Human-induced warming reached approximately 1°C above pre-industrial levels in 2017. At the present rate, global temperatures would reach 1.5°C around 2040. Graphic: IPCC

By Coral Davenport
7 October 2018
INCHEON, South Korea (The New York Times) – A landmark report from the United Nations’ scientific panel on climate change paints a far more dire picture of the immediate consequences of climate change than previously thought and says that avoiding the damage requires transforming the world economy at a speed and scale that has “no documented historic precedent.”The report, issued on Monday by the Intergovernmental Panel on Climate Change, a group of scientists convened by the United Nations to guide world leaders, describes a world of worsening food shortages and wildfires, and a mass die-off of coral reefs as soon as 2040 — a period well within the lifetime of much of the global population.The report “is quite a shock, and quite concerning,” said Bill Hare, an author of previous I.P.C.C. reports and a physicist with Climate Analytics, a nonprofit organization. “We were not aware of this just a few years ago.” The report was the first to be commissioned by world leaders under the Paris agreement, the 2015 pact by nations to fight global warming.The authors found that if greenhouse gas emissions continue at the current rate, the atmosphere will warm up by as much as 2.7 degrees Fahrenheit (1.5 degrees Celsius) above preindustrial levels by 2040, inundating coastlines and intensifying droughts and poverty. Previous work had focused on estimating the damage if average temperatures were to rise by a larger number, 3.6 degrees Fahrenheit (2 degrees Celsius), because that was the threshold scientists previously considered for the most severe effects of climate change.The new report, however, shows that many of those effects will come much sooner, at the 2.7-degree mark.Avoiding the most serious damage requires transforming the world economy within just a few years, said the authors, who estimate that the damage would come at a cost of $54 trillion. But while they conclude that it is technically possible to achieve the rapid changes required to avoid 2.7 degrees of warming, they concede that it may be politically unlikely. For instance, the report says that heavy taxes or prices on carbon dioxide emissions — perhaps as high as $27,000 per ton by 2100 — would be required. But such a move would be almost politically impossible in the United States, the world’s largest economy and second-largest greenhouse gas emitter behind China. Lawmakers around the world, including in China, the European Union and California, have enacted carbon pricing programs.President Trump, who has mocked the science of human-caused climate change, has vowed to increase the burning of coal and said he intends to withdraw from the Paris agreement. And on Sunday in Brazil, the world’s seventh-largest emitter of greenhouse gas, voters appeared on track to elect a new president, Jair Bolsonaro, who has said he also plans to withdraw from the accord. […]Absent aggressive action, many effects once expected only several decades in the future will arrive by 2040, and at the lower temperature, the report shows. “It’s telling us we need to reverse emissions trends and turn the world economy on a dime,” said Myles Allen, an Oxford University climate scientist and an author of the report. To prevent 2.7 degrees of warming, the report said, greenhouse pollution must be reduced by 45 percent from 2010 levels by 2030, and 100 percent by 2050. It also found that, by 2050, use of coal as an electricity source would have to drop from nearly 40 percent today to between 1 and 7 percent. Renewable energy such as wind and solar, which make up about 20 percent of the electricity mix today, would have to increase to as much as 67 percent.“This report makes it clear: There is no way to mitigate climate change without getting rid of coal,” said Drew Shindell, a climate scientist at Duke University and an author of the report. [more]

Major Climate Report Describes a Strong Risk of Crisis as Early as 2040Spatial and seasonal pattern of present-day warming: Regional warming for the 2006–2015 decade relative to 1850–1900 for the annual mean (top), the average of December, January and February (bottom left) and for June, July and August (bottom right). Warming is evaluated by regressing regional changes in the (Cowtan and Way, 2014) dataset onto the total (combined human and natural) externally-forced warming (yellow line in Figure 1.2). Graphic: IPCC

INCHEON, Republic of Korea, 8 October 2018 (IPCC) – Limiting global warming to 1.5ºC would require rapid, far-reaching and unprecedented changes in all aspects of society, the IPCC said in a new assessment. With clear benefits to people and natural ecosystems, limiting global warming to 1.5ºC compared to 2ºC could go hand in hand with ensuring a more sustainable and equitable society, the Intergovernmental Panel on Climate Change (IPCC) said on Monday.The Special Report on Global Warming of 1.5ºC was approved by the IPCC on Saturday in Incheon, Republic of Korea. It will be a key scientific input into the Katowice Climate Change Conference in Poland in December, when governments review the Paris Agreement to tackle climate change.“With more than 6,000 scientific references cited and the dedicated contribution of thousands of expert and government reviewers worldwide, this important report testifies to the breadth and policy relevance of the IPCC,” said Hoesung Lee, Chair of the IPCC. Ninety-one authors and review editors from 40 countries prepared the IPCC report in response to an invitation from the United Nations Framework Convention on Climate Change (UNFCCC) when it adopted the Paris Agreement in 2015. The report’s full name is Global Warming of 1.5°C, an IPCC special report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty.“One of the key messages that comes out very strongly from this report is that we are already seeing the consequences of 1°C of global warming through more extreme weather, rising sea levels, and diminishing Arctic sea ice, among other changes,” said Panmao Zhai, Co-Chair of IPCC Working Group I.The report highlights a number of climate change impacts that could be avoided by limiting global warming to 1.5ºC compared to 2ºC, or more. For instance, by 2100, global sea level rise would be 10 cm lower with global warming of 1.5°C compared with 2°C. The likelihood of an Arctic Ocean free of sea ice in summer would be once per century with global warming of 1.5°C, compared with at least once per decade with 2°C. Coral reefs would decline by 70-90 percent with global warming of 1.5°C, whereas virtually all (> 99 percent) would be lost with 2ºC. “Every extra bit of warming matters, especially since warming of 1.5ºC or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some ecosystems,” said Hans-Otto Pörtner, Co-Chair of IPCC Working Group II.Limiting global warming would also give people and ecosystems more room to adapt and remain below relevant risk thresholds, added Pörtner. The report also examines pathways available to limit warming to 1.5ºC, what it would take to achieve them and what the consequences could be.“The good news is that some of the kinds of actions that would be needed to limit global warming to 1.5ºC are already underway around the world, but they would need to accelerate,” said Valerie Masson-Delmotte, Co-Chair of Working Group I. The report finds that limiting global warming to 1.5°C would require “rapid and far-reaching” transitions in land, energy, industry, buildings, transport, and cities. Global net human-caused emissions of carbon dioxide (CO2) would need to fall by about 45 percent from 2010 levels by 2030, reaching ‘net zero’ around 2050. This means that any remaining emissions would need to be balanced by removing CO2 from the air.“Limiting warming to 1.5ºC is possible within the laws of chemistry and physics but doing so would require unprecedented changes,” said Jim Skea, Co-Chair of IPCC Working Group III. Allowing the global temperature to temporarily exceed or ‘overshoot’ 1.5ºC would mean a greater reliance on techniques that remove CO2 from the air to return global temperature to below 1.5ºC by 2100. The effectiveness of such techniques are unproven at large scale and some may carry significant risks for sustainable development, the report notes.“Limiting global warming to 1.5°C compared with 2°C would reduce challenging impacts on ecosystems, human health and well-being, making it easier to achieve the United Nations Sustainable Development Goals,” said Priyardarshi Shukla, Co-Chair of IPCC Working Group III. The decisions we make today are critical in ensuring a safe and sustainable world for everyone, both now and in the future, said Debra Roberts, Co-Chair of IPCC Working Group II.“This report gives policymakers and practitioners the information they need to make decisions that tackle climate change while considering local context and people’s needs. The next few years are probably the most important in our history,” she said. The IPCC is the leading world body for assessing the science related to climate change, its impacts and potential future risks, and possible response options.The report was prepared under the scientific leadership of all three IPCC working groups. Working Group I assesses the physical science basis of climate change; Working Group II addresses impacts, adaptation and vulnerability; and Working Group III deals with the mitigation of climate change. The Paris Agreement adopted by 195 nations at the 21st Conference of the Parties to the UNFCCC in December 2015 included the aim of strengthening the global response to the threat of climate change by “holding the increase in the global average temperature to well below 2°C above preindustrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels.”As part of the decision to adopt the Paris Agreement, the IPCC was invited to produce, in 2018, a Special Report on global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways. The IPCC accepted the invitation, adding that the Special Report would look at these issues in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. Global Warming of 1.5ºC is the first in a series of Special Reports to be produced in the IPCC’s Sixth Assessment Cycle. Next year the IPCC will release the Special Report on the Ocean and Cryosphere in a Changing Climate, and Climate Change and Land, which looks at how climate change affects land use. The Summary for Policymakers (SPM) presents the key findings of the Special Report, based on the assessment of the available scientific, technical and socio-economic literature relevant to global warming of 1.5°C. The Summary for Policymakers of the Special Report on Global Warming of 1.5ºC (SR15) is available at http://www.ipcc.ch/report/sr15/or www.ipcc.ch.

Key statistics of the Special Report on Global Warming of 1.5ºC

91 authors from 44 citizenships and 40 countries of residence – 14 Coordinating Lead Authors (CLAs) – 60 Lead authors (LAs) – 17 Review Editors (REs) 133 Contributing authors (CAs) Over 6,000 cited references A total of 42,001 expert and government review comments(First Order Draft 12,895; Second Order Draft 25,476; Final Government Draft: 3,630)

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Summary for Policymakers of IPCC Special Report on Global Warming of 1.5ºC approved by governments