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IPCC Publishes Special Report on 1.5ºC Warming

Updated: Jan 9, 2019

The UN Intergovernmental Panel on Climate Change (IPCC) published a report on preventing 1.5ºC of warming from pre-industrial levels and what failure could mean for the planet.

The cover page for the IPCC special report. Image credit:

Without a radical transformation of our energy, transportation, and agriculture, the world will pass the 1.5ºC warming target of the Paris Climate Accord – by mid-century, according to a new report by the Intergovernmental Panel on Climate Change (IPCC).

Failing to cap global warming near that threshold dramatically increases risks to the entirety of human civilization, and to all of the world according to the new report. This report gives the approximate date of 2030.

To keep the planet under 1.5ºC of warming, the IPCC says that we will have to get global CO2 emissions to 45% of 2010 levels by 2030, and then reaching net zero emissions (offsetting any remaining emissions with removing carbon dioxide from the atmosphere). Other climate pollutants, such as methane and nitrous oxide have to be reduced to in order to reach this target.

This report is a follow-up to the Paris Climate Agreement and shows the risks to society of 1.5ºC of warming. The world has been warmed approximately 1ºC as of the end of 2017.

"Currently, we are on pace to blow past 1.5 degrees Celsius in a couple decades"

said Pennsylvania State University climate scientist Michael Mann. He said that on the current scenario, the world is on track to warm 3-4 degrees Celsius. He also stated:

"Every half-degree matters, and 2 degrees Celsius and 1.5°C warming shouldn't be thought of as cliffs we walk off. A better analogy is a minefield. The further out on to that minefield we go, the more explosions we are likely to set off"

The New-Found Effects of 1.5ºC of Warming

According to the study, 1.5ºC means catastrophic effects on the environment. The panel warned that, most of the world's coral reefs will die, droughts and heat waves will continue to intensify, and an additional 10 million people will face greater risks from rising sea level, including deadly storm surges and flooded coastal areas (the most at risk are millions of people in less developed parts of the world). In addition, livestock will decrease by 7.5% to 9.6%, as well as a 15% loss of wheat and corn.

Half a Degree Makes a Difference

The report is very certain that the risk of extreme heat waves will increase. The increase from 1.5ºC to 2.0ºC pushes extreme heat higher than the upper limit of current variability, as well as a new climate particularly in the tropics. The report also shows these devastating effects:

  • Risk from extreme precipitation would dramatically increase (2.0ºC).

  • 2.0ºC warming would entail 4 inches more of sea level rise than 1.5ºC, affecting 10 million more people.

  • An extra 580,000 to 1 million square miles of permafrost melted at 2.0ºC than 1.5ºC.

  • At 1.5ºC of warming, the Arctic is forecasted to be ice-free once per century, but at 2.0ºC, that would happen once every 10 years.

"It is difficult to comprehend the scale of crises confronting vulnerable communities in a world that is 1.5°C or 2.0°C hotter"

said International Federation of Red Cross President Francesco Rocca in response to the IPCC report. The IFRC shows that 23.5 million people were displaced from extreme weather activities, activities that are accelerated by climate change.

"What sounds like small increments in temperature can have devastating effects in terms of climate impacts on growing human populations"

said University of Florida sea level rise expert Andrea Dutton. Sea level rise is already causing frequent flooding and contaminating fresh water supplies on low-lying islands. In Indonesia, the rising water and erosion has overrun poor coastal communities where the residents can't afford to move.

Satellite measurements from recent years show sea level rising faster than anticipated, and new data from ancient ice layers, tree rings, and other sources suggest the polar ice sheets are more vulnerable to extensive melting at 1.5°C warming than previously believed.

Financial Impacts

The report also details some of the financial effects of climate change. For each 1.8º of warming that happens, the world GDP will drop 1.2%. In addition, after 2.7º of warming from pre-industrial levels, it will cost the world 54 trillion dollars. For 3.6º, it is 69 trillion dollars.

What's Missing From the Report?

Critics say that the report, which details all the climatic effects of more than 1.5ºC of warming, does not warn leaders enough about the consequences of passing these climate tipping points beyond climate, such as mass migration from the areas affected by climate change, and major conflicts over resources.

According to Bob Ward, policy and communications director for the Grantham Research Institute on Climate Change and the Environment, the IPCC has a reputation for leaving out high-impact, low-probability impacts. He also noted that there have been several studies on the risks of disruption of key ocean circulation that keeps Europe in mild temperatures despite the high latitude. This disruption could cause some parts of Western Europe to have Scandinavian like climates.

Is the Paris Climate Agreement Enough?

Is the Paris Climate Agreement enough to stop climate change? The short answer is no. In 2015, world leaders signed an agreement pledging to cut down greenhouse gas emissions; the Paris Climate Agreement. However, scientists say that these existing pledges will not limit our warming to 1.5°C above pre-industrial levels, or even 2°C. They say that it will end up being more like 3-4°C of warming with the current pledges.

"This report shows that dealing with climate change will become more dangerous and more expensive the longer we wait. Governments must get ready to commit to much more aggressive climate targets by 2020 at the latest, and they have to ditch coal"

said Bill Hare, CEO of Climate Analytics, a climate science and policy think tank. According to the IPCC, renewable energy needs to make up over half of the global energy by 2050, and coal must be almost completely phased out. If the average global temperature reaches 1.7°C of warming, then CO2 removal would have the be deployed at a scale "that might not be achievable given considerable implementation challenges," the report says.

In December, talks in Katowice, Poland about finalizing rules for the Paris Climate Agreement will take place, and the IPCC report will be a key discussion topic

Christopher Weber, global lead scientist for Climate and Energy for the World Wildlife Fund said that negotiators in Poland should focus on the science, not the politics. He added,

"This is not a political negotiation, it's a science report. We're already seeing impacts like super storms, wildfires and heat waves from 1 degree of warming. This report underscores that many of the impacts we thought we would see at 2 degrees we will see sooner, and they may be unstoppable above that"


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