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Aissat Abduljub and Habiba Wellba show Baaba Maal their failed crops this year. The maize has gone dry so is inedible.
Aissat Abduljub and Habiba Wellba show Baaba Maal their failed corn crops in Mauritania. Oxfam International via Flickr.
16 August 2016 17:01

IPCC special report to scrutinise ‘feasibility’ of 1.5C climate goal

Roz Pidcock

Roz Pidcock

Roz Pidcock

Roz Pidcock

16.08.2016 | 5:01pm
IPCCIPCC special report to scrutinise ‘feasibility’ of 1.5C climate goal

The head of the United Nation’s climate body has called for a thorough assessment of the feasibility of the international goal to limit warming to 1.5C.

Dr Hoesung Lee, chair of the Intergovernmental Panel on Climate Change (IPCC), told delegates at a meeting in Geneva, which is designed to flesh out the contents of a special report on 1.5C, that they bore a “great responsibility” in making sure it meets the expectations of the international climate community.

To be policy-relevant, the report will need to spell out what’s to be gained by limiting warming to 1.5C, as well as the practical steps needed to get there within sustainability and poverty eradication goals.

More than ever, urged Lee, the report must be easily understandable for a non-scientific audience. The IPCC has come under fire in the past over what some have called its “increasingly unreadable” reports.


In between the main “assessment reports” every five or six years, the IPCC publishes shorter “special reports” on specific topics. Past ones have included extreme weather and renewable energy.

The IPCC was “invited” by the United Nations Convention on Climate Change (UNFCCC) to do a special report on 1.5C after the Paris Agreement codified a goal to limit global temperature rise to “well below 2C” and to “pursue efforts towards 1.5C”.

The aim for this week’s meeting in Geneva is, in theory, simple: to decide on a title for the report; come up with chapter headings; and write a few bullet points summarising what the report will cover.

On day two of three, Carbon Brief understands six “themes” have emerged as contenders. Judging by proceeding so far,  it seems likely that the feasibility of the 1.5C goal features highly on that list.

Referring to a questionnaire sent out to scientists, policymakers and other “interested parties” ahead of the scoping meeting to ask what they thought the 1.5C report should cover, Lee told the conference:

“One notion that runs through all this, is feasibility. How feasible is it to limit warming to 1.5C? How feasible is it to develop the technologies that will get us there?…We must analyse policy measures in terms of feasibility.”

The explicit mention of 1.5C in the Paris Agreement caught the scientific community somewhat off-guard, said Elena Manaenkova, incoming deputy secretary-general of the World Meteorological Organization.

Speaking in Geneva yesterday, she told delegates she felt “proud, but also somewhat concerned” about the outcome of the Paris talks. She said:

“I was there. I know the reason why it was done…[P]arties were keen to do even better, to go faster, to go even further…The word ‘feasibility’ is not in the Paris Agreement, is not in the decision. But that’s really what it is [about].”


Dr Andrew King, a researcher in climate extremes at the University of Melbourne, echoes the call for a rational discussion about the way ahead, now that the dust has settled after Paris. The question of what it would take to achieve the 1.5C goal has been largely sidestepped so far, he tells Carbon Brief:

“I think one unintended outcome of the Paris Agreement was that it made the public think limiting warming to 1.5C is possible with only marginally stronger policy from government on reducing emissions and this is simply not the case.”

Carbon Countdown: How many years of current emissions would use up the IPCC's carbon budgets for different levels of warming?

Carbon Countdown: How many years of current emissions would use up the IPCC’s carbon budgets for different levels of warming? Infographic by Rosamund Pearce for Carbon Brief.

The reality is that staying under the 1.5C threshold is now nigh-on impossible, says King. Meeting the 1.5C target now means overshooting and coming back down using negative emissions technologies that “suck” carbon dioxide out of the air. The report will need to be explicit about this, he says.

King is cautious about overstating the world’s ability to meet the 1.5C goal, given that no single technology yet exists approaching the scale that would be required. He tells Carbon Brief:

“We will need negative emissions on a large-scale and for a long period of time to bring global temperatures back down to 1.5C. This isn’t possible with current technologies.”

Earlier this year, Carbon Brief published a series of articles on negative emissions, including a close up on the most talked-about option – Bioenergy with Carbon Capture and Storage (BECCS) – and a survey of which technologies climate experts think hold the most potential.

‘A great responsibility’

Another point on which the special report must be very clear is the difference between impacts at 1.5C compared to 2C, noted Thelma Krug, chair of the scientific steering committee for the special report.

The first study to compare the consequences at both temperatures found that an extra 0.5C could see global sea levels rise 10cm more by 2100 and is also “likely to be decisive for the future of coral reefs”.

King tells Carbon Brief:

“We need to know more about the benefits of limiting warming to 1.5C. If scientists can demonstrate to policymakers that we would see significantly fewer and less intense extreme weather events by putting the brakes on our emissions then it might lead to the necessary action to protect society and the environment from the worst outcomes of climate change.”

Infographic: How do the impacts of 1.5C of warming compare to 2C of warming?

Infographic: How do the impacts of 1.5C of warming compare to 2C of warming? By Rosamund Pearce for Carbon Brief.

The timing of the 1.5C special report is critical, said Lee yesterday. Due for delivery in September 2018, the IPCC’s aim is that the report should be “in time for” the UNFCCC’s “facilitative dialogue” scheduled that year.

This will be the first informal review under the global stocktake – a process that will enable countries to assess progress towards meeting the long-term goals set out under the Paris Agreement.

Expectations will be high, Lee told delegates yesterday:

“You can be sure that the report, when it is available in two years’ time…will attract enormous attention. So you have a great responsibility.”

Any scientist wishing their research to be included in the special report on 1.5C will need to submit it to a peer-reviewed journal by October 2017, and have it accepted for publication by April 2018, according to the IPCC’s timeline.

The scientific community is already mobilising behind this tight deadline. An international conference at Oxford University in September will see scientists, policymakers, businesses and civil society gather to discuss the challenges of meeting the 1.5C goal, which the organisers say “caught the world by surprise”.

Clearer communication

More than ever, the IPCC should strive to communicate the special report on 1.5C as clearly and accessibly as possible, Lee told the conference yesterday.

Given the primary audience will be non-specialists, the authors should think from the outset about how FAQs (Frequently Asked Questions) and graphics could be used to best effect, he said.

“The special report on 1.5C is not intended to replicate a comprehensive IPCC regular assessment reports. It should be focused on the matter at hand.”

The importance of the 1.5C topic calls for a different approach to previous IPCC reports, says King. He tells Carbon Brief:

“The report will fail to have much effect if the findings aren’t communicated well to policymakers and the public. This could be seen as a failing of the climate science community in the past. It has led to much weaker action on reducing climate change than is needed; this report needs to change this.”

A couple of recently published papers might give the authors some food for thought on this point.

The first study looks at how the process by which governments approve the IPCC’s Summaries for Policymakers (SPMs) affects their “readability”. Of the eight examples the study considers, all got longer during the government review stage. On average, they expanded by 30% or 1,500-2,000 words. The review process improved “readability” in half of cases, though all eight scored low for “storytelling”.

A second paper explores the power of visuals for communicating climate science to non-specialists, and highlights where the IPCC may be falling short. Giving the examples below from the IPCC’s third and fourth assessment reports, the paper notes:

“A feeling of confusion among non-climate students is certainly not congruent with positive engagement yet this emotional state was frequently reported for SPM visuals.”

Images and infographics can be powerful, but only if the trade-off between scientific credibility and ease of understanding is carefully handled, the paper concludes.

Four examples of visuals used in the IPCC's third and fourth assessment reports. Source: McMahon et al., (2016)

Four examples of visuals used in the IPCC’s third and fourth assessment reports. Source: McMahon et al., (2016)

With all this mind, the scientists will leave the Geneva conference on Wednesday and prepare an outline for the 1.5C report based on their discussions over the previous three days.

They will submit the proposed plan to the IPCC panel at its next meeting in Bangkok in October. If the outline meets the panel’s expectations, it will accept it and things move forward. If it falls short, they can request changes be made. The discussions in Geneva are, therefore, unlikely to be the last word.

Sharelines from this story
  • IPCC special report to scrutinise 'feasibility' of 1.5C climate goal
  • Ronal Larson

    Congratulations. This was one of your best daily lead stories. Graphics ARE critical and your Ms Pearce produced two outstanding NEW ones in this 16 August version of your daily report on an IFCC document that itself is important – also emphasizing readability – on which you do a great job.

    • RozPidcock

      Thanks Ronal. Your feedback is much appreciated!

  • Ace Otana

    The IPCC is far too conservative (as usual). We’ll reach and pass 2C before 2020. We’ll reach 4C at least by mid 2020’s. Though it’s possible it could go as high as 10C by 2030. Due to feedback loops, the loss of global dimming and such. We’ve already reached and passed 1.3C this year alone. Also the Arctic is rapidly losing it’s ice, it’s expected to go completely ice-free before 2020.
    There is no carbon budget….

    • RozPidcock

      Hi Ace, thanks for your comment. The IPCC reflects the weight of evidence, it doesn’t have its own position or opinions. Most scientists would not agree with the timelines you state here – at least 4C by the mid 2020s and a sea ice-free Arctic before 2020. Do you have references for your assertions? Thank you.

  • Richard A. Rosen

    I hope that Carbon Brief will follow up this important story by providing readers with as many of the actual documents generated by this conference on the Special Report as possible.

    • RozPidcock

      We certainly will, thanks Richard. Nothing has been released yet but as soon as there are any updates, we’ll let you know.

  • gasdive

    Reporting on this sort of thing must be very weird. So the IPCC is tasked with reporting in 2 years time if it’s possible to avoid crossing the 1.5 degree line in the sand 6 months after we cross the 1.5 degree line in the sand. March was 1.565.

    If it was a movie about crazy bureaucracy gone mad, people would have trouble suspending disbelief in order to go along with the movie. Truth is really much stranger than fiction.

  • André Balsa

    This is an excellent article that touches and discusses the essential issues of the 1.5C warming threshold which the Paris agreement stated should be pursued.
    One of the main issues with the consecutive IPCC reports has been, as the article makes clear, that the language used has led to inadequate and insufficient emissions reductions policies being implemented worldwide, and that in my opinion is the main issue that should be addressed by this 1.5C special report.
    As long as climate scientists worldwide use such terms as “carbon budget”, we can be certain that such “carbon budget” estimates will be exceeded – by far. A similar issue is that of including estimates of the requirements for negative emissions measures, when the technology for large scale negative emissions is simply non-existent. And then there is also the somewhat mysterious term for the layman, “overshoot”. While it is perhaps useful for climate model programmers, it is a no-no for policy makers, who cannot differentiate between a “temporary overshoot” lasting 50 years or more, and a permanent global disaster.
    In conclusion, I would suggest that the IPCC special report on the 1.5C warming threshold absolutely AVOID mentioning these three concepts:
    – “Carbon budget”, because essentially there is none left.
    – “Negative emissions”, because the technology does not exist for such, making it pure wishful thinking.
    – “Overshoot”, when it really means “catastrophe, affecting billions of human beings over generations”.
    If by 2018 climate scientists worldwide are convinced that the 1.5C target is impossible to achieve, they should come out and say so clearly and loud enough, without reverting to half-words and obscure terms to describe non-existent technologies that will save no one.

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