Net loss of biomass predicted for tropical biomes in a changing climate

Tropical ecosystems store over half of the world’s aboveground live carbon
as biomass, and water availability plays a key role in its distribution.
Although precipitation and temperature are shifting across the tropics,
their effect on biomass and carbon storage remains uncertain. Here we use
empirical relationships between climate and aboveground biomass content to
show that the contraction of humid regions, and expansion of those with
intense dry periods, results in substantial carbon loss from the
neotropics. Under a low emission scenario (RCP4.5) this could cause a
~14.4–23.9 Pg C (6.8–12%) net reduction of aboveground live carbon from
1950–2100. Under a high emissions scenario (RCP8.5), net carbon losses
could double across the tropics ~28.2–39.7 Pg C (13.3–20.1%). The
contraction of humid regions in South America accounts for ~40% of this
change. Climate mitigation strategies could prevent half of the carbon
losses and help maintain the natural tropical net carbon sink.