Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Review Article
  • Published:

Towards a comprehensive river barrier mapping solution to support environmental management

Nature Water volume 3, pages 38–48 (2025)Cite this article

Subjects

Abstract

The environmental effects of large dams on river connectivity are well recognized and mapped globally. However, datasets describing the distribution and attributes of smaller barriers (such as weirs and culverts) are lacking or incomplete for many regions. This has hindered accurate impact assessments for water resource planning, biased understanding of restoration potential and limited research aiming to understand and mitigate river fragmentation effects. Developing an efficient method to accurately record river barriers, including small ones, has become a priority. We critically examine barrier mapping approaches, from field survey to automated detection, showcasing recent approaches to recording, counting and classifying river barriers. We demonstrate how incomplete barrier databases, particularly those lacking many small barriers, provide a flawed basis for water management and ecological restoration planning. We discuss the efficiency and accuracy of alternative barrier mapping approaches, highlight future priorities and emphasize harmonizing barrier assessment methods to generate reliable, freely available information for effective basin-level management.

Access through your institution
Buy or subscribe

This is a preview of subscription content, access via your institution

Access options

Access through your institution

Buy this article

  • Purchase on SpringerLink
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Different types of river barrier.
Fig. 2: Framework for river barrier detection and the evolution of a suite of detection methods.

Similar content being viewed by others

References

  1. Reid, A. J. et al. Emerging threats and persistent conservation challenges for freshwater biodiversity. Biol. Rev. 94, 849–873 (2019).

    Article  PubMed  Google Scholar 

  2. Brauns, M. et al. A global synthesis of human impacts on the multifunctionality of streams and rivers. Glob. Change Biol. 28, 4783–4793 (2022).

    Article  CAS  Google Scholar 

  3. Wohl, E. et al. The natural sediment regime in rivers: broadening the foundation for ecosystem management. Bioscience 65, 358–371 (2015).

    Article  Google Scholar 

  4. Wohl, E. et al. The natural wood regime in rivers. Bioscience 69, 259–273 (2019).

    Article  Google Scholar 

  5. Poff, N. L. et al. The natural flow regime. Bioscience 47, 769–784 (1997).

    Article  Google Scholar 

  6. Tonkin, J. D. et al. The role of dispersal in river network metacommunities: patterns, processes, and pathways. Freshwat. Biol. 63, 141–163 (2018).

    Article  Google Scholar 

  7. Spinti, R. A., Condon, L. E. & Zhang, J. The evolution of dam induced river fragmentation in the United States. Nat. Commun. 14, 3820 (2023).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Hughes, K. et al. The World’s Forgotten Fishes (WWF, 2021); https://wwf.panda.org/discover/our_focus/freshwater_practice/the_world_s_forgotten_fishes

  9. He, F. et al. Hydropower impacts on riverine biodiversity. Nat. Rev. Earth Environ. https://doi.org/10.1038/s43017-024-00596-0 (2024).

    Article  Google Scholar 

  10. Grill, G. et al. Mapping the world’s free-flowing rivers. Nature 569, 215–221 (2019).

    Article  CAS  PubMed  Google Scholar 

  11. Barbarossa, V. et al. Impacts of current and future large dams on the geographic range connectivity of freshwater fish worldwide. Proc. Natl Acad. Sci. USA 117, 3648–3655 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  12. Caldas, B. et al. Identifying the current and future status of freshwater connectivity corridors in the Amazon Basin. Conserv. Sci. Pract. 5, e12853 (2023).

    Article  Google Scholar 

  13. Garcia de Leaniz, C. & O’Hanley, J. R. Operational methods for prioritizing the removal of river barriers: synthesis and guidance. Sci. Total Environ. 848, 157471 (2022).

    Article  CAS  PubMed  Google Scholar 

  14. Januchowski-Hartley, S. R. et al. Restoring aquatic ecosystem connectivity requires expanding inventories of both dams and road crossings. Front. Ecol. Environ. 11, 211–217 (2013).

    Article  Google Scholar 

  15. Couto, T. B. A. & Olden, J. D. Global proliferation of small hydropower plants – science and policy. Front. Ecol. Environ. 16, 91–100 (2018).

    Article  Google Scholar 

  16. Belletti, B. et al. More than one million barriers fragment Europe’s rivers. Nature 588, 436–441 (2020).

    Article  CAS  PubMed  Google Scholar 

  17. Anderson, D., Moggridge, H., Warren, P. & Shucksmith, J. The impacts of ‘run-of-river’ hydropower on the physical and ecological condition of rivers. Water Environ. J. 29, 268–276 (2015).

    Article  Google Scholar 

  18. Fantin-Cruz, I. et al. Further development of small hydropower facilities will significantly reduce sediment transport to the Pantanal wetland of Brazil. Front. Environ. Sci. 8, 577748 (2020).

    Article  Google Scholar 

  19. Abbott, K. M., Zaidel, P. A., Roy, A. H., Houle, K. M. & Nislow, K. H. Investigating impacts of small dams and dam removal on dissolved oxygen in streams. PLoS ONE 17, e0277647 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  20. da Cruz, R. F. et al. Water quality impacts of small hydroelectric power plants in a tributary to the Pantanal floodplain, Brazil. River Res. Appl. 37, 448–461 (2021).

    Article  Google Scholar 

  21. Macedo, M. N. et al. Land-use-driven stream warming in southeastern Amazonia. Phil. Trans. R. Soc. B 368, 20120153 (2013).

    Article  PubMed  PubMed Central  Google Scholar 

  22. Zaidel, P. A. et al. Impacts of small dams on stream temperature. Ecol. Indic. 120, 106878 (2021).

    Article  Google Scholar 

  23. Arroita, M. et al. Water abstraction impacts stream ecosystem functioning via wetted‐channel contraction. Freshwat. Biol. 62, 243–257 (2017).

    Article  CAS  Google Scholar 

  24. Couto, T. B. A. et al. Effects of small hydropower dams on macroinvertebrate and fish assemblages in southern Brazil. Freshwat. Biol. 68, 956–971 (2023).

    Article  Google Scholar 

  25. Lessard, J. L. & Hayes, D. B. Effects of elevated water temperature on fish and macroinvertebrate communities below small dams. River Res. Appl. 19, 721–732 (2003).

    Article  Google Scholar 

  26. Sun, J., Galib, S. M. & Lucas, M. C. Are national barrier inventories fit for stream connectivity restoration needs? A test of two catchments. Water Environ. J. 34, 791–803 (2020).

    Article  Google Scholar 

  27. Sun, J. et al. Convolutional neural networks facilitate river barrier detection and evidence severe habitat fragmentation in the Mekong River biodiversity hotspot. Water Resour. Res. 60, e2022WR034375 (2024).

    Article  Google Scholar 

  28. Couto, T. B. A., Messager, M. L. & Olden, J. D. Safeguarding migratory fish via strategic planning of future small hydropower in Brazil. Nat. Sustain. 4, 409–416 (2021).

    Article  Google Scholar 

  29. Engel, F. et al. Phytoplankton gross primary production increases along cascading impoundments in a temperate, low-discharge river: insights from high frequency water quality monitoring. Sci. Rep. 9, 6701 (2019).

    Article  PubMed  PubMed Central  Google Scholar 

  30. Jones, P. E. et al. Selective effects of small barriers on river‐resident fish. J. Appl. Ecol. 58, 1487–1498 (2021).

    Article  Google Scholar 

  31. Morden, R., Horne, A., Bond, N. R., Nathan, R. & Olden, J. D. Small artificial impoundments have big implications for hydrology and freshwater biodiversity. Front. Ecol. Environ. 20, 141–146 (2022).

    Article  Google Scholar 

  32. Sun, J. et al. River fragmentation and barrier impacts on fishes have been greatly underestimated in the upper Mekong River. J. Environ. Manage. 327, 116817 (2023).

    Article  PubMed  Google Scholar 

  33. Zarfl, C., Lumsdon, A. E., Berlekamp, J., Tydecks, L. & Tockner, K. A global boom in hydropower dam construction. Aquat. Sci. 77, 161–170 (2015).

    Article  Google Scholar 

  34. Yu, Y. et al. Transboundary cooperation in infrastructure operation generates economic and environmental co-benefits in the Lancang-Mekong River Basin. Nat. Water 2, 589–601 (2024).

    Article  Google Scholar 

  35. Lehner, B. et al. High‐resolution mapping of the world’s reservoirs and dams for sustainable river‐flow management. Front. Ecol. Environ. 9, 494–502 (2011).

    Article  Google Scholar 

  36. Birnie-Gauvin, K., Tummers, J. S., Lucas, M. C. & Aarestrup, K. Adaptive management in the context of barriers in European freshwater ecosystems. J. Environ. Manage. 204, 436–441 (2017).

    Article  PubMed  Google Scholar 

  37. Mulligan, M. et al. Global Dam Watch: curated data and tools for management and decision making. Environ. Res. Infrastruct. Sustain. 1, 033003 (2021).

    Article  Google Scholar 

  38. Flecker, A. S. et al. Reducing adverse impacts of Amazon hydropower expansion. Science 375, 753–760 (2022).

    Article  CAS  PubMed  Google Scholar 

  39. King, S., O’Hanley, J. R., Newbold, L. R., Kemp, P. S. & Diebel, M. W. A toolkit for optimizing fish passage barrier mitigation actions. J. Appl. Ecol. 54, 599–611 (2017).

    Article  Google Scholar 

  40. Silva, A. T. et al. The future of fish passage science, engineering, and practice. Fish Fisher. 19, 340–362 (2018).

    Article  Google Scholar 

  41. Sun, J., Tummers, J. S., Galib, S. M. & Lucas, M. C. Fish community and abundance response to improved connectivity and more natural hydromorphology in a post-industrial subcatchment. Sci. Total Environ. 802, 149720 (2022).

    Article  CAS  PubMed  Google Scholar 

  42. Jumani, S. et al. A decision‐support framework for dam removal planning and its application in northern California. Environ. Chall. 12, 100731 (2023).

    Article  Google Scholar 

  43. Winemiller, K. O. et al. Balancing hydropower and biodiversity in the Amazon, Congo, and Mekong. Science 351, 128–129 (2016).

    Article  CAS  PubMed  Google Scholar 

  44. Thieme, M. et al. Measures to safeguard and restore river connectivity. Environ. Rev. 32, 366–386 (2023).

    Article  Google Scholar 

  45. Ziv, G., Baran, E., Nam, S., Rodriguez-Iturbe, I. & Levin, S. A. Trading-off fish biodiversity, food security, and hydropower in the Mekong River Basin. Proc. Natl Acad. Sci. USA 109, 5609–5614 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  46. Almeida, R. M. et al. Strategic planning of hydropower development: balancing benefits and socioenvironmental costs. Curr. Opin. Environ. Sustain. 56, 101175 (2022).

    Article  Google Scholar 

  47. Opperman, J. J. et al. Balancing renewable energy and river resources by moving from individual assessments of hydropower projects to energy system planning. Front. Environ. Sci. 10, 1036653 (2023).

    Article  Google Scholar 

  48. Yang, X. et al. Mapping flow‐obstructing structures on global rivers. Water Resour. Res. 58, e2021WR030386 (2022).

    Article  Google Scholar 

  49. Zhang, A. T. & Gu, V. X. Global Dam Tracker: a database of more than 35,000 dams with ___location, catchment, and attribute information. Sci. Data 10, 111 (2023).

    Article  PubMed  PubMed Central  Google Scholar 

  50. Lehner, B. et al. The Global Dam Watch database of river barrier and reservoir information for large-scale applications. Sci. Data 11, 1069 (2024).

    Article  PubMed  PubMed Central  Google Scholar 

  51. Donchyts, G. et al. High-resolution surface water dynamics in Earth’s small and medium-sized reservoirs. Sci. Rep. 12, 13776 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  52. World Register of Dams (International Commission on Large Dams, 2022); https://www.icold-cigb.org/GB/world_register/world_register_of_dams.asp

  53. Les Obstacles à l’Écoulement des Eaux de Surface – Continuité Écologique (Onema, 2022); https://www.eaufrance.fr/les-obstacles-lecoulement-des-eaux-de-surface

  54. Mulligan, M., van Soesbergen, A. & Sáenz, L. GOODD, a global dataset of more than 38,000 georeferenced dams. Sci. Data 7, 31 (2020).

    Article  PubMed  PubMed Central  Google Scholar 

  55. Gao, J., Castelletti, A., Burlado, P., Wang, H. & Zhao, J. Soft-cooperation via data sharing eases transboundary conflicts in the Lancang-Mekong River Basin. J. Hydrol. 606, 127464 (2022).

    Article  Google Scholar 

  56. Lin, J. et al. Making China’s water data accessible, usable and shareable. Nat. Water 1, 328–335 (2023).

    Article  Google Scholar 

  57. Sheer, M. B. & Steel, E. A. Lost watersheds: barriers, aquatic habitat connectivity, and salmon persistence in the Willamette and Lower Columbia river basins. Trans. Am. Fish. Soc. 135, 1654–1669 (2006).

    Article  Google Scholar 

  58. Jones, J. et al. A comprehensive assessment of stream fragmentation in Great Britain. Sci. Total Environ. 673, 756–762 (2019).

    Article  CAS  PubMed  Google Scholar 

  59. Mapping Hydropower Opportunities and Sensitivities in England and Wales (Entec, 2010).

  60. Baumgartner, L. J., Marsden, T., Duffy, D., Horta, A. & Ning, N. Optimizing efforts to restore aquatic ecosystem connectivity requires thinking beyond large dams. Environ. Res. Lett. 17, 014008 (2022).

    Article  Google Scholar 

  61. Marsden, T., Baumgartner, L. J., Duffy, D., Horta, A. & Ning, N. Evaluation of a new practical low-cost method for prioritising the remediation of fish passage barriers in resource-deficient settings. Ecol. Eng. 194, 107024 (2023).

    Article  Google Scholar 

  62. Mouchlianitis, F. A. AMBER Barrier Tracker: Using Citizen Science to Track Barriers in Europe (World Fish Migration Foundation, 2022); https://damremoval.eu/wp-content/uploads/2023/01/BarrierTracker_report2022finale.pdf

  63. Atkinson, S. et al. The value of a desk study for building a national river obstacle inventory. River Res. Appl. 34, 1085–1094 (2018).

    Article  Google Scholar 

  64. Whittemore, A. et al. A participatory science approach to expanding instream infrastructure inventories. Earth Future 8, e2020EF001558 (2020).

    Article  Google Scholar 

  65. Buchanan, B. P. et al. A machine learning approach to identify barriers in stream networks demonstrates high prevalence of unmapped riverine dams. J. Environ. Manage. 302, 113952 (2022).

    Article  PubMed  Google Scholar 

  66. Parks, M. V., Garcia de Leaniz, C., Jones, P. E. & Jones, J. Modelling remote barrier detection to achieve free-flowing river targets. Environ. Res. Lett. 19, 084055 (2024).

    Article  Google Scholar 

  67. Arsenault, M. et al. Remote sensing framework details riverscape connectivity fragmentation and fish passability in a forested landscape. J. Ecohydraul. 8, 121–132 (2023).

    Article  Google Scholar 

  68. Kroon, F. J. & Phillips, S. Identification of human-made physical barriers to fish passage in the Wet Tropics region, Australia. Mar. Freshwat. Res. 67, 677–681 (2016).

    Article  Google Scholar 

  69. Lehner, B., Verdin, K. & Jarvis, A. New global hydrography derived from spaceborne elevation data. Eos 89, 93–94 (2008).

    Article  Google Scholar 

  70. Januchowski-Hartley, S. R., Jézéquel, C. & Tedesco, P. A. Modelling built infrastructure heights to evaluate common assumptions in aquatic conservation. J. Environ. Manage. 232, 131–137 (2019).

    Article  PubMed  Google Scholar 

  71. Jing, M. et al. Detecting unknown dams from high-resolution remote sensing images: a deep learning and spatial analysis approach. Int. J. Appl. Earth Obs. Geoinf. 104, 102576 (2021).

    Google Scholar 

  72. Hübinger, C., Fluet-Chouinard, E., Hugelius, G., Peña, F. J. & Jaramillo, F. Automating the detection of hydrological barriers and fragmentation in wetlands using deep learning and InSAR. Remote Sens. Environ. 311, 114314 (2024).

    Article  Google Scholar 

  73. Sharma, K. High performance GPU based optimized feature matching for computer vision applications. Optik 127, 1153–1159 (2016).

    Article  CAS  Google Scholar 

  74. Ioannidou, C. T., Neeson, T. M. & O’Hanley, J. R. Boosting large‐scale river connectivity restoration by planning for the presence of unrecorded barriers. Conserv. Biol. 37, e14093 (2023).

    Article  PubMed  PubMed Central  Google Scholar 

  75. Garcia de Leaniz, C. et al. in From Sea to Source 2.0: Protection and Restoration of Fish Migration in Rivers Worldwide (eds Brink, K. et al.) 142–145 (World Fish Migration Foundation, 2018).

  76. Cowx, I. G. et al. Understanding the threats to fish migration: applying the global swimways concept to the Lower Mekong. Rev. Fisher. Sci. Aquacult. https://doi.org/10.1080/23308249.2024.2401018 (2024).

  77. Perkin, J. S. & Gido, K. B. Fragmentation alters stream fish community structure in dendritic ecological networks. Ecol. Appl. 22, 2176–2187 (2012).

    Article  PubMed  Google Scholar 

  78. Branco, P., Amaral, S. D., Ferreira, M. T. & Santos, J. M. Do small barriers affect the movement of freshwater fish by increasing residency? Sci. Total Environ. 581–582, 486–494 (2017).

    Article  PubMed  Google Scholar 

  79. Marsden, T., Peterken, C., Baumgartner, L. & Thorncraft, G. Guideline to Prioritising Fish Passage Barriers and Creating Fish Friendly Irrigation Structures (Mekong River Commission, 2014); https://researchoutput.csu.edu.au/files/19101127/2014_Holistic_Approach_to_Fish_Passage_Remediation_Mekong.pdf

  80. Rosa, C. et al. Burying water and biodiversity through road constructions in Brazil. Aquat. Conserv. 31, 1548–1550 (2021).

    Article  Google Scholar 

  81. Azevedo-Santos, V. M. et al. Irrigation dams threaten Brazilian biodiversity. Environ. Manage. 73, 913–919 (2024).

    Article  PubMed  Google Scholar 

  82. Cote, D., Kehler, D. G., Bourne, C. & Wiersma, Y. F. A new measure of longitudinal connectivity for stream networks. Landsc. Ecol. 24, 101–113 (2009).

    Article  Google Scholar 

  83. Jumani, S. et al. River fragmentation and flow alteration metrics: a review of methods and directions for future research. Environ. Res. Lett. 15, 123009 (2020).

    Article  Google Scholar 

  84. Li, M. et al. Human barriers fragment three-quarters of all rivers in the Mekong basin. Renew. Sustain. Energy Rev. 210, 115158 (2025).

    Article  Google Scholar 

  85. O’Hanley, J. R., Wright, J., Diebel, M., Fedora, M. A. & Soucy, C. L. Restoring stream habitat connectivity: a proposed method for prioritizing the removal of resident fish passage barriers. J. Environ. Manage. 125, 19–27 (2013).

    Article  PubMed  Google Scholar 

  86. Branco, P., Segurado, P., Santos, J. M. & Ferreira, M. T. Prioritizing barrier removal to improve functional connectivity of rivers. J. Appl. Ecol. 51, 1197–1206 (2014).

    Article  Google Scholar 

  87. King, M., van Zyll de Jong, M. & Cowx, I. G. A dynamic dendritic connectivity assessment tool for the planning and design of barrier mitigation strategies in river networks. Landsc. Ecol. 38, 1431–1446 (2023).

    Article  Google Scholar 

  88. Slagter, B. et al. Monitoring road development in Congo Basin forests with multi-sensor satellite imagery and deep learning. Remote Sens. Environ. 315, 114380 (2024).

    Article  Google Scholar 

  89. Tang, Q. et al. Automatic extraction of glacial lakes from Landsat imagery using deep learning across the Third Pole region. Remote Sens. Environ. 315, 114413 (2024).

    Article  Google Scholar 

  90. Fish-friendly Irrigation: Guidelines to Prioritising Fish Passage Barriers in the Lower Mekong River Basin (Mekong River Commission, 2023); https://www.mrcmekong.org/wp-content/uploads/2024/08/Fish-Friendly-Irrigation-Guidelines-to-Prioritize-Fish-Passage-Barriers-in-the-Lower-Mekong-River-Basin.pdf

Download references

Acknowledgements

J.S. was funded by the National Natural Science Foundation of China (grant no. 42301064). J.D.O. was supported by the Richard C. and Lois M. Worthington Endowed Professor in Fisheries Management from the School of Aquatic and Fishery Sciences, University of Washington. T.B.A.C. is funded by the United Kingdom Research and Innovation (UKRI) Future Leaders Fellowship (grant no. MR/W011085/1). We thank M. Thieme and B. Lehner for valuable discussions and comments on the topic.

Author information

Authors and Affiliations

  1. Yunnan Key Laboratory of International Rivers and Transboundary Eco-security, Yunnan University, Kunming, China

    Jingrui Sun (孙璟睿)

  2. Institute of International Rivers and Eco-security, Yunnan University, Kunming, China

    Jingrui Sun (孙璟睿)

  3. Ministry of Education Key Laboratory for Transboundary Eco-Security of Southwest China, Yunnan University, Kunming, China

    Jingrui Sun (孙璟睿)

  4. Department of Biosciences, University of Durham, Durham, UK

    Martyn C. Lucas

  5. School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, USA

    Julian D. Olden

  6. Lancaster Environment Centre, Lancaster University, Lancaster, UK

    Thiago B. A. Couto

  7. Gubali Institute, Charles Sturt University, Albury, New South Wales, Australia

    Nathan Ning, Deanna Duffy & Lee J. Baumgartner

Authors
  1. Jingrui Sun (孙璟睿)
    View author publications

    Search author on:PubMed Google Scholar

  2. Martyn C. Lucas
    View author publications

    Search author on:PubMed Google Scholar

  3. Julian D. Olden
    View author publications

    Search author on:PubMed Google Scholar

  4. Thiago B. A. Couto
    View author publications

    Search author on:PubMed Google Scholar

  5. Nathan Ning
    View author publications

    Search author on:PubMed Google Scholar

  6. Deanna Duffy
    View author publications

    Search author on:PubMed Google Scholar

  7. Lee J. Baumgartner
    View author publications

    Search author on:PubMed Google Scholar

Contributions

All authors contributed to the conceptualization of the Review and discussions of the content. J.S. led the writing and all authors contributed substantially to the drafts of the manuscript. All authors reviewed and edited the manuscript before submission.

Corresponding author

Correspondence to Jingrui Sun (孙璟睿).

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Water thanks Luca De Felice, Xiao Yang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Sun, J., Lucas, M.C., Olden, J.D. et al. Towards a comprehensive river barrier mapping solution to support environmental management. Nat Water 3, 38–48 (2025). https://doi.org/10.1038/s44221-024-00364-w

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s44221-024-00364-w

Search

Advanced search

Quick links

Nature Briefing Anthropocene

Sign up for the Nature Briefing: Anthropocene newsletter — what matters in anthropocene research, free to your inbox weekly.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing: Anthropocene