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Climate change impacts on water availability and hydrological extremes are major concerns as regards the Sustainable Development Goals. Impacts on hydrology are normally investigated as part of a modelling chain, in which climate projections from multiple climate models are used as inputs to multiple impact models, under different greenhouse gas emissions scenarios, which result in different amounts of global temperature rise. While the goal is generally to investigate the relevance of changes in climate for the water cycle, water resources or hydrological extremes, it is often the case that variations in other components of the model chain obscure the effect of climate scenario variation. This is particularly important when assessing the impacts of relatively lower magnitudes of global warming, such as those associated with the aspirational goals of the Paris Agreement. In our study, we use ANOVA (analyses of variance) to allocate and quantify the main sources of uncertainty in the hydrological impact modelling chain. In turn we determine the statistical significance of different sources of uncertainty. We achieve this by using a set of five climate models and up to 13 hydrological models, for nine large scale river basins across the globe, under four emissions scenarios. The impact variable we consider in our analysis is daily river discharge. We analyze overall water availability and flow regime, including seasonality, high flows and low flows. Scaling effects are investigated by separately looking at discharge generated by global and regional hydrological models respectively. Finally, we compare our results with other recently published studies. We find that small differences in global temperature rise associated with some emissions scenarios have mostly significant impacts on river discharge-however, climate model related uncertainty is so large that it obscures the sensitivity of the hydrological system.

We use the 100-member Grand Ensemble with the climate model MPI-ESM to evaluate the controllability of mean and extreme European summer temperatures with the global mean temperature targets in the Paris Agreement. We find that European summer temperatures at 2 °C of global warming are on average 1 °C higher than at 1.5 °C of global warming with respect to pre-industrial levels. In a 2 °C warmer world, one out of every two European summer months would be warmer than ever observed in our current climate. Daily maximum temperature anomalies for extreme events with return periods of up to 500 years reach return levels of 7 °C at 2 °C of global warming and 5.5 °C at 1.5 °C of global warming. The largest differences in return levels for shorter return periods of 20 years are over southern Europe, where we find the highest mean temperature increase. In contrast, for events with return periods of over 100 years these differences are largest over central Europe, where we find the largest changes in temperature variability. However, due to the large effect of internal variability, only four out of every ten summer months in a 2 °C warmer world present mean temperatures that could be distinguishable from those in a 1.5 °C world. The distinguishability between the two climates is largest over southern Europe, while decreasing to around 10% distinguishable months over eastern Europe. Furthermore, we find that 10% of the most extreme and severe summer maximum temperatures in a 2 °C world could be avoided by limiting global warming to 1.5 °C.

Carbon dioxide removal from the atmosphere (CDR)-also known as 'negative emissions'-features prominently in most 2 °C scenarios and has been under increased scrutiny by scientists, citizens, and policymakers. Critics argue that 'negative emission technologies' (NETs) are insufficiently mature to rely on them for climate stabilization. Some even argue that 2 °C is no longer feasible or might have unacceptable social and environmental costs. Nonetheless, the Paris Agreement endorsed an aspirational goal of limiting global warming to even lower levels, arguing that climate impacts-especially for vulnerable nations such as small island states-will be unacceptably severe in a 2 °C world. While there are few pathways to 2 °C that do not rely on negative emissions, 1.5 °C scenarios are barely conceivable without them. Building on previous assessments of NETs, we identify some urgent research needs to provide a more complete picture for reaching ambitious climate targets, and the role that NETs can play in reaching them.

PurposeThis paper brings insights from accounting scholarship to the measurement and reporting challenges of metagovernance approaches to sustainable development. Where scholarship on metagovernance—the combination of market, hierarchical and network governance—proposes deductive approaches to such challenges, we contend that a historically informed “abductive” approach offers valuable insight into the realpolitik of intergovernmental frameworks.Design/methodology/approachThe paper adopts a Foucauldian “archaeological–genealogical” method to investigate the inclusion of climate change as a Sustainable Development Goal (SDG). It analyses more than 100 documents and texts, tracking the statement forms that crystallise prevailing truth claims across the development of climate and SDG metagovernance.FindingsWe show how the truth claims now enshrined in the Paris Agreement on Climate Change constrained the conceptualisation and operationalisation of SDG 13: Take urgent action to combat climate change and its impacts. The paper thereby reframes recent measurement and reporting challenges as outcomes of conceptual conflicts between the technicist emphasis of divisions within the United Nations and the truth claims enshrined in intergovernmental agreements.Originality/valueThis paper demonstrates how an archaeological–genealogical approach may start to address the measurement and reporting challenges facing climate and SDG metagovernance. It also highlights that the two degrees target on climate change has a manifest variability of interpretation and shows how this characteristic has become pivotal to operationalising climate metagovernance in a manner that respects the sovereignty of developing nations.

Emission inventories (EIs) are the fundamental tool to monitor compliance with greenhouse gas (GHG) emissions and emission reduction commitments. Inventory accounting guidelines provide the best practices to help EI compilers across different countries and regions make comparable, national emission estimates regardless of differences in data availability. However, there are a variety of sources of error and uncertainty that originate beyond what the inventory guidelines can define. Spatially explicit EIs, which are a key product for atmospheric modeling applications, are often developed for research purposes and there are no specific guidelines to achieve spatial emission estimates. The errors and uncertainties associated with the spatial estimates are unique to the approaches employed and are often difficult to assess. This study compares the global, high-resolution (1 km), fossil fuel, carbon dioxide (CO2), gridded EI Open-source Data Inventory for Anthropogenic CO2 (ODIAC) with the multi-resolution, spatially explicit bottom-up EI geoinformation technologies, spatio-temporal approaches, and full carbon account for improving the accuracy of GHG inventories (GESAPU) over the domain of Poland. By taking full advantage of the data granularity that bottom-up EI offers, this study characterized the potential biases in spatial disaggregation by emission sector (point and non-point emissions) across different scales (national, subnational/regional, and urban policy-relevant scales) and identified the root causes. While two EIs are in agreement in total and sectoral emissions (2.2% for the total emissions), the emission spatial patterns showed large differences (10~100% relative differences at 1 km) especially at the urban-rural transitioning areas (90–100%). We however found that the agreement of emissions over urban areas is surprisingly good compared with the estimates previously reported for US cities. This paper also discusses the use of spatially explicit EIs for climate mitigation applications beyond the common use in atmospheric modeling. We conclude with a discussion of current and future challenges of EIs in support of successful implementation of GHG emission monitoring and mitigation activity under the Paris Climate Agreement from the United Nations Framework Convention on Climate Change (UNFCCC) 21st Conference of the Parties (COP21). We highlight the importance of capacity building for EI development and coordinated research efforts of EI, atmospheric observations, and modeling to overcome the challenges.

The chemical weathering of rocks currently absorbs about 1.1 Gt CO2 a−1 being mainly stored as bicarbonate in the ocean. An enhancement of this slow natural process could remove substantial amounts of CO2 from the atmosphere, aiming to offset some unavoidable anthropogenic emissions in order to comply with the Paris Agreement, while at the same time it may decrease ocean acidification. We provide the first comprehensive assessment of economic costs, energy requirements, technical parameterization, and global and regional carbon removal potential. The crucial parameters defining this potential are the grain size and weathering rates. The main uncertainties about the potential relate to weathering rates and rock mass that can be integrated into the soil. The discussed results do not specifically address the enhancement of weathering through microbial processes, feedback of geogenic nutrient release, and bioturbation. We do not only assess dunite rock, predominantly bearing olivine (in the form of forsterite) as the mineral that has been previously proposed to be best suited for carbon removal, but focus also on basaltic rock to minimize potential negative side effects. Our results show that enhanced weathering is an option for carbon dioxide removal that could be competitive already at 60 US $ t−1 CO2 removed for dunite, but only at 200 US $ t−1 CO2 removed for basalt. The potential carbon removal on cropland areas could be as large as 95 Gt CO2 a−1 for dunite and 4.9 Gt CO2 a−1 for basalt. The best suited locations are warm and humid areas, particularly in India, Brazil, South-East Asia and China, where almost 75% of the global potential can be realized. This work presents a techno-economic assessment framework, which also allows for the incorporation of further processes.

This article discusses the importance of the recently concluded Paris Rulebook, the extent to which it limits national discretion, instils discipline and generates ambition and accountability, and the challenges that lie ahead in implementing the 2015 Paris Agreement. It discusses, in particular, the rules on mitigation, transparency, the global stocktake and the implementation and compliance mechanism, in order to highlight the choices Parties made on three overarching issues that have long bedevilled the climate change regime—prescriptiveness (the level of detail of the rules), legal bindingness (the extent to which particular rules are legally binding) and differentiation (the extent to which particular rules accommodate differences between Parties or apply uniformly to all Parties).

Since its launch in 1971, the EU generalised scheme of preferences (GSP) has represented a landmark tool of the Union’s common commercial policy, aiming at heightening market access for developing and least developed countries through preferential tariff treatment conceded voluntarily, non-reciprocally and on a non-discriminatory basis. Over the decades, the EU GSP has evolved, from a measure apt at sustaining industrialisation in vulnerable third countries to an instrument fostering sustainable development beyond the Union’s borders. As such, the present GSP regulation, through its GSP+ arrangement, subordinates both the granting and temporary withdrawal of tariff preferences upon, inter alia, implementation of twenty-seven international conventions, also related to the environment. The regulation, however, is to be put to the test by the most pressing ecological issue of the present millennium, notably climate change. Accordingly, does the EU GSP regime pro-vide for a form of climate-led conditionality, connected to the respect of the landmark Paris Agreement on climate change (PA)? The article first reconstructs the origins and structure of the EU GSP regime, with the aim of exploring to what extent both a positive and a negative climate-led conditionality can be envisaged thereof. Secondly, the analysis dwells on the 2021 Commission’s proposal for the revision of the GSP regulation, putting ahead the leeway of granting and temporarily withdrawing trade preferences upon respect of the Paris Agreement on climate change. Against this backdrop, the investigation ponders the systemic limitations of the proposal, whose operationalisation through the lens of the PA remains nebulous.

BackgroundThe credibility and effectiveness of country climate targets under the Paris Agreement requires that, in all greenhouse gas (GHG) sectors, the accounted mitigation outcomes reflect genuine deviations from the type and magnitude of activities generating emissions in the base year or baseline. This is challenging for the forestry sector, as the future net emissions can change irrespective of actual management activities, because of age-related stand dynamics resulting from past management and natural disturbances. The solution implemented under the Kyoto Protocol (2013–2020) was accounting mitigation as deviation from a projected (forward-looking) “forest reference level”, which considered the age-related dynamics but also allowed including the assumed future implementation of approved policies. This caused controversies, as unverifiable counterfactual scenarios with inflated future harvest could lead to credits where no change in management has actually occurred, or conversely, failing to reflect in the accounts a policy-driven increase in net emissions. Instead, here we describe an approach to set reference levels based on the projected continuation of documented historical forest management practice, i.e. reflecting age-related dynamics but not the future impact of policies. We illustrate a possible method to implement this approach at the level of the European Union (EU) using the Carbon Budget Model.ResultsUsing EU country data, we show that forest sinks between 2013 and 2016 were greater than that assumed in the 2013–2020 EU reference level under the Kyoto Protocol, which would lead to credits of 110–120 Mt CO2/year (capped at 70–80 Mt CO2/year, equivalent to 1.3% of 1990 EU total emissions). By modelling the continuation of management practice documented historically (2000–2009), we show that these credits are mostly due to the inclusion in the reference levels of policy-assumed harvest increases that never materialized. With our proposed approach, harvest is expected to increase (12% in 2030 at EU-level, relative to 2000–2009), but more slowly than in current forest reference levels, and only because of age-related dynamics, i.e. increased growing stocks in maturing forests.ConclusionsOur science-based approach, compatible with the EU post-2020 climate legislation, helps to ensure that only genuine deviations from the continuation of historically documented forest management practices are accounted toward climate targets, therefore enhancing the consistency and comparability across GHG sectors. It provides flexibility for countries to increase harvest in future reference levels when justified by age-related dynamics. It offers a policy-neutral solution to the polarized debate on forest accounting (especially on bioenergy) and supports the credibility of forest sector mitigation under the Paris Agreement.

This study aims to introduce a novel coupling coordination degree (CCD) model to evaluate the degree of coupling coordination between socio-economic development and CO2 emission of 76 contracting countries in The Paris Agreement. The efficiency of the novel CCD model is demonstrated by scenario analysis in the contracting countries during the period between 2005 and 2015 on the basis of the theory of environmental Kuznets curve. The following results are obtained. Firstly, the subjectivity of the traditional CCD model contaminates the robustness of the evaluation. Secondly, the novel CCD of contracting countries during the survey period ranged between approximately 0.35 and 0.4, which is in the overall development stage of low coordination. Thirdly, the novel CCD of the two systems at the global level is not symmetrical in spatial distribution, and the European continent is generally higher than the African, while other continents sit on an intermediate level. Lastly, the novel CCD between socio-economy and CO2 emission systems presents a positive correlation with regional resident income in groups with varied income levels. The findings of this research provide rich policy references for facilitating global climate cooperation by balancing socio-economic development with CO2 emission mitigation.