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Science Alert: Experts Respond

1.5°C limit still on the table at climate negotiations – Expert reaction

Posted in Science Alert: Experts Respond on December 10th, 2015.

A new draft has been presented to delegates at the at the UN climate conference in Paris, offering a much slimmer version but still with many points of contention – not the least of which is whether the world should be aiming to keep the global rise in temperature under 1.5 or 2 degrees Celsius.

Climate badge2The new draft issued this morning (NZT) comes in at 29 pages.  Currently the draft has three options relating to part of it’s core purpose, detailed below (square brackets denote language yet to be agreed upon):

(a) To hold the increase in the global average temperature to

Option 1: below 2 °C above pre-industrial levels,
Option 2: well below 2°C above pre-industrial levels [and to [rapidly] scale up global efforts to limit temperature increase to below 1.5 °C] [,while recognizing that in some regions and vulnerable ecosystems high risks are projected even for warming above 1.5 °C],
Option 3: below 1.5°C above pre-industrial levels,

taking into account the best available science, equity, sustainable development, the need to ensure food security and the availability of means of implementation, by ensuring deep reductions in global greenhouse gas [net] emissions;

Negotiators are aiming to have a final version of the agreement settled by the weekend.

Our colleagues at the UK Science Media Centre collected the following expert commentary:

Prof Simon Lewis, Chair in Global Change Science at University College London, comments:

“The new text is not substantially different to the previous version, but is more streamlined. The major political differences remain. Whether the purpose of the agreement is to keep global average temperature to 2 degrees or 1.5 degrees is still open. Whether the stated reductions in emissions this century are enough to keep temperatures below 2 degree goal is still open. A robust mechanism to get from where countries are now to move to zero greenhouse gas emissions this century is still open. The levels and predictability of funding for developing countries to leap-frog the fossil fuel age as they develop is still open. Whether poor countries will get compensation for the impacts of climate change caused, in large part, by rich countries is still open.

“Any robust agreement from Paris starts with the goal. Whether it is limiting global warming to 1.5 or 2 degrees, three key ingredients are needed. First, the  emissions cuts in the agreement must be scientifically credible. For 2 degrees that means immediate rapid reductions in greenhouse gas emissions to zero emissions by the middle of the century (and then negative emissions). Second, the current pledges by countries are well above the requirements of 2 degrees, so a mechanism to transparently review progress and increase commitments is needed. Third, substantial and predictable funding will be required so all countries, including the world’s poorest, can pay their part in reducing emissions to near zero over the coming decades.”

Prof Nigel Arnell, Professor of Climate Change Science at the University of Reading, and funded by NERC, comments:

“Today’s draft of an agreement marks a step forward from Sunday’s draft which included many important issues that were still to be decided. A commitment to support adaptation is virtually finalised, although there will be still much discussion on the size of the funds pledged.

“There remain two big issues which are still not resolved. The first is the target for the rise in temperature. The text offers up ‘below 2 degrees’, ‘well below 2 degrees’ and ‘below 1.5 degrees’ as options for discussion. However none of those targets is properly defined, so whichever option is chosen it could still be open to interpretation. The 1.5 degree target in particular looks very ambitious.

“The second problem is the long-term goal for what to do after 2030. We know that the pledges in themselves are not enough to achieve even 2 degrees without deeper reductions after 2030. The draft text still contains several alternative variations, some of which are very vague, but there is a commitment to review progress in the future, which is good.

“Overall the draft text provides a really good starting point for the final stages of negotiation, but there are lots of details to confirm before we get an agreement.”

Prof Piers Forster, Professor of Climate Change at the University of Leeds, comments:

“It appears the ‘below 2C’ option is now back on the table, compared to last weekend’s draft that had ‘well below 2C’ as the weakest long term commitment.  My hunch and hope is that this is a negotiating ploy and we will end up with ‘well below 2C’ in the final draft.

“The main sticking points are still around the ratchet mechanism that by-and-large the developed countries want, as well as acknowledgement of loss and damage that the developing countries want.  We will either get a strong agreement with both included or a weaker agreement without either.”

Prof Gabi Hegerl, Professor of Climate System Science at the University of Edinburgh, comments:

“As a scientist I am pleased that there is a draft agreement which takes input from climate science, impact and economics into account.  As a mom I am incredibly relieved that an agreement is being developed that sets us on a path to limit global warming. Phasing out CO2 emissions will not be easy but it should make the world a safer place.”

Prof Joanna Haigh, Professor of Atmospheric Physics and Co-Director of Grantham Institute for Climate Change and Environment at Imperial College London, comments:

“The inclusion of a 1.5 degree option in the draft agreement is remarkable, as is the ambitious proposed mitigation pathway of 70-95% cuts by 2050 leading to zero carbon emissions by the latter half of the century.

“Showing the seriousness of this intention is the proposed request for the IPCC to produce a special report by 2018 on the potential climate impacts of a 1.5 degree world. Perhaps some of these more ambitious options will not reach the final document but the fact that these targets are being seriously discussed is hugely positive.”

Dr Matthew Watson, Reader in Natural Hazards at the University of Bristol, comments:

“Any agreement to cut emissions and reduce our dependency on carbon-based fuels is a really good thing. However, an agreement to keep to below 1.5 degrees C of warming has significant and, worryingly, unstated consequences.

“Current scientific thinking suggests we cannot limit warming to less than 1.5 degrees without large scale intervention in the climate system.  Implicit in this agreement, then, is acceptance of some form of climate engineering.

“I am not suggesting we shouldn’t drastically reduce our reliance on fossil fuels; we must, and I welcome this agreement. However, we’ve already used up two thirds of the 1.5 degree C limit. This agreement promotes the tacit acceptance of geoengineering in some form, which could be described as ‘too much, too late’.  We must enter into this agreement with our eyes wide open.”

Prof Chris Rapley, Professor of Climate Science at University College London, comments:

“The inclusion in the draft text of options to limit global warming to well below 2 degrees, or even to below 1.5 degrees, reveals a fundamental shift in the tone and content of the negotiations.  Now that nations have declared their voluntary emissions reductions commitments, the focus has turned to ramping up ambition.

“This is an historic change, and may at last herald the beginning of ‘the Greatest Collective Action in History’!”

Prof Richard Betts, Head of Climate Impacts Research at the Met Office Hadley Centre, comments:

“For me, there is important detail in Article 3 bis – REDD-PLUS. Incentivising forest conservation goes beyond just carbon stocks and includes enhancing non-carbon benefits. This is crucial because the role of the land biosphere goes beyond carbon alone – protecting biodiversity is a key factor when considering using the land to try to mitigate climate change, for example through bioenergy. If not done with care, it’s possible to misfire on this and induce worse impacts than those that mitigation aims to avoid. Also, rainforests affect climate through other processes in addition to acting as carbon sinks and stores – they promote evaporation, which keeps the land cooler and helps recycle rainfall.”

Dr Chris Huntingford of the UK Centre for Ecology and Hydrology comments:

“A fundamental problem to date with the climate change debate is that it has been heavily polarised. Some debunk the science because they oppose emissions reductions, believing this will protect economies presently so dependent on fossil fuel use. Others wish for near-immediate cessation of all greenhouse emissions due to fears of pushing the climatic system to a dangerous state.

“To maximise climatic safety alongside economic security for the largest number of people, there is probably an intermediate trajectory in energy use change. The COP21 statement encapsulates that, setting out a set of compromises needed in the decades ahead, and recognising that individual contributions and needs will be strongly country-specific.

“The COP21 statement may well encourage thoughtful and much needed bridge-building between those holding opposing views on how to approach global warming”

Prof Alice Bows-Larkin, Prof of Climate Science and Energy Policy and Director of the Tyndall Centre, Manchester, comments:

“The draft text of the Paris Agreement has removed reference to international shipping and aviation emissions – two sectors that each contribute currently about the same amount of CO2 as Germany, and where CO2 emissions are anticipated to grow to 2050. This seemingly contradicts other parts of the document where reference is made to ‘reach the global temperature goal…informed by the best available science’.

“Missing out two sectors that would constitute a ‘top 10 emitter’ essentially ignores what the ‘best available science’ is saying about urgent, deep and sustained mitigation commensurate with 2C. It also sends a signal to these industries that on-going growth in international transport CO2 ‘fits’ within a scientific interpretation of the temperature goal (which will be at least ‘below 2°C above pre-industrial levels’), which is not the case.

“Moreover, it provides little decarbonisation incentive for these industries, delaying any move towards low-carbon operational, demand-side and technology options, and risks locking them into stranded high-carbon assets.”

  Prof William Collins, Prof of Meteorology at the University of Reading, comments:

“The parties have put together an ambitious document. If the agreed limit on warming is reduced to 1.5 degrees this will be very challenging to achieve and will require removing carbon dioxide from the atmosphere by the end of the century.

“The most ambitious scenario assessed by the IPCC had an average warming of 1.6 degrees above pre-industrial and we are currently exceeding the emissions in that scenario.”

  Prof Dave Reay, Professor of Carbon Management & Education at the University of Edinburgh, comments:

“The overt inclusion of a 1.5 degree C target is good to see, but it puts the big shortfall in collective emissions reductions into even starker relief. Even if every nation delivers on its stated plans – and that’s a big if – we would still be on a 3 degree pathway to dangerous climate change.

“A big disappointment is the lack of a clear and robust ‘ratchet mechanism’ to ensure all nations regularly revise their targets beyond 2020, based on the best available science.  A ratchet with no teeth raises the prospect of emissions targets through to 2030 that simply cannot deliver the global impact required.”

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