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This paper discusses options to increase mitigation ambition in crediting mechanisms that serve the Paris Agreement (PA), such as the Article 6.4 mechanism. Under the Clean Development Mechanism and other crediting mechanisms, baselines have been specified in the form of greenhouse gas (GHG) intensity factors and linked to business-as-usual developments. This means that with increasing production of goods and services through carbon market activities, absolute emissions may increase or fall only slowly. At a global level, such an approach widens the "emissions gap". To enable continued use of emissions intensity baselines in crediting mechanisms while being in line with the PA’s goal to pursue efforts to limit temperature rise to 1.5˚C, we propose to apply an "ambition coefficient" to emissions intensities of technologies when establishing the baseline. This coefficient would decrease to reflect increasing ambition over time, and reach zero when a country needs to reach net zero emissions. Due to the principle of common but differentiated responsibilities and respective capabilities, the coefficient would fall more quickly for developed than for developing countries. The latter would be able to generate emission reduction credits well beyond 2050, while for the former, crediting would stop around 2035 or before. An ambition coefficient approach would generate certainty for carbon market investors and preserve trust in international carbon markets that operate in line with the agreed, long-term ambition of the international climate regime.

The creation and curation of environmental data present numerous challenges and rewards. In this study, we reflect on the increasing amount of freely available glacier data (inventories and changes), as well as on related demands by data providers, data users, and data repositories in-between. The amount of glacier data has increased significantly over the last two decades as remote sensing techniques have improved and free data access is much more common. The portfolio of observed parameters has increased as well, which presents new challenges for international data centers, and fosters new expectations from users. We focus here on the service of the Global Terrestrial Network for Glaciers (GTN-G) as the central organization for standardized data on glacier distribution and change. Within GTN-G, different glacier datasets are consolidated under one umbrella, and the glaciological community supports this service by actively contributing their datasets and by providing strategic guidance via an Advisory Board. To assess each GTN-G dataset, we present a maturity matrix and summarize achievements, challenges, and ambitions. The challenges and ambitions in the democratization of glacier data are discussed in more detail, as they are key to providing an even better service for glacier data in the future. Most challenges can only be overcome in a financially secure setting for data services and with the help of international standardization as, for example, provided by the CoreTrustSeal. Therefore, dedicated financial support for and organizational long-term commitment to certified data repositories build the basis for the successful democratization of data. In the field of glacier data, this balancing act has so far been successfully achieved through joint collaboration between data repository institutions, data providers, and data users. However, we also note an unequal allotment of funds for data creation and projects using the data, and data curation. Considering the importance of glacier data to answering numerous key societal questions (from local and regional water availability to global sea-level rise), this imbalance needs to be adjusted. In order to guarantee the continuation and success of GTN-G in the future, regular evaluations are required and adaptation measures have to be implemented.

Inverse synthetic aperture radar is a commonly adopted technique for producing high-resolution images of moving targets. This article investigates the imaging capabilities of high-frequency and high-bandwidth systems by means of two distinct experiments. The deployed sensor is the Fraunhofer FHR MIRANDA-35, a millimeter-wave synthetic aperture radar airborne system, which transmits frequency-modulated continuous-wave signals at the Ka-band and is capable of achieving centimeter resolution. The performances are assessed by comparing the derived estimates (e.g., radial velocity and acceleration, and dimensions) with independent ground measurements. The resulting accuracy can be summarized as follows: the mean value of the percent error is 2.05% and 2.11% for radial velocity and acceleration, respectively, and 4.27% for the target dimensions.

Digital surface models (DSMs) are sets of elevation data of the Earth's surface, useful for applications such as urban studies and height estimation of buildings. They can be derived from a set of synthetic aperture radar (SAR) images acquired in an interferometric or tomographic configuration. Each image acquisition is usually focused in radar geometry. In this work, we present steps required to derive DSMs from SAR single-look complex (SLC) products focused in map geometry (geocoded). We modified existing tomographic reconstruction techniques to be able to operate with geocoded SLCs and extended methods to operate with 3-D geocoded SLCs. The performance analysis showed that methods using 3-D geocoded SLC products yielded DSMs with fewer outliers and retained more information of the illuminated area, with a cost of higher computational complexity. Compressive sensing methods using 2-D geocoded SLCs can be a good alternative due to their comparatively moderate computational complexity.

Climate data records (CDRs) of essential climate variables (ECVs) as defined by the Global Climate Observing System (GCOS) derived from satellite instruments help to characterize the main components of the Earth system, to identify the state and evolution of its processes, and to constrain the budgets of key cycles of water, carbon, and energy. The Climate Change Initiative (CCI) of the European Space Agency (ESA) coordinates the derivation of CDRs for 21 GCOS ECVs. The combined use of multiple ECVs for Earth system science applications requires consistency between and across their respective CDRs. As a comprehensive definition for multi-ECV consistency is missing so far, this study proposes defining consistency on three levels: 1) consistency in format and metadata to facilitate their synergetic use (technical level); 2) consistency in assumptions and auxiliary datasets to minimize incompatibilities among datasets (retrieval level); and 3) consistency between combined or multiple CDRs within their estimated uncertainties or physical constraints (scientific level). Analyzing consistency between CDRs of multiple quantities is a challenging task and requires coordination between different observational communities, which is facilitated by the CCI program. The interdependencies of the satellite-based CDRs derived within the CCI program are analyzed to identify where consistency considerations are most important. The study also summarizes measures taken in CCI to ensure consistency on the technical level, and develops a concept for assessing consistency on the retrieval and scientific levels in the light of underlying physical knowledge. Finally, this study presents the current status of consistency between the CCI CDRs and future efforts needed to further improve it.

We present results from the Munich Nitrogen dioxide (NO2) Imaging Campaign (MuNIC), where NO2 near-surface concentrations (NSCs) and vertical column densities (VCDs) were measured with stationary, mobile, and airborne in situ and remote sensing instruments in Munich, Germany. The most intensive day of the campaign was 7 July 2016, when the NO2 VCD field was mapped with the Airborne Prism Experiment (APEX) imaging spectrometer. The spatial distribution of APEX VCDs was rather smooth, with a horizontal gradient between lower values upwind and higher values downwind of the city center. The NO2 map had no pronounced source signatures except for the plumes of two combined heat and power (CHP) plants. The APEX VCDs have a fair correlation with mobile multi-axis differential optical absorption spectroscopy (MAX-DOAS) observations from two vehicles conducted on the same afternoon (r=0.55). In contrast to the VCDs, mobile NSC measurements revealed high spatial and temporal variability along the roads, with the highest values in congested areas and tunnels. The NOx emissions of the two CHP plants were estimated from the APEX observations using a mass-balance approach. The NOx emission estimates are consistent with CO2 emissions determined from two ground-based Fourier transform infrared (FTIR) instruments operated near one CHP plant. The estimates are higher than the reported emissions but are probably overestimated because the uncertainties are large, as conditions were unstable and convective with low and highly variable wind speeds. Under such conditions, the application of mass-balance approaches is problematic because they assume steady-state conditions. We conclude that airborne imaging spectrometers are well suited for mapping the spatial distribution of NO2 VCDs over large areas. The emission plumes of point sources can be detected in the APEX observations, but accurate flow fields are essential for estimating emissions with sufficient accuracy. The application of airborne imaging spectrometers for studying NSCs is less straightforward and requires us to account for the non-trivial relationship between VCDs and NSCs.

Adaptation needs in high mountain communities are increasingly well documented, yet most efforts to address these needs continue to befall mountain people who have contributed little to the problem of climate change. This situation represents a contravention of accepted norms of climate justice and calls attention to the need for better understanding of prospects for externally resourced adaptation initiatives in high mountain areas. In response, this paper examines the architecture of formal adaptation support mechanisms organized through the United Nations Framework Convention on Climate Change (UNFCCC) and how such mechanisms might help to meet adaptation needs in high mountain communities. It outlines key global adaptation initiatives organized through the UNFCCC, clarifies idealized linkages between these global adaptation initiatives and meeting local adaptation needs, and evaluates actual progress in connecting such support with discrete adaptation needs in the upper Manaslu region of Nepal. The paper then critically examines observed shortcomings in matching adaptation support organized through the UNFCCC with local adaptation needs, including complications stemming from the bureaucratic nature of formal adaptation support mechanisms, the intervening role of the state in delivering aid, and the ways in which these complexities intersect with the specific socio-cultural contexts of mountain communities. It concludes by highlighting several prospects for increasing the quantity and quality of adaptation support to mountain communities. These opportunities are considered alongside several salient concerns about formal adaptation support mechanisms in an effort to provide a well-rounded assessment of the prospects for planned adaptations in high mountain communities.

Pressure on the biodiversity of ecosystems along many rivers is growing continuously due to the increasing number of hydropower facilities regulating downstream flow and sediment regimes. Despite a thorough understanding of the short-term processes and interactions at this hydro-biosphere interface, long-term analyses of the impacts on floodplain dynamics are lacking. We used interannual Landsat 4, 5, 7, and 8 time series to analyze the effects of hydrological events on floodplain vegetation in four mountainous floodplains in the Swiss Alps. Using a spectral mixture analysis approach, we demonstrate that the floodplain vegetation dynamics of mountainous rivers can be recovered at a spatial resolution of 30 m. Our results suggest that interactions between floods and floodplain vegetation are complex and not exclusively related to flood magnitude. Of the four reaches analyzed, only data gathered along the submountainous reach with a quasi-natural flow regime show a clear link between remotely sensed vegetation indices and floods. In addition, our 29-year time series shows a continuous upward trend in vegetation indices along the floodplains, strongest in the reaches affected by hydropower facilities. The approach presented in this study can be easily replicated in other mountain ranges by providing available flow data to verify the impact of hydropower on floodplain vegetation dynamics.

Spectral Information Systems provide a framework to assemble, curate, and serve spectral data and their associated metadata. This article documents the evolution of the SPECCHIO system, devised to enable long-term usability and data-sharing of field spectroradiometer data. The new capabilities include a modern, web-based client-server architecture, a flexible metadata storage scheme for generic metadata handling, and a rich application programming interface, enabling scientists to directly access spectral data and metadata from their programming environment of choice. The SPECCHIO system source code has been moved into the open source domain to stimulate contributions from the spectroscopy community while binary distributions, including the SPECCHIO virtual machine, simplify the installation and use of the system for the end-users.

The issue of climate related loss and damage (L&D) has re-emerged and gained significant traction in international climate policy in recent years. However, many aspects remain unclear, including how aspects of liability and compensation in relation with L&D will be treated under the UNFCCC, human rights and environmental law. Furthermore, the type of scientific evidence required to link climate change impacts for each of these L&D mechanisms needs to be clarified. Here we analyze to which degree different types of scientific evidence can inform L&D discussions and policies. We distinguish between (i) L&D observation, (ii) understanding causation, and (iii) linking L&D to anthropogenic emissions through attribution studies. We draw on three case studies from Australia, Colombia and Alaska to demonstrate the relevance of the different types of evidence. We then discuss the potential and limitations of these types of scientific evidence, in particular attribution, for informing current L&D discussions and policies. Attribution (iii) sets the highest bar, but also provides the most complete set of information to support adaptation, risk reduction and L&D policies. However, rather than suggesting that attribution is a necessary requirement for L&D policies we want to highlight its potential for facilitating a more thematically structured, and thus hopefully a more constructive, policy and justice discussion.

A significant number of countries classified as “developing” during the negotiation of the UNFCCC in the early 1990s have experienced rapid economic growth and increase of greenhouse gas emissions since then. We assess whether governments of such countries are considering taking up responsibility for emissions mitigation in the context of the UNFCCC’s principle of common but differentiated responsibility (CBDR). While an expansion of mitigation responsibility to Non-Annex I countries has been strongly opposed by overarching groups such as the G 77, we find countries such as South Africa and Indonesia that have clearly supported binding commitments. Other countries like China and Singapore oppose binding commitments but increasingly engage in domestic mitigation action. Moreover, China has pledged a significant amount of climate finance. Even in the countries of the Gulf Cooperation Council, which adamantly refuse mitigation commitments, some mitigation action seems to emerge. We thus foresee that countries will increasingly adopt differentiated positions regarding their responsibility for mitigation. This could provide new dynamics in international climate negotiations.

Novel strategies are required to reduce uncertainties in the assessment of ecosystem transpiration (T). A major problem in modelling T is related to the complexity of constraining canopy stomatal resistance (rsc), accounting for the main biological controls on T besides non biological controls such as aerodynamic resistances or energy constraints. The novel Earth observation signal sun-induced chlorophyll fluorescence (SIF) is the most direct measure of plant photosynthesis and offers new pathways to advance estimates of T. The potential of using SIF to study ecosystem T either empirically or in combination with complex mechanistic models has already been demonstrated in recent studies. The diversity of environmental drivers determining diurnal and seasonal dynamics in T and SIF independently requires additional investigation to guide further developments towards robust SIF-informed T retrievals. This study consequently aims to identify relevant biotic and abiotic environmental drivers affecting the capability of SIF to inform estimates of ecosystem T. We used observational data from a temperate mixed forest during the leaf-on period and a Penman-Monteith (PM) based modelling framework, and observed varying sensitivities of SIF-informed approaches for diurnal and seasonal T dynamics (i.e. r2 from 0.52 to 0.58 and rRMSD from 17 to 19%). We used the PM based modelling framework to investigate systematically the sensitivity of SIF to diurnal and seasonal variations in rsc when empirically and mechanistically embedded in the models. We used observations and the Soil-Vegetation-Atmosphere-Transfer model SCOPE to study the dependence of SIF and T on abiotic and biotic environmental drivers including net radiation, air temperature, relative humidity, wind speed, and leaf area index. We conclude on the potential of SIF to advance estimates of T and suggest preferring more sophisticated modelling frameworks constrained with SIF and other Earth observation data over the single use of SIF to assess reliably ecosystem T across scales.

Purpose of Review: Understanding of how fire affects the carbon cycle and climate is crucial for climate change adaptation and mitigation strategies. As those are often based on Earth system model simulations, we identify recent progress and research needs that can improve the model representation of fire and its impacts. Recent Findings: New constraints of fire effects on the carbon cycle and climate are provided by the quantification of the carbon ages and effects of vegetation types and traits. For global scale modelling, the low understanding of the human–fire relationship is limiting. Summary: Recent developments allow improvements in Earth system models with respect to the influences of vegetation on climate, peatland burning and the pyrogenic carbon cycle. Better understanding of human influences is required. Given the impacts of fire on carbon storage and climate, thorough understanding of the effects of fire in the Earth system is crucial to support climate change mitigation and adaptation.

Shifts in phenology are important traces of climate change affecting mountainous ecosystems. We present an analysis of changes in spring phenology using a suite of Earth observation based parameters, i.e., start of season (SOS), snow cover extent and meteorological variables from 1991 up to 2012/2014 for the European Alps. Our results show that SOS tends to occur earlier throughout the Alps during this period and spring temperatures have increased in the Eastern Alps. Spring temperatures presented a predominant influence on SOS for both, grasslands and forests across elevations between 500–2,200 m asl, while this effect is particularly pronounced in the northeastern Alps. Snow cover duration and snow cover melting days showed secondary impact on SOS. Our research provides a comprehensive observation of spatiotemporal changes in alpine spring vegetation phenology and its driving factors. They improve our understanding of the sensitivity of the European Alps ecosystems to a changing climate.

In rugged terrain, topography substantially influences the illumination and observation geometry, and thus, the bidirectional reflectance distribution function (BRDF) of a surface. While this problem has been known and investigated for spaceborne optical data since the 1980s, it has led to several well-known topographic correction methods. To date, the methods developed for spaceborne data were equivalently applied to airborne data with distinctly higher spatial resolution, illumination/observation angle configurations and finally (instantaneous) field of view (FOV). On the one hand, this article evaluates, whether such a transfer of methods from spaceborne to airborne acquisitions is reasonable. On the other hand, a new Lambertian/statistical-empirical correction method is introduced. While in the spaceborne case the Modified Minnaert (MM) and the Statistical-Empirical (SE) methods performed best, MM led to the statistically and visually best compromise for the airborne data. Our results suggest further that with a higher spatial resolution various effects come into play (FOV widening; changing the fraction of geometric, volumetric and isotropic scattering, etc.), compromising previously successful methods, such as the SE method.

Climate journalism gathers, evaluates, selects, and presents information about climate change, its characteristics, causes, and impacts, as well as ways to mitigate it, and distributes them via technical media to general and specialist audiences. It is an important source of information about climate change for many people. Currently, however, the media ecosystem surrounding climate journalism is changing, with economic conditions becoming more strenuous, more communicators joining the debate, and social media changing the affordances of communication. This advanced review synthesizes scholarship on the status quo and the changes taking place in climate journalism in the Global North and the Global South. While it demonstrates that the scholarship has distinct gaps and biases, it does distill several robust findings. First, it shows that the organizational embedding of climate journalism is changing, with specialist reporters becoming scarce and working under more strenuous conditions and with the emergence of online-born news media and niche sites specializing in climate journalism. It also suggests that few specialist climate journalists exist in the Global South. Second, it demonstrates that the range of roles available to climate journalists has diversified, with a shift from “gatekeeping” to “curating” roles. Third, it indicates that climate journalists’ relationships with their sources have changed. Elite sources have been, and still are, important, but their composition has shifted from scientists to a broader range of stakeholders. Correspondingly, there seems to be a strong and rising influence of stakeholder PR on climate journalism.

As the international community’s best expression of a collective vision of a desirable future, the 2015 UN Sustainable Development Goals (SDGs) present a framework against which to assess the broader impact of emerging technologies. Implications of technologies and practices for removing CO2 from the atmosphere (CDR) are not fully understood and have not yet been mapped against the full range of SDGs. CDR is widely seen as necessary to achieve the Paris Agreement’s global goal of limiting warming to 1.5-2°C, yet local geographical, socio-economic, and political interdependencies are often overlooked. This review synthesizes the best available understandings of potential implications of CDR options aiming to complement emissions reductions. It seeks to identify effects on and interactions between specific social, environmental, and policy environments, in which various CDR options could be pursued. Climate change mitigation and co-benefits from CDR could significantly benefit SDGs, yet poorly designed CDR policies could also challenge SDGs. Specific CDR options could generate conflicts over land, water, biomass, or electric power resources, and exclude communities from policy benefits with negative cascading effects for a range of SDGs. In the literature, implications of CDR activities on sustainable development are derived from current pilot activities, inferred from similar practices already operational or model outputs regarding land, energy, or material requirements. Important gaps remain. We identify questions for further disciplinary and inter- or transdisciplinary work strengthening understanding of how CDR could either support or threaten the achievement of the SDGs. Key policy insights CO2 removal (CDR) appears essential for limiting warming to well below 2°C; such stabilization of global climate is a precondition for at least partially achieving the SDGs. CDR options can generate positive and negative local/regional impacts on various SDGs via physical, social, economic, and political channels. None of these options are universally ‘good’ or ‘bad’. The scale of implementation of CDR and related impacts are highly dependent on policy design and national planning processes. More research is needed to clarify how policy design can allow CDR options to generate synergies between, and prevent harm across, multiple SDGs.

In 2019, several countries across Western Europe experienced record-breaking temperatures and heatwaves which, in some cases, reached temperatures of over 40 °C for three to four consecutive days during June and July. Extreme event attribution (EEA) studies show that anthropogenic climate change increased the likelihood of these events by at least three to ten times (with different results for different countries), and increased the temperature by 1.2 to 3.0 °C. The heatwaves resulted in more than 2500 deaths. Based on a content analysis of 267 articles taken from 20 of the most visited online news websites in four of the countries most affected by the heatwaves (France, Germany, the Netherlands, and the UK), we find strong variations between countries and media outlets in how much attention journalists pay to links between climate change and the heatwaves (the UK media the most, and politically left-leaning titles more than right-leaning ones); many different types of statements depicting the link but in general, the presence of accurate, science-based descriptions; a strong presence of EEA studies in the coverage; and more quotes from climate scientists than politicians and NGOs, with a minimal presence of climate change skeptics. These results contribute to our understanding of media coverage around extreme weather events in different countries and media outlets, and how such events might serve as opportunities for public engagement with climate change.

This article explores the growing interest in care within geography. Focusing on care as waged work, we trace current transformations through commodification and digitalisation. We discuss how the private household is turning into a precarious and feminised workplace for a growing number of workers, and we show how this development is promoted by the rise of labour agencies that facilitate the transnational recruitment of care workers. The literature on global care chains illustrates how the recruitment of migrant workers fills care deficits in destination countries while opening up care gaps in sending countries. We review this literature from economic geography and beyond and reflect on the continuing feminisation and devaluation of care labour. Based on these critical insights, we examine how processes of digitalisation contribute to reshaping care work. We discuss the ambivalent effects of digital technologies on care and argue that there is an urgent need to intensify our engagement with the processes and effects of digital transformations. In our conclusions, we call for strengthening the budding debate on alternative visions of caring within geography and point to avenues for future engagement.

Major boreal forest disturbance and associated carbon emissions have been reported in the coldest region of the Northern Hemisphere. Related biophysical feedbacks to climate remain highly uncertain but might reduce warming effects expected from carbon emissions. This study quantifies albedo change after disturbance, primarily fires, in larch‐dominated forests around Yakutsk as compared to undisturbed areas with natural albedo variability, using satellite‐based time series. The related annual mean shortwave radiative forcing was −6.015 W/m2 for the 13 years following forest disturbance. It was highly negative during snow‐covered months (−3.738 to −13.638 W/m2), but positive (+5.441 W/m2) for the summer months in the first year after disturbance, decreasing afterward and also turning into a negative forcing after 5 years. Forcing by surface shortwave radiation must be considered to assess the impact of boreal forest disturbance on climate and additional feedbacks, such as increased permafrost thaw or transition to alternative ecosystem states., Plain Language Summary: Boreal forests of northeastern Siberia are experiencing disturbances such as fires and permafrost degradation. These disturbances can trigger changes in biomass and heating dynamics resulting in major feedbacks to the local and regional climate. This study quantifies albedo, the ratio of reflected sunlight to incoming sunlight, in a larch‐dominated forest area in Siberia over a time span of 13 years after fire disturbance. Land surface albedo showed significant changes due to larch forest disturbance, which often recovered to a birch‐dominated forest. During summer months of the first 4 years after the forest fire, the decrease in albedo caused a local warming. For snow‐covered seasons, forest disturbance and the corresponding albedo change caused low local cooling directly after disturbance, and this cooling effect increased during the following decade., Key Points: Major boreal forest cover disturbance in the coldest region of the Northern Hemisphere (Yakutsk, Siberia) during 2001–2014 resulted in a significant change in surface albedo Surface albedo change‐related mean annual surface shortwave radiative forcing was −6.015 W/m2 but varied with season and strongly decreased during the 13 years following disturbance Shortwave radiative forcing can be directly linked to a vegetation trajectory from deciduous needleleaf to broadleaf dominated forest

Sustainable development (SD) co-benefits have increasingly become relevant in the discussions about the performance of international carbon market mechanisms. Actually, the Clean Development Mechanism (CDM) of the Kyoto Protocol always had the formal objective to promote SD. However, the principle of sovereignty has prevented mandatory rules to ensure the actual accrual of SD co-benefits. After increasingly strident media and NGO criticisms about CDM projects actually leading to negative impacts on SD, the UNFCCC CDM regulators provided a voluntary tool for SD benefit assessment. However, only a very small share of CDM activities has actually used this tool. The main drivers for ensuring SD benefits nowadays are the heightened political sensitivity about the linkages between climate and sustainable development since the adoption of the Agenda 2030 as well as differentiation of demand for international credits, with a number of buyers having prohibited the import of credits with perceived low SD contributions. For the new market mechanisms under Article 6 of the Paris Agreement (PA), the rules currently under negotiations foresee a continuation of the voluntary approach to SD contributions. It remains to be seen whether buyer power enforces a ‘de facto’ SD benefit regulation.

The Paris Agreement’s success depends on parties’ implementation of their Nationally Determined Contributions (NDCs) towards the Paris Agreement’s goals. In these climate action plans, most developing countries make their mitigation and adaptation contributions conditional upon receiving international support (finance, technology transfer and/or capacity building). While provision of support for NDC implementation could enhance equity among countries, the feasibility of NDC implementation might be challenged by the large number of conditional NDCs. This paper addresses the implications of this tension based on an analysis of all 168 NDCs. We find that feasibility is challenged because conditions applied to NDCs are often not well defined. Moreover, the costs of implementing all conditional contributions are too high to be covered by existing promises of support from developed countries, even if the entire annual $100 billion of climate finance were earmarked for NDC implementation. Consistent with principles of equity and the prioritization in the Paris Agreement, a higher proportion of Least Developed Countries (LDCs) and Small Island Developing States (SIDS) have conditional NDCs than do other countries. However, differences between the distribution of countries requesting support and those currently receiving support, in particular among middle-income countries, demonstrates potential tensions between feasibility and equity. The article concludes with recommendations on how cost estimates and updated NDCs can be strengthened to ensure support for NDC implementation is targeted more equitably and cost-effectively. Key policy insights -Support requested by developing countries to implement conditional NDCs far exceeds existing funding pledges. -Differences between existing patterns of financial assistance, and those implied by requests under conditional NDCs, mean that supporting NDCs may require a significant shift in provider countries’ priorities for allocating climate finance. This may challenge feasibility. -The Paris Agreement’s provisions on prioritizing LDCs and SIDS offer valuable guidance in making difficult choices on allocating support. -To increase the likelihood of attracting support, developing countries (assisted by capacity building as needed), should include credible cost estimates in future NDCs and formulate investment plans. -By outlining plans to mobilize support in their NDCs, developed countries can reassure developing countries that raising the ambition of NDCs is feasible

The Paris Agreement requires mitigation contributions from all Parties. Therefore, the determination of additionality of activities under the market mechanisms of its Article 6 will need to be revisited. This paper provides recommendations on how to operationalize additionality under Article 6. We first review generic definitions of additionality and current approaches for testing of additionality before discussing under which conditions additionality testing of specific activities or policies is still necessary under the new context of the Paris Agreement, that is, in order to prevent increases of global emissions. We argue that the possibility of ‘hot air’ generation under nationally-determined contributions (NDCs) requires an independent check of the NDC’s ambition. If the NDC of the transferring country does contain ‘hot air’, or if the transferred emission reductions are not covered by the NDC, a dedicated additionality test should be required. While additionality tests of projects and programmes could continue to be done through investment analysis, for policy instruments new approaches are required. They should be differentiated according to type of policy instrument. For regulation, we suggest calculating the resulting pay-back period for technology users. If the regulation generates investments exceeding a payback period threshold, it could be deemed additional. Similarly, carbon pricing policies that generate a carbon price exceeding a threshold could qualify; for trading schemes an absence of over-allocation needs to be shown. The threshold should be differentiated according to country categories and rise over time. Key policy insights Without additionality testing, market mechanisms under the Paris Agreements might lead to an international diffusion of ‘hot air’. To avoid this, an independent assessment of NDC ambition is in order. Otherwise, activities under the mechanisms need to undergo specific additionality tests. Additionality testing of projects and programmes should build on the experience developed under the Kyoto Protocol mechanisms. Bold approaches are needed for assessing additionality of policies. To avoid cumbersome assessment of all activities triggered by such policies, highly aggregated approaches are suggested, ranging from payback period thresholds for technologies mandated by regulation to minimum price levels triggered by carbon pricing policies. Over time, the stringency of threshold values should increase.

Journal of Geophysical Research: Earth Surface, 123 (6), ISSN:0148-0227, ISSN:2169-9003, ISSN:2169-9011

While glacier mass changes in the Himalaya since the year 2000 are relatively well investigated, there is still a lack of knowledge about the long-term changes and their climatic drivers. We use historical and recent remote sensing data to study glacier changes of the Lahaul-Spiti region in western Himalaya, India, over the last four decades (1971–2013). The glaciers were losing mass moderately between 1971 and 1999 (− 0.07 ± 0.1 m w.e. year−1) while the losses have increased significantly after 2000 (− 0.30 ± 0.1 m w.e. year−1). During both periods, the debris-covered glaciers and glaciers having pro-glacial lakes lost more mass than glaciers with little debris cover. Mass changes of Chhota Shigri, a benchmark glacier, closely matched the average of the overall study area. Analysis of gridded climate data covering the period 1948–2015 shows that the mean annual air temperature increased, especially since 1995. One dataset shows a significant increase in summer temperature after 2000 while others do not show any trend. The mean annual precipitation started decreasing around 1995 and reached a minimum around 2000, after which it increased again. One dataset shows a significant decrease in winter precipitation after 2000 while the others show no trend. The climate data indicate that the increase in mean annual temperature from 1995, combined with no significant trend/significant decrease of winter precipitation in the period after 2000, has probably resulted in accelerated mass loss of the glaciers.

In order to mobilize the volume of mitigation required to reach a global emissions path consistent with 1.5°C, policy instruments need to be much more stringent than they have been to date. They wi...

Field spectroscopy is increasingly used in various fields of science: either as a research tool in its own right or in support of airborne- or space-based optical instruments for calibration or validation purposes. Yet, while the use of the instruments appears deceptively simple, the processes of light and surface interactions are complex to be measured in full and are further complicated by the multidimensionality of the measurement process. This study exemplifies the cross validation of in situ point spectroscopy and airborne imaging spectroscopy data across all processing stages within the spectroscopy information hierarchy using data from an experiment focused on vegetation. In support of this endeavor, this study compiles the fundamentals of spectroscopy, the challenges inherent to field and airborne spectroscopy, and the best practices proposed by the field spectroscopy community. This combination of theory and case study shall enable the reader to develop an understanding of 1) some of the commonly involved sources of errors and uncertainties, 2) the techniques to collect high-quality spectra under natural illumination conditions, and 3) the importance of appropriate metadata collection to increase the long-term usability and value of spectral data.

Field spectroradiometers are often comprised of several spectral detectors to sample the full range of reflected solar irradiance. An example of such an instrument is the Analytical Spectral Devices (ASD) full-range spectroradiometer, featuring three spectral detectors to capture spectra between 350 and 2500 nm. The resulting spectra often exhibit radiometric steps at the joints of these detectors. This study investigates the influence of external temperature and humidity on the magnitude of these steps by experiments based on a climate chamber. Relative radiometric errors at the detector borders were found to reach up to 16% for the visible and near infrared and 21% for the shortwave infrared 2 (SWIR2), whereas relative reflectance errors are target dependent, typically ranging between 2% and 6%. The derived sensor model provides a physically based explanation of the changes in radiometry due to temperature and demonstrates that all spectral bands are affected to a higher or lesser degree. The model can be used to correct for the effect of temperature on the recorded radiances. Applying the model to ASD instruments that were not tested in the climate chamber still leads to reasonable correction results with RMSE values of 0.6%.

In this paper, we report the outcomes of the 2015 data fusion contest organized by the Image Analysis and Data Fusion Technical Committee (IADF TC) of the IEEE Geoscience and Remote Sensing Society. As for previous years, the IADF TC organized a data fusion contest aiming at fostering new ideas and solutions for multisource studies. The 2015 edition of the contest proposed a multiresolution and multisensorial challenge involving extremely high resolution RGB images (with a ground sample distance of 5 cm) and a 3-D light detection and ranging point cloud (with a point cloud density of approximatively 65 pts/m2 ). The competition was framed in two parallel tracks, considering 2-D and 3-D products, respectively. In this Part B, we report the results obtained by the winners of the 3-D contest, which explored challenging tasks of road extraction and ISO containers identification, respectively. The 2-D part of the contest and a detailed presentation of the dataset are discussed in Part A.

Agroecosystems play an important role in providing economic and ecosystem services, which directly impact society. Inappropriate land use and unsustainable agricultural management with associated nutrient cycles can jeopardize important soil functions such as food production, livestock feeding, and conservation of biodiversity. The objective of this study was to integrate remotely sensed land cover information into a regional land management model (LMM) to improve the assessment of spatially explicit nutrient balances for agroecosystems. Remotely sensed data and an optimized parameter set contributed to an improved LMM output, allowing for a better land allocation within the model. The best input parameter combination was based on two different land cover classifications with overall accuracies of 98%, improving the land allocation performance compared with using nonspatially explicit input. We conclude that the combined use of remote sensing data and the LMM has the potential to provide valuable guidance for farm practices. It further helps to generate a spatial description of farm-level nutrient balance, a crucial ability when choosing policy options related to sustainable management of agricultural soils.

The role of market mechanisms was far from certain in the lead up to the 2015 Paris Climate Conference. The use of ‘constructive ambiguity’ led to Article 6 of the Paris Agreement, with Article 6.2 specifying a mechanism with limited international oversight, and Article 6.4 establishing a ‘Sustainable Development Mechanism’ (SDM) subject to detailed rules. Clear operationalization of these mechanisms remains a challenge, especially regarding the critical accounting issue that could not be resolved at the 2018 Katowice Climate Conference (COP24) – how to apply corresponding adjustments, especially regarding sectors not covered by targets under nationally-determined contributions (NDCs). By using fictitious examples, we explain two possible approaches to using Internationally Transferred Mitigation Outcomes (ITMOs) under Article 6.2 for achieving NDCs: a ‘target-based’ one where the acquiring Party adds the ITMO amount to the target level of its NDC; and a ‘tally-based’ one where the acquiring Party removes the ITMO amount from the final tally of its NDC. We discuss how these approaches influence the way to make corresponding adjustments and to avoid ‘double counting’. The first one leads to ‘target/budget-based accounting’, the second one to ‘emission-based accounting’. For mitigation outside the scope of the host Party's NDC, we propose using a tally-based interpretation of ITMO use, as opposed to the target-based variety used in the 1997 Kyoto Protocol, and stress the need for additionality testing. This interpretation allows for mandatory corresponding adjustments for all ITMO usage, while the host Party NDC level remains unchanged. A buffer registry is created for corresponding non-NDC adjustments of the selling party. Key policy insights Under the Paris Agreement, transfers of emissions units between two countries through the Article 6 mechanisms need a corresponding adjustment on both sides to prevent double counting. Corresponding adjustments can be applied either to emissions targets under NDCs or measured emissions levels. The transfer of emissions reduction credits generated outside an NDC should lead to a corresponding adjustment of a buffer registry of the selling country, but not its emissions level/NDC target. Such credits should only be generated if additionality of the reductions is shown.

Natural floodplains are characterized by a complex habitat mosaic. However, damming, water storage, and hydropower production affect many floodplains by altering their natural habitat diversity. Field sampling data and imaging spectroscopy are used in combination with statistical models to assess resource allocation strategies of willow stands in perialpine floodplains. Three contrasting floodplain reaches located along two rivers in Switzerland serve as test beds: The Sarine River is partitioned into an upstream and downstream segment under the influence of a dam and a hydropower plant, while the Sense River represents an undisturbed, natural floodplain. Airborne imaging spectrometer data allow mapping of spatially distributed Competitor/Stress tolerator/Ruderal (CSR) strategies using a partial least square modeling approach. Using cross validation, we demonstrate that a statistical modeling approach can reveal variations in CSR scores based on the StrateFy model. Such intraspecific variation of CSR scores cannot be captured by a strategy categorization based solely on the species. Results reveal that willows shifted toward more competition and less stress tolerance along hydrologically altered reaches compared to the willows strategy along the natural control. Moreover, the overall distribution of strategies indicates that stress factors (i.e., limiting growth factors), rather than disturbance (i.e., events leading to partial or total destruction), shape the plant traits of alluvial willow trees. Detailed assessments of resource allocation strategies contribute to a more complete understanding of the continuous and reciprocal shaping between flow regimes, landforms, and alluvial vegetation.

The Paris Agreement will greatly benefit from the past experience with international market mechanisms for greenhouse gas (GHG) emissions reductions and related regulatory systems, which have gone through four periods with specific challenges. The first period 1997 - 2004 operationalized the mechanisms defined in the Kyoto Protocol, the Clean Development Mechanism (CDM) and Joint Implementation (JI). Pilot activities in different sectors were undertaken by the public sector, and the first baseline and monitoring methodologies officially approved. Between 2005 and 2011, the carbon markets expanded massively. The EU emission trading scheme (EU ETS) was linked to the Kyoto mechanisms, creating demand for carbon credits from the private sector. During this “gold rush” period criticism emerged with regarding the uneven geographical distribution of projects, as well as environmental integrity problems related to baselines and additionality. The next period saw a collapse in carbon prices between 2012 and 2014, limiting the development of new projects. The quantitative limits on the offset use in the EU ETS were reached and the failure to agree on a new international regime resulted in a drying up of demand from governments. The 2015 – 2018 period is characterized by a gradual stabilization of the international climate regime. The Paris Agreement adopted in 2015 increases complexity through global participation in mitigation. Future carbon markets will therefore face both old challenges – supply-demand balance, environmental integrity, transaction costs – and new ones – interactions with other policies and national targets, and sectoral/policy baselines and additionality checks preventing hot air proliferation.

Knowing the height of the snowfall limit during precipitation events is crucial for better understanding a number of hydro-climatic processes, for instance glacier-climate interactions or runoff from high mountain catchments. However, knowledge on heights of the phase change during precipitation events is limited by the small number of meteorological measurements available at high altitudes, such as the Himalayas. The bright band (BB) of satellite based radar data may be a promising proxy for the snow/rain transition during particular stratiform precipitation events over high mountain regions. The BB is a horizontal layer of stronger radar reflectivity caused by the melting of hydrometeors at the level where solid precipitation turns into rain. Here, we present BB heights detected by the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) 2A23 algorithm over a mountainous area. To assess the performance of BB heights, we have compared a 17‑year data set of BB estimations of the TRMM PR with radiosonde observations and meteorological station data from Srinagar, Kashmir Valley, India. During March to November, the BB lies mostly about 200 to 800 m below the freezing level (FL) recorded by radiosondes. The correlation between BB and FL heights extrapolated from a ground-based station is smaller and depends on the timing of the air temperature measurement – an important finding for applying extrapolation techniques in data sparse regions. Further on, we found a strong seasonal and monthly variability of the BB height, e.g. extending in summer months from about 2700 m to almost 6000 m asl. Comparison with near surface rain intensity from the TRMM PR product 2A25 indicates that – during intense monsoonal summer precipitation events – the BB height is concentrated between about 3500 and 4000 m asl. We can conclude that TRMM PR BB data deliver valuable complementary information for regional or seasonal variability in snow/rain transition in data sparse regions and, further on, BB data from surrounding lowlands could be used to validate extrapolation approaches to assess snowfall limit for mainly stratiform precipitation events where stations at high elevations are missing.

The nine papers in this special section focus on the development of new computer vision techniques for the interpretation of remote sensing images. These papers represent a follow-up of two workshops held in conjunction with the IEEE Conference on Computer Vision and Pattern Recognition (CVPR) 2015, that was held in Boston, MA, EARTHVISION 2015 and MSF 2015. The purpose of both workshops and of this special issue is to foster fruitful collaboration of computer vision, Earth observation, and geospatial analysis communities.

The 28 papers in this special issue present a collection of papers focusing on the application of remote sensing to urban areas.

Ongoing (2014–16) drought in the state of California has played a major role in the depletion of groundwater. Within California’s Central Valley, home to one of the world’s most productive agricultural regions, drought and increased groundwater depletion occurs almost hand in hand, but this relationship appears to have changed over the last decade. Data derived from 497 wells have revealed a continued depletion of groundwater lasting a full year after drought, a phenomenon that was not observed in earlier records before the twenty-first century. Possible causes include 1) lengthening of drought associated with amplification in the 4–6-yr drought and El Niño frequency since the late 1990s and 2) intensification of drought and increased pumping that enhances depletion. Altogether, the implication is that current groundwater storage in the Central Valley will likely continue to diminish even further in 2016, regardless of the drought status.

It has been shown using simulated data that phase estimation of cross-track multibaseline synthetic aperture radar (SAR) interferometric data was most efficiently achieved through a maximum likelihood (ML) method. In this paper, we apply and assess the ML approach on real data, acquired with an experimental Ka-band multibaseline system. Compared to simulated data, dealing with real data implies that several calibration steps be carried out to ensure that the data fit the model. A processing chain was, therefore, designed, including steps responsible for compensating for imperfections observed in the data, such as beam elevation angle dependent phase errors or phase errors caused by imperfect motion compensation. The performance of the ML phase estimation was evaluated by comparing it to results based on a coarse-to-fine (C2F) algorithm, where information from the shorter baselines was used only to unwrap the phase from the longest available baseline. For this purpose, flat areas with high coherence and homogeneous texture were selected in the acquired data. The results show that with only four looks, the noise level was marginally better with the C2F approach and contained fewer outliers. However, with more looks, the ML method consistently delivered better results: noise variance with the C2F approach was slightly but steadily larger than the variance obtained with ML method.