The latest report by the Intergovernmental Panel on Climate Change (IPCC) details the need to limit global warming to 1.5°C and the potential impacts if this isn’t achieved.
Dr Jo House, Reader in Environmental Science and Policy at the Cabot Institute, University of Bristol, said:
“This report highlights the need to rapidly replace fossil fuel emissions with low cost renewable energy technologies that are already widely available. The report also highlights the urgent needs to protect forests and peatlands – these store more carbon than fossil fuel reserves, but also suck it out of the atmosphere, removing nearly a third of our current carbon dioxide emissions. Planting new forests can remove carbon from the atmosphere, as can using plants’ biomass for energy with carbon capture and storage technology (BECCS). Some scenarios rely on planting up to 700Mha of land to bioenergy crops, that’s twice the size of India. To avoid relying on land for bioenergy mitigation, competing with food and nature, we have to address fossil fuel and industrial emissions. The IPCC will produce a Special Report on Climate Change and Land next year to look further into land based mitigation and the co-benefits and trade-offs.”
Prof Euan Nisbet, Prof of Earth Sciences at Royal Holloway University of London, said:
“The report shows the frightening consequences of allowing global warming to go more than 1.5C above pre-industrial norms. There are very strong reasons to try as hard as we can to keep below this level. If warming goes further, the implications both for the biosphere and for human economies are very dangerous
“The good news is that there are ways of achieving this ambitious target of keeping warming below 1.5C, but it will need very strong cuts in CO2 emissions, and we will almost certainly need actively to remove carbon from the air, for example by regrowing forests.
“A very interesting part of the report is that it shows the powerful benefits of urgently cutting non-CO2 greenhouse warmers such as methane, black carbon and nitrous oxide. Reducing these will help very significantly. Cutting methane and black carbon emissions is a relatively low cost option, somewhat neglected by policymakers. It’s an obvious target.
“We really do need to limit warming below 1.5C: given the danger, it’s not a choice. Yes, it’ll be hard, but there are feasible ways we can do that: we can get there.”
Prof Martin Manning, Victoria University in Wellington NZ, said:
“Hopefully the statement that future change caused by the anthropogenic emissions that have occurred so far are unlikely to cause a global warming of more than 1.5C is correct. But it is noted that there is only a medium confidence this is the case. One of the more obvious reasons for concern is that the cause for significant increases in atmospheric methane over the last 12 years, and therefore how long it may continue, is still not understood.
“Figure 3a shows that the pathways considered, for keeping to 1.5C, have methane decreasing before 2030 and continuing to decrease very rapidly until 2040. This shows that Figure 1d showing non-CO2 radiative forcing being reduced after 2030 is more pessimistic than what was actually used in the climate models.
“Figure 1 shows that the effect of faster reductions in non-CO2 greenhouse gases is similar to having 15 more years to reach net zero CO2 emissions and therefore should be seen as having a very high priority. Also paragraph A2.2. notes that larger reductions in non-CO2 radiative forcing may be required due to earth system feedbacks. This is particularly relevant if the recent rise in methane is due to changes in atmospheric chemistry, in which case a larger reduction in anthropogenic methane emissions will be even more urgent.
“BECCS (Bioenergy with carbon capture and storage) for a net removal of CO2 from that atmosphere are seen as essential for both the 2C and 1.5C options. However, methods for removal of methane from the atmosphere need to be considered as well.”
Prof Richard Betts, Head of Climate Impacts Research at the Met Office and Chair in Climate Impacts at the University of Exeter, said:
“The report shows that we now risk being stuck between a rock and a hard place if we don’t take the right courses of action. Crucially, the report discusses pathways that aim to limit warming to 1.5C without making poor and disadvantaged people worse off. The report also notes that many proposals to avoid the risks of 2C warming could, if done badly, threaten food security by using land for afforestation and bioenergy in the wrong way.
“Some climate change impacts, such as a certain amount of sea level rise, are already locked-in for the long term and will require adaptation, especially in vulnerable countries. Limiting warming to 1.5C would help limit these impacts and reduce the risk of them becoming unmanageable, but doing this effectively and fairly without causing other problems is a huge challenge.”
Prof Corinne Le Quéré FRS, Director of the Tyndall Centre for Climate Change Research at the University of East Anglia, said:
“The report provides an incredibly detailed picture of the risks of a warming planet and how they grow as the warming intensifies. The message could not be clearer. Widespread, concerted and sustained action across the economy is needed to cut carbon emissions down to zero and limit the risks of a warming climate. For the UK, this means a rapid switch to renewable energy and electric cars, insulating our homes, planting trees, where possible walking/cycling and eating well (more plants/less meat), and developing an industry to capture carbon and store it underground. It also means adapting to the growing impacts of climate change that are felt here, particularly to the increasing flood risks from heavy rainfall and from sea level rise along our coasts. The solutions are already here. “
Prof William Collins, Professor of Meteorology at the University of Reading, said:
“This report is extremely important in showing the need to restrict climate change to 1.5 degrees, and showing that it is possible to do so provided very significant steps are taken to reduce our emissions. Reducing CO2 alone won’t be enough to achieve the 1.5 degree climate target; the IPCC show that it is essential also to reduce other strong greenhouse gases such as methane and nitrous oxide that have large sources from agriculture and waste treatment.
“Not only will the steps taken reduce the harm to climate, a significant side benefit of pursuing a goal limiting temperatures to 1.5C is the reduction in emissions of harmful air pollutants, such as those leading to fine particles or ground-level ozone. The IPCC report assesses that reducing fossil fuel burning in order to achieve the 1.5 C temperature target will reduce air pollution deaths by 100 million between now and the end of the century. This makes it all the more important to strongly reduce the use of fossil fuels.
“The IPCC to assess that air quality policies to reduce particle hazes on their own will make achieving a 1.5 degree target more difficult, however combining these with policies to reduce methane (which generates ground level ozone) would mean overall measures taken to improve air quality could make the 1.5 degree target easier to achieve.”
Dr Sally Brown, Researcher at the University of Southampton and Bournemouth University, and Lead author in Chapter 3 of the report, said:
“This report highlights the importance of climate change mitigation to reduce the long-term effects of rising sea-levels – including over centennial timescales. With millions of people exposed to coastal flooding today, the 1.5°C target gives hope that the worst impacts of sea-level rise can be avoided for vulnerable people, such as those living in low-lying islands or deltas, who have a close connection to the sea. Even mitigating at 1.5°C or 2.0°C, we still will need to adapt to effects of sea-level rise, taking account of those who rely on the coast for their livelihoods, whilst promoting sustainability and growth of coastal ecosystems.”
Prof Piers Forster, Director of the Priestley International Centre for Climate at the University of Leeds and Lead Author of Chapter 2 of the report, said:
“I’m exhausted but elated. As expected, we had all-night battles over the important numbers, but with the hard work of my amazing colleagues and strong support from small island nations and Europe, we won the day.
“The result is the most policy-relevant solution focussed report on climate change yet. All the countries that have endorsed our report have signed off on some challenging numbers. They tell how global warming of more than 1.5C will be a huge risk and to prevent it we (i.e the whole world) must halve our emissions in 10 years. Current policies put us on course for a super -risky 3C of warming. Transformations on energy that are already underway need to be massively scaled up, and transport, buildings and agricultural need to go zero carbon. Just like our negotiations this will be challenging, requiring global cooperation of an unprecedented level: the report shows that limiting warming to 1.5C is barely feasible and every year we delay the window of feasibility halves. Nevertheless, if we were to succeed, we go onto show that benefits across society will be huge and the world will be all the richer for it. It’s a battle worth winning.”
Prof Dave Reay, Professor of Carbon Management at the University of Edinburgh, said:
“As ever, a detailed, comprehensive and timely report from the IPCC. The effort involved from the scores of authors, synthesising the science and responding to over 40,000 comments from experts and governments along the way, is incredible. It’s clear that more warming, even just half a degree, comes with big costs. From extra sea level rise and flooding to widespread destruction of the world’s coral reefs and more heat-related deaths.
“None of the pathways that can lead the world to a safer, ‘1.5 degree’ future is easy. All require seismic changes in our energy, food, housing and transport systems. Some rely on unproven ‘negative emission’ technologies – like large-scale direct capture of carbon dioxide from the air – to claw our way back to a safer climate should we overshoot.
“The strapline to this whole special report could arguably be that hackneyed advice to lost travellers ‘If you want to get there, I wouldn’t start from here’. But here we all are. With each year that rolls by without global emission cuts so our opportunities to avoid dangerous climate change diminish.
“The IPCC have shown us what could be, the world must now decide what will be.”
Dr Dann Mitchell, lecturer in climate science at the University of Bristol, said:
“Every scientist worth their salt would have told you that stabilising climate at 1.5C instead of 2C above preindustrial levels would be the right play, but the surprisingly thing about this report is just how many different climate impacts were detected with very high confidence between the two temperature scenarios. Certain coral reefs, fisheries, and flooding of coastal areas are amongst these inevitable repercussions. All directly impact us living on the planet, perhaps none more so than the clear increase in heat and heatwaves on species mortality, which was detected with high confidence in the special report. The report provides a tangible way to avoid these climate consequences; governments now have no excuse to claim ignorance.”
Prof Andrew Shepherd, Director of the Centre for Polar Observation and Modelling at the University of Leeds, said:
“We are more sure of the IPCC’s predictions now than ever before, as we can check their skill against decades of satellite measurements.
“If we want to avoid major changes to Earth’s ice – including an extra 10cm of sea level rise and a sea ice-free Arctic Ocean every decade – then global warming must be limited to 1.5C.
“These changes are not small; they will lead to frequent city flooding that will take major construction to manage, the destruction of natural habitats that can’t be recovered, and they will also lock us in to even further climate change as our planets ice is lost forever.
“Now is the time to act.”
Dr Emily Shuckburgh, Deputy Head of Polar Oceans at the British Antarctic Survey, said:
“This report presents two starkly different futures. It methodically articulates how the risks of extreme weather and sea level rise, of species loss and extinction, and of a deterioration in many dimensions of human wellbeing increase substantially from 1.5°C to 2°C of warming. The report also warns, for instance, that catastrophic loss of ice sheets in Greenland and Antarctica, which would eventually result in many metres of sea level rise, could be triggered at around 1.5°C to 2°C of global warming.
“Everyone should take careful note: governments, businesses and individuals. Today we are on a pathway to reach 3°C by the end of the century. The report makes clear that decisions made across society over the next few years will make a radical difference to our future climate and will determine the fate of future generations.”
Prof John Shepherd FRS, Emeritus Professor in Earth System Science at the University of Southampton, said:
“There are no surprises here. The report finds that the risks and impacts of climate change if warming remains below the 1.5 C threshold are substantially less than those at 2 C and above.
“However, the actions required to limit climate change and stay below the 1.5 C threshold will be very challenging. It will require a massive international effort to reduce global CO2 emissions very rapidly – much greater efforts than the modest actions that have been taken up until now. Governments will need to adopt much stricter policies and actively create new mechanisms and economic incentives to make it happen. Decarbonisation of the energy supply and generation of more low-carbon electricity are vital so that we can stop using fossil fuels for heating. Even if emissions are reduced sufficiently and rapidly, considerable adaptation to change will still be needed, and it will probably be necessary to adopt novel technologies to remove excess CO2 from the atmosphere. These CDR technologies are not cheap or easy alternatives, and most would probably involve additional costs and risks. Most such novel technologies have not yet been adequately researched, and they are not yet ready to be used on the large scale that would be required, so steep emissions reductions must remain the top priority. It may even become necessary to try to reduce warming by reflecting a little sunlight away from the Earth, but the feasibility, risks and impacts of doing this are much less well understood, and this possibility is not assessed in the report.”
Prof Mark Maslin, Professor of Climatology at University College London, said:
“The IPCC 1.5˚C Special Report provides a revolutionary vision for a better, safer future for everyone. It shows us how we can limit climate change while ensuring sustainable and a more equitable society. Limiting global warming to 1.5˚C is still possible if we are prepared to take far ranging action encompassing energy production, energy use, transport and land use. The more action we take now, the less reliant we will be on developing expensive technology to remove carbon dioxide from the atmosphere in the second half of this century.
“Critically, this report does not consider climate change in isolation but as one of many critical issues we need to deal with in the twenty first century. By linking climate change mitigation and adaptation options to the Sustainability Development Goals, we now – for the first time ever – have a blueprint of how to save the planet while improving the well-being of all the predicted 10 billion people on Earth by 2050.
“At the end of this century historians will look back and realize that the IPCC 1.5˚C Special Report was the moment when a new vision for the twenty first century emerged, leading to a safer, sustainable and more equitable world.”
Dr Phil Renforth, Lecturer in Engineering Geology at Cardiff University, said:
“Achieving the 1.5 C target may be impossible unless we accelerate the research, development, and deployment of proposals to remove CO2 from the atmosphere, which work alongside rapid emission reduction. Planting more trees, for instance, will be an important contributor, but will also compete with other land uses when scaled to the level that is required. Other approaches, like accelerating the weathering of minerals or sucking CO2 from the air, have enormous potential but are still in their infancy. The report makes the point that any single technology will have limitations at scale, and that deploying a range of proposals to achieve the same cumulative effect may be more feasible.”
Prof Chris Rapley, Professor of Climate Science at University College London, said:
“Alexander Nix, of the now defunct Cambridge Analytica, observed that to drive human action a narrative ‘doesn’t have to be true, it just has to be believed’. Dan Kahan, Yale Professor of Law and Psychology , observes that ‘What you believe about climate change doesn’t reflect what you know, it expresses who you are’. Combine the two, and the fate of the IPCC’s latest “Special Report on Global Warming of 1.5 degrees” is predictable. Those who already accept that human actions are driving the climate system into a dangerous state, requiring urgent and massive preventative action, will be yet more convinced. And those who don’t, won’t. This despite the fact that the rigour of the process and the weight of the evidence achieve an impressive new high. The fact that the damages incurred in a world warmed by two degrees are materially greater that one warmed by 1.5 degrees is a hugely important insight – not least as regards the implication for the 3 degree world to which we are currently heading. But it remains just a fact. And at a time when unity of purpose is critical if the 1.5 degree guardrail is to be respected, the ironic outcome will almost certainly be a doubling down of beliefs. So the trajectory of the planet, and the fate of its residents, will continue to rely on the margin between those striving for a clean, green and inexhaustible future, and those seeking to resist. In the meantime, the planet remains indifferent.”
Dr Robert Larter, British Antarctic Survey, said:
“During the last interglacial period (~125,000 years ago) average global temperatures reached about 2C above pre-industrial and associated peak global mean sea levels were between 6 and 9 m above modern. Therefore, if we get near to 2C we can expect that we will be committing to substantial sea-level rise.
“A further concern is that as ice sheets melted after the last glacial period there were times when sea level rose at a rate of more than 3 m per century, which is an order of magnitude faster than the current rate. This implies that there are situations in which ice sheets can melt much more rapidly than they have over the period we have been observing them. Therefore, we should be very cautious about disturbing these sleeping giants.”
“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” was published by the IPCC at 2am UK time Monday 8 October 2018.
Dr Renforth: I was a reviewer of one of the earlier drafts of the report.
Prof Shepherd: I was not involved in preparing the report, and have no financial interests to declare. I contributed to the recent reports by EASAC on “Negative emission technologies” and by the Royal Society on “Greenhouse Gas Removal”
Dr Shuckburgh: No interests to declare.
Dr Mitchell: I was a contributing author on the report.
Prof Le Quéré: I reviewed an early version of the report.
Prof Reay was an expert reviewer for this report.
Prof Betts: I was a reviewer of the report, co-hosted one of the Lead Author meetings, and was part of the process for informing the IPCC’s decision on whether to go ahead with the report after it had been requested in the Paris Agreement.