Plastic harms ecosystem health and human livelihood on land, in rivers, and in the sea. To prevent and reduce plastic pollution, we must know how plastics move through the environment. Extreme events, such as floods, bring large amounts of plastic into rivers around the world. This article summarizes how different flood types (excessive rainfall, high river flow, or floods from the sea) flush or deposit plastic pollution, and how this impacts the environment. Furthermore, this paper also discusses how improved resilience to floods is important to prevent and reduce plastic pollution.

Plastic pollution is ubiquitous in the environment and threatens terrestrial, freshwater, and marine ecosystems. Reducing plastic pollution requires a thorough understanding of its sources, sinks, abundance, and impact. The transport and retention dynamics of plastics are however complex, and assumed to be driven by natural factors, anthropogenic factors, and plastic item characteristics. Current literature shows diverging correlations between river discharge, wind speed, rainfall, and plastic transport. However, floods have been consistently demonstrated to impact plastic transport and dispersal. This paper presents a synthesis of the impact of floods on plastic pollution in the environment. For each specific flood type (fluvial, pluvial, coastal, and flash floods), we identified the driving transport mechanisms from the available literature. This paper introduces the plastic-flood nexus concept, which is the negative feedback loop between floods (mobilizing plastics), and plastic pollution (increasing flood risk through blockages). Moreover, the impact of flood-driven plastic transport was assessed, and it was argued that increasing flood resilience also reduces the impact of floods on plastic pollution. This paper provides a perspective on the importance of floods on global plastic pollution. Increasing flood resilience and breaking the plastic-flood nexus are crucial steps toward reducing environmental plastic pollution.

Floods have a large impact on plastic pollution transport, which can be reduced through improved flood resilience

Despite growing recognition of the importance of transdisciplinary research in addressing complex sustainability challenges, in practice it has been much hampered by persistent inequities, power disparities, and epistemological disconnect. Planetary health as an emerging field offers a unique lens highlighting the need for knowledge integration across the environment, health, and development (EHD) nexus. Drawing upon extensive analyses, including a meta-analysis of existing transdisciplinary frameworks, a literature review of practices in these fields, and a case study of a planetary health action research project in Indonesia and Fiji, we propose a framework to guide the design and implementation of transdisciplinary research.

The proposed framework was iteratively designed, starting with existing frameworks, complemented by findings and practice recommendations from a literature review of 36 publications of recent transdisciplinary practices in the EHD fields and an in-depth case study of a planetary health research from Indonesian perspectives. The practice framework focuses on the stakeholder collaboration process, and emphasizes reflexivity and co-learning throughout all research phases: initiation (co-design); implementation (adaptive co-management), and monitoring and refinement (co-monitoring). Foundational considerations for stakeholder engagement could inform process design by reflecting on stakeholder contributions, interactions, integration, and expected outcomes. As suggested by development studies, and implicitly agreed upon but insufficiently elaborated within environment and health, attention to the local context of the research, mapping of power dynamics, and the values of equity and inclusivity are pertinent if research is to produce credible, relevant, and legitimate knowledge and outcomes. A renewed focus on addressing power equities can help ensure stakeholders' perspectives and interests are equally valued and potential solutions are not inadvertently excluded as a legacy of systemic power imbalance. The practice framework is most effectively applied in the initial process co-design, by process initiators and funders assessing proposals for international transdisciplinary research in power-diverse settings or resource-poor contexts.

How can researchers across diverse fields collaborate with renewed focus on power inequities to accelerate progress towards the Sustainable Development Goals?

Powerful influences on societal knowledge, values, and behavior, artificial intelligence-infused media systems, new and old, currently reinforce the interlinked problems of inequality and unsustainable consumption. This problem is rarely discussed in environmental research and policy, and even less so how it might be overcome. Discussing this consequential blind spot and the power structures that underpin it, this article argues that sustainability researchers should centrally explore the need and possibilities for democratic reconfiguration of the political economies and charters of media systems to achieve sustainability and other broad, inclusive public goals.

Powerful influences on societal knowledge, values and behavior, artificial intelligence-infused media systems, new and old, currently tend to reinforce the interlinked problems of inequality and unsustainable consumption. This problem is rarely discussed in environmental research and policy, and even less so how it might be overcome. Discussing this consequential blind spot and the power structures that underpin it, this article argues that sustainability researchers should centrally explore the possibilities for democratic governance and reconfiguration of the political economies of media systems to foster human wellbeing and just transformations toward sustainability.

Sustainability transformations require ‘signification steering’ and interventions in media systems' configurations.

The question of how science can become a lever in achieving the Sustainable Development Goals permeates most recent sustainability research. Wide-ranging literature calling for a transformative approach has emerged in recent years. This ‘transformative turn’ is fueled by publications from fields such as sustainability science, social-ecological research, conservation science, sustainability transitions, or sustainability governance studies. However, there is a lack of a shared understanding specifically of what is meant for research to be transformative in this developing discourse around doing science differently to tackle sustainability problems. We aim to advance transformative research for sustainability. We define transformative research and outline six of its characteristics: (1) interventional nature and a theory of change focus; (2) collaborative modes of knowledge production, experimentation and learning; (3) systems thinking literacy and contextualization; (4) reflexivity, normative and inner dimensions; (5) local agency, decolonization, and reshaping power; (6) new quality criteria and rethinking impact. We highlight three tensions between transformative research and traditional paradigms of academic research: (1) process- and output-orientation; (2) accountability toward society and toward science; (3) methodologies rooted in scientific traditions and post-normal methodologies. We conclude with future directions on how academia could reconcile these tensions to support and promote transformative research.

Dominant ways of doing research are not enough to achieve the UN Sustainable Development Goals. The typical response of science to dealing with the current local and global sustainability crises is to produce and accumulate more knowledge. Transformative research seeks to couple knowledge production with co-creating change. This paper defines the transformative way of doing research to pro-actively support society's fight against pressing societal and environmental problems. We present six characteristics of transformative research. We reflect on the challenges related to implementing these characteristics in scientific practice and on how academia can play its part.

Sustainability transformation needs to be reflected in science, but what makes sustainability research transformative?

Transdisciplinary approaches for sustainability brings natural and social science researchers together with non researchers to fill gaps in scientific knowledge and catalyze change. By connecting diverse academic fields and sectors, it addresses complex problems and enables learning for problem solving. However, institutional barriers, funding constraints, time limitations, and evaluation criteria hinder collaborative progress. Our review reveals tensions at institutional and individual levels. Our findings underscore the significance of soft skills in assembling effective transdisciplinary teams. Embracing transdisciplinary science, as suggested by our review, can enhance problem-solving, and foster transformations for sustainability and resilience.

Sustainability challenges in the age of the Anthropocene require researchers and practitioners to collaborate across multiple academic disciplines and multiple professions outside of universities. In this paper we draw on theories of institutional logics to explore how those involved in transdisciplinary environmental research and practice draw on particular sets of values and norms but encounter challenges to collaboration. These institutional logics include (among others) seeking societal/environmental impact, commercial objectives, and academic knowledge generation. In this paper we review the growing literature on the research experience of transdisciplinarity in sustainability; discuss the processes of managing such research; and present a framework that outlines the challenges and tensions at each stage of the innovation/research process. We set out an agenda for managing tension that calls for recognizing the challenges, learning how to work with tensions, and building capabilities for future careers involving transdisciplinary research. The paper shows a key competence or skill for transdisciplinarians is the ability to develop complex collaborative relationships for sustainability drawing together different institutional logics, approaches, methods, goals, and values.

Transdisciplinary science: bridging disciplines, solving challenges. Soft skills and collaboration key to success.

Greenhouse gas emissions and land use change – from deforestation, forest degradation, and agricultural intensification – are contributing to climate change and biodiversity loss. Important land-based strategies such as planting trees or growing bioenergy crops (with carbon capture and storage) are needed to achieve the goals of the Paris Climate Agreement and to enhance biodiversity.

The integrated Land Ecosystems Atmospheric Processes Study (iLEAPS) is an international knowledge-exchange and capacity-building network, specializing in ecosystems and their role in controlling the exchange of water, energy and chemical compounds between the land surface and the atmosphere. We outline priority directions for land–atmosphere interaction research and its contribution to the sustainable development agenda.

Greenhouse-gas emissions from human activities and land use change (from deforestation, forest degradation, and agricultural intensification) are contributing to climate change and biodiversity loss. Afforestation, reforestation, or growing bioenergy crops (with carbon capture and storage) are important land-based strategies to achieve the goals of the Paris Climate Agreement and to enhance biodiversity. The effectiveness of these actions depends on terrestrial ecosystems and their role in controlling or moderating the exchange of water, heat, and chemical compounds between the land surface and the atmosphere.

The integrated Land Ecosystems Atmospheric Processes Study (iLEAPS), a global research network of Future Earth, enables the international community to communicate and remain up to date with developments and concepts about terrestrial ecosystems and their role in global water, energy, and biogeochemical cycles. Covering critically important topics such as fire, forestry, wetlands, methane emissions, urban areas, pollution, and climate change, the iLEAPS Global Research Programme sits center stage for some of the most important environmental questions facing humanity. In this paper, we outline the new challenges and opportunities for land–atmosphere interaction research and its role in supporting the broader sustainable development agenda.

Future directions for research into land–atmosphere interactions that supports the sustainable development agenda

Human societies are changing where and how water flows through the atmosphere. However, these changes in the atmospheric water cycle are not being managed, nor is there any real sense of where these changes might be headed in the future. Thus, we develop a new economic theory of atmospheric water management, and explore this theory using creative story-based scenarios. These scenarios reveal surprising possibilities for the future of atmospheric water management, ranging from a stock market for transpiration to on-demand weather. We discuss these story-based futures in the context of research and policy priorities in the present day.

Humanity is modifying the atmospheric water cycle, via land use, climate change, air pollution, and weather modification. Historically, atmospheric water was implicitly considered a ‘public good’ since it was neither actively consumed nor controlled. However, given anthropogenic changes, atmospheric water can become a ‘common-pool’ good (consumable) or a ‘club’ good (controllable). Moreover, advancements in weather modification presage water becoming a ‘private’ good, meaning both consumable and controllable. Given the implications, we designed a theoretical framing of atmospheric water as an economic good and used a combination of methods in order to explore possible future scenarios based on human modifications of the atmospheric water cycle. First, a systematic literature search of scholarly abstracts was used in a computational text analysis. Second, the output of the text analysis was matched to different parts of an existing economic goods framework. Then, a group of global water experts were trained and developed story-based scenarios. The resultant scenarios serve as creative investigations of the future of human modification of the atmospheric water cycle. We discuss how the scenarios can enhance anticipatory capacity in the context of both future research frontiers and potential policy pathways including transboundary governance, finance, and resource management.

Story-based scenarios reveal novel future pathways for the management of the atmospheric water cycle.

The general public became familiar with the term and definition of zoonosis during the COVID-19 pandemic. Because of the pandemic, several responses to mitigate zoonotic risk has been put forward. Often cited are stricter biodiversity conservation and wildlife protection but there are also suggestions to educate people who traditionally consume wildlife for food. This implicit condemnation of culture also manifested explicitly in the form of racism especially against Asians during the height of the pandemic. If the world is to avoid a pandemic, it also needs to work against Orientalism and ensure research is inclusive, equitable, and just.

The COVID-19 pandemic widely introduced the term and definition of zoonosis to the general public. More than just a knee-jerk reaction, stricter biodiversity conservation and wildlife protection are now seen as essential strategies in mitigating zoonotic risks while some researchers have called for education campaigns that should discredit ingrained cultural practices such as wildlife consumption. This implicit condemnation of culture may have been initially confined to research papers but it eventually manifested as explicit racism in everyday life during the height of the pandemic, highlighting the need to decolonize Western scientific views on pandemic prevention and to refrain from Orientalism. This Intelligence Briefing makes the case for the inclusion of history and culture as necessary elements in zoonosis research alongside a critical reflection of transdisciplinary approaches. Emphasizing epistemic humility and authentic interest to learn from other actors such as Indigenous communities on the frontlines of human-wildlife interfaces, this Intelligence Briefing recommends the Future Earth Health Knowledge-Action Network to stay the course toward promoting approaches that are ‘transdisciplinary, multi-scalar, inclusive, equitable, and broadly communicated’ in zoonosis research.

History and culture are necessary elements of zoonosis research alongside transdisciplinary approaches.

Oil palm has been criticized for being an environmentally unfriendly oil crop. In recent decades, oil palm plantations have extended into conservation landscapes, causing severe environmental damage and harming biodiversity. Nevertheless, oil palm remains a highly productive oil crop from which most of the world's vegetable oil is produced. Therefore, measuring the environmental impact of oil palm plantations and identifying suitable land to support its sustainable development is crucial.

To meet the rising global palm oil demand sustainably, we tracked annual land cover changes in oil palm plantation and mapped areas worldwide suitable for sustainable oil palm cultivation. From 1982 to 2019, 3.6 Mha of forests were converted to oil palm plantations. Despite a recent decline in overall conversion, the shift from forest to oil palm plantations has become increasingly more common over the last decade, rising from 14.1 to 34.5% between 2009 and 2019. During 1982–2019, 2.23 Mha of peatland and 0.1 Mha of protected areas were converted for oil palm plantations. The potential sustainable land amounts to 103.5–317.9 Mha (Asia: 44.6–105.1 Mha, Africa: 34.7–96.4 Mha, and Latin America: 35.2–116.5 Mha). Future oil palm expansion is anticipated to take place in countries like Brazil, Nigeria, Colombia, Indonesia, Ivory Coast, the Democratic Republic of the Congo, and Ghana, where more sustainable land is available for cultivation. Malaysia, on the other hand, is about to exceed the area of sustainable cultivation, and further expansion is not recommended. These findings can advance our understanding of the environmentally damaging impacts of oil palm and enhance the feasibility of sustainable oil palm development.

How should suitable land be chosen for the establishment of oil palm plantations to support the sustainable development of the oil palm plantation industry?

Evolutionary biology considers how organisms and populations change over multiple generations, and so is naturally focused on issues of sustainability through time. Yet, sustainability science rarely incorporates evolutionary thinking and most scientists and policy makers do not account for how evolutionary processes contribute to sustainability. Understanding the interplay between evolutionary processes and nature's contribution to people is key to sustaining life on Earth.

Evolution, the change in gene frequencies within populations, is a process of genetically based modification by descent, providing the raw material essential for adaptation to environmental change. Therefore, it is crucial that we understand evolutionary processes if we aim for a sustainable planet. We here contribute to this development by describing examples of contemporary, rapid evolutionary changes of concern for sustainability, specifically highlighting the global spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and how the evolutionary toolbox allowed tracking the origins and evolution of SARS-CoV-2 in real time and predicting potential future outbreaks. We also consider how urban development accelerates evolutionary processes such as altered phenotypic and physiological changes and the spread of infectious and zoonotic diseases. We show the importance of evolutionary concepts and techniques for public-health decision making. Many examples of the potential of evolutionary insights contributing to crucial sustainability challenges exist, including infectious and zoonotic diseases, ecosystem and human health, and conservation of natural resources. We thus join recent calls advocating for a stronger collaboration between evolutionary biologists and the sustainability community, increasing interdisciplinarity and the awareness about the knowledge of evolutionary processes for decision making and policies.

Evolution is fundamental to sustaining life on Earth and should be incorporated in sustainability measures and policies.

This article takes stock of the 2030 Agenda and focuses on five governance areas. In a nutshell, we see a quite patchy and often primarily symbolic uptake of the global goals. Although some studies highlight individual success stories of actors and institutions to implement the goals, it remains unclear how such cases can be upscaled and develop a broader political impact to accelerate the global endeavor to achieve sustainable development. We hence raise concerns about the overall effectiveness of governance by goal-setting and raise the question of how we can make this mode of governance more effective.

A recent meta-analysis on the political impact of the Sustainable Development Goals (SDGs) has shown that these global goals are moving political processes forward only incrementally, with much variation across countries, sectors, and governance levels. Consequently, the realization of the 2030 Agenda for Sustainable Development remains uncertain. Against this backdrop, this article explores where and how incremental political changes are taking place due to the SDGs, and under what conditions these developments can bolster sustainability transformations up to 2030 and beyond. Our scoping review builds upon an online expert survey directed at the scholarly community of the ‘Earth System Governance Project’ and structured dialogues within the ‘Taskforce on the SDGs’ under this project. We identified five governance areas where some effects of the SDGs have been observable: (1) global governance, (2) national policy integration, (3) subnational initiatives, (4) private governance, and (5) education and learning for sustainable development. This article delves deeper into these governance areas and draws lessons to guide empirical research on the promises and pitfalls of accelerating SDG implementation.

As SDG implementation lags behind, this article explores 5 governance areas asking how to strengthen the global goals.

Multiple global crises – including the pandemic, climate change, and Russia's war on Ukraine – have recently linked together in ways that are significant in scope, devastating in effect, but poorly understood. A growing number of scholars and policymakers characterize the situation as a ‘polycrisis’. Yet this neologism remains poorly defined. We provide the concept with a substantive definition, highlight its value-added in comparison to related concepts, and develop a theoretical framework to explain the causal mechanisms currently entangling many of the world's crises. In this framework, a global crisis arises when one or more fast-moving trigger events combine with slow-moving stresses to push a global system out of its established equilibrium and into a volatile and harmful state of disequilibrium. We then identify three causal pathways – common stresses, domino effects, and inter-systemic feedbacks – that can connect multiple global systems to produce synchronized crises. Drawing on current examples, we show that the polycrisis concept is a valuable tool for understanding ongoing crises, generating actionable insights, and opening avenues for future research.

The term ‘polycrisis’ appears with growing frequently to capture the interconnections between global crises, but the word lacks substantive content. In this article, we convert it from an empty buzzword into a conceptual framework and research program that enables us to better understand the causal linkages between contemporary crises. We draw upon the intersection of climate change, the covid-19 pandemic, and Russia's war in Ukraine to illustrate these causal interconnections and explore key features of the world's present polycrisis.

Multiple global crises – including the pandemic, climate change, and Russia's war on Ukraine – have recently linked together in ways that are significant in scope, devastating in effect, but poorly understood. A growing number of scholars and policymakers characterize the situation as a ‘polycrisis’. Yet this neologism remains poorly defined. We provide the concept with a substantive definition, highlight its value-added in comparison to related concepts, and develop a theoretical framework to explain the causal mechanisms currently entangling many of the world's crises. In this framework, a global crisis arises when one or more fast-moving trigger events combines with slow-moving stresses to push a global system out of its established equilibrium and into a volatile and harmful state of disequilibrium. We then identify three causal pathways – common stresses, domino effects, and inter-systemic feedbacks – that can connect multiple global systems to produce synchronized crises. Drawing on current examples, we show that the polycrisis concept is a valuable tool for understanding ongoing crises, generating actionable insights, and opening avenues for future research.

No longer a mere buzzword, the ‘polycrisis’ concept highlights causal interactions among crises to help navigate a tumultuous future.

The popularity of the term polycrisis suggests a growing demand for new thinking about the world's intersecting crises, but loose and haphazard uses of the concept impede knowledge generation. The special issue, ‘Polycrisis in the Anthropocene’, aims to close the gap. This introductory comment first elaborates upon three key contributions of the lead article ‘Global Polycrisis: The Causal mechanisms of Crisis Entanglement’: a conceptualization of crisis as systemic disequilibrium; the distinction between the slow-moving stresses and the fast-moving trigger events that interact to generate a crisis; and a grammar with which to map the causality of crisis interactions. The commentary then explores three key debates around the polycrisis concept: Are we in a polycrisis, at risk of a polycrisis, or neither? Is the present polycrisis truly unique and unprecedented? And where are power and agency in a systemic approach to polycrisis? These ongoing debates suggest promising directions for polycrisis research that could feature in this special issue and advance the field of polycrisis analysis.

This commentary introduces the special issue ‘Polycrisis in the Anthropocene’ by elaborating upon three major contributions of its lead article, ‘Global Polycrisis: The Causal Mechanisms of Crisis Entanglement’, and exploring three key debates surrounding the polycrisis concept. It invites others to contribute to the special issue in order to advance polycrisis analysis, build a community of knowledge and practice, and generate new insights and strategies with which to address the world's worsening crises.

The popularity of the term polycrisis suggests a growing demand for new thinking about the world's intersecting crises, but loose and haphazard uses of the concept impede knowledge generation. The special issue, ‘Polycrisis in the Anthropocene’, aims to close the gap. This introductory comment first elaborates upon three key contributions of the lead article ‘Global Polycrisis: The Causal mechanisms of Crisis Entanglement’: a conceptualization of crisis as systemic disequilibrium; the distinction between the slow-moving stresses and the fast-moving trigger events that interact to generate a crisis; and a grammar with which to map the causality of crisis interactions. The commentary then explores three key debates around the polycrisis concept: Are we in a polycrisis, at risk of a polycrisis, or neither? Is the present polycrisis truly unique and unprecedented? And where are power and agency in a systemic approach to polycrisis? These ongoing debates suggest promising directions for polycrisis research that could feature in this special issue and advance the field of polycrisis analysis.

Inviting contributions and debates to Global Sustainability journal's special issue ‘Polycrisis in the Anthropocene’.

Information on social aspects of climate change intervention, such as behavioral choices and public acceptance, are often not included in global climate models. As a result, they have been critiqued for not adequately reflecting ‘real world’ conditions. At the same time, these models are important and influential policy tools. To improve these models, calls are being made for more interaction – or integration – between the social science and modelling research communities. Yet, it remains unclear how to achieve this. Responding to this gap, we explore what kind of integration is currently taking place, how, and opportunities for further development.

The importance of social drivers of climate change interventions, or social aspects, is currently underrepresented in computational modelling projections. These parameters are largely excluded from estimates of technical mitigation potential, feasibility, and tools like integrated assessment models (IAMs) and other large-scale models that influence the development of climate policies and notable bodies like the Intergovernmental Panel on Climate Change. This paper contributes to calls being made within the research community to address this gap and strengthen linkages between modelling practices and social science insights. Using nature-based solutions (NbS) as a framing, we present the results of a critical literature review and interviews with multidisciplinary experts reflecting on the current state of integration around IAMs and opportunities to better capture social aspects within large-scale modelling processes. Our findings confirm the need to incorporate social aspects in IAMs, but highlight that how this happens in practice may depend on context, project objectives, or pragmatic choices rather than conceptual notions about what ‘good’ integration is. Nevertheless, some integration strategies are better than others, and concerns about data limitations and low capacity of the IAM community for engaging in integration can be overcome with sufficient support and complementary efforts from the broader research community.

Integrating social aspects in large-scale models requires complementary efforts from the broader research community.

In 2015, the United Nations articulated the ambition to move toward a prosperous, socially inclusive, and environmentally sustainable future for all by adopting the Sustainable Development Goals (SDGs). However, little is known about the pathways that could lead to their concurrent achievement. We provide an overview of the current literature on quantitative pathways toward the SDGs, indicate the commonly used methods and indicators, and identify the most comprehensive pathways that have been published to date. Our results indicate that there is a need for more scenarios toward the full set of SDGs, using a wider range of underlying narratives.

Quantitative goal-seeking scenario studies could help to explore the needed systems' transformations to implement the 2030 Agenda for Sustainable Development by identifying enabling conditions and accounting for the synergies and trade-offs between the SDGs. Given that the SDGs were adopted some time ago, here, we review the existing global scenario literature to determine what it can offer in this context. We found only a few scenarios that address a large set of SDGs, while many more deal with specific clusters of 2–6 SDGs. We identified the most frequent clusters and compared the results of the most comprehensive sustainable development scenarios. The latter is complicated because of the diversity of methods, indicators, and assumptions used. Therefore, we suggest that an effort is needed to develop a wider set of scenarios that would achieve multiple SDGs, using a more standardized framework of targets and indicators.

This study reviews the current global pathways toward the SDGs and shows the need for a broader set of SDG scenarios.

In this paper, we explore how critically important ecosystems on the land provide evaporation to the atmosphere, which will later fall as precipitation elsewhere. Using a model-based analysis that tracks water flowing through the atmosphere, we find that more than two-thirds of the precipitation over critically important ecosystem areas is supplied by evaporation from other land. Likewise, more than 40% of the evaporation from critically important ecosystems falls as precipitation on other land. We conclude our work by discussing the policy implications for how these critically important ecosystems connect spatially distant wild and working lands via the atmospheric water cycle.

Global ecosystems are interconnected via atmospheric water vapor flows. Land use change can modify evaporation from land, altering atmospheric moisture recycling and potentially leading to significant changes in downwind precipitation and associated ecological impacts. We combine insights on global ecosystem-regulated moisture recycling with an analysis of critical natural assets (CNA, the 30% of global land providing most of nature's contributions to people) to reveal the sources and sinks of atmospheric water cycle regulation. We find that 65% of the precipitation over CNA is supplied by evaporation from other land areas. Likewise, CNA regions supply critical moisture as precipitation to terrestrial natural ecosystems and production systems worldwide, with 44% of CNA evaporation falling on terrestrial surfaces. Specifically, the Congo River basin emerges as a hotspot of overlap between local atmospheric water cycle maintenance and concentration of nature's contributions to people. Our results suggest global priority areas for conservation efforts beyond and in support of CNA, emphasizing the importance of sparsely populated managed forests and rangelands, along with wild forests, for fostering moisture recycling to and within CNA. This work also underlines the manifold benefits associated with achieving United Nations Sustainable Development Goal #15, to sustainably manage terrestrial life and conserve biodiversity.

Critically important ecosystems are essential for connecting distant landscapes via the atmospheric water cycle.

Scenarios compatible with the Paris agreement's temperature goal of 1.5 °C involve carbon dioxide removal measures – measures that actively remove CO2 from the atmosphere – on a massive scale. Such large-scale implementations raise significant ethical problems. Van Vuuren et al. (2018), as well as the current IPCC scenarios, show that reduction in energy and or food demand could reduce the need for such activities. There is some reluctance to discuss such societal changes. However, we argue that policy measures enabling societal changes are not necessarily ethically problematic. Therefore, they should be discussed alongside techno-optimistic approaches in any kind of discussions about how to respond to climate change.

The 1.5 °C goal has given impetus to carbon dioxide removal (CDR) measures, such as bioenergy combined with carbon capture and storage, or afforestation. However, land-based CDR options compete with food production and biodiversity protection. Van Vuuren et al. (2018) looked at alternative pathways including lifestyle changes, low-population projections, or non-CO2 greenhouse gas mitigation, to reach the 1.5 °C temperature objective. Underlined by the recently published IPCC AR6 WGIII report, they show that demand-side management measures are likely to reduce the need for CDR. Yet, policy measures entailed in these scenarios could be associated with ethical problems themselves. In this paper, we therefore investigate ethical implications of four alternative pathways as proposed by Van Vuuren et al. (2018). We find that emission reduction options such as lifestyle changes and reducing population, which are typically perceived as ethically problematic, might be less so on further inspection. In contrast, options associated with less societal transformation and more techno-optimistic approaches turn out to be in need of further scrutiny. The vast majority of emission reduction options considered are not intrinsically ethically problematic; rather everything rests on the precise implementation. Explicitly addressing ethical considerations when developing, advancing, and using integrated assessment scenarios could reignite debates about previously overlooked topics and thereby support necessary societal discourse.

Policy measures enabling societal changes are not necessarily as ethically problematic as commonly presumed and reduce the need for large-scale CDR.