or increased (Fig. 4 D–F). Of the
tropical evergreen forest, 69.4% (5.4 million km2) recorded
a net decrease in precipitation of, on average, 16.6% (Fig. 4A),
whereas rainfall remained the same or increased across 30.6%
(2.8 million km2) of the area between 2000 and 2012. The
decrease in precipitation accounted for about 55% of the observed
decline in NDVI. Although the size of this decline was
small (0.8%), the implications could be considerable, because
the trend has been observed over 13 y and across an area of 5.4
million km2. For comparison, the estimated 1 billion tons carbon
released during the 2005 drought (8) corresponds to an 8% reduction
of satellite-observed NDVI below the seasonal mean but
only across an area of 0.32 million km2 (19) (Figs. S4 and S5).
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