- Projections of global change impacts on biodiversity show continuing and, in many cases, accelerating species extinctions, loss of natural habitat and changes in the distribution and abundance of species over the 21st century.
This is one of the key conclusions from the third Global Biodiversity Outlook report recently published by Diversitas and UNEP World Conservation Monitoring Centre.
Combined changes in land use, exploitation of forests and marine resources, rising atmospheric CO2 concentrations, climate change and eutrophication are all expected to cause significant changes in the distribution and abundance of species, species groups and biomes.
In particular, pressures on the global environment are increasing the risk of crossing tipping points in which ecosystems change rapidly from one state to another with devastating consequences for biodiversity.
Centre researcher Oonsie Biggs, who previously has shown how early warning indicators of regime shifts can turn things back from the brink, contributed to the report with examples of potential regime shifts that may occur if tipping points are exceeded. One example is the Miombo woodland in south-central Africa.
- Besides well-known regime shifts such as lake eutrophication, interactions between land use and climate change will potentially shift the large areas of the Miombo woodland to agricultural land, with substantial consequences for biodiversity and carbon sequestration. Once converted, restoration is extremely difficult at large scales, she says.
Hard to predict, control and reverse
The report warns that thresholds, amplifying feedbacks and time-lag effects leading to tipping points are widespread and will make the impacts of biodiversity hard to predict, control and revert once they begin.
The report also warns that that rising atmospheric CO2 concentrations and climate change could lead to major biodiversity transformations at levels near or below the 2 degrees Celsius limit defined by IPCC as “dangerous".
- Widespread coral reef degradation, large shifts in marine plankton community structure especially in the Arctic ocean, extensive invasion of tundra by boreal forest, destruction of many coastal ecosystems etc., are projected to occur and will be essentially irreversible over the next several centuries, the report states.
What to do
Despite the grim outlook, the report also offers some modest ground for optimism if action is taken on all levels. The bad news is considered the good news as the opportunities for conserving biodiversity are greater than previously expected.
- Strong and urgent action at international, national and local levels could significantly reduce or reverse some of the many undesirable and dangerous transformations, the report says.
International regulation of fishing in non-territorial waters and improved governance at local to global scales are key to avoiding widespread modifications of marine food chains and collapse of important fisheries.
Improved natural resource protection, with or without active community participation, is one of the most effective means of biodiversity conservation provided the protected areas are properly respected.
Similarly, improved ecosystem-based management approaches can contribute to climate change mitigation and adaptation and to sustainable development more broadly.
Source: Leadley, P., H.M. Pereira, R. Alkemade, J.F. Fernandez-Manjarrés, V. Proença, J.P.W. Scharlemann, M.J. Walpole, et al. 2010. Biodiversity Scenarios: Projections of 21st century change in biodiversity and associated ecosystem services. 132 pp. Convention on Biological Diversity, Montreal, Canada. ISBN 92-9225-219-4.
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