Transformation pathways for the land sector in line with the Paris Agreement depend on the assumption of globally implemented greenhouse gas (GHG) emission pricing, and in some cases also on inclusive socio-economic development and sustainable land-use practices. In such pathways, the majority of GHG emission reductions in the land system is expected to come from low- and middle-income countries, which currently account for a large share of emissions from agriculture, forestry and other land use (AFOLU). However, in low- and middle-income countries the economic, financial and institutional barriers for such transformative changes are high. Here, we show that if sustainable development in the land sector remained highly unequal and limited to high-income countries only, global AFOLU emissions would remain substantial throughout the 21st century. Our model-based projections highlight that overcoming global inequality is critical for land-based mitigation in line with the Paris Agreement. While also a scenario purely based on either global GHG emission pricing or on inclusive socio-economic development would achieve the stringent emissions reductions required, only the latter ensures major co-benefits for other Sustainable Development Goals, especially in low- and middle-income regions.
Geographical place, socioeconomic status and citizenship matter in the context of climate change. The most vulnerable members of society are frequently the ones hardest hit by climate‐induced extreme events. Vulnerable communities often live in climate‐exposed locations, and have access to fewer resources to prepare for and respond to disasters. This is the case for Haitian migrants in The Bahamas ‐ vulnerable communities located within a climate‐vulnerable country. Haitian communities were the locus of the majority of deaths and missing people attributed to the 2019 Hurricane Dorian and faced a series of distributional, procedural and recognition injustices. We investigate the historical factors and contemporary conditions of Haitian communities in The Bahamas that resulted in significant inequities, disproportional impacts and infractions of human rights by the Bahamian government. We show how this experience complexifies discourse on loss and damage and climate‐induced migration in small island developing states and exemplifies the need for human rights approaches to loss and damage that incorporate multi‐scalar dimensions of climate justice.
Scientifically rigorous guidance to policy makers on mitigation options for meeting the Paris Agreement long-term temperature goal requires an evaluation of long-term global-warming implications of greenhouse gas emissions pathways. Here we employ a uniform and transparent methodology to evaluate Paris Agreement compatibility of influential institutional emission scenarios from the grey literature, including those from Shell, BP, and the International Energy Agency. We compare a selection of these scenarios analysed with this methodology to the Integrated Assessment Model scenarios assessed by the Intergovernmental Panel on Climate Change. We harmonize emissions to a consistent base-year and account for all greenhouse gases and aerosol precursor emissions, ensuring a self-consistent comparison of climate variables. An evaluation of peak and end-of-century temperatures is made, with both being relevant to the Paris Agreement goal. Of the scenarios assessed, we find that only the IEA Net Zero 2050 scenario is aligned with the criteria for Paris Agreement consistency employed here. We investigate root causes for misalignment with these criteria based on the underlying energy system transformation.
Sustainable irrigation expansion over water limited croplands is an important measure to enhance agricultural yields and increase the resilience of crop production to global warming. While existing global assessments of irrigation expansion mainly illustrate the biophysical potential for irrigation, socioeconomic factors such as weak governance or low income, that demonstrably impede the successful implementation of sustainable irrigation, remain largely underexplored. Here we provide five scenarios of sustainable irrigation deployment in the 21st century integrated into the framework of Shared Socioeconomic Pathways, which account for biophysical irrigation limits and socioeconomic constraints. We find that the potential for sustainable irrigation expansion implied by biophysical limits alone is considerably reduced when socioeconomic factors are considered. Even under an optimistic scenario of socio-economic development, we find that additional calories produced via sustainable irrigation by 2100 might reach only half of the maximum biophysical potential. Regions with currently modest socioeconomic development such as Sub-Saharan Africa are found to have the highest potential for improvements. In a scenario of sustainable development, Sub-Saharan Africa would be able to almost double food production and feed an additional 70 million people compared to 2020, whereas in a scenario where regional rivalry prevails, this potential would be halved. Increasing sustainable irrigation will be key for countries to meet the projected food demands, tackle malnutrition and rural poverty in the context of increasing impacts of anthropogenic climate change on food systems. Our results suggest that improving governance levels for example through enhancing the effectiveness of institutions will constitute an important leverage to increase adaptive capacity in the agricultural sector.
Cereal production systems in semi-arid environments in Senegal are extensive and highly depend on weather and climate-related effects. Assessing climate change impacts on the main staple food crops is essential to ensure food security. This study aims to assess climate change impacts on millet and sorghum in Niakhar and Toubacouta, two locations in the Senegalese groundnut basin. Field experiment and climate data from RCP4.5 and RCP8.5 greenhouse gas concentration pathways were used to simulate future crop yield and growth cycle length. For each crop, two varieties were considered, a short (90 days) and a long (120 days) maturation cycle. Projections made using the SARRA–O model showed a downward trend of crop yield for all considered varieties and scenarios. These results were, however, more pronounced for the short-cycle variety. In addition, the short-cycle variety showed greater variability in yield trends with larger confidence intervals. In Niakhar, millet and sorghum yield loss for short duration is estimated around 30% by 2050, while the long-cycle variety yield gap was less than 20% compared to the reference period yield (1976–2005). Millet and sorghum yield reduction by 2050 is less pronounced in Toubacouta with around 20%. A slight relationship was inferred between rainfall and yield change, whereas a significant negative linear relationship was inferred between temperature and yield change. The future impact of climate change on these cereals would be mainly a loss of yield induced by rising temperatures. Thus, a thorough consideration of temperature effects will be essential for better adapting cereal production to future climatic conditions.
The 2015 Paris Agreement sets the objectives of global climate ambition as expressed in its long-term temperature goal and mitigation goal. The scientific community has explored the characteristics of greenhouse gas emission reduction pathways in line with the Paris Agreement. However, when categorizing such pathways, the focus has been put on the temperature outcome and not on emission reduction objectives. Here we propose a pathway classification that aims to comprehensively reflect the climate criteria set out in the Paris Agreement. We show how such an approach allows for a fully consistent interpretation of the Agreement. For Paris Agreement compatible pathways, we report net zero CO2 and greenhouse gas emissions around 2050 and 2065, respectively. We illustrate how pathway design criteria not rooted in the Paris Agreement, such as the 2100 temperature level, result in scenario outcomes wherein about 6 - 24% higher deployment (interquartile range) of carbon dioxide removal is observed. Greenhouse gas emissions pathways compatible with the Paris Agreement simultaneously pursue warming of less than 1.5 °C, very likely never exceed 2 °C and achieve net zero greenhouse gas emissions by the second half of the century. They can require smaller amounts of carbon dioxide removal.
We describe the latest version of the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP-CMIP6). The archive contains downscaled historical and future projections for 1950–2100 based on output from Phase 6 of the Climate Model Intercomparison Project (CMIP6). The downscaled products were produced using a daily variant of the monthly bias correction/spatial disaggregation (BCSD) method and are at 1/4-degree horizontal resolution. Currently, eight variables from five CMIP6 experiments (historical, SSP126, SSP245, SSP370, and SSP585) are provided as procurable from thirty-five global climate models.
King et al. raise important issues, several of which pertain to the broader policy discourse surrounding international climate negotiations and countries’ climate pledges rather than the modeling conducted in our Policy Forum. We agree with King et al. that the updated Paris Agreement pledges could paint an overly optimistic picture of the future, especially if their success depends on postponing deeper reductions until after 2030. To illustrate a less-optimistic future, our Policy Forum includes scenarios showing what would happen if countries continued to implement current policies alone. The “Current policy” scenarios in the Policy Forum result in less than a 10% chance of limiting global warming to below 2°C this century, whereas the “Updated pledges” scenarios result in at least a 33% chance of achieving the same temperature goal. Additional policy measures could help bridge emission gaps between current policies, updated pledges, and the global emission levels needed to cost-effectively achieve the Paris Agreement’s climate goals
Human intervention in forested ecosystems is hoped to perform a fundamental shift within the next decade by reverting current forest loss – a major source of CO2 emissions – to net forest gain taking up carbon and thus aiding climate change mitigation. The demanded extensive establishment of forests will change the local surface energy fluxes, and with it the local climate, in addition to competing with food and fiber production for land and water. Scenario building models encompass this competition for resources but have turned a blind eye to the biogeophysical (BGP) local surface energy flux disturbance so far. We combine the benefit of CO2 sequestration of Afforestation/Reforestation (A/R) with the additional incentive or penalty of local BGP induced cooling or warming by translating the local BGP induced temperature change to a CO2 equivalent. We then include this new aspect in the land-use model MAgPIE via modifying the application of the price on greenhouse gases (GHG). This enables us to use MAgPIE to produce A/R scenarios that are optimized for both their potential CO2 sequestration and the CO2 equivalent local BGP effect, as well as the socio-economic trade-offs of A/R. Here we show that optimal A/R patterns are substantially altered by taking the local BGP effects into account. Considering local cooling benefits of establishing forests triples (+203.4%) the viable global A/R area in 2100 from 116 Mha to 351 Mha under the conditions of the Shared Socio-economic Pathway 2 (SSP2) scenario driven by the same GHG price. Three quarters (76.0%, +179 Mha) of the additionally forested area is established in tropical climates alone. Therefore, further neglect of BGP effects in scenario building models undervalues the benefit of tropical forests while simultaneously running the risk of proposing counterproductive measures at high latitudes.
The expected growth in the demand for passenger and freight services exacerbates the challenges of reducing transport GHG emissions, especially as commercial low-carbon alternatives to petroleum fuels are limited for shipping, air and long-distance road travel. Biofuels can offer a pathway to significantly reduce emissions from these sectors, as they can easily substitute for conventional liquid fuels in internal combustion engines. In this paper, we assess the potential of bioenergy to reduce transport GHG emissions through an analysis leveraging various integrated assessment models and scenarios, as part of the 33rd Energy Modeling Forum study (EMF-33). We find that bioenergy can contribute a significant, albeit not dominant, proportion of energy supply to the future transport sector: in scenarios aiming to keep the temperature increase below 2 °C by the end of the twenty-first century, models project that in 2100 bioenergy can provide on average 42 EJ/yr (ranging from 5 to 85 EJ/yr) for transport (compared to 3.7 EJ in 2018), mainly through lignocellulosic fuels. This makes up 9–62% of final transport energy use. Only a small amount of bioenergy is projected to be used in transport through electricity and hydrogen pathways, with a larger role for biofuels in road passenger transport than in freight. The association of carbon capture and storage (CCS) with bioenergy technologies (BECCS) is a key determinant in the role of biofuels in transport, because of the competition for biomass feedstock to provide other final energy carriers along with carbon removal. Among models that consider CCS in the biofuel conversion process the average market share of biofuels is 21% in 2100 (ranging from 2 to 44%), compared to 10% (0–30%) for models that do not. Cumulative direct emissions from the transport sector account for half of the emission budget (from 306 to 776 out of 1,000 GtCO2). However, the carbon intensity of transport decreases as much as other energy sectors in 2100 when accounting for process emissions, including carbon removal from BECCS. Lignocellulosic fuels become more attractive for transport decarbonization if BECCS is not feasible for any energy sectors. Since global transport service demand increases and biomass supply is limited, its allocation to and within the transport sector is uncertain and sensitive to assumptions about political as well as technological and socioeconomic factors.
A transition of the Bolivian power sector towards a renewable energy dominated system has been inhibited by a series of laws and policies including heavy subsidies for power generation using domestic natural gas. Within this context, alternative techno-economic scenarios are designed based on key characteristics of the system, and a series of six policy levers are used to analyze impacts on the development of the power sector. The energy-system optimization modeling framework OSeMOSYS is utilized to analyze power sector transition pathways. Techno-economic characteristics and policies are combined to develop bracketing scenarios for the future energy system, contrasting business-as-usual with an ambitious renewable energy policy scenario. Results from the analyzed scenarios show that achieving significant reductions of GHG emissions in the Bolivian electric system will heavily depend on:1) reducing the artificial competitiveness of thermal power plants through subsidies, but also a price on carbon emissions; 2) banning high impact power plants (mainly very large hydropower plants); and 3) defining clear long-term objectives for the participation of renewables in the system, starting with objectives in current short-term plans. By examining several scenarios, relative system costs as a function of emissions reductions are determined as well. For high penetration of variable renewable energy, addition of storage will eventually be needed as dispatchable renewable resources are limited.
There is in an ongoing expansion of powerlines as a result of an increasing global demand for energy. Powerlines have the potential to negatively impact wild bird populations through collisions and/or electrocution, and reducing bird powerline collision and electrocution risk is a priority for companies running high-voltage pow-erlines (known as Transmission System Operators (TSOs)). Most TSOs are legally required to assess any potentially significant impacts via Enivronmental Impact Assessments, and so potentially collect a significant amount of data on the presence of species, species behaviour, and observed mortality rates. The value of such data, if available, for reducing and preventing bird casualties could be enhanced by increasing availability across TSOs and other decision-makers. We review the extent to which the sharing of data is happening across Europe, and how the quality, scope and availability of bird data collected by European TSOs could be improved, through use of a questionnaire and workshop with TSOs, conservationists and academics. Sixteen European TSOs responded to the questionnaire and 30 stakeholders attended the workshop. There was wide recognition of the value of different types of data on birds at powerlines, and a positive attitude to working together to share and enhance data across stakeholders to achieve the shared goal of reducing bird mortalities. Key barriers to the sharing of data included a lack of a centralised database, the lack of standardised methods to collect bird data and concerns over the confidentiality of data and reports. In order to overcome these barriers and develop a collaborative approach to data sharing, and ultimately inform best practice to reduce significant negative impacts on bird populations, we suggest a stepwise approach that (1) develops guidance around the field methods and data to be collected for mitigation effectiveness and (2) shares meta-data/bibliography of studies of powerline impacts/ mitigation effectiveness for birds. In time, a more structured approach to the sharing of data and information could be developed, to make data findable, accessible, interoperable and reusable.
The contributions of single greenhouse gas emitters to country-level climate change are generally not disentangled, despite their relevance for climate policy and litigation. Here, we quantify the contributions of the five largest emitters (China, US, EU-27, India, and Russia) to projected 2030 country-level warming and extreme hot years with respect to pre-industrial climate using an innovative suite of Earth System Model emulators. We find that under current pledges, their cumulated 1991–2030 emissions are expected to result in extreme hot years every second year by 2030 in twice as many countries (92%) as without their influence (46%). If all world nations shared the same fossil CO 2 per capita emissions as projected for the US from 2016–2030, global warming in 2030 would be 0.4 °C higher than under actual current pledges, and 75% of all countries would exceed 2 °C of regional warming instead of 11%. Our results highlight the responsibility of individual emitters in driving regional climate change and provide additional angles for the climate policy discourse.
High-level assessments of climate change impacts aggregate multiple perils into a common framework. This requires incorporating multiple dimensions of uncertainty. Here we propose a methodology to transparently assess these uncertainties within the ‘Reasons for Concern’ framework, using extreme heat as a case study. We quantitatively discriminate multiple dimensions of uncertainty, including future vulnerability and exposure to changing climate hazards. High risks from extreme heat materialise after 1.5–2 °C and very high risks between 2–3.5 °C of warming. Risks emerge earlier if global assessments were based on national risk thresholds, underscoring the need for stringent mitigation to limit future extreme heat risks.
Without additional support policies, clean cooking could become unaffordable for about 470 million people by 2030 if a post-pandemic recovery is slow, and about 200 million people by 2030 under ambitious climate mitigation action. Acceleration of clean cooking transitions by tapping into pandemic recovery and climate funds to target the poorest people and regions globally is urgently needed. The world is off track with SDG7. A slow pandemic recovery and ambitious climate mitigation may slow down efforts to extend clean cooking access and make universal access by 2030 more challengingPopulations in sub-Saharan Africa, developing Asia and Latin America (the regions with the biggest access gaps today) are most vulnerable to being unable to transition to clean cooking in the futureThere is an urgent need to prioritize commitments, investments and coordinated policies to make clean cooking more accessible and affordable in the poorest regions and for the poorest populationsTransitioning away from solid biomass cooking can reduce growth in future cooking energy demand, with subsequent benefits for air quality, climate and healthPledges to COVID-19 recovery funds, international climate finance and the value of losses suffered by those lacking access all dwarf estimates of investment needs for universal clean cooking access The world is off track with SDG7. A slow pandemic recovery and ambitious climate mitigation may slow down efforts to extend clean cooking access and make universal access by 2030 more challenging Populations in sub-Saharan Africa, developing Asia and Latin America (the regions with the biggest access gaps today) are most vulnerable to being unable to transition to clean cooking in the future There is an urgent need to prioritize commitments, investments and coordinated policies to make clean cooking more accessible and affordable in the poorest regions and for the poorest populations Transitioning away from solid biomass cooking can reduce growth in future cooking energy demand, with subsequent benefits for air quality, climate and health Pledges to COVID-19 recovery funds, international climate finance and the value of losses suffered by those lacking access all dwarf estimates of investment needs for universal clean cooking access
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