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The IPBES Global Assessment: five things we learnt about freshwater ecosystems

May 10, 2019
The critically endangered Panamanian golden frog (Atelopus zeteki). More than 40% of global amphibian species are at risk of extinction. Image: Brian Gratwicke | Flickr Creative Commons

A landmark global report summarised earlier this week suggests that around 1 million animal and plant species are threatened with extinction. For many species, extinction could occur within decades. The global rate of species extinction is already at least tens to hundreds of times higher than the average rate over the past 10 million years and is accelerating, the report states.

The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) Global Assessment Report on Biodiversity and Ecosystem Services outlines the state of knowledge regarding the planet’s ecosystems and the contributions they make to people.

Compiled by 145 expert authors from 50 countries over the past three years, with inputs from another 310 contributing authors, the Report assesses changes to biodiversity and ecosystems over the past five decades.

“The overwhelming evidence of the IPBES Global Assessment, from a wide range of different fields of knowledge, presents an ominous picture,” said IPBES Chair, Sir Robert Watson. “The health of ecosystems on which we and all other species depend is deteriorating more rapidly than ever. We are eroding the very foundations of our economies, livelihoods, food security, health and quality of life worldwide.”

“The Report also tells us that it is not too late to make a difference, but only if we start now at every level from local to global,” he said. “Through ‘transformative change’, nature can still be conserved, restored and used sustainably – this is also key to meeting most other global goals. By transformative change, we mean a fundamental, system-wide reorganization across technological, economic and social factors, including paradigms, goals and values.”

A wetland ecosystem in North Carolina, USA. More than 85% of wetlands present in 1700 had been lost by 2000 according to the IPBES Global Assessment. Image: Jim Liestman | Flickr Creative Commons

Based on the review of around 15,000 scientific and government sources, the IPBES Report also draws on indigenous and local knowledge. It outlines the relationships between economic development pathways and their impacts on nature, and offers a range of possible scenarios for the coming decades.

“Ecosystems, species, wild populations, local varieties and breeds of domesticated plants and animals are shrinking, deteriorating or vanishing. The essential, interconnected web of life on Earth is getting smaller and increasingly frayed,” said Assessment co-chair Prof. Josef Settele from the Helmholtz-Centre for Environmental Research (UFZ). “This loss is a direct result of human activity and constitutes a direct threat to human well-being in all regions of the world.”

What does the IPBES Report tell us about the state of global freshwater environments?

Drivers of ecosystem decline assessed in the IPBES Global Assessment. Image: IPBES

1. Land use change is the key driver of freshwater ecosystem decline

The IPBES Report ranks the five key drivers of freshwater ecosystem decline and biodiversity loss. The drivers are, in descending order: (1) changes in land use; (2) direct exploitation of organisms; (3) climate change; (4) pollution and (5) invasive alien species.

Agriculture is a key part of this picture: more than a third of the world’s land surface, and nearly 75% of freshwater resources, are now devoted to crop or livestock production. Agriculture can have numerous impacts on freshwater ecosystems, including fertiliser and pesticide pollution, habitat loss, water extraction, and alterations to waterways themselves.

The IPBES Report notes that greenhouse gas emissions have doubled since 1980, raising average global temperatures by at least 0.7 degrees Celsius. Climate change is predicted to be an increasingly powerful driver of ecosystem change and biodiversity loss in coming decades: shifting species distributions, changing phenology, altering population dynamics and the composition of species assemblages, as well as interacting with other drivers such as land use change.

2. Aquatic pollution is significant and widespread

Water pollution is one of the five key drivers of freshwater ecosystem degradation. Excessive or inappropriate application of agricultural fertilisers can lead to run off from fields entering freshwater and coastal ecosystems. Such pollution has caused more than 400 hypoxic ‘dead’ zones in coastal and transitional waters globally since 2008, affecting a total area of more than 245,000 km2 – an area larger than the United Kingdom.

The IPBES Report suggests that more than 80% of global wastewater is discharged untreated into the environment, causing nutrients, chemicals, bacteria, microplastics and many other pollutants to enter waterways. Such pollution ‘cocktails’ can have numerous, long-lasting effects on both human and non-human life.

Globally, plastic pollution has increased ten-fold since 1980. In freshwaters, ongoing research is showing how both plastics, and the microplastics they break down into, can have significant effects on aquatic life. A startling 300-400 million tons of heavy metals, solvents, toxic sludge and other wastes from industrial facilities are dumped annually into the world’s waters.

3. Wetlands are being lost at alarming rate

The IPBES Report states that indicators suggest that global ecosystem extent and condition has decreased, on average, by 47% compared to estimated ‘natural’ baselines. Many global ecosystems continue to decline in extent and condition by at least 4% per decade. It is estimated that ecological and evolutionary processes still operate with minimal human intervention in only around a quarter of terrestrial and freshwater ecosystems.

Wetlands are disappearing across the world at an alarming rate, the IPBES Report suggests. More than 85% of wetlands present in 1700 had been lost by 2000. The loss of global wetlands (0.8% per year between 1970 to 2008) is currently three times faster, in percentage terms, than global forest loss. Wetlands are extremely valuable ecosystems, not only providing habitat for both resident and migratory species, but also providing services such as water filtration and flood buffering to humans.

Extinction rates across species groups assessed in the IPBES Global Assessment. Image: IPBES

4. Amphibians are particularly threatened with extinction

The IPBES Report states that, on average, 25% of species across terrestrial, freshwater and marine vertebrate, invertebrate and plant groups that have been studied in sufficient detail are threatened with extinction.

Amphibians are particularly threatened, with more than 40% of amphibian species – many of which rely on freshwater ecosystems – at risk of extinction globally. Amphibian species across the world are impacted by habitat loss, climate change, and the the spread of the deadly fungal disease chytridiomycosis. A 2011 study in Nature suggests that areas of greatest amphibian species richness are often the same areas subject to the greatest combined threat of habitat loss and climate change.

Environmental governance approaches advocated by the IPBES Global Assessment. Image: IPBES

5. Governance options exist to protect and restore freshwater ecosystems

The IPBES Report emphasises the role of unsustainable human activities in driving global biodiversity loss, and highlights the need for widespread political and economic change to safeguard the future of life on Earth.

Freshwater systems are given significant attention, with the IPBES Report authors emphasising that sustaining freshwater in the context of climate change, rising demand for water extraction and increased levels of pollution requires significant cross-sectoral policy interventions.

Key policy priorities including: more inclusive water governance for collaborative water management; better integration of water resource management and landscape planning across scales; promoting practices to reduce soil erosion, sedimentation and pollution run-off; increasing water storage; promoting investment in water projects with clear sustainability criteria; and addressing the fragmentation of many freshwater policies.

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Read the IPBES Global Assessment Summary for Policymakers

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