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PRESS OFFICE
PRESS RELEASE
Osvaldo Sala, a professor at Brown University, alerts to the biodiversity losses the
Earth will suffer to the year 2100, at a lecture given in the BBVA Foundation
Mediterranean biodiversity is the most
gravely imperiled
March 6, 2008. Osvaldo Sala, Full Professor of Biology at Brown University (United States)
and a lead author of the Millennium Ecosystem Assessment – a report drafted by 1,360
experts from 95 countries at the request of the United Nations Environment Program –
explains his latest research findings on the future of the Earth’s biodiversity at a talk in
the BBVA Foundation, focusing on the scale of the changes that ecosystems will suffer
to the year 2100.
Sala’s research starts by identifying the five most important determinants of changes in
biodiversity at the global scale: changes in land use, atmospheric CO2 concentration,
nitrogen deposition and acid rain, climate, and biotic exchanges (deliberate or
accidental introduction of plants and animals to an ecosystem).
Having identified these drivers, the next step is to utilize a scenario generated by global
models of climate, vegetation and land use to estimate the change in magnitude of
the drivers of biodiversity change for each biome up to the year 2100. These expected
changes can then be ranked on a scale from 1 to 5, in ascending order from small to
large.
Table 1. Expected changes for the year 2100 in the five major drivers of biodiversity change (land
use, atmospheric composition CO2, nitrogen deposition, climate and biotic exchange) for the
principal terrestrial biomes (arctic tundra, alpine tundra, boreal forest, grasslands, savannas,
Mediterranean ecosystems, deserts, northern temperate forests, southern temperate forests, and
tropical forests).
The model projects that land-use change could cause mass extinctions of fauna and
flora this century in the tropical forests and in the temperate forests of South America,
but have far fewer deleterious effects in arctic and alpine zones (where human
population density probably will remain low) and northern temperate forests (where
reforestation is expected to exceed deforestation).
The extent of habitat modification is projected to be modest in desert and boreal forest
and intermediate in savannas, grasslands, and Mediterranean ecosystems.
Atmospheric CO2 mixes globally each year, so the assumption used is that all biomes
will experience the same change in CO2 concentration. Nitrogen deposition is largest in
the northern temperate zone near cities and is smallest in biomes such as the arctic
and southern temperate forests, which generally are distant from sources of pollution.
Climate, meantime, is expected to warm most dramatically at high latitudes (arctic
and boreal zones), to change least in the tropics, and to show intermediate changes in
other biomes.
The pattern of biotic exchange reflects the pattern of human activity. Remote areas
with little human intervention receive fewer exotic species than areas that are in the
middle of trade routes or that host intense human activity. With globalization,
involuntary introductions of species may take on a greater role.
Future scenarios
Land-use change is the most severe driver of changes in biodiversity. For example,
conversion of temperate grasslands into croplands or tropical forests into grasslands
results in local extinction of most plant species and the associated animals whose
habitat is largely determined by plant species composition. Below- ground organisms
are also affected most severely by land-use change.
Scientific scenarios to the year 2100 suggest that between 12% and 15% of plant
species will disappear from the face of the planet due to the combined action of the
five global change drivers. And the situation is even worse for the Mediterranean, the
world’s most vulnerable area, with between 20% and 25% of plant species threatened
with extinction.
For further information, contact the
BBVA Foundation Press Office (+34 91 537 6615 /+34 94 487 4627)
Si desea más información, puede ponerse en contacto con el Departamento de
Comunicación de la Fundación BBVA (91537 66 15 y 94 487 46 27)
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