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Basin-scale planning is needed to minimize impacts in mega-diverse rivers

By presenting the most comprehensive GlObal geOreferenced Database of Dams to date containing more than 38,000 dams as well as their associated catchments, we enable new and improved global analyses of the impact of dams on society and environment and the impact of environmental change (for example land use and climate change) on the catchments of dams. This paper presents the development of the global database through systematic digitisation of satellite imagery globally by a small team and highlights the various approaches to bias estimation and to validation of the data. The following datasets are provided (a) raw digitised coordinates for the location of dam walls (that may be useful for example in machine learning approaches to dam identification from imagery), (b) a global vector file of the watershed for each dam.

Growing conditions for crops such as coffee and wine grapes are shifting to track climate change. Research on these crop responses has focused principally on impacts to food production impacts, but evidence is emerging that they may have serious environmental consequences as well. Recent research has documented potential environmental impacts of shifting cropping patterns, including impacts on water, wildlife, pollinator interaction, carbon storage and nature conservation, on national to global scales. Multiple crops will be moving in response to shifting climatic suitability, and the cumulative environmental effects of these multi-crop shifts at global scales is not known. Here we model for the first time multiple major global commodity crop suitability changes due to climate change, to estimate the impacts of new crop suitability on water, biodiversity and carbon storage. Areas that become newly suitable for one or more crops are Climate-driven Agricultural Frontiers. These frontiers cover an area equivalent to over 30% of the current agricultural land on the planet and have major potential impacts on biodiversity in tropical mountains, on water resources downstream and on carbon storage in high latitude lands. Frontier soils contain up to 177 Gt of C, which might be subject to release, which is the equivalent of over a century of current United States CO 2 emissions. Watersheds serving over 1.8 billion people would be impacted by the cultivation of the climate-driven frontiers. Frontiers intersect 19 global biodiversity hotspots and the habitat of 20% of all global restricted range birds. Sound planning and management of climate-driven agricultural frontiers can therefore help reduce globally significant impacts on people, ecosystems and the climate system.

1. Protected areas, although often terrestrially focused and less frequently designed to protect freshwater resources, can be extremely important for conserving freshwater biodiversity and supporting human water security necessary for people to survive and thrive.2. This study measured the quantity of water that is being provided by protected areas to areas downstream, and how threatened protected areas are in terms of their water provision.3. Building on a Freshwater Provision Index, the numbers of people who live downstream from these protected areas around the world were then assessed. The same process was applied to areas where there are no protected areas.4. Protected areas deliver 20% of the global total of approximately 40 000 km 3 year À1 of continental runoff. More than one-quarter of water provisions supplied by the world's protected areas are exposed to low levels of threat and less than 10% are exposed to high levels of threat; this is compared with higher levels of threat for provisions from non-protected areas, where nearly one quarter of the provisions are exposed to high threat and only 10% are exposed to low threat. 5. Nearly two-thirds of the global population is living downstream of the world's protected areas as potential users of freshwater provisions supplied by these areas. Despite the overall large volume of low-threat water supplied by protected areas, globally 80% of the downstream human community users receive water from upstream protected areas under high threat, and no continent has less than 59% of its downstream users receiving water from upstream protected areas under high threat.6. Globally, increased attention to reduce the threats to fresh water in areas under protection, as well as designation and management of additional areas, are needed to safeguard freshwater flows, and support biodiversity conservation and the provision of freshwater ecosystem services.

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