In this study, the key conclusions of the IPCC special report on climate change and land (SRCCL) on land-climate interactions, food system and food security, land degradation and desertification, and sustainable land management were summed up. And the most controversial scientific issues in the report, such as greenhouse gas emissions from the food system, bio-energy and the estimate of carbon dioxide emissions and removals for the land sector were analyzed. Some scientific issues, such as the estimation of greenhouse gas emissions in the overall life cycle of food system, and the retrieval of greenhouse gas emissions based on remote sensing and ground-based measurement of atmospheric concentration and other data, need to be further studied in China. In the meanwhile, China should continue to implement sustainable land management, and improve corresponding technical measures and capacity-building.
IPCC released its new assessment report entitled IPCC special report on climate change and land (SRCCL) in August 2019. SRCCL is a joint effort of three IPCC working groups and an integrated assessment of interactive changes of climate and land cover/use, including changing climate on land, climate change impacts on terrestrial ecosystems and land use, as well as land-based climate change adaptation and mitigation. SRCCL focuses on new understanding on land-climate issues since AR5, with special attention on issues related to desertification, land degradation, and food security. The key findings of SRCCL include: land surface air temperature risen two times faster than the global mean surface temperature, shifting climate regimes in the Arctic and drylands, synergies in response of terrestrial ecosystems and land use to climate change, trade-off between food security and bioenergy in climate change mitigation, and urgent needs for coordinated actions across regions and sectors. It provides clear message for policy makers on risks from potential impacts of global temperature rise on elements of the land system and potential global contribution of response options to mitigation, adaptation, combating desertification and land degradation, and enhancing food security.
Land is a critical resource supporting human livelihoods. Land is substantially affected by climate change, whereas changes in land conditions also play a key role in the climate system. The latest IPCC special report climate change and land (SRCCL) presents the latest scientific understandings of climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems, and further assesses how to implement more sustainable land use and management in response to land-related climate change issues. This paper focuses on changes in extreme weather and climate events as well as their impacts on land with the combination of the major conclusions of SRCCL and other relevant studies. We show that in the context of global warming, changes in weather and climate extremes have impacted and will continue to impact desertification and land degradation processes, and threaten food security; the feedback from land to the climate system will exacerbate climate change and increase the occurrence probability and severity of extreme events. Given that land is under the enormous pressures brought by climate change, especially by extreme events, adhering to sustainable land management and reducing greenhouse gas emissions from all sectors including land and food systems, is essential to make it possible to limit the global mean surface temperature rise to within 2℃ and mitigate the negative impacts of climate change on land and food systems.
Summary for policymakers (SPM) for the special report on climate change and land of the IPCC has been approved on August 7, 2019. The Chapter 3 of the report assesses the relationship between climate change and desertification, and some new insights include: drylands and desertification range, desertification process and influencing factors, desertification change detection and attribution, desertification impacts on natural and socio-economic systems, desertification response to climate change, future climate change impacts and risks to desertification, the linking of the response to desertification and adaptation and mitigation to climate change. There are still shortcomings in estimating desertification change, detection and attribution of desertification change, the impacts of desertification on natural and socio-economic systems, desertification response to climate change, the linking of addressing desertification and adaptation and mitigation to climate change. These understandings recognize China’s dryland and desertification range changes, desertification impacts factors and process, desertification change detection and attribution, the impacts of desertification on natural and socio-economic systems, desertification response to climate change, and future climate change impacts on desertification. There are important implications for risks and the links between combating desertification and adapting and mitigating climate change.
Food security is widely affected from climate change not only on food production quantity but also on food quality, and the cascading effects on farmers’ livelihood as well as the food value chain; in the meanwhile, a series of environmental consequences, including agricultural greenhouse gases (GHGs) emission to enhance the global warming, has been resulted from the food system for the food security. An IPCC special report on climate change and land (SRCCL) has been published in August 2019, the report systematically assessed the impacts of climate change on the whole value chain of food production, processing, storage, transportation, and consumption, as well as the impacts of food system on climate change with the enhanced warming from agricultural GHG emissions, the supply-side and demand-side adaptations and mitigations as well as the synergy and trade-offs between them, and the policy environment for food security. It is concluded from SRCCL that about 21%-37% of total global anthropogenic GHG emissions are attributable to the food system due to the increased use of N fertilizer and water, etc., agriculture and food system are key to global climate change responses, integrated measures in supply-side and demand-side can reduce food loss and waste then result in the reduction of GHG emissions, and help build a resilient food system. The future work for the food system coping with climate change should be focusing on how to enrich and expand the assessments on climate change impacts on agriculture and food system, quantify the adaptation effects, increase the scientific understanding on synergies and trade-offs of adaptation and mitigation, and enhance the capacity building with specified issues.
Summary for policymakers (SPM) for the IPCC special report on climate change and land (SRCCL) was approved on August 7, 2019. The report involved an assessment of different options for land-based climate change response and gained some new insights. These include quantitative assessment of the benefits of 40 comprehensive land-based measures for climate change mitigation and adaptation, combating desertification and land degradation, enhancing food security, conserving biodiversity and water resources, and sustainable development, linking addressing desertification, land degradation, and food security with climate change adaptation and mitigation measures, as well as assessment of risks, limitation, barriers and safeguard policies for implementing different measures. There are still some shortcomings in the classification of measures, the subject of climate change adaptation, the risk and policy analysis. These conclusions of this report will have important implications for China’s establishment of land-based responses to climate change, and the promotion of combating climate change and combating desertification and land degradation, protecting the ecological environment and enhancing food security, and formulating relevant policies.
Based on homogeneity-adjusted temperature data of meteorological stations in China, NOAA monthly mean sea temperature data, and CMIP5 climate model data from 1961 to 2013, the contribution of the Pacific Decadal Oscillation (PDO) to the interdecadal variability of China’s winter minimum temperature was quantitatively analyzed by using climatic statistic methods. Results show that the interdecadal sequence of PDO has significant positive correlation with minimum temperature pattern of decadal filtering at most areas in China, winter minimum temperature is low when PDO is in negative phase, while conversely is high. The phenomenon of hiatus of winter minimum temperature after 2006, is mainly caused by cooling effect of natural variability, in which PDO plays a leading role, accounting for about 40% of natural variability contribution. The contribution of PDO to temperature presents an obvious interdecadal change. PDO has negative contribution to warming, and gradually increase to exceed 50% during 2006-2013.
Based on five climate model simulation results of the Coupled Model Intercomparison Project Phase 5 (CMIP5) and the FloodArea model, this paper analyzes the extreme precipitation and inundation risks of Beijing with global warming of 1.5℃ and 2.0℃ under the scenario of RCP8.5. The extreme precipitation in Beijing shows a decreasing distribution trend from southwest to northeast. When the temperature rises to 2.0℃, the risk of extreme precipitation and inundation increases more obviously than when the temperature rises to 1.5℃. The districts with the most obvious increase in extreme precipitation in suburbs are Fangshan and Mentougou, and Haidian, Shijingshan and Fengtai are the districts with the most obvious increase in extreme precipitation in urban areas. Haidian district has the largest area of flood risk, followed by Fengtai and Shijingshan district. The suburbs of Yanqing and Huairou are the areas with the largest flood area.
The strategic position of China’s coastal areas is very important, which has shown a trend that urban development centers are moving to coastal cities on national level, and coastal cities are developing close to seafront. However, the coastal cities are facing many severe challenges such as sea level rise and frequent extreme events caused by global climate change. In order to solve the conflict and clash between China’s development strategy towards the sea and global climate change at the strategic level, this paper puts forward the development strategy of China’s coastal cities to address climate change. The overarching goal is to build coastal climate resilient cities suitable for China’s national conditions. The principles are “planning leading the way, coordinating land and sea, adapting actively, mitigating positively, keeping moderate redundancy, and increasing resilience”. Meanwhile, eight main tasks have been clarified as follows: strengthening the management and control of urban planning, controlling the spatial development direction, optimizing urban layout, rigidly restricting the reclamation of the sea and island, improving planning and design standards of infrastructure, strengthening coastal protection facilities, consolidating urban infrastructure, and improving monitoring and early warning.
HFC-23 is an unintentional by-product of the production of HCFC-22, which is an important emission source of HFCs in China. Moreover, HFC-23 is under the control of UNFCCC and Montreal Protocol. An HFC-23 abatement policy was introduced in China in 2015, providing subsidies to support HFC-23 emission reduction. Analysis on the emission reduction verification reports indicates the policy brought about effectively incentive for HCFC-22 producers and their disposal rate of HFC-23 reached 98%. The cumulative emission reduction of HFC-23 from 2014 to 2018 reached about 52 kt (608 Mt CO2-eq). Additionally, some suggestions are given out to help fulfill the obligations of Multilateral Environmental Agreements (MEAs) after the closure of this policy in 2020.
Mitigation and adaptation are complementary strategies in response to climate change. However, adaptation had long been subordinate to mitigation in the negotiation process under the United Nations Framework on Climate Change (UNFCCC). Generally, the adaptation negotiation under UNFCCC over the past more than 20 years could be divided into five stages: early slow progress, science and technical discussion, parity with mitigation, enhanced adaptation action and full-scale adaptation action. The adaptation-related agenda items and their importance have been increased under the UNFCCC negotiation regime over the past decade, which reflects the deepening understanding of the significance of climate change impacts and adaptation of human society as well as increasing challenges for climate change adaptation globally. Future adaptation will focus on how to enhance global, regional and national adaptation actions through existing UNFCCC mechanisms, and how to mobilize adaptation finance to meet the increasing adaptation needs of developing countries.
Article 6 of the Paris Agreement establishes two market-based mechanisms, i.e. cooperative approaches and sustainable development mechanism. Influenced by the diversity of NDC mitigation targets and the uncertainties of future mitigation efforts of Parties, carbon market established under the Paris Agreement are faced with enormous risks and challenges in the design and implementation, including risks in environmental integrity caused by un-robust accounting and inappropriate additionality assessment, as well as risks to discourage Parties from extending the scope of NDC and increasing their mitigation efforts. To address these risks, it is imperative to establish a robust accounting system, take into appropriate consideration NDC commitment in additionality assessment, and ensure that the market mechanisms will incentivize Parties to extend the scope of NDC through establishing participation requirements. China should identify the requirements and possible impacts of participating in the market mechanisms under the Paris Agreement, carry out relevant capacity building activities and establish stringent supervision system and organizations, considering the development status of domestic carbon market, so as to enable its effective participation in the carbon market under the Paris Agreement.
Interpretation of IPCC SROCC on polar
system changes and their impacts and adaptations