IPCC report on mitigating climate change – experts respond

The Intergovernmental Panel on Climate Change (IPCC)’s Working Group 3 report on greenhouse gas mitigation has been finalised in Berlin.

The report deals with the mitigation of climate change. It sets out the technological, economic and institutional requirements and associated risks of climate change policies at the global, national and sub-national level, investigates mitigation measures for all major sectors, and assesses investment and finance issues.

Scenarios show that to have a likely chance of limiting the increase in global mean temperature to two degrees Celsius, means lowering global greenhouse gas emissions by 40 to 70 percent compared with 2010 by mid-century, and to near-zero by the end of this century. Ambitious mitigation may even require removing carbon dioxide from the atmosphere.

You can read more about the report and summary for policy makers, including a press release, on the IPCC website.

The authors of the report, including many New Zealanders, and representatives from IPCC member governments gathered in Berlin to approve the Summary for Policymakers, checking the text line by line. They approved the full report, which besides the Summary of Policymakers consists of a Technical Summary, 16 chapters and three annexes.

The report on mitigating the effects of climate change follows the earlier work of Working Group I, The Physical Science Basis released in September 2013 and Working Group II, Impacts, Adaptation and Vulnerability, released just two weeks ago.

NB: New Zealand released its most recent greenhouse gas inventory on Friday. Expert reaction is available on the SMC website. 

The SMC has rounded up the following expert commentary on the IPCC AR5 WGIII report. If you would like help contacting a New Zealand lead author of the IPCC WG3 report or one of the experts below, please contact the SMC (021 230 8938).

Prof Ralph Sims, Sustainable Energy, School of Engineering and Advanced Technology, Massey University, lead author of IPCC AR5 WG3 report, comments:

“The argument that New Zealand produces only 0.14% of the world’s greenhouse gas emissions no longer holds. On average, each New Zealander is responsible for emitting around eight tonnes of carbon dioxide a year and, with all the other greenhouse gases, now produces twice those of the average Chinese person and around eight times those of someone living in india. This means we are now the fourth highest emitters per person in the world, behind Australia, the United States, and Canada.

“New Zealand has set a modest target to reduce our total greenhouse gas emissions by five per cent below the 1990 gross emission level in just six years time, yet no one knows how we will achieve this. In our Sixth Communication document to the United Nations in December 2013, the Ministry of Environment projected our net greenhouse gas emissions (the total emitted minus the carbon dioxide absorbed by forests planted after 1990) will reach more than 75 million tonnes in 2020 if we continue with business as usual. To reach the five per cent reduction target below our 1990 emissions, we will need to somehow reduce these to 55 million tonnes.

“The various means of achieving this are clearly outlined in the IPCC Mitigation report released today. They relate to buildings, transport, industry, energy supplies, food production and processing, and forests, all of which can lead to the better “green economy” recently outlined in a New Zealand Royal Society report. Many of these solutions also provide major  additional benefits such as less air pollution, better health, reduced traffic congestion, more employment and they actually save money.

“In the foreword of New Zealand’s recent Communications document to the United Nations, Minister Groser stated, ‘The emissions reduction opportunities available to other nations through conversion to renewables, mass public transport and energy efficiency in industry have already been done or have far less scope in New Zealand’. The IPCC Mitigation report clearly shows this is far from correct.”

Bob Lloyd, Associate Professor and Director of Energy Studies, Physics Department, University of Otago, comments:

“There is no way that mitigation can be effective unless we get buy-in by all countries of the world. The atmosphere does not care if the emissions come from New Zealand or India or any other specific nation.

“In particular the report states that mitigation will not be effective if all the individual nations of the world are intent on achieving their own selfish interests. In this regard it might be mentioned that in international climate change negotiations NZ is regarded as a particularly ‘tough’ negotiator. By ‘tough’ read ‘selfish’. NZ has obtained concessions in terms of emissions reductions that many other countries would regard as not being a fair contribution to obtaining equitable global reductions.

“In this regard the NZ Government negotiators have been trying to advance the NZ economy for the people of NZ by avoiding the short term financial costs of agreeing to substantial reductions. From the developing country viewpoint there is a substantial ethical issue here; one of equity. The IPCC report in fact points out that achieving ethical equity in emissions reductions is paramount to mitigation targets. This issue has been one of the main reasons international climate negotiations have stalled.

“To get global buy-in NZ must act as a global leader in emissions reductions not a selfish backwater. In this regards NZ is better placed than nearly all countries in the world with a particularly high proportion of its electricity supply already coming from renewable sources including hydro, geothermal and wind.

“Instead of exploring for more hydrocarbons by permitting off shore oil and gas drilling, NZ should be extending its lead in renewables and assisting other countries to adopt the same.

“The urgency of attending to climate change mitigation cannot be overstated because unless we ‘turn the curve’, that is the rapidly increasing current world CO2 emissions curve, from business as usual, the IPCC report suggests we are on the way to a climate regime with temperature increases from between 3.7 and 4.8 degrees.”

Dr James Renwick, Assoc Prof, School of Geography, Environment and Earth Sciences, Victoria University of Wellington, comments:

“The latest WGIII report pulls no punches. Despite many international agreements and pledges, global greenhouse gas emissions are accelerating: they grew more quickly between 2000 and 2010 than in each of the three previous decades. Emissions during 2000-2010 were nearly 70% higher than they were in the late 20th century. Half of all our greenhouse gas emissions (since 1750) have occurred in the last 40 years. The climate system is now running hard to catch up, as evidenced by increasing melt of the Greenland and Antarctic ice sheets, increased rates of sea level rise, and dramatic loss of sea ice in the Arctic. Continued ‘business as usual’ will lead to 4 degrees or more of global warming, something well outside all of human experience.

“As the report demonstrates, we have the technologies to move away from ‘business as usual’, but we need a concerted international effort. Climate change action will help alleviate many other pressing problems, and does not have to be economically damaging. But the issue is clearly about more than economics. It is as much an ethical or moral issue, associated with international and inter-generational equity.

“The WGIII report charts many possible futures where we cap the warming at 2 degrees. Action, such as moving to 100% renewable electricity generation, needs to start immediately. New Zealand is as well-placed as any nation to lead the world on this, provided we have the political will. That appears to be lacking right now – there’s plenty of talk about emissions reductions targets, while at the same time we’re opening the country up to more oil drilling and coal mining. The latest MfE report shows New Zealand’s emissions have gone up 25% since 1990, and they are on track to keep rising.

“Per head of population, we are some of the biggest emitters on the planet. Clean and green? 100% pure? Right now – I don’t think so.”
Prof Susan Krumdieck, Dept of Mechanical Engineering, University of Canterbury comments:

“The IPCC third working group report on climate change mitigation says what the consensus of scientific evidence has said before, and what the next and the next and the next will say.

“The safe loading limit for extraction of of fossil carbon locked up in the earth’s crust for over 100 million years, and converting it into CO2 gas has been exceeded and the climate has changed. These changes are measurable and consistent with modelling.

“At the current fossil carbon conversion rate in less than 20 years, the catastrophic failure limit will have been exceeded. With the additional effects of other infrared absorbing gasses and permafrost melt, and land use change, the catastrophic failure limit could be reached in 10 years.

“There aren’t any responsible leaders, competent engineers, or sensible people who would suggest we should exceed safety limits. Who in the world would say that as a matter of convenience, we should push essential systems to collapse?

“There is also no way to mitigate the impacts of a catastrophic failure.

“The only option now is for all responsible, competent and sensible people to demand action from engineers, planners and business leaders to change every system that produces and uses climate affecting materials so dramatically reduce the production and use of fossil fuels and reduce the emissions of other greenhouse gasses.”

Dr Jim Salinger, climate scientist and former president of the Commission for Agricultural Meteorology at the World Meteorological Organisation comments:

“The release of the IPCC Working Group 3 report shows that the world is currently on course for a world 3 to 4°C warmer by 2100, creating large impacts on all countries and economies. New Zealand’s growth in greenhouse gases over the last decade parallels the global growth so we are very much laggards in emissions reductions policies.

“The report notes that ambitious mitigation would reduce this growth by around 0.06 percentage points a year, far less than the impact of climate extremes such as drought on our economy. These underlying estimates do not take into account economic benefits of reduced climate change. Stabilising greenhouse gas concentrations in the atmosphere requires emissions reductions from energy production and use, transport, buildings, industry, land use, and human settlements. Low hanging fruit for New Zealand is by using energy efficiency measures as well as incentives for homeowners to produce their own power from solar panels. It’s up to us now.”

Prof Martin Manning, New Zealand Climate Change Research Institute, Victoria University of Wellington comments:
“The Working Group III Summary for Policymakers is showing very clearly that, while human behaviour has already changed our climate and damaged the environment that we depend on, there is now a rapidly growing challenge for that to shift towards a much clearer focus on behaving sustainably.

“More than three quarters of greenhouse gas emissions are of CO2 and this is predominantly due to our use of fossil fuels. While growth in these emissions was decreasing due to improvements in technology over 1971 – 2000, they increased significantly over 2001 – 2010. Some point at rapid development in China as the reason for that, but this new analysis shows the importance of looking at how we behave collectively, because it also involved significant changes in international trade as China became a globally dominant supplier.

“However, collective response does not mean that all countries should do the same thing, or wait for others to act, because the report also makes it very clear that there is a wide range of capacities to reduce greenhouse gas emissions across different countries as determined by their local circumstances.

“New analyses covered in this report have shown that decreasing greenhouse gas emissions to keep to 2°C could reduce global economic growth by 0.06% per annum, whereas the report by Working Group II that came out last month suggests that the effects of not doing so could have more significant long term effects on water and food supply.

“While governments have agreed that global warming should not exceed 2°C, analyses by 31 teams of experts have now shown that present commitments fall short of achieving that. In particular, unless a lot more is done by 2030 than currently planned, subsequent changes to keep to that target would have to reach drastic levels such as reducing CO2 emissions by 6% every year. So a very clear point coming from this report is that any further delay in response would raise some serious questions about whether the human race can behave sustainably.”

Our colleagues at the AusSMC collected the following expert commentary.

Professor Glenn Albrecht is Director of the Institute for Social Sustainability at Murdoch University, WA. He comments:

“The Working Group III Contribution to the Fifth Assessment Report of the intergovernmental Panel on Climate Change focuses on the scientific, technological, environmental, economic and social aspects of mitigation of climate change. The ethical implications of this report deserve particular attention because while global warming and consequent climate change are the subjects of increasing scientific investigation, our responses to such knowledge must lie within the realm of ethics. When the consensus on the accuracy of the science is near 100%, we must ask, why are we imposing such a massive risk of social, economic, industrial and agricultural disruption and failure on ourselves? The ethics of greenhouse gas mitigation require of all nations and people to reduce greenhouse gas emissions to levels that will deliver a safer world for all. In Australia, given the dominant role that burning fossil fuels has in generating  greenhouse gas emissions, to do our just share to reduce the risk, we must urgently and systematically reduce our use and export of coal, petroleum and gas. At the same time, we must invest ethically and economically in a new era where we make a just and equitable transition to non-polluting, renewable energy sources.”

Professor Joseph Reser is from the School of Applied Psychology at Griffith University, Queensland. He comments:

“These comprehensive reports covering the past five years of intensive research bring into sharp relief the increasingly critical urgency for adequate global response. Yet many crucial considerations relating to the human dimensions and impacts of climate change have not been on the radar of climate change science. Climate change adaptation and mitigation, for example, are closely inter-related processes and responses from a psychological and individual experience and behaviour perspective. Personal engagement with the issue and ‘taking action’ in the context of one’s own life style and circumstances can play crucial roles and provide multiple benefits in addition to reducing one’s carbon footprint. Being engaged and doing something helps people to come to terms with the reality and implications of climate change, and feel that they are making a difference, being informed and responsible, and part of the solution and not just the collective problem. These psychological adaptation processes and outcomes reflect powerful and interactive synergies between coping and doing. Yet rarely do we hear about the psychological side of this ongoing environmental threat and stressor, and accompanying personal sense making, concern, distress, and resolve.

“Heartening research findings show that many Australians not only accept that climate change is happening, and feel that this is an issue of high personal importance, but are actively adapting to this ongoing threat and unfolding global disaster. It is important to not lose sight of these more psychological ‘human dimensions’ of climate change, as this is where ‘public engagement’, and adaptation and mitigation policies and initiatives, either work or fail in influencing crucial individual and collective lifestyle adjustments and changes.

“Climate change is a quintessentially human as well as ecological issue and challenge in terms of causes and consequences, and the psychological and social environmental impacts on human communities of global climate change in terms of quality of life and environment, health and well-being – and the life support systems of all species – are likely to be profound, and with us for many generations if not millennia.

“Issue engagement at an individual level brings the biosphere home, and makes this otherwise complex and distant and seemingly insurmountable phenomenon, personal, local, known, and a collective problem and responsibility about which much can and critically needs to be done.

“The Australian Psychological Society offers some excellent advice and insights on coping with climate change”

Professor Hugh Outhred, Senior Visiting Fellow at the School of Electrical Engineering & Telecommunications at The University of New South Wales, comments:

“The IPCC Working Group 3 Summary for Policymakers reinforces the key messages from Working Groups 1 and 2 that climate change is real has dangerous consequences for humanity and requires our immediate action to mitigate human-?caused climate change emissions. Australia is particularly vulnerable to climate change and is heavily dependent on fossil fuels for both domestic use and export. Australian society has demonstrated that it has the capability to take a leading role in developing and implementing low-?emission technologies and adopting low-?emission lifestyles. However, that seems unlikely given the present combative and ill?informed political debate about climate change and the influence of the fossil fuel lobby.”

Dr Liz Hanna is a Fellow of the National Centre for Epidemiology & Population Health at the Australian National University, and President of the Climate and Health Alliance. She is also currently Director of an NHMRC Project: Working in the Heat – health risks and adaptation needs. She comments:

Text in brackets is taken from the Summary for Policymakers

[On the Summary for Policymakers (SPM) Chapter 3 –  Trends in stocks and flows of greenhouse gases and their drivers: ‘Total anthropogenic GHG emissions have continued to increase over 1970 to 2010 with larger absolute decadal increases toward the end of this period’]

“This means that despite all the negotiations, agreements and promises, governments around the world, including Australia, have failed. In the face of an increasingly likely crisis, they have continued to put lives of millions at risk. Grandstanding, passing the buck of responsibility and waiting for others to reduce their carbon emissions wastes precious time, time that we simply do not have.

“Decarbonising our lives is everybody’s business.  Governments, industries communities and every household needs to do everything within their capacity to stop releasing carbon into the atmosphere.  Per capita, Australians contribute more to the problem than every other OECD country.

“Contrary to the scare tactics, moving away from fossil fuel based economy can lead to a better, more fruitful, and healthier life than we have today. Cities promoting effective public transport systems and active transport, where people walk and cycle more, have cleaner air, more green spaces for recreation and this improves mental health.”

[On baseline scenarios, those without additional mitigation, result in global mean surface temperature increases in 2100 from 3.7 to 4.8oC compared to pre-industrial levels  (the range is 2.5°C to 7.8°C when including climate uncertainty)]

“We have been tracking along the higher end of this range, and increasing rates of emissions guarantees us future high levels of warming. We must stop. This warming is not compatible with human existence.

“These figures of average warming  are not the full story. From a health perspective, it is the weather extremes that this brings. On average,  Australia has warmed less than one degree, and this have delivered already record heat waves, temperature over 46 degrees in our major cities. The Intergovernmental Panel on Climate Change (IPCC) Working Group II report makes the situation quite clear. The scale and pace of climate change puts humanity into clear and evident danger.

[On delaying mitigation efforts beyond those in place today 1 through 2030 is estimated to substantially 2 increase the difficulty of the transition to low longer?term emissions levels and narrow the range 3 of options consistent with maintaining temperature change below 2°C relative to pre?industrial 4 levels (high confidence) and delaying additional 24 mitigation further increases mitigation costs in the medium to long term (Table SPM.2, blue 5 segment). Many models could not achieve atmospheric concentration levels of about 450 ppm 26 CO2eq by 2100 if additional mitigation is considerably delayed or under limited availability of key 27 technologies, such as bioenergy, CCS, and their combination (BECCS).]

“Delaying strong mitigation efforts lowers the likelihood that warming could be curtailed at 2 degrees. This wilful disregard for human safety should be recognised for what it is, short term gain at the expense of a collective future in a world that is habitable.

“Delay also incurs increasingly prohibitive mitigation costs. Combined, these subject todays’ children and young adults to a world where governments must spend more to mitigate, at a time when more extreme weather events necessitate higher costs on repairing infrastructure, and relocating vital services away from coastlines. Diminished funds will be available for health and education and nation building.

“Prompt action is an economic imperative, and a moral imperative.”

Amanda McKenzie, Chief Executive Officer of the Climate Council, comments:

“Renewable energy is critical to tackling climate change. Australians have already taken steps to increase renewable energy and this report shows we need to do more. It’s clear that the renewables race has begun.

“Shifting away from fossil fuels to renewable energy is a key part of tackling climate change and has other benefits, for instance growing new jobs, industries and investment. Australians know that solar power is just common sense here, so there is a lot of community support for greater investment in renewables.

“On the other side of the ledger, Australia is also home to some very inefficient and aging coal fired power plants. That means our current electricity supply is one of the most emissions intensive and least efficient in the world.”

Comments from Australian experts who contributed to the report:

Professor David Stern is from the Crawford School of Public Policy at the The Australian National University and a lead author of Chapter 5: Trends, Drivers, and Mitigation. He comments:

“Over the last four decades, per capita emissions from all sources – energy use, land-clearing etc – declined in both the poorest and the richest countries but rose in middle income countries. Because of population growth, total emissions rose in all regions. Total emissions from developing countries (low and middle income) now exceed those from the developed countries.

“Global greenhouse gas emissions rose more rapidly between 2000 and 2010 than in the previous three decades and this is mainly because of rapid growth in emissions in middle income countries like China. The decline in per capita emissions in low-income countries is because of a reduction in per capita emissions from agriculture and land-clearing and an absolute reduction in those emissions in the decade 2000 to 2010.

“However, per capita emissions remain very unequal globally with emissions per capita in high-income countries averaging nine times the level in the lowest income countries. This means that there is a lot of scope for “catch-up growth” in emissions under business as usual and points to the need to switch to low carbon energy sources as soon as possible. This is because the majority of emissions are derived from energy use and energy efficiency improvements have historically been insufficient to offset the growth in income per capita let alone population growth, especially in the decade 2000 to 2010.”

Professor Richard Harper is Chair in Sustainable Water Management, Leader of Agriculture at Murdoch University, WA and a lead author on Chapter 11: Agriculture, Forestry and Other Land-Uses (AFOLU). He comments:

“The new report from the IPCC’s Working Group III contains a chapter on the land sector – Agriculture, Forestry and Other Land Uses. This clearly outlines how the land both contributes to global emissions, but also provides some real options for emissions management.

“Basically, there are three ways the land can contribute to carbon management – by reducing emissions from existing carbon stocks (e.g. clearing forests) or agricultural activities, by increasing carbon stocks in soils or vegetation (carbon sinks), or by replacing fossil fuel emissions by burning biomass or using wood products.

“The report considers each of these options, and in particular the opportunities that may arise and also the trade-offs. For example, reducing the rate of deforestation can protect biodiversity, planting trees on farmland can improve water supplies, applying nitrogen fertilizers more efficiently can reduce both emissions into the air and water ways. However, with an increasing global population that will demand more food per capita and future climate change itself, a challenge is to ensure that these measures complement, rather than displace food production.”

Our colleagues at the UK SMC collected the following expert commentary.

Prof Peter Styring, Director of the UK Centre for Carbon Dioxide Utilization at the University of Sheffield and Chair of the EPSRC CO2Chem Grand Challenge Network, said:

“The IPCC report makes it clear that CO2 mitigation is a priority if temperature rises are to be avoided. CCS is still regarded as a technology to achieve this in the short term although only medium confidence is applied to these assumptions. The main reason is despite the technology reaching a degree of maturity, it has not been demonstrated on a commercial scale globally.

“It is also clear that additional strategies may be required to remove CO2 from the atmosphere as well as at the end of pipe in the power and industrial sectors. Air capture poses technological challenges due to relatively low concentrations when compared to post combustion flue gas sources. While there is some evidence to support materials that can achieve air capture at the pilot scale, these are again a way off maturity.

“What the report fails to recognise is the growing importance of carbon capture and utilization (CCU) or carbon dioxide utilization (CDU) as it is otherwise known. With CCU the CO2 is transformed into value added products. While CCS is a waste mitigation technology so cannot yield a profit, CDU will eventually produce profits once capital expenditure has been recovered. The rapid advancement in CDU has shown many processes developed to turn CO2 into products such as polymers and cement and aggregates, fuels and chemical intermediates.  CDU is also a means for energy storage, taking renewable, intermediate energy sources and storing the energy at times of low demand: times at which the power sources would otherwise be switched off.

“This is backed up by the World Economic Forum who have identified carbon dioxide utilisation as one of the Top 10 Emerging Transformative Technologies.”

Dr Dan Osborn, independent consultant and former chair of the evaluation panel for the AVOID research programme, said:

“This report illustrates the challenges the world faces on mitigation but it could be good news for those businesses and countries willing to lead the way on all kinds of low-carbon technologies. Burning oil and gas will be frowned on by future generations because this resource is valuable for other purposes. The sooner we start on mitigation the lower adaptation costs will be. Relying on a non-existent Plan B is not a wise option. Time to act is limited. The world must not put its head in the sand. Global action is needed to reduce emissions whilst there is still time.”

Dr Neil Edwards, Reader in Earth Systems Science at the Open University, said:

“The WG3 SPM highlights a number of key issues: Firstly, where we are in terms of mitigation and where we need to be (to have a good chance of respecting the 2C limit) are still a long way apart. The changes needed to bridge the gap include transformative, non-incremental changes, particularly of the energy system and behaviour in areas such as energy efficiency, modes of mobility, and potentially diet changes. Such transformative changes remain eminently possible, but concerted action is needed. In particular, BECCS (bio-energy with carbon capture and storage) is a critical component of most strong mitigation scenarios, allowing negative effective emissions, but is still not demonstrated at large scale.

“These results have been seen in many studies including the ERMITAGE project  which I coordinated from the OU, just finished, which addressed (amongst other things) the conflicting demands for food, energy and forest conservation that complicate mitigation measures related to bioenergy.

“Another key issue to point out is that the current generation of modelling studies, as well as not properly accounting for the economic benefits of avoiding the impacts of climate change, cannot properly address the potential for green growth opportunities because their underlying structure, which generally assumes full employment and optimal use of resources. For this reason non-optimal models tend to be more optimistic.”

William Powrie FREng, Dean of the Faculty of Engineering and the Environment, University of Southampton, UK   

“The report presents powerful and comprehensive evidence of the urgent need to curb greenhouse gas emissions by reducing energy use, increasing energy efficiency and an increasing the proportion of our energy that is generated from renewable resources. It also sets out ways in which this can be achieved – for example in the built environment, through appropriate urban and land use planning, demand management and investment in public transport.

“Behaviour change and economic instruments will be as important as technological innovation; all should be viewed as opportunities rather than threats. Action must be swift, decisive and above all global. The report leaves no doubt that we really are in the last chance saloon as far as addressing climate change is concerned.”

Prof Stephen Long, from the Department of Crop Sciences at the University of Illinois, said:

“In ‘approaches to climate change mitigation’ the report espouses high ideals to which we can all agree, and that no policymaker would dare deny.  However, these ideals are far from achieved in today’s business-as-usual operations.  The danger here is that we will be, and as evidenced by much legislation around biofuels and bioenergy between AR4 and AR5, holding new mitigation options to higher standards than business-as-usual.  Such statements also encourage development of policies around imagined rather than proven issues.  The result is obvious, maintain business-as-usual – it is so much easier.

“The section on ‘Agriculture, Forestry and Other Land Uses (AFOLU)’  clearly failed to see the elephant in the room.  Output of primary foodstuffs such as grain and seed needs to increase 70% by 2050 to keep pace with demand.  We are failing to increase yields per unit land area to achieve this goal.  If we do not address this problem first, then the result is obvious: we will spill over on to less productive and less sustainable land which will prevent or even reverse other mitigation options of afforestation, bioenergy, and soil improvement.

“The report tells policymakers that ‘the most cost-effective effective options in forestry are afforestation’ – i.e. planting land currently in other uses with trees and then forgoing all other potential uses of that land.  Measures under the Common Agricultural Policy reform of the EU in particular are intended to continue to promote the reafforestation of agricultural land, which began in the 1990s.  Ironically this conversion of land has coincided with a doubling of net imports of primary foodstuffs by the EU.

“The report for policymakers fails to expose the major caveats of afforestation.  First, it is one off, once the forest reaches maturity it is no longer a sink for carbon, but a store that will be lost with the next fire or insect attack.  Second the land could be used far more effectively in providing a continuous supply of energy, e.g. as coppice for combustion, which over a period of years would continually displace fossil fuel emissions.  By contrast, the section on bioenergy where we have real evidence of benefits is submerged in inhibitory caveats, which will hardly be enticing to policymakers.

“While reafforestation of agricultural land is not flagged as competition with food, bioenergy is.  Yet it fails to note the many opportunities outside of the relatively small area of land suited to food production.  In particular, the report fails to give emphasis to the real successes and need of analysis of the bases of these successes.  The example of the Brazilian sugarcane ethanol industry which resulted in more ethanol than gasoline use in 2010 (between AR4 and AR5) is not noted.  The report casts doubt on its value (with ‘high certainty’).  Yet no one can deny it has resulted in large scale mitigation of fossil fuel consumption, achieved at a time when the country has massively increased food crop productivity per unit area of land.

“It has also provided the best example of how learning by doing has continually improved GHG balance, so that more realistic estimates of technology gain in the bioenergy sector could be generated and applied in the models.  With the area now mapped by the Brazilian government, ethanol produced here could equal 15% of current global liquid fuel use.  With significant areas of the globe’s former sugarcane lands abandoned and many other areas of marginal land available in the tropics, what options are there to expand this successful model?  Biomass for combustion, like ethanol, is low hanging fruit, it can be implemented and used on a short time scale, perhaps buying time for more sophisticated and ultimately better technologies to develop.

“There are many opportunities here that would be win-win for society and mitigation, such as use of lands that have become salinated or are too arid for food production, but would support biomass production – giving employment back to decimated communities.  But instead of picking the low hanging fruit, the report is a thinly veiled attempt to sell carbon dioxide capture and storage (CCS), giving the impression that bioenergy only has value if it can be combined with CCS.

“This will be highly inhibitory to achieve mitigation through bioenergy.  Unlike bioenergy, with many mature technologies from planting to heat and electricity generation, CCS is still in the gestation phase.  There is little practical evidence of whether it will be acceptable and safe, or even economically viable.  It is clear that it will be far too expensive for any small scale rural energy projects.  The report is wrong to tie CCS so strongly to bioenergy – it is a laudable goal, but will be inhibitory to a mitigation option that we can achieve within out life times; and one that could bring employment and development opportunities to poor communities.”

Dr Dave Reay, Reader in Carbon Management, University of Edinburgh, comments:

‘There is no hiding from this report. Without international cooperation to deliver far-reaching cuts in emissions over the coming decades we throw the door wide open to ‘dangerous climate change’. The myriad solutions covered in this report are a cause for optimism – from smart agriculture that slashes emissions and boosts yields to low carbon homes that bolster energy security.  We have the science. We have the technology. Do we now have the collective will to shut the door?’

Prof Sir Andy Haines, London School of Hygiene and Tropical Medicine ( Review editor IPCC Working Group II Health Chapter), comments:

“The report of Working Group III summarises extensive evidence about the need for and the scope of interventions to reduce the emissions of greenhouse gases and other climate active pollutants. The report shows how policies to reduce the probability of dangerous climate change are often accompanied by ancillary benefits (co-benefits) and sometimes co-harms. Recent WHO estimates suggest that ambient (outdoor) air pollution in both cities and rural areas caused 3.7 million premature deaths worldwide in 2012 and around 4.3 million people a year die from the exposure to household air pollution, with some overlap between the two sources of exposure. Major opportunities therefore exist to reduce the burden of ambient air pollution by policies to reduce the combustion of fossil fuels for electricity generation (particularly coal)  and in the transport sector. Providing universal access to electricity and clean fuels for cooking and heating for the 3 billion or so people who are dependent on traditional solid fuels for domestic uses will also yield major health and other benefits.  Additional health co-benefits could result, for example, from increased physical activity from policies to promote active travel (walking and cycling) and from policies in the food and agriculture sector.   Well designed mitigation policies should therefore capitalise on the potential health and other co-benefits and seek to minimise harms, such as those that arise from policies promoting biofuels that compete with food production. Because projected co-benefits are based on well established causal relationships and will often be experienced in the near term, they can make important contributions to the compelling case for the urgent implementation of more effective policies to reduce climate change.”

Prof Godfrey Boyle, Emeritus Professor of Renewable Energy at The Open University and reviewer for parts of the WG3 report, said:

“Encouragingly, the IPCC AR5 WG3 Summary Report acknowledges the rapid performance improvements and cost reductions that have been seen in renewable energy technologies since the AR4 Report in 2007.  It observes that in 2012, renewables (mainly wind, solar and hydro) contributed just under half the world’s new electricity generating capacity. It sees the renewable sector playing a leading role in boosting the world’s share of low carbon electricity to at least 80% by 2050, and stresses that policy support for renewables should be maintained.

“In the light of this enthusiastic IPCC endorsement, it is disappointing that the European Commission’s recent policy proposals for growth in renewables are unambitious and unspecific. Post-2020, the EU will abandon its existing country-specific renewable targets, aiming instead for a modest Europe-wide target of 27% of energy from renewables by 2030. So instead of setting a leading example to the world by moving rapidly towards a low carbon future, the developed nations of Europe are in danger of falling well short of the IPCC’s latest standards.”

Dr Matt Watson, Senior Lecturer in Natural Hazards at the University of Bristol, said:

“Working group 3’s summary for policy makers is a comprehensive review of mitigation options including scenarios that assume the removal of carbon dioxide both at source and from the dilute atmosphere.

“Carbon Dioxide Removal (CDR) is one type of climate engineering that might be used to curb increasing concentrations and potentially keep temperature increases bearable and/or to compensate for overshoot under circumstances of lesser political and personal action. The IPCC rightly highlights the risks associate with CDR strategies and points out that none of the technologies are ready to be deployed at suitable spatio-temporal scales.  This points to the need for thoughtful, open and transparent research into climate engineering.

“Anyone that suggests CDR is a distraction and a potential moral hazard does not understand the extent to which these imaginaries are already embedded in climate scenarios and should also better consider the severity of the peril we face.  Conversely, anyone touting CDR technologies as a panacea is not being realistic about the cost and timescales involved in their deployment.

“The only sensible policy option, as stated by the IPCC in the summary, is the rapid and wholehearted transition to renewables and less selfish lifestyles.”

Dr Jeremy Leggett, Associate Fellow at Oxford University’s Environmental Change Institute, said:

“It is useful to see so many experts agree that the electricity sector can completely decarbonised as a major contribution to keeping global warming below unacceptable danger levels, but many of us on the front lines of renewable energy would say that the IPCC has underestimated the speed with which our technologies, in concert with energy efficiency, can displace fossil fuels in the years ahead.

“Similarly, growing numbers of financial analysts would say that the IPCC has given inadequate consideration to the soaring capital expenditures of carbon-fuel companies, and the extent to which that constraint can help drive capital to the declining-cost technologies that dominate the renewables family.”

Prof Andrew Watson FRS, Royal Society Research Professor at the University of Exeter, said:

“This is a very responsible report. It has a clear message that there is no painless or risk-free approach to the problem we face.  For sure, there are economic and societal risks involved with mitigation approaches, whether these involve reducing fossil fuel burning, or the use of carbon dioxide sequestration and removal techniques. However, there are even bigger risks if we do nothing and rely exclusively on being able to ride out climate change and adapt to it – which is what will happen unless governments take stronger steps to slow the increase of greenhouse gases.

“We have to encourage both the switch to renewables and pilot projects for carbon sequestration technologies.”

Dr Shaun Fitzgerald of Girton College, Cambridge University, said:

“The report states, ‘Cutting emissions from electricity production to near zero is a common feature of ambitious mitigation scenarios. But using energy efficiently is also important.’ What is intriguing is that the energy efficiency argument is often the second point, perhaps the after-thought. The world of energy is a set of scales – demand and supply. It is obvious that by cutting demand, or at least stemming the growth in demand, the issue of how to supply CO2 friendly power is made easier.

“The true cost of reducing CO2 emissions is generally lower by using energy efficiency measures than by installing green power schemes. It is bewildering why governments use tax break schemes on specific technology initiatives such as feed in tariffs for solar to force behaviour, when in fact the market can figure out which is the most cost effective means of reducing CO2 emissions.

“Take a building for example – who is best placed to determine whether a builder should use more insulation, install an energy efficient ventilation system or PV panels? The contractor and their expert team of designers and procurement team, or the government who oversees feed-in-tariffs? In this case, ‘the government would do more by trying to do less!’ The government should set targets on CO2 emissions for buildings but then let the market sort out the detail to get the lowest cost solution. If government really let the market work, we’d have more energy efficient systems being adopted everywhere.”

Prof Tim Benton, UK Champion for Global Food Security & Professor of Population Ecology at the University of Leeds, said:

“The three IPCC reports highlight the extent to which climate change is caused by our emissions, the impacts that they are likely to have and how we can change our consumption behaviour to mitigate the effects.  We are currently on course for a world that may average 4 degrees hotter by 2100, with the frightening implications this may have for food security as outline in the WGII report.

“The WGIII report emphasises if we are to act to keep to about 2 degrees of warming, we have to do it over the next decade or so, or the costs will be prohibitive, and we have to reduce GHG emissions by 40-70% in the next 3-4 decades.  Agriculture and forestry are responsible for about a quarter of all GHG emissions and there is significant scope to reduce this.  Perhaps the most important route is via reducing deforestation – which is occurring widely for production of palm oil and soy – and increasing afforestation.

“Farming can become more ‘climate smart’ by, for example, increasing carbon storage in soils and this may have a range of other benefits for sustainability and resilience.  Changing our diets, especially eating less meat, may have significant impacts, as will reducing our wastage of food.

“There are many ways that individuals can contribute, but the report also emphasises that collective action is necessary: if individuals and institutions at local, national or super-national level put their own interests first, mitigation at the necessary scale will not come about.”

Dr Hannah Chalmers, Lecturer in Power Plant Engineering and Carbon Capture at the University of Edinburgh, said:

“The scientists of the IPCC have produced an excellent overview of the importance of developing and deploying a broad range of low carbon technologies. The UK has well-advanced plans to accelerate the deployment of carbon capture and storage (CCS) as part of its wide-ranging reforms of the UK electricity market. This report confirms that this support is timely and has an important role to play in global CO2 emissions mitigation efforts.

“The increased emphasis given to the likely role of ‘negative’ emissions technologies that draw CO2 from the atmosphere is important.  They could be essential to allow climate change mitigation to be delivered in ways that are acceptable to society. Some technologies are available today, but there is scope for improvement and also scientific breakthroughs in this area.  Members of the UK CCS Research Centre are among the scientists currently working hard to ensure that priority technologies and effective strategies for using them are rapidly developed and implemented.”

Prof John Shepherd FRS, Professor of Ocean and Earth Science at the University of Southampton, said:

“Cutting CO2 emissions enough to reduce climate change and ocean acidification is going to be difficult, but the alternatives are not easy either. Adapting to climate change is also going to be expensive, and will not always be possible. None of the proposals for geo-engineering the climate looks like being sufficiently safe or effective either.

“If we just carry on burning fossil fuels, and suffer the consequences, the impacts will be very serious, especially for people who are poor and vulnerable, and least able to adapt. It is not for scientists to determine policy, but in my opinion cutting CO2 emissions is the safest and most predictable way to respond to man-made climate change.

Dr Konstantinos Chalvatzis of UEA’s Norwich Business School and a reviewer of chapters on industry and energy for IPCC WGIII, said:

“The IPCC WGIII report outlines the options available to mitigate the effects of climate change. It is the consensus reached by hundreds of scientists after careful consideration of all the available evidence which has emerged since the publication of the last report in 2007.

“The artificially maintained debate on climate change distracts our attention from the major risks that businesses are facing in nearly all aspects of their operations. The climate is changing and we need to do more to manage supply chain and operational vulnerabilities.

“The energy sector, both demand and supply, will have to be entirely transformed in the following decades. If climate change mitigation is not enough to convince us, then energy supply security and rising energy prices should.”

Prof Jason Lowe, Head of Mitigation Advice at the Met Office, said:

“The earlier parts of the IPCC 5th assessment have already shown that cumulative carbon budgets need to be constrained in order to limit peak warming. This new report highlights how society might actually reduce emissions of greenhouse gases to achieve this. To avoid the most dangerous changes in future climate requires greenhouse emissions to peak in the near future and then decline. The remaining scientific and economic uncertainties mean it’s not possible to provide a single precise date when emissions need to peak, but peaking later means more rapid emissions reductions or reliance on untested technologies in the future.

“A major unknown surrounds artificial greenhouse gas removal, which, in theory, would allow more flexibility in the timing of fossil fuel emission reductions. However, there is great uncertainty around the potential size of the removal and its side effects are poorly understood. Although simple metrics, such as global average warming, are a useful short hand when discussing future climate change, it is vital to remember that the consequences of a changing climate happen locally and often involve extreme weather and climate events. More work is required to better understand these.”

Prof Stuart Haszeldine, Professor of Carbon Capture and Storage at the University of Edinburgh, said:

“Climate change is happening; as predicted, ‘weird weather’ and harvest shortages are already having an impact. It’s clear beyond doubt that much, much, stronger and faster action is needed to reduce these global effects.

“The UK talks positively about what must be done, and has achieved a great deal in analysis and regulation, but lags behind in practical action.  Being prosecuted for air quality, halting the carbon price escalator, extending the life of polluting coal power plants, failing to improve energy efficiency for the poorest households, and allowing new gas power plant to be built without carbon capture – these are all signs that the UK evades long-term decisions and has yet to take a firm grip on the solutions.

“Energy is not the problem; there are many ways to generate energy.  The problem is an overdosing on fossil carbon. There is a global carbon budget – that is the amount we can emit before sliding into dangerous climate change – and humans are halfway through their carbon party.

“Politicians need a big visionary project in order to provide leadership; climate change is it.

“Extraction and combustion of fossil carbon can only continue if that easy energy is matched, tonne for tonne, by the recapture and storage of carbon. It doesn’t matter if that is by Carbon Capture and Storage (CCS), by Bio Energy Capture and Storage (BECCS), by direct air capture, or by enhanced mineral weathering – all of these will be needed.

“The important things are to make a start – and sooner than 2030 – embedding carbon budgeting into every business and every behaviour, and make these actions sustainable without destroying natural ecosystems or diversity with biomass farms.”

David Symons, director in consultancy WSP’s environment business said:

“The largest opportunity to cut emissions by far lies in energy efficiency.  Since UK electricity prices are forecast to be 30% higher by 2020 than today, largely due to higher fossil fuel prices, this is the obvious place to start.

“What’s more, action doesn’t need to be complicated.  At international level, Brussels needs to zero rate VAT on insulation products.  National Governments should set high building and product standards, and enforce them.  And business can get much better at tracking energy use.”

Dr Charlie Wilson, of the school of Environmental Sciences at the University of East Anglia (UEA) and the UEA-based Tyndall Centre for Climate Change Research, said:

“Analysing different future scenarios gives us a robust insight into how we can reduce emissions now and into the future to avoid dangerous climate change.

“If we delay a concerted global effort to reduce climate change, it will lead to increased future costs, reduced flexibility, and an increased reliance on commercially unproven technologies.

“By contrast, taking immediate action to improve energy efficiency and reduce energy demand would be cost-effective, feasible, and it would provide multiple benefits to the economy, public health, and the environment.

“This sends a very clear message to policymakers meeting in Paris next year to negotiate a global climate change agreement.”

Roberto Palacin, Senior Research Associate at Newcastle University leading the Railway Systems Research Group at NewRail, said:

“The well-known socio-economic and demographic challenges that 9bn world population will bring by 2050 mean we cannot afford to ignore the clear warning of climate change.

“This is particularly relevant when 75% of the world population is expected to inhabit urban areas by 2050.  So any efforts to reduce or prevent emission of greenhouse gases (GHG) must involve the way we move people and goods.

“Mobility is a key driver for the world’s economy as well as allowing access to jobs, education and health care.  But in order to mitigate the effects of GHG emissions, we must radically change our transport.  We must rebalance transport in urban areas by shifting away from private vehicles and towards high quality public transport.  Mass transit systems are key to achieving these goals.

“These are by no means the only aspects to be considered of course; clean technology and energy, customer service, use of smart devices and above all, a radical change in behaviour are required if we want to have a chance to mitigate the effects of climate change.”

Prof Sir Brian Hoskins, Director of the Grantham Institute for Climate Change, Imperial College London, said:

“The science shows us that we need substantial and sustained reductions in greenhouse gas emissions if we are to limit the risks posed by climate change.  This is not that difficult – we already have the technologies that are required and they will get better and cheaper in the years to come. Potential competitiveness issues, affecting a small number of very energy intensive industries, can be handled.  We should stop wringing our hands and just get on with it.”

Dr Simon Buckle, Policy Director at the Grantham Institute for Climate Change, Imperial College London, said:

“We can achieve a reduction in emissions without damaging the economy if countries act together and have the right policies in place.  Indeed, tackling climate change is vital to support continued economic development.

Most of the reductions in emissions to 2020 needed to limit climate risks could come from action on energy efficiency, limits on the construction and use of inefficient coal plants, dealing with fugitive methane emissions and reducing subsidies for fossil fuels without harming growth.  These measures can save companies money and, in the case of methane emissions, have significant health and agricultural benefits. ”

Ajay Gambhir, Research Fellow at the Grantham Institute for Climate Change, Imperial College London, said:

“Low-carbon technologies are becoming cheaper and some are already competitive with fossil fuels in many locations. Renewable technologies such as solar photovoltaics have tremendous potential to address cost-effectively the needs of the 1.3 billion people in the world who do not have access to electricity.

Various analyses, including a study from Imperial College London, suggest that halving the world’s emissions by 2050 might be achievable at a cost of a few percent of GDP or less depending on the future price of fossil fuels.”

Declared interests, from SMC UK experts

Prof Lowe is lead scientist on the ‘avoid2’ programme.

Prof Haszeldine has been, and is, an advisor to DECC, and Scottish Government on energy and on carbon storage.  He receives research support from EPSRC, NERC, SFC, and research consortia of Scottish Government, Scottish Enterprise, oil companies and power generation companies.  He has no shares, payments from, or consultancies with, any of these organisations, and does not have to gain any clearance from sponsors or employers before making public statements on his research results or interpretations.

Dr Chalmers has received funding from a broad range of sources including the UK Research Councils, UK Government the International Energy Agency Greenhouse Gas R&D Programme (which operates under an implementing agreement of the International Energy Agency) and, where appropriate, relevant industrial players.

Dr Fitzgerald is Managing Director of Breathing Buildings, a natural ventilation company based in Cambridge who sell energy efficient ventilation systems to the building market.

Dr Leggett is founder and chairman of Solarcentury and founder and Chairman of SolarAid, an African solar lighting charity set up with five percent of Solarcentury’s annual profit’s, itself parent to a social venture, SunnyMoney, retailer of solar lights in Africa.  He chairs the financial-sector think tank CarbonTracker, and is a risk consultant to large corporations. He lectures on short courses in business and society at the universities of Cambridge and St Gallen.

Dr Watson: ‘I am the principle investigator  for SPICE and a co-investigator on EuTRACE (a FP7 funded project on climate engineering). I focus on solutions that emulate the effects of volcanism under the general heading of solar radiation management (SRM). SRM is not mentioned once in the WGiii SPM and is not yet being considered by the IPCC as a policy option. I do not and will not hold intellectual property and have no mechanism or desire to profit from the development or deployment of climate engineering technologies.’