Millennium Ecosystem Assessment- Research Needs

Millennium Ecosystem Assessment- Research Needs - POLICY...

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www.sciencemag.org SCIENCE VOL 314 13 OCTOBER 2006 257 POLICY FORUM T he Millennium Ecosystem Assessment (MA) was designed to meet the needs of decision-makers for scientific infor- mation on the consequences of ecosystem change for human well-being ( 1 3 ). Even though the intended audience is deci- sion-makers, the scientific com- munity is involved as assessments are being made, especially when research and data gaps become apparent. Here we summa- rize the most important information needs encountered in the MA work. Basic Theory We lack a robust theoretical basis for linking ecological diversity to ecosystem dynamics and, in turn, to ecosystem services underlying human well-being. We all need this informa- tion to understand the limits and consequences of biodiversity loss and the actions needed to maintain or restore ecosystem functions. The most catastrophic changes in eco- system services identified in the MA involved nonlinear or abrupt shifts. We lack the ability to pre- dict thresholds for such changes, whether or not a change may be reversible, and how individuals and societies will respond. Thus, the risks of ecosystem catastrophes are poorly quantified. Major ecosystem degradation tends to occur as syn- dromes of simultaneous failure in multiple services. For example, the populous dry lands of the world are facing a combination of fail- ing crops and grazing, declining quality and quantity of fresh water, and loss of tree cover. Similarly, many rivers and lakes have experi- enced increases in nutrient pollution (eutro- phication), toxicity, and biodiversity loss. Relations between ecosystem services and human well-being are poorly understood. One gap relates to the consequences of changes in ecosystem services for poverty reduction. The poor are most dependent on ecosystem serv- ices and vulnerable to their degradation. Empirical studies are needed. Local to Global Scales Local processes sometimes spread to become important regionally or globally, but ecosys- tem services at more aggregated scales are sel- dom simple summations of the services at finer scales. An example of a cross-scale effect is the loss of buffering coastal ecosystems that exposed extensive regions to catastrophic damage in the 2004 Asian tsunami and the 2005 Gulf of Mexico hurricanes. Conversely, most services are delivered at the local scale, but their supply is influenced by regional or global-scale processes (see figure). Although there are many case studies, our capability of predicting emergence of cross-scale effects and their impacts on ecosystem services is lim- ited. A related problem is the mismatch be- tween the scales at which natural and human systems organize. These lead to failures in feedback, when, for instance, benefits accrue at one scale, but costs are carried at another. We need robust, manageable frameworks for
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Millennium Ecosystem Assessment- Research Needs - POLICY...

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