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Get insights into the IPCC's special report on global warming of 1.5°C, including its history, framing, pathways to limit warming, and the importance of sustainable development. Learn about the key findings and the need for a global response to address climate change.
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Understanding the IPCC Special Report on Global Warming of 1.5C Justin Schoof Professor and Chair, Geography and Environmental Resources Southern Illinois University Carbondale Saluki Energy Forum 11/8/18
Background: The IPCC • The Intergovernmental Panel on Climate Change (IPCC) was established by the WMO and UNEP in 1988 to provide policymakers with regular climate change science assessments, identify implications and risks, and put forward adaptation/mitigation strategies. To date, the IPCC has released five climate assessment reports (most recently AR5, 2013/2014) and many special reports. • IPCC Working Groups: • I: Physical Science Basis • II: Impacts, Adaptation, and Vulnerability • III: Mitigation • The Special Report on Global Warming of 1.5C: • 91 authors from 44 citizenships and 40 countries of residence • Over 6,000 cited references • More than 42,000 expert and government review comments
History of the 1.5C report: Paris, 2015 At the Paris Climate Meeting in 2015 (21st Convention of Parties, or COP21), commitments to a common goal were made by most of the worlds countries: “Holding the increase in the global average temperature to well below 2C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change”. Under the agreement, each country is to develop a plan, known as a Nationally Determined Contribution (NDC). Specific guidelines to limit warming in accord with the Paris Agreement will be the focus of COP24 in Poland next month. Credit: Wikimedia Commons
History of the 1.5C Report: Paris, 2015 Before concluding the meeting, the UNFCCC invited the IPCC to develop a special report with the following questions in mind: • What will it take to limit global warming to 1.5C above pre-industrial levels? • What climate impacts can be avoided by limiting global warming to 1.5C (as opposed to 2C or greater)? • How can we limit the worst impacts of climate change and adapt to those that are unavoidable? Current pledges (NDCs) from Paris: (1) only include plans to 2030 (2) are not sufficient to limit warming to 1.5C
The IPCC Special Report on Global Warming of 1.5C • Framing and Context • Mitigation Pathways to 1.5C • Impacts of 1.5C • Strengthening/Implementing the Global Response • Sustainable Development, Poverty, Eradication, and Reducing Inequalities “There is no single answer to the question of whether it is feasible to limit warming to 1.5C and adapt to the consequences.” “Stabilization of global temperature at any level requires that net CO2 emissions are reduced to zero.” “The required global transformation needed to limit warming to 1.5C requires links, synergies, and trade-offs between mitigation, adaptation, and sustainable development, each of which have many dimensions – geophysical, environmental-ecological, technological, economic, socio-cultural, and institutional…” IPCC 2018
Framing and context: Climate Modeling and Projections • Socio-economic narratives emissions estimates • Climate/carbon-cycle models atmospheric concentrations • Earth system models (ESMs) climate outcomes IPCC 2013 van Vuuren et al. 2011
Framing and Context: Historical warming • Temperature changes are considered relative to pre-industrial (1850-1900) climatology. • Key points: • We have warmed by 1C (+/- 0.2C) and are now warming at a rate of 0.2C/decade. • Warming > 1.5C has already occurred in some regions and 20-40% of the global population lives in regions that have already warmed by more than 1.5C in at least one season. • Climate change is already happening and there will be substantive impacts regardless of the future temperature trajectory. IPCC 2018
Pathways to 1.5C: Overview There is no single definitive pathway to limit warming to 1.5C. Pathways consistent with 1.5C of warming are those that provide a 1/2-2/3 chance of keeping warming below 1.5C or returning to 1.5C by 2100 following an overshoot. • Past emissions are unlikely to commit us to 1.5C of warming, but do commit us to other changes (e.g., committed sea level rise). • Impacts of 1.5C of warming depend critically on the path. • Any path that limits global warming to 1.5C will require ambitious approaches to mitigation, but some allow greater emissions than others. IPCC 2018
Pathways to 1.5C: Carbon Dioxide Removal (CDR) All pathways that overshoot the 1.5C target and then return before 2100 require the use of Carbon Dioxide Removal (CDR). Examples include: • Afforestation/Reforestation • Land restoration • Soil carbon sequestration • Bioenergy with carbon capture and storage (BECCS) • Direct air carbon capture and storage (DACCS) • Enhanced weathering • Ocean alkalinization Science, 10/14/16 CDR is unproven at scale and therefore represents a major challenge for keeping warming below 1.5C!
Pathways to 1.5C: CO2 Emissions IPCC 2018
Pathways to 1.5C: Examples IPCC 2018
Pathways to 1.5C: Energy Transitions • Limiting warming to 1.5C will require rapid declines in the carbon intensity of electricity production Massive transition to renewable energy Fossil fuels used sparingly and with CDR • By 2050, renewables supply 49-67% of primary energy in 1.5C consistent pathways (vs. ~15% now). NREL
Pathways to 1.5C: Demand-side considerations Lifestyle choices lowering energy demand and the carbon intensity of food can further support achievement of 1.5C. IPCC 2018
Impacts of 1.5C: Overview Human-induced historical warming (1C) has already produced numerous climate system changes including: • increases in the frequency of both land and marine heatwaves • increases in the heavy precipitation events Detectable increases in temperature and precipitation extremes have occurred in recent decades (1991-2010) relative to earlier periods (e.g., 1960-1979), a period accounting for approximately 0.5C of warming. Key aspects of 1.5C changes and impacts: • Overshooting pathways = greater risks to human and natural systems, especially since higher overshoots could be associated with long-lasting and/or irreversible impacts, such as ecosystem losses. • There are substantial differences in impacts associated with warming of 1.5C and 2C, especially for regional temperature extremes. • Impacts will also depend on changes in the resilience of human and natural systems. IPCC 2018
Examples of Impacts of 1.5C Relative to 2C • Lower risks for heat-related morbidity/mortality associated with extremely hot days in most regions. • Limits the extent of increased flooding from extreme precipitation, including rainfall from hurricanes. • Lowers the rate of sea level rise, impacting an estimated 10 million fewer people. • Limits the reduction in yields and nutritional quality of rice, wheat, and other major crops. • Poses far lower risks of species extinction and impacts on ecosystems (and ecosystem services) • Substantially reduces risk to marine biodiversity, ecosystems and their services, especially warm water coral ecosystems which will be decimated by 2C. Under 1.5C, we may only lose 70-90%. • At 1.5C, we should expect a sea-ice free Arctic perhaps once per century. At 2C, it will happen approximately once per decade. Relative to 2C, limiting warming to 1.5C requires faster emissions reductions and will be much more costly. Recent studies have indicated that there is an overall economic benefit to doing so. Burke et al. 2018, Nature
Warming of 1.5C and Sustainable development goals Sustainable development is defined in the report as ‘development that meets the needs of the present and future generations through balancing economic, social, and environmental considerations’ To limit warming to 1.5C, it will be necessary to align mitigation/adaptation options with sustainability-oriented goals. The UN Sustainable Development Goals (SDGs) provide a framework for understanding the role of warming pathways on sustainable futures. IPCC 2018
Climate resilient development pathways (CRDPs) CRDPs are those pathways that simultaneously limit warming to 1.5C while meeting SDGs. IPCC 2018
Interactions between mitigation options and SDGs Examples of synergies (positive interactions) and trade-offs (negative interactions): • Synergy: Sustainable forest management can optimize carbon storage potential while providing valuable ecosystem services (e.g., cleaner water/air). • Trade off: People escaping from poverty and hunger consume more energy. The final chapter of the Special Report on Warming of 1.5C includes an in-depth analysis of such interactions.
Summary points • We are already experiencing the impacts of global warming. Warming of 1.5C will be associated with additional risks to health, food security, water supply, human security, and economic growth. • Given our current trajectory, warming will likely rise to 1.5C above pre-industrial levels between 2030 and 2050. • Meeting the 1.5C target will require a transition in our energy systems resulting in “deep emissions reductions in all sectors, a wide portfolio of mitigation options and a significant upscaling of investments in those options.” • There is a substantial role, especially for pathways that overshoot 1.5C, for negative emissions technologies that have not been tested at scale. • There are strong (and generally positive) interactions between limiting warming to 1.5C and meeting established Sustainable Development Goals. • Regardless of whether or not we meet the 1.5C or 2C target, the framework presented in this report represents a large step forward. THANK YOU!
