2016 Spring Flood in North Louisiana. A man looking down a flooded railway line.

cracked earth from drought

An important new report has been released by The Intergovernmental Panel on Climate Change (IPCC*) on Oct. 8th 2018 that provides a comparison between the anticipated impacts and consequences of 1.5°C vs 2°C of global average warming above pre-industrial levels (Read 1.5 Report here). There’s good news and bad news.  For the background to the report read on, for a summary of key points, skip to the text in bold below.

According to the UN’s press release 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 pre-industrial 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 this year, 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.

The report’s full title 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.
To summarize, these are the key findings of this report to take away:

  1. Humanity has about a decade to act decisively to limit global warming to 1.5°C, some of the necessary actions have begun, but these must be accelerated. It’s possible if we have the will. 
  2. Even a world with 1.5°C increase in global average warming above pre-industrial levels will incur major negative impacts at the level previously thought to occur in a 2°C world. 
  3. If humanity acts decisively, and sensibly, there will be major economic gains and the world is expected to be 3% wealthier by the end of the 21st Century and may avoid considerable unpleasantness.

There is growing concensus that climate change represents the greatest threat to human welfare, click here to see the video of speech by the UN Secretary General on Climate Change in which he states that climate change is his absolute priority for the UN. http://webtv.un.org/search/antónio-guterres-secretary-general-delivers-speech-on-climate-change-and-his-vision-for-the-2019-climate-change-summit/5833142929001/

According to the UN’s press release the report highlights a number of 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 cm lower with global warming of 1.5°C compared with 2°C.
  • The likelihood of anArctic 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 2°C.

“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,” says 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 1.5°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.

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 1.5°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 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.

Debra Roberts, Co-Chair of IPCC Working Group II says that the decisions we make today are critical in ensuring a safe and sustainable world for everyone, both now and in the future.

“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.

Global Warming of 1.5°C 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 1.5°C (SR15) is available at https://www.ipcc.ch/report/sr15.

*The IPCC is the leading international body for the assessment of climate change. It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988 to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts. In the same year, the UN General Assembly endorsed the action by WMO and UNEP in jointly establishing the IPCC. http://www.ipcc.ch/report/sr15/