INCHEON, South Korea, October 8, 2018 (ENS) – Humankind has just 20 years to confine global warming to 1.5°C above pre-industrial levels, and that will require rapid, far-reaching, unprecedented changes in all aspects of society, climate scientists working with the United Nations warn in a new assessment released today.
The authors found that if greenhouse gas emissions continue at the present rate, the atmosphere will heat up to 2.7 degrees Fahrenheit (1.5 degrees Celsius) above pre-industrial levels by 2040, flooding shorelines and bringing droughts, food shortages, wildfires and poverty.
A massive die-off of coral reefs is forecast as soon as 2040. Coral reefs would decline by 70-90 percent with global warming of 1.5°C, whereas virtually all coral reefs would be lost with 2°C of warming.
The report gives 2040 as an approximate date to reach 1.5°C Human activities are estimated to already have caused approximately 1.0°C of global warming above pre-industrial levels, with a likely range of 0.8°C to 1.2°C.
“Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate,” the report states.
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.
On the other hand, with clear benefits to people and natural ecosystems, limiting global warming to 1.5°C compared to 2°C could go together with ensuring a more sustainable and equitable society, says the IPCC report.
Ninety-one authors and review editors from 40 countries working with the Intergovernmental Panel on Climate Change, IPCC, prepared the Special Report on Global Warming of 1.5°C in response to an invitation from the United Nations Framework Convention on Climate Change, UNFCCC, when it adopted the Paris Agreement on climate.
The Paris Agreement, adopted by 195 nations at the 21st Conference of the Parties to the UNFCCC in December 2015, includes the goal of “holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels.”
The Special Report on Global Warming of 1.5°C was approved by the IPCC on Saturday in Incheon. It will be a key scientific input into the UN’s Katowice Climate Change Conference in Poland in December, when governments review implementation and financing for the Paris Agreement.
“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 of South Korea, who chairs the IPCC.
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.
“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, who serves as co-chair of IPCC Working Group I.
The report spotlights climate change impacts that could be avoided by limiting global warming to 1.5°C compared to 2°C, or more.
For instance, by 2100, global sea level rise would be 10 centimeters (3.93 inches) 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.
California’s Governor Jerry Brown, who has been working and advocating for a limit to global warming, said, “This IPCC report makes unmistakably clear that the world must radically change. It must decarbonize and establish a totally renewable basis for all economic activity. The big powers – the United States, China, India and the European Union – must show the way. We can do it but only if the deniers, the skeptics and the comfortable wake up to what the scientists are telling us.”
“Every extra bit of warming matters, especially since warming of 1.5°C 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, explains Pörtner.
The report also examines pathways available to limit warming to 1.5°C, 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 1.5°C are already underway around the world, but they would need to accelerate,” said Valerie Masson-Delmotte, co-chair of Working Group I.
“Limiting warming to 1.5°C 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 1.5°C would mean a greater reliance on techniques that remove CO2 from the air to return global temperature to below 1.5°C by 2100. The effectiveness of such techniques are unproven at large scale and some may carry significant risks for sustainable development, the report observes.
“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,” she said. “The next few years are probably the most important in our history.”