Conserving just 35% of U.S. waterways could sustain freshwater biodiversity

Study evaluated resilience and protected status of rivers and streams across the contiguous US

PLOS

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The Ashuelot River in New Hampshire drains over 400 square miles of mostly forest and forested wetlands before meeting the Connecticut River.

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Credit: Jerry Monkman/ Ecophotography, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

By evaluating the health of waterways across the US, researchers have identified about one-third of rivers and streams that, if conserved and restored, could sustain the nation’s freshwater biodiversity in the face of habitat degradation and climate change. Mark Anderson of the Nature Conservancy, US, led the new study, published September 16, 2026, in the open access journal PLOS One.

During the past century, streams and lakes in the US have deteriorated, as more than 150,000 dams have fragmented river networks, and changes to the landscape and groundwater usage have altered how and where the water flows. Many freshwater species are now in rapid decline, exacerbated by the impacts of climate change.

To address this crisis, The Nature Conservancy worked with 66 freshwater con­servationists to map out freshwater networks in the contiguous US and evaluate their resilience to degradation. Each watershed was scored based on its connectivity, condition, water availability and naturalness of flow, and checked against local surveys of freshwater biodiversity. They put together a patchwork of rivers and streams – named the Freshwater Resilient and Connected Network – that covers 35% of the lower 48 states but could preserve our freshwater biodiversity. Conserving this network will be challenging, however, as currently, only 6% of the area is both protected and resilient, and 14% needs both protection and restoration.

The analysis also showed that of the 5.2 million miles of rivers and streams in the contiguous US, 33% rated as above-average for resilience. While rivers that are above average should continue to support similar patterns of biodiversity in the future, those just above average may still require restoration. These networks are concentrated in the Pacific Coast, the Northern Rocky Mountains, Great Lake areas in Wisconsin and Minnesota, Northern Maine and coastal regions along the southeastern US and the Gulf of Mexico. Vulnerable or below-average river networks made up 15% of those miles and were concentrated in the Southwest deserts, lower New England, the shortgrass prairie east of the Rocky Mountains and the agricultural lands of the midwestern states.

The study provides a solid foundation for conservation efforts to sustain biodiversity in freshwater systems and provides a clear picture of the challenges ahead. Researchers said the analysis has already been used to identify dams for removal, prioritize land protection in key headwaters and improve conditions in river systems that need restoration. The team acknowledges the maps do not take into account human needs, but data representing human dimensions could be combined with this analysis to identify them.

The authors add: “Resilience to climate changes adds important context to our efforts to conserve freshwater biodiversity. We hope our study will help our state, federal, Tribal and other conservation partners make investments where they have the greatest chance to succeed into the future.”

 

 

In your coverage, please use this URL to provide access to the freely available article in PLOS One: https://plos.io/4Ae7W6j

Citation: Anderson MG, Olivero AP, Barnett AR, Khoury ML, Martin EH (2026) A freshwater resilient and connected network to sustain biodiversity under a changing climate. PLoS One 21(9): e0351782. https://doi.org/10.1371/journal.pone.0351782

Author countries: USA.

Funding: Anonymous Donor, Volgenau Foundation, Kia America, and Enterprise Mobility Fund. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

The Lower Pecos River is fed by a regional aquifer sustaining a unique and biodiverse ecosystem and critical inflows to the lower Rio Grande basin.

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Ryan Smith, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

Components and results of the analysis. A. Climatic Regions, B. Freshwater Resilience, C. Freshwater Recognized Biodiversity Value. D. Freshwater Opportunity Map. D. Freshwater Conservation Status. F. FRCN Conservation Status. G. Freshwater Resilient and Connected Network (FRCN). These maps were created with ArcGIS Pro 3.5.2 (ESRI, Redlands, CA). Hillshade used in Figures A-F from World Hillshade (Sources: Esri, Airbus DS, USGS, NGA, NASA, CGIAR, N Robinson, NCEAS, NLS, OS, NMA, Geodatastyrelsen, Rijkswaterstaat, GSA, Geoland, FEMA, Intermap, and the GIS User Community) [75]. Hillshade used in Figure G from Herwig G. Schutzler, 1965, Shaded Relief Archive, https://shadedreliefarchive.com/usa-schutzler.html. 

Credit

Anderson et al., 2026, PLOS One, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

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Journal

PLOS One

DOI

10.1371/journal.pone.0351782

Method of Research

Observational study

Article Title

A freshwater resilient and connected network to sustain biodiversity under a changing climate

Article Publication Date

16-Sep-2026

 

The Local Costs of Remote Sensing: Examining the Ethics of Laser Scanning in Tropical Forests

Max Planck Institute of Geoanthropology

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Laser scanning, often referred to as Lidar, has rapidly transformed how tropical forest regions are studied, monitored, and understood across academic disciplines. The technology enables researchers to peer through dense forest canopy, rapidly providing high resolution scans of the landscape below. This growing observational power is central to the scientific value of remote sensing technologies, but also brings into focus the conditions, interests, and power structures under which they are used.

Now in a new paper in Nature Ecology and Evolution, an international team of researchers argues that the visibility brought by high-resolution remote sensing may result in the loss of what have long been cultural refuges against dominant powers, and that ethical considerations should be integral to research planning when using such data.

“Remote sensing research has often been framed as a technical exercise to support more efficient management and observation,” says Patrick Roberts, director of the Department of Coevolution of Land Use and Urbanisation at the Max Planck Institute of Geoanthropology (MPI GEA), and corresponding author of the study. “Yet, mapping is never only a technical practice, and decisions about what is revealed, how, where are inherently ethical and political.”

The new paper acknowledges the value of remote sensing but argues that while discipline-specific ethical discussions around the technology have occurred, they have tended to focus on technicalities of research and data presentation rather than whether and under what conditions to map. The authors organize these considerations into three broad areas:

1. Knowledge, access, and control – who decides when to map, why, and who controls the data?
2. Population rights, exposure and dispossession – how might this data be used to ‘expose’ communities, marginalized groups in society, or resources for extraction?
3. The material costs of seeing – how might the process of remote sensing, in turn, contribute to the climatic and environmental impacts it is seeking to prevent?

“These issues challenge us to think about the oft-promoted but simplistic idea of mapping ‘for the greater good,’” says Gabriel Hes of the University of Toulouse, lead author of the current paper. “Whose ‘greater good’ are we talking about and are forest mapping technologies reinforcing imbalances in knowledge production, political power and environmental impacts? In this paper, we urge our colleagues to reflect on the ethical costs of their methods, considering the potential intersectional impacts (on race, age, gender, wealth, class) of high-resolution mapping of tropical forests.”

“We are not arguing that remote sensing is inherently ‘bad’,” Roberts adds, “indeed it has been used by local communities to safeguard their territories and rights. Rather, we urge consideration by scientists of the varied ethical dimensions impacting their research whether they carry out mapping on local, regional or global scales.”

The authors conclude with a framework for helping researchers decide when mapping is inappropriate. In reframing environmental science as an asset for transformative change, they hope that these considerations will ensure that tropical forest mapping best serves the needs of those impacted most by the current global ecological crisis.

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Journal

Nature Ecology & Evolution

DOI

10.1038/s41559-026-03187-y

Method of Research

Commentary/editorial

Article Title

The ethical costs of remotely sensing tropical forest understories

Article Publication Date

16-Sep-2026

 

Food & drink manufacturers can greatly improve sustainability and healthiness of their products with small changes – Oxford research

University of Oxford

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The authors looked at the foods sold in the UK by 44 major food and beverage manufacturers – that account for approximately 50% of the UK food retail market – and assigned scores for nutrition and sustainability per 100g to each product. They found significant variation in similar products between different manufacturers. For instance, a ready meal from one manufacturer might be much less nutritious and sustainable than a similar bar at another manufacturer. 

The authors then looked at what might happen if the manufacturers swapped some of their least nutritious and sustainable products with products that had closer to average scores and found significant potential for improvement. And for many manufacturers, more than half the potential improvements were achieved by changing 10% or less of their product line. 

Two well-known British supermarkets, whose own brands collectively account for 28.9% of sales value in this analysis, have some of the largest scope to improve their scores for both environment and nutrition, the authors find. But manufacturers with narrow product ranges, such as snack and energy drink manufacturers, generally have lower scope to improve their scores. 

“Ours is the first study we are aware of to assess the capacity for food & beverage manufacturers to support nutrition and environmental sustainability through changes within their existing product portfolios,” explains lead author Eleanor Hammond, who conducted the research while working at the University of Oxford. 

“If food systems are to transition to more nutritious and environmentally sustainable outcomes, food manufacturers are going to have to change the products they sell. This change can either be driven by food & beverage manufacturers, or imposed on them by government policy. Our findings show manufacturers can get a head start on this necessary transition by making small changes to their product portfolios today,” says co-author Dr Michael Clark, Associate Professor, Sustainable Food Solutions at the Smith School of Enterprise and the Environment.

The timing of the study is significant as the UK Government is under pressure to bring forward legislation requiring mandatory reporting on the nutrition of UK food and beverage products. “Our study demonstrates how the UK Government could monitor both sustainability and nutritional outcomes together. It could also be used for ESG reporting and support regulatory frameworks such as the EU's Corporate Sustainability Reporting Directive,” says Dr Clark. 

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Journal

Nature Food

DOI

10.1038/s43016-026-01420-2

Method of Research

Observational study

Subject of Research

Not applicable

Article Publication Date

16-Sep-2026

 

Policy instruments are never neutral — they shape ideas, actors, and change

ECNU Review of Education

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When education systems introduce a new test, school-evaluation framework, performance indicator, or accreditation procedure, the change may appear technical. Yet such tools do much more than implement decisions already made. Indeed, they define what counts as a policy problem, establish which knowledge is credible, allocate roles to different actors, and shape how schools and education systems are governed.

That is the central message of a new scoping review published online on August 1, 2026, in ECNU Review of Education. Luís Miguel Carvalho and Catarina Gonçalves, of the Institute of Education, University of Lisbon, examined 42 peer-reviewed articles published between 2005 and 2023. Their study maps research in the sociology of policy instruments in education and asks what this perspective reveals about contemporary policy and educational change.

The sociology of policy instruments treats instruments as both technical and social devices. Legislation, contracts, assessments, benchmarks, indicators, funding mechanisms, and communication platforms embody specific values and assumptions about the relationship between government, education professionals, learners, and society. Studying them therefore makes it possible to see how power operates through apparently technical and practical arrangements.

According to the literature reviewed, researchers have concentrated especially on performance-based instruments such as PISA, national large-scale assessments, school evaluation and self-evaluation, indicators, standards, and accreditation. This focus reflects a broader shift toward governance through comparison, data, and performance-oriented accountability. The review also finds growing attention to European education governance, global intergovernmental organizations, private companies, and intermediary actors working between national policy and local practice.

The authors organize existing knowledge around three dimensions: the institutional ideas embedded in instruments, the trajectories instruments follow as they are designed and used, and the effects they generate. Instruments do not simply travel unchanged from policymaking centers to schools. National traditions, political interests, professional identities, and local conditions can lead to adoption, opposition, hybridization, or the creation of new tools. Similar instruments may therefore take quite different forms in different systems.

The review identifies six recurring effects. Instruments can legitimize certain actors and coalitions, reorganize political spaces and timelines, privilege certain forms of knowledge and expertise, gather actors around common issues, produce hybrid policies when several tools and governing logics interact, and generate unintended consequences. For example, comparative assessments may strengthen the authority of international organizations and structure national debate, while indicators designed to inform policy can become simplified rankings. Performance tools intended to encourage innovation may also intensify supervision or standardize practice.

“Studies on policy instruments are well suited to address the complexity of education policy: the multiple policy scales as interdependent contexts, the variety of individual and collective actors involved, and the various governance patterns, ranging from state-oriented to market-oriented regimes, and from norm-based governance patterns to performance-oriented ones”, said Carvalho and Gonçalves.

The study also identifies important gaps. The evidence base remains strongly centered on Europe, and researchers have paid less attention to combinations of multiple instruments. The authors call for a broader geo-cultural range of studies, clearer theoretical foundations, and more systematic explanations of why the same instrument follows different trajectories in different settings.

For policymakers and education leaders, the findings offer a practical caution: choosing a policy instrument is itself a political decision. A test, indicator, contract, or platform may affect not only whether a policy achieves its goals, but also what goals appear legitimate, who gains authority, and which realities remain visible or become obscured. For researchers, the review provides a map of a developing field and a framework for examining the complex links between technical devices, institutional change, and power in education.

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Journal

ECNU Review of Education

DOI

10.1177/20965311261467767

Method of Research

Literature review

Subject of Research

Not applicable

Article Title

Research on Policy Instruments in Education, 2005-2023: A Scoping Review

 

The high cost of climate change on worker productivity

Study quantifies the price of heat stress for workers around the world

University of California - Davis

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A cotton trailer outfitted with benches and a sunshade offers farmworkers a reprieve from the sun as they take a break from picking cantaloupe melons in Firebaugh, Calif.

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Credit: Joe Proudman/UC Davis

As the climate warms, people are more exposed to heat stress, which depresses their productivity and the global economy. A study from the University of California, Davis, quantifies the cost of heat stress on global labor. 

The study, published today in the journal Nature Climate Change, estimates that each ton of carbon dioxide emitted in 2025 cost $41 in lost productivity. 

Highly populated areas meeting critical thresholds for heat and humidity were particularly affected, the study found. This includes India, Nigeria, China and Pakistan, as well as countries in the Middle East and sub-Saharan Africa.  

“Our study contributes to the body of evidence about what the real costs of climate change are,” said lead author Frances Moore, a professor in the UC Davis Department of Environmental Science and Policy. “Based on these new numbers, labor is the second-largest contributor to the total social cost of carbon, just behind heat-related deaths.”

The social cost of carbon and its value

The social cost of carbon, or SC-CO2, is the quantifiable cost of one additional ton of CO2 emissions. The measurement is highly relevant for policy decisions related to cost-benefit analyses, infrastructure planning, utility regulation and carbon taxes. 

The study lends strong support for a social cost of carbon value of $200, a value similar to that estimated by the U.S. Environmental Protection Agency in 2023. Current federal guidance does not recognize the metric and discourages monetizing the impacts of greenhouse gas emissions in regulatory analysis. However, the study states “we can confidently rule out a SC-CO2 of zero or below.”

“We’re getting better and better at evaluating climate damages,” Moore said. “We’re getting more confident in the social cost of carbon, and it is a metric that should be used. This number is ready to help inform good climate policy analysis.”

Heat stress varies by region, job, A/C access 

To reach their findings, the authors combined projections from a heat stress metric called the “wet-bulb globe temperature” (WBGT) with job and region-specific estimates of work intensity and outdoor exposure across different economic sectors. WBGT captures the physical risks of hot temperatures by accounting for weather variables that influence the body’s ability to dissipate heat, including humidity and wind speed. 

Exposure to heat stress by both indoor and outdoor workers varied across the globe depending on the local environment, strenuousness of the work and access to shade and air conditioning.

Agricultural and construction laborers are far more exposed to heat than office or service workers because they often perform strenuous, outdoor work. However, indoor workers with minimal or no air conditioning also are at risk. For example, a dataset of residential air conditioning adoption in 33 countries showed A/C penetration rates ranging from 0% in South Sudan to 90% in Japan.

In addition to air conditioning, more shade, water, breaks and shifting work to cooler hours of the day when possible can protect workers from heat stress.

“Heat is very dangerous,” Moore said. “Employers and policymakers need to be treating it as the real health hazard that it is and thinking seriously about ways to mitigate those damages because we’re going to keep seeing more frequent, more intense heat extremes.”

The study’s additional authors include Iman Haqiqi, Uris Baldos, Matthew Huber and Thomas Hertel of Purdue University; Qinqin Kong and Lisa Rennels of Stanford University and Hamsa Ganapathi of UC Davis.

The research was funded by the National Science Foundation, Yale Institute for Biospheric Studies Bass Fellowship, Rockefeller Foundation Bellagio Fellowship, National Institutes of Health, NASA, Stanford Energy Postdoctoral Fellowship and Precourt Institute for Energy.

A farmworker takes a drink of water while taking a break from harvesting cantaloupes in Firebaugh, Calif.

Credit

Joe Proudman/UC Davis

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Journal

Nature Climate Change

DOI

10.1038/s41558-026-02749-z

Article Title

New labour and agricultural damages improve climate cost estimates'

Article Publication Date

16-Sep-2026

 

Temperature measurement error may cause climate-impact studies to understate impacts by 15% or more

Wake Forest University

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When policymakers and city officials plan for climate change, they rely on economic studies showing how extreme heat impacts violent crime, public health, energy grids and crop yields.

However, a new study published in the Journal of the Association of Environmental and Resource Economists reveals a hidden problem in that research: the temperatures used in many climate-impact studies can contain substantial measurement error, leading researchers to misestimate the true impacts of temperature and, on average, potentially understate climate impacts by at least 15%.

The study, co-authored by Wake Forest Assistant Professor of Economics Alex Yu and Distinguished Professor of Economics Richard Carson (UC San Diego), demonstrates that standard methods researchers use to construct temperature measures can introduce substantial measurement error that varies systematically across locations and geography.

Why temperature measurement can be inaccurate

Because physical weather stations are miles apart, researchers use statistical estimates of temperatures in specific cities, neighborhoods or farm fields. The study reveals that these best guesses or “proxies” carry substantial measurement errors that traditional statistical assumptions fail to capture:

• Microclimate blindspots: In mountainous regions like Boulder, Colorado, standard weather proxies differed from actual temperatures by an average of nearly 15°F. In flatter, more densely monitored areas like Chicago, errors were as low as 1°F.

• Distorting the temperature signal: Measurement errors can persist over time and vary systematically with local geography. When researchers apply these estimated temperatures to real-world outcomes—such as crime or heat-related illnesses—the resulting estimates can be biased upward or downward.

• Larger than climate targets: For one commonly used weather proxy—temperature measurement errors averaged 3.3°F (1.85°C)—an error magnitude larger than the global Paris Climate Agreement warming limit of 1.5°C.

What this means for public policy

Using more than 20 million crime records, the researchers first estimated the relationship between extreme heat and violent crime using city-level crime and temperature data as a benchmark. They then aggregated both crime and temperature to the county level and estimated the same relationship, finding that the estimated effect of extreme heat became smaller at this coarser geographic scale.

"If climate-impact studies misestimate how severely extreme heat drives crime rates, crop loss, or health emergencies, policymakers may also misestimate the scale of the responses needed to address those impacts," said Yu.

Improving temperature measurement

The research doesn't just expose the problem; it provides practical guidance for researchers. No single temperature proxy works best everywhere: in areas with dense weather-station networks, nearby station measurements can outperform more complex gridded products, while gridded data may perform better where monitoring is sparse.

More broadly, the study highlights the value of better spatial monitoring of temperature. Expanding and maintaining dense weather-station networks—and more carefully matching temperature measurements to where people, farms, businesses and ecosystems are actually exposed—can reduce measurement error at its source.

About the researchers

• Chu (Alex) Yu, Assistant Professor of Economics, Wake Forest University (yua@wfu.edu)

• Richard T. Carson, Distinguished Professor of Economics, UC San Diego (rcarson@ucsd.edu)

Data and study availability:

The full study, "Mismeasured and Misunderstood: Unmasking the Temperature Proxy Problem in Climate Impact Estimates," is published in the Journal of the Association of Environmental and Resource Economists. 

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DOI

10.1086/74210

Method of Research

News article

Subject of Research

Not applicable

Article Title

Temperature measurement error may cause climate-impact studies to understate impacts by 15% or more

Article Publication Date

14-Sep-2026