Global Freshwater Crisis

Freshwater systems around the globe are currently experiencing various levels of stress due to human activities such that nearly 80% of the world’s population is currently vulnerable to water scarcity and associated aquatic biodiversity is threatened. Vörösmarty et al. (2010) studied and mapped 23 stressors that threaten water quality and availability as well as aquatic biodiversity. The stressors were grouped into 4 categories:

Expert opinion was used to calculate the weights of each stressor, capturing differences between human water security and aquatic biodiversity.

Vörösmarty et al. (2010) summarized the combined effects of the stressors in a map characterizing the overall threat to both human water security and biodiversity. This overall threat could be offset by an “investment benefit factor” representing possible technological mitigation. However, despite the explicit goals of the Millenium assessment, the lack of major policy and financial commitments has contributed to the continued scarcity of basic sanitation services particularly in poor countries.

Poor countries are not the only areas under threat. Regions of the world with intensive agriculture and dense human centers, such as the United States and Europe, experience some of the highest threat level to both human water security and aquatic biodiversity. Croplands are one of the dominant stressors to aquatic systems due to the transport of excess fertilizers and pesticides to the river networks by surface runoff.

The authors intended to quantify the effects of the stressors on aquatic biodiversity (per se), but the paucity of global biodiversity data made it difficult to accurately represent these effects. The authors emphasized the need for better habitat monitoring and species inventories to help elucidate these stressor-biodiversity connections. The impacts are not inconsequential, with other studies estimating that 10,000 to 20,000 freshwater species are either extinct or at risk. Engineered impoundments and flow restriction present one of the greatest threats to biodiversity despite the fact that dam operations and rules could be changed to maintain economic benefits while protecting aquatic biodiversity.

The authors argue that financial investments in integrated management strategies are urgently needed to prevent further declines in water security and aquatic biodiversity around the world. The authors are part of the Earth System Science Partnership (ESSP), in particular representing the Global Water System Project and DIVERSITAS-freshwaterBIODIVERSITY.  DIVERSITAS is one of the scientific consortia supporting the creation of an International science policy platform on Biodiversity and Ecosystem Services (IPBES) that, if it was approved by the UN general assembly, could provide a scientifically sound, uniform and consistent framework for tackling changes to biodiversity and ecosystem services, the equivalent of the IPCC for climate change science.

References:

M.A. Palmer. 2010. Water resources: Beyond infrastructure. Nature 467:534-535. (30 Sep. 2010) (link)

C. J. Vörösmarty, P. B. McIntyre, M. O. Gessner, D. Dudgeon, A. Prusevich, P. Green, S. Glidden, S. E. Bunn, C. A. Sullivan, C. Reidy Liermann & P. M. Davies. 2010. Global threats to human water security and river biodiversity. Nature 467: 555-561. (30 Sep. 2010) (link)

Other links:

DIVERSITAS, IPBES

Co-author:  Wendy Peterman