cbd-ts-66-en

Part I: Impacts of Climate-related Geoengineering on Biological Diversity
3.2.2 Projected impacts of climate change on terrestrial ecosystems
The geographical locations where greatest terrestrial biodiversity change might be expected has been assessed using
multi-model ensembles and IPCC SRES A2 and B1 emission scenarios to predict the appearance or disappearance
of new and existing climatic conditions (Figure 3.5).122 The A2 scenario indicates that, by 2100, 12–39% of the
Earth’s land surface will experience “novel” climatic conditions (where the 21st century climate does not overlap
with 20th century climate); in addition, 10–48% will experience disappearing climatic conditions (where the 20th
century climate does not overlap with the 21st century climate).
Figure 3.5: Novel and disappearing terrestrial climatic conditions by 2100
Model projections of novel (upper) and disappearing (lower) terrestrial climatic conditions by 2100. Left-hand maps: based
on A2 emission scenario; right-hand maps: based on B1 emission scenario. Novel climatic conditions are projected to develop
primarily in the tropics and subtropics. Disappearing climatic conditions are concentrated in tropical montane regions and
the poleward parts of continents. Scale shows relative change, with greatest impact at the yellow/red end of the spectrum.
Montane habitats (e.g., cloud forests, alpine ecosystems) and endemic species (e.g. on actual islands or “stranded”
species) have also been identified123 as being particularly vulnerable because of their narrow geographic and
climatic ranges, and hence limited—or non-existent—dispersal opportunities. Other terrestrial and coastal habitats
considered to be at high risk include tundra ecosystems, tropical forests and mangroves. For coastal habitats, rising
sea level will be an additional environmental stress.
122 Williams et al. (2007).
123 Secretariat of the Convention on Biological Diversity (2009a).
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