Actualité scientifique
Scientific news
© IRD / Pierre Laboute
© IRD / Marie-Noëlle Favier
The loss of biodiversity will
continue in the 21st
Century. Global-scale
extinctions will increase
strongly, the average
species abundance1 will
decline and their
distribution will be
disturbed. Scientists
thought until recently that
the complexity of
biodiversity made it
unfeasible to predict future
trends. Now, however, like
the climatologists, life
science specialists are
able to predict future
situations. A group of
international experts2,
including several IRD
researchers, have just
published a compilation of
global-scale quantitative
scenarios depicting
possible changes in
biodiversity. In spite of a
degree of uncertainty in
the models elaborated, the
possible trends converge.
If the processes of human
and economic
development do not
change radically, the Earth
is heading for disaster.
With changes in land use,
in climate and
overexploitation of natural
resources, humans
activities are central to the
major threats to
biodiversity. The scenarios
developed nevertheless
point to possible lines of
action.
© IRD / Toma Diagne
Octobre 2010
What future for biodiversity?
Scenarios for action.
© IRD / Sylvain Petek
N° 358
Actualidad cientifica
Scenarios for future tends in biodiversity indicate that during the 21st Century biological richness will remain threatened and many species will be destined for
extinction. The leatherback turtle, the whale shark, dugongs and wild giraffes of West Africa are already on the IUCN (International union for Conservation of Nature)
Red list of threatened species.
Like their counterparts in the IPCC (Intergovernmental Panel on Climate Change) on the future
climate, life sciences specialists can now attempt to
predict changes in the biodiversity. For that domain,
the future is scarcely any brighter. Biological diversity
will continue to decline throughout the 21st Century.
A group of international experts2, including several
IRD scientists, recently published a summary compilation of model scenarios depicting the worldwide
scale changes and developments in biodiversity. All
the predictions point to the same conclusion:
increase in the number of global extinctions, a fall in
the abundance of species and substantial changes
in their distribution.
Biodiversity in crisis
Even the most optimistic scenarios predict the
decline, even the extinction, of many species over
the next century. Most plants and animals will be
subject to regression of their distribution area or
abundance. The research team announces, for
example, that the overall abundance of terrestrial
species could diminish from 10 to 20% during the
first half of the century. In the “biodiversity crisis”, it
is a change in composition of communities more
than the disappearance of species which will be the
most critical factor for humans.
Causes and consequences
The main factors behind loss of biodiversity are the
degradation and destruction of natural habitats,
climate change and overexploitation of biological
resources. Changes in land use, brought on for
instance by urbanization or the conversion of equatorial forest into pasture and arable land, is therefore
the principal threat to biodiversity. It affects firstly the
countries of the South, such as Central and
Southern Africa, the Atlantic areas of South America
and part of South-East Asia. Climate change is also
severely upsetting habitats and disturbing ecosys-
For further information
tems. It leads for example to invasion of Arctic
tundra by boreal forest, which is shifting towards the
Poles as the climate warms up. Other threats are
acidification of oceans, rise in sea level and pollution
which alter the coral reefs and destroy a significant
number of coastal ecosystems. Overfishing leads to
a decline in the top predators, such as tuna and
shark, thereby completely disturbing the marine
food chain.
The resulting loss of biodiversity can have strong
effects on human well-being and development. For
example, irreversible degradation of littoral habitats
exposes coasts to heightening risk of damage from
waves and storm surges and loss of fishing productivity. Projections indicate that most factors behind
erosion of diversity will persist and that climate
change will amplify this trend over the next century
Real progress is possible
The research team never theless shows that
means for controlling the decline exist. Limiting
deforestation can help counter the trend. The
researchers forecast that, depending on the
measures taken now, in the most advantageous
cases, there will be an overall world increase in
forest cover between now and 2030 of about
15%, amounting to 10 million km², equivalent to the
surface area of Canada or China. Conversely, the
worst scenario indicates a reduction by over 10% of
the surface area of des forests.
Increasing the efficiency of agriculture, reducing
greenhouse gas emissions, large-scale reforestation, reinforcement of fishing regulations, creation
of both terrestrial and marine nature reserves, are
all measures that could also enable humans to
lessen their impact on the biodiversity.
Contacts
Thierry OBERDORFF,
director of research at the IRD
Tel: 33 (0)1 40 79 37 67
thierry.oberdorff@ird.fr
UMR Biologie des Organismes et
Ecosystèmes Aquatiques – BOREA
(IRD / MNHN/ CNRS/ UPMC)
Address
Muséum national d’histoire naturelle
43 rue Cuvier
75005 PARIS, France
These optimistic scenarios strive to remain coherent
with the economic constraints and populations’ use
of resources. Nevertheless, they indicate an imperative for radical changes in the present mode of
development. In line with this, biodiversity specialists
can now make predictions available to political decision-makers. Like the IPCC, an Intergovernmental
Platform on Biodiversity and Ecosystem Services
(IPBES) is being formed. At national level, a wideranging programme was initiated in July 2010 aiming
to continue the research and refine the models by
the Fondation pour la recherche sur la biodiversité3,
of which the IRD is founder member.
Paul LEADLEY,
Professor at Université Paris-Sud
Tel: 01 69 15 72 22
paul.leadley@u-psud.fr
UMR Ecologie, systématique
et évolution (Paris-Sud/CNRS/
AgroParisTech)
Address
Laboratoire d’écologie, systématique
et évolution
Bâtiment 362
Université Paris-Sud 11
91405 ORSAY Cedex, France
Reference
Pereira H.M., Leadley P. et al.,
Scenarios for Global Biodiversity in the
21st Century, Sciencexpress,
26 Octobre 2010.
DOI: 10.1126/science.1196624
Copy editor – Gaëlle Courcoux - DIC, IRD
Translation – Nicholas FLAY
Key words
Biodiversity, extinction, scenarios
1. Number of individuals of a species per unit of surface area or volume.
2. These investigations were conducted by DIVERSITAS (international research programme on biodiversity) and the United Nations
Environment Programme World Conservation Monitoring Centre for the Secretariat of the Convention on Biological Diversity. This
summary was carried out by research scientists from the Université Paris-Sud, the Universidade de Lisboa and Universidade de
Évora au Portugal, the IRD, the Departamento de Biodiversidad y Biología Evolutiva in Madrid, Spain, from the Netherlands
Environmental Assessment Agency, the PNUE-WCMC, Imperial College London and the University of East Anglia in the United
Kingdom, Stockholm University in Sweden, the Universidad Nacional Autónoma de México in Mexico, University of Maryland, the
Hawaii Pacific University, from the Joint Global Change Research Institute, The Nature Conservancy and from the Pew Environment
Group in the United States, the Secretariat of the Convention on Biological Diversity and the University of British Columbia, Canada
and CSIR Natural Resources and Environment in South Africa.
Coordination
Gaëlle Courcoux
Délégation à l’information
et à la communication
Tel.: +33 (0)4 91 99 94 90
Fax: +33 (0)4 91 99 92 28
fichesactu@ird.fr
3. http://www.fondationbiodiversite.fr/
Press office
Vincent Coronini
+33 (0)4 91 99 94 87
presse@ird.fr
Conversion of equatorial forest into pasture and arable land destroys the natural habitat of numerous species and is one of the principal threats to
biodiversity.
© IRD / Bernard Osès
© IRD / Daniel Sabatier
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