The term carbon (C) sequestration has not just become a buzzword but is something of a siren’s call to scientific communicators and media outlets. Carbon sequestration is the removal of C from the atmosphere and the storage, for example, in soil. It has the potential to partially compensate for anthropogenic greenhouse gas emissions and is, therefore, an important piece in the global climate change mitigation puzzle. However, the term C sequestration is often used misleadingly and, while likely unintentional, can lead to the perpetuation of biased conclusions and exaggerated expectations about its contribution to climate change mitigation efforts. Soils have considerable potential to take up C but many are also in a state of continuous loss. In such soils, measures to build up soil C may only lead to a reduction in C losses (C loss mitigation) rather than result in real C sequestration and negative emissions. In an examination of 100 recent peer-reviewed papers on topics surrounding soil C, only 4% were found to have used the term C sequestration correctly. Furthermore, 13% of the papers equated C sequestration with C stocks. The review, further, revealed that measures leading to C sequestration will not always result in climate change mitigation when non-CO2 greenhouse gases and leakage are taken into consideration. This paper highlights potential pitfalls when using the term C sequestration incorrectly and calls for accurate usage of this term going forward. Revised and new terms are suggested to distinguish clearly between C sequestration in soils, SOC loss mitigation, negative emissions, climate change mitigation, SOC storage, and SOC accrual to avoid miscommunication among scientists and stakeholder groups in future.
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Improved knowledge of glacial-to-interglacial global temperature change yields Charney (fast-feedback) equilibrium climate sensitivity 1.2 ± 0.3°C (2σ) per W/m2, which is 4.8°C ± 1.2°C for doubled CO2. Consistent analysis of temperature over the full Cenozoic era—including ‘slow’ feedbacks by ice sheets and trace gases—supports this sensitivity and implies that CO2 was 300–350 ppm in the Pliocene and about 450 ppm at transition to a nearly ice-free planet, exposing unrealistic lethargy of ice sheet models. Equilibrium global warming for today’s GHG amount is 10°C, which is reduced to 8°C by today’s human-made aerosols. Equilibrium warming is not ‘committed’ warming; rapid phaseout of GHG emissions would prevent most equilibrium warming from occurring. However, decline of aerosol emissions since 2010 should increase the 1970–2010 global warming rate of 0.18°C per decade to a post-2010 rate of at least 0.27°C per decade. Thus, under the present geopolitical approach to GHG emissions, global warming will exceed 1.5°C in the 2020s and 2°C before 2050. Impacts on people and nature will accelerate as global warming increases hydrologic (weather) extremes. The enormity of consequences demands a return to Holocene-level global temperature. Required actions include: (1) a global increasing price on GHG emissions accompanied by development of abundant, affordable, dispatchable clean energy, (2) East-West cooperation in a way that accommodates developing world needs, and (3) intervention with Earth’s radiation imbalance to phase down today’s massive human-made ‘geo-transformation’ of Earth’s climate. Current political crises present an opportunity for reset, especially if young people can grasp their situation.
As climate change transforms the biosphere, more comprehensive and biologically relevant measurements of changing conditions are needed. Traditional climate measurements are often constrained by geographically static, coarse, sparse and biased sampling, and only indirect links to ecological responses. Here we discuss how animal-borne sensors can deliver spatially fine-grain, biologically fine-tuned, relevant sampling of climatic conditions in support of ecological and climatic forecasting. Millions of fine-scale meteorological observations from over a thousand species have already been collected by animal-borne sensors. We highlight the opportunities that these growing data have for the intersection of biodiversity and climate science, particularly in terrestrial environments. Tagged animals worldwide could close critical data gaps, provide insights about changing ecosystems and broadly function as active environmental sentinels.
Wildfires, exacerbated by climate change and human activities, threaten global ecosystems and societies. Urgent soil restoration strategies are needed to combat the resulting land degradation. Nature-based solutions (NBS) are emerging as sustainable methods to revitalize fire-affected soils and improve ecosystem recovery and resilience. Herein we provide an overview of key NBS strategies, namely microbial soil remediation, biochar application, mulching, seeding, and erosion control. Challenges in scaling and standardizing NBS remain and require robust evaluation frameworks. Further research should quantify the effectiveness of NBS, facilitate its integration into policy and mitigation strategies, and promote public and scientific acceptance. NBS offers a proactive approach to address escalating wildfire risks and harness nature’s resilience to restore fire-affected landscapes and maintain the delicate balance between communities and ecosystems in the face of growing environmental challenges.
Efforts to avert dangerous climate change by conserving and restoring natural habitats are hampered by concerns over the credibility of methods used to quantify their long-term impacts. Here we develop a flexible framework for estimating the net social benefit of impermanent nature-based interventions that integrates three substantial advances: (1) conceptualizing the permanence of a project’s impact as its additionality over time; (2) risk-averse estimation of the social cost of future reversals of carbon gains; and (3) post-credit monitoring to correct errors in deliberately pessimistic release forecasts. Our framework generates incentives for safeguarding already credited carbon while enabling would-be investors to make like-for-like comparisons of diverse carbon projects. Preliminary analyses suggest nature-derived credits may be competitively priced even after adjusting for impermanence.
The remaining carbon budget (RCB), the net amount of CO2 humans can still emit without exceeding a chosen global warming limit, is often used to evaluate political action against the goals of the Paris Agreement. RCB estimates for 1.5 °C are small, and minor changes in their calculation can therefore result in large relative adjustments. Here we evaluate recent RCB assessments by the IPCC and present more recent data, calculation refinements and robustness checks that increase confidence in them. We conclude that the RCB for a 50% chance of keeping warming to 1.5 °C is around 250 GtCO2 as of January 2023, equal to around six years of current CO2 emissions. For a 50% chance of 2 °C the RCB is around 1,200 GtCO2. Key uncertainties affecting RCB estimates are the contribution of non-CO2 emissions, which depends on socioeconomic projections as much as on geophysical uncertainty, and potential warming after net zero CO2.
There is a growing need for coastal and marine restoration, but it is not clear how to pay for it given that environmental funding is low, and national budgets are stretched in response to natural hazards. We use risk-industry methods and find that coral reef and mangrove restoration could yield strong Return on Investment (ROI) for flood risk reduction on shorelines across more than 20 Caribbean countries. These results are robust to changes in discount rates and the timing of restoration benefits. Data on restoration costs are sparse, but the Present Value (PV) of restored natural infrastructure shows that ROI would be positive in many locations even if restoration costs are in the hundreds of thousand per hectare for mangroves and millions per km for reefs. Based on these benefits, we identify significant sources of funding for restoring these natural defenses.
Little is currently known about how climate modulates the relationship between plant diversity and soil organic carbon and the mechanisms involved. Yet, this knowledge is of crucial importance in times of climate change and biodiversity loss. Here, we show that plant diversity is positively correlated with soil carbon content and soil carbon-to-nitrogen ratio across 84 grasslands on six continents that span wide climate gradients. The relationships between plant diversity and soil carbon as well as plant diversity and soil organic matter quality (carbon-to-nitrogen ratio) are particularly strong in warm and arid climates. While plant biomass is positively correlated with soil carbon, plant biomass is not significantly correlated with plant diversity. Our results indicate that plant diversity influences soil carbon storage not via the quantity of organic matter (plant biomass) inputs to soil, but through the quality of organic matter. The study implies that ecosystem management that restores plant diversity likely enhances soil carbon sequestration, particularly in warm and arid climates.
Improving the effectiveness of conservation practice requires better use of evidence.
Since 2004, researchers from the Conservation Evidence group (University of Cambridge) have engaged with over 1100 named practitioners, policymakers, funders and other academics from across the world to identify needs and develop a range of principles, tools and resources to embed evidence in decision making. The goal of this engagement (the Conservation Evidence Programme) was to deliver improved conservation practice leading to benefits for nature and society. Together, we developed a theory of change with five key strategies for delivering change, alongside a freely available Evidence Toolkit to support decision makers in achieving that change.
The authors describe the toolkit, a collection of freely available tools and resources developed by the collaborative programme, and how co-design, employing different levels of partner engagement, enabled its development.
Reflecting on our experiences highlighted a number of insights and recommendations, including the need to identify where deep engagement is a necessary condition for success; the importance of collective agreement of the roles of different partners; the need to consider how to facilitate uptake of new tools or practices, particularly where that requires changes to organisational practices or culture; and the importance of establishing processes/channels for ongoing engagement with stakeholders, with a willingness to be flexible and open to incorporating new suggestions and perspectives as needed.
The Conservation Evidence Programme has enabled practitioners, funders and policymakers to become part of a network of forward-thinking organisations that is working collaboratively to help drive more effective conservation practice through improved evidence use.
With its whopping greenhouse gas (GHG) emissions, enormous deforestation footprint, and massive waste lagoons (some visible even from space!), industrial animal agriculture is often dubbed the new fossil fuel. Dominated by a handful of mega-corporations, the livestock industry is already a major driver of the climate crisis.1 Given its projected growth, the industry is likely, by 2030, to use up 49% of the allowable budget for a relatively safe 1.5°C temperature rise.2 Yet, the climate commitments of big meat and dairy companies are little more than a cop-out. Their emissions reporting is inadequate at best, and fraught with greenwashing at worst. Despite this, between 2015 and 2020, 2,500 financial institutions ranging from high-street banks to pension funds and asset managers to universities shelled out over $478 billion USD to back meat and dairy operations globally.3 With stricter climate regulations on the horizon, these loans and investments run the risk of turning into “stranded assets,” suffering write-downs or devaluations.
On the one hand the Special Issue provides a diagnosis of the justice implications embedded in recent efforts to renature cities. Placed in the breadth of existing scholarship, it aims to explore the type of socio-environmental contradictions and contestations emerging through the deployment of nature-based solutions in a range of geographies. On the other hand, this Special Issue works towards shaping a prognosis, or a potential future for the governance of nature-based solutions, that brings social justice, indigenous knowledge and more-than-human thinking into the design and execution of projects on nature-based solutions. More generally, this Special Issue contributes to the growing literature in critical urban geography, planning and ecology on how different types of ‘natures’ are deployed and instrumentalized to defend dominant economic representations. Yet, for nature-based solutions to truly stand up to their promise, the logic and apparatus of urban development need to be decoupled from the ‘growth-at-all-costs’ mental cage by exploring degrowth narratives, for example as only then can environmental justice in its various manifestations be sought, defended and unfolded.
Climate extremes are on the rise. Impacts of extreme climate and weather events on ecosystem services and ultimately human well-being can be partially attenuated by the organismic, structural, and functional diversity of the affected land surface. However, the ongoing transformation of terrestrial ecosystems through intensified exploitation and management may put this buffering capacity at risk. Here, we summarise the evidence that reductions in biodiversity can destabilise the functioning of ecosystems facing climate extremes. We then explore if impaired ecosystem functioning could, in turn, exacerbate climate extremes. We argue that only a comprehensive approach, incorporating both ecological and hydrometeorological perspectives, enables to understand and predict the entire feedback system between altered biodiversity and climate extremes. This ambition, however, requires a reformulation of current research priorities to emphasise the bidirectional effects that link ecology and atmospheric processes.
Land-based carbon sequestration projects, such as tree planting, are a prominent strategy to offset carbon emissions. However, we risk reducing natural ecosystems to one metric – carbon. Emphasis on restoring ecosystems to balance ecosystem services, biodiversity conservation, and carbon sequestration is a more appropriate strategy to protect their functioning.
Two factors have elevated recent academic and policy interest in tropical deforestation: first, the realization that it is a major contributor to climate change; and second, a revolution in satellite-based measurement that has revealed that it is proceeding at a rapid rate. We begin by reviewing the methodological advances that have enabled measurement of forest loss at a fine spatial resolution across the globe. We then develop a simple benchmark model of deforestation based on classic models of natural resource extraction. Extending this approach to incorporate features that characterize deforestation in developing countries—pressure for land use change, significant local and global externalities, weak property rights, and political economy constraints—provides us with a framework for reviewing the fast-growing empirical literature on the economics of deforestation in the tropics. This combination of theory and empirics provides insights not only into the economic drivers and impacts of tropical deforestation but also into policies that may affect its progression. We conclude by identifying areas where more work is needed in this important body of research.
The rate and extent of global biodiversity change is surpassing our ability to measure, monitor and forecast trends. We propose an interconnected worldwide system of observation networks — a global biodiversity observing system (GBiOS) — to coordinate monitoring worldwide and inform action to reach international biodiversity targets.
Across the globe, the expansion of large-scale commodity agriculture is occurring not into empty space but over existing social systems. An understanding of the dynamics of expansion and associated impacts of commodity agriculture thus fundamentally requires examining how existing control regimes are dissolved and, simultaneously, how novel ones are assembled in order to make way for the changes in resources use that characterize these transitional moments. With this in mind, in this article, I provide a broad review of the strategies used to secure control over land prospected for agricultural commodity production, distinguishing between the tactics that are applied by agro-interested actors in order to ‘break down’ forms of existing land control, those they apply in parallel to ‘build up’ new control structures, and those strategies that are applied by actors (often smallholders) wishing to ‘hold on to’ the control that they have. I then present a framework for examining the dynamics of control transfer that builds on this analytical structure of ‘breaking down’, ‘building up’, and ‘holding on to’ control.
In water sector, nature-based solutions (NBS) are increasingly recognized as solutions to address societal challenges, while simultaneously providing human well-being and biodiversity benefits. NBS contribute to climate mitigation and adaptation, to increase flooding resilience of cities, reduce pollution, support biodiversity restoration, and enable ecosystems services provision. However, the implementation of nature-based water management solutions remains slow for several reasons. First, NBS are still novel concept, relatively unknown for many water-related stakeholders, necessitating more insight efforts to generalize their adoption. Moreover, concerns exist over their reliability, cost-effectiveness, and their long-term performance. Alongside those concerns, financial and governance barriers to implementing NBS exist, exhibiting additional needs for further research. Least but not last, technical barriers can also represent impediments in NBS implementation. In this communication, we consolidate the NBS definition comparatively to related infrastructures, such as natural, green or hybrid systems and synthesize the knowledge related to research and operational outcomes from fullscale implementation of nature-based water management solutions with the aim to identify delivered benefits but also potential drawbacks and requirements for a successful implementation. At the end, the ways to overcome the identified barriers and research recommendations are presented with the aim to foster the NBS implementation within water governance and urban planning sectors.
This planetary boundaries framework update finds that six of the nine boundaries are transgressed, suggesting that Earth is now well outside of the safe operating space for humanity. Ocean acidification is close to being breached, while aerosol loading regionally exceeds the boundary. Stratospheric ozone levels have slightly recovered. The transgression level has increased for all boundaries earlier identified as overstepped. As primary production drives Earth system biosphere functions, human appropriation of net primary production is proposed as a control variable for functional biosphere integrity. This boundary is also transgressed. Earth system modeling of different levels of the transgression of the climate and land system change boundaries illustrates that these anthropogenic impacts on Earth system must be considered in a systemic context.
The world is warming at an unprecedented pace and humaninduced climate change has already caused widespread adverse impacts on people and nature (IPCC, 2022e). There are already observed increases in frequency and intensity of climate and weather extremes in every inhabited region of the world, including heat waves, heavy precipitation events that cause flooding, drought and fire and this is expected to intensify (IPCC, 2022e). Progress on the Sustainable Development Goals has been inhibited and the most vulnerable people are disproportionately affected (IPCC, 2022e). This is only the beginning as global temperatures will continue to rise until at least the middle of the 21st century in all currently possible emission scenarios. If deep emission cuts do not occur, the temperature will rise at least 2.1°C to 3.5°C or even up to 5.7°C by the end of the century (IPCC, 2021).
In light of the critical role of tropical forests in stabilizing the global climate system through both carbon and noncarbon pathways, maintaining and increasing incentives for large-scale forest conservation is an essential component of climate action. Demand for carbon credits, one of the most promising mechanisms for funding large-scale forest conservation, has grown rapidly in recent years, with the voluntary carbon market seeing transactions worth almost US$2 billion in 2021. In 2022, however, the volume of transactions leveled off, at least in part due to concerns about reputational risk from corporate buyers afraid of greenwashing accusations.
Twenty-five years since foundational publications on valuing ecosystem services for human well-being1,2, addressing the global biodiversity crisis3 still implies confronting barriers to incorporating nature’s diverse values into decision-making. These barriers include powerful interests supported by current norms and legal rules such as property rights, which determine whose values and which values of nature are acted on. A better understanding of how and why nature is (under)valued is more urgent than ever4. Notwithstanding agreements to incorporate nature’s values into actions, including the Kunming-Montreal Global Biodiversity Framework (GBF)5 and the UN Sustainable Development Goals6, predominant environmental and development policies still prioritize a subset of values, particularly those linked to markets, and ignore other ways people relate to and benefit from nature7. Arguably, a ‘values crisis’ underpins the intertwined crises of biodiversity loss and climate change8, pandemic emergence9 and socio-environmental injustices10. On the basis of more than 50,000 scientific publications, policy documents and Indigenous and local knowledge sources, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) assessed knowledge on nature’s diverse values and valuation methods to gain insights into their role in policymaking and fuller integration into decisions7,11. Applying this evidence, combinations of values-centred approaches are proposed to improve valuation and address barriers to uptake, ultimately leveraging transformative changes towards more just (that is, fair treatment of people and nature, including inter- and intragenerational equity) and sustainable futures.
Carbon offsets from voluntary avoided-deforestation projects are generated on the basis of performance in relation to ex ante deforestation baselines. We examined the effects of 26 such project sites in six countries on three continents using synthetic control methods for causal inference. We found that most projects have not significantly reduced deforestation. For projects that did, reductions were substantially lower than claimed. This reflects differences between the project ex ante baselines and ex post counterfactuals according to observed deforestation in control areas. Methodologies used to construct deforestation baselines for carbon offset interventions need urgent revisions to correctly attribute reduced deforestation to the projects, thus maintaining both incentives for forest conservation and the integrity of global carbon accounting.
Reducing emissions from deforestation and forest degradation (REDD) projects are intended to decrease carbon emissions from forests to offset other carbon emissions and are often claimed as credits to be used in calculating carbon emission budgets. West et al. compared the actual effects of these projects with measurable baseline values and found that most of them have not reduced deforestation significantly, and those that did had benefits substantially lower than claimed (see the Perspective by Jones and Lewis). Thus, most REDD projects are less beneficial than is often claimed.
Conserving tropical forests is of utmost importance for the future of humanity and biodiversity. Changes in land use, mostly deforestation in the tropics, emit 5 billion metric tons of carbon dioxide annually—second only to fossil fuel use, which emits 35 billion tons (1). Reducing emissions to net zero is necessary to stabilize global temperatures (2). One controversial approach to tackle fossil-fuel emissions from private companies, individuals, and governments has been to “offset” them by investing in projects to either stop emissions that would have otherwise occurred, such as by reducing deforestation, or by investing in carbon uptake projects, such as forest restoration. On page 873 of this issue, West et al. (3) show that offsetting through paying projects to reduce emissions by conserving tropical forests is not reducing deforestation as claimed and is worsening climate change.
Nature-Based Solutions can be considered one of the best answers to the various consequences and problems caused by climate change, poor urbanisation and population growth. They are used not only as measures for the protection, sustainable management and restoration of natural and modified ecosystems but also as measures to mitigate certain natural disasters such as erosion, flooding, drought, storm surge and landslide. The benefit is for both biodiversity and human well-being. This paper reviews articles about optimising the selection and placement of Nature-Based Solutions. It presents several Operations Research approaches used in the context of climate adaptation. The analysis provided in this paper focuses on various case studies, state-of-the-art on Nature-Based Solutions, Operations Research algorithms, dissertations, and other papers dealing with infrastructure placement approaches in the context of climate adaptation.
Adaptation is increasing across all sectors globally. Yet, the effectiveness of adaptation is inadequate, and examples of maladaptation are increasing. To reduce the risk of maladaptation, we propose the framework, Navigating the Adaptation–Maladaptation continuum (NAM). This framework is composed of six criteria relating to outcomes of adaptation for ecosystems, the climate (greenhouse gases emissions) and social systems (transformational potential) as well as equity-related outcomes for low-income populations, women/girls and marginalized ethnic groups. We apply the NAM framework to a set of representative adaptation options showing that considerable variation exists in the potential for adaptation or the risk of maladaptation. We suggest that decision-makers assess adaptation interventions against the NAM framework criteria and prioritize responses that reduce the risk of maladaptation.