Live IPCC blog: UN releases AR5 climate science report

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-World on course to break 2C target by 2100
-Sea levels to continue to rise in 21st century
-Warming of climate system ‘unequivocal’
-Human influence on climate is ‘clear’
-Polar ice sheets have lost mass in past two decades
-Atmospheric CO2 concentrations ‘unprecedented’
-Climate models have improved since AR4
-Oceans to continue to warm and acidify
-Global carbon budget for sub 2C = 800-880 gigaton carbon
-Click here for access to the IPCC report.

It’s 5pm in the UK, and we are wrapping up our live coverage of the largest climate science report the UN has ever published. The key message from scientists involved in the IPCC process is that humans are causing the climate to change, and without efforts to cut emissions the planet is likely to get a lot warmer, and a lot more unpredictable.

If you’re interested in further reading, my colleague Sophie Yeo has identified the key issues in the report. IPCC lead author Piers Forster has explained the mammoth study in 18 tweets, Ed King has asked what the findings mean in the context of the UN climate talks, and we’ve also collated the views of John Kerry, William Hague, Christiana Figueres, Ban Ki Moon and other leading political and business figures here. Thanks for following.

CO2 concentrations have increased by 40% since pre-industrial times, prim arily from fossil fuel emissions. (Pic: UN Fish & Wildlife Service)

1640 Tom Delay, Chief Executive of UK-based Carbon Trust, asks why climate change is any different to smoking. We were quick to give up smoking when scientists linked it to cancer, but now hold back in making the necessary changes to cut emissions despite the warnings from science: When it comes to climate change the world is like a 40 year smoker. It’s not too late for us to give up but it will be harder and more costly each year we delay.  

1635 Alden Meyer, UCS’s strategy and policy director, has attended United Nations climate negotiations for more than 20 years. He said the report demonstrates the need for more ambitious action to achieve policymakers’ stated goals: The United States and other countries need to greatly step up their efforts to limit emissions of heat-trapping gases if we’re going to avoid the worst consequences of climate change.

1631 One final point from the IPCC report: “Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes. This evidence for human influence has grown since AR4. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.”

1629 Nobel Laureate in chemistry, Dr. Mario Molina, has written exclusively for, stating “let there be no doubt, man-made climate change is real.” He urges us “to educate audiences all over the world on the importance of these scientific findings and the seriousness of the threat.”

1626 Dr Celine Herweijer, partner, sustainability & climate change, PwC, comments on the IPCC report acknowledging the breadth of data presented by the IPCC this morning: There’s no doubt that the communication and the language of climate change play a part. Science debates have alienated many from the real issues. In reality, when working on climate risk assessments with companies, I don’t hear much debate about climate sensitivity or the heat of the ocean in 50 years’ time. It’s not the language of business decisions. Let’s be clear about one thing. Planning for a 2°C world is about business resilience. Planning for a 3°C or a 4°C world is about business survival, or societal survival. It’s not a world any of us should be planning for.

1602 UK climate minister Greg Barker on 5 News: “The overwhelming majority of the world’s leading scientists have come together, scientists that specialise in climate science to produce this comprehensive report that’s more authoritative than any report that’s gone before it.”

1557 Tony Abbott, are you watching? It’s unlikely, but Erwin Jackson, Deputy CEO of Australian NOG the Climate Institute says it’s an important study for his government: Among developed nations Australia is most exposed to climate risks. We have the technology, the wealth, and the talent to avoid dangerous climate change. But do we have the political will and the credible domestic policies? It is in our national interest to do what we can to help avoid 2°C warming.

1547 Ambassador Marlene Moses, Chair of Alliance of Small Island States says AOSIS has already submitted a plan to help decision makers to implement necessary changes to mitigate climate change and reduce the damage being done to small island nations: “The latest research further confirms that governments need to put forward more ambitious emissions reduction targets as soon as possible. We think redoubling our efforts to enable all parties to take more ambitious action domestically can restore trust in the process and increase the chances of securing a new international climate agreement.

Ambassador Marlene Moses, Chair of Alliance of Small Island States. (Pic: UN)

1541 Anthony Hobley, Partner at international law firm Norton Rose says: It is critical that the science of climate change is translated into the language of business so that businesses can understand what it means and so consider the systemic risks to their business created by an increase in temperature, as well as the commercial opportunities from adapting and innovating to a changing climate.

1534 Sam Bickersteth, director, PwC, and CEO, The Climate & Development Knowledge Network, specialist in developing country impacts, AR5 communication and outreach to policy makers says: Countries like El Salvador, Kenya and Pakistan are not sitting on their hands waiting for a perfect answer in the science or a global climate deal. Rather they are taking action now on the best available information and science drawing on their own resources and capabilities. The IPCCs latest assessment will enable a better assessment of risk and future opportunities to inform future decision making at both the national and international levels.

1520 More from the report: “Climate models have improved since the AR4. Models reproduce observed continental-scale surface temperature patterns and trends over many decades, including the more rapid warming since the mid-20th century and the cooling immediately following large volcanic eruptions”.

1509 UK Leader of the Opposition Ed Miliband had this to say:

1505 The New York Times has run a piece on  Ken Caldeira, a climate scientist at the Carnegie Institution and Stanford University, who said the basics of climate change were clear long ago and that the response to global warming is more about ethics and economics than data:

1455 Snippet from the IPCC report: “Total radiative forcing is positive, and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO 2 since 1750”.

1444 Jigar Shah, partner at Inerjys, clean energy investment company and a board member of the Carbon War Room has this to say:

1439 Jeremy Leggett, Chairman of Solarcentury says: “The IPCC’s carbon budget assessment recognises the amount of emissions to keep within 2°C is finite. This inclusion reinforces Carbon Tracker’s conclusion that significant fossil fuel reserves need to stay in the ground to limit climate change to a safe level.”

1416 Ed King takes a look at what world’s leaders will do with the wealth of infomation from the IPCC analysis: What effect will the IPCC report have on UN climate negotiations? 1415 Sophie Yeo rounds up the urgent message laid out in the IPCC report: IPCC: world on course to break 2C warming limit by 2100.

1403 More from the report: “The atmospheric concentrations of carbon dioxide (CO2 ), methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. CO2 concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions. The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification”.

1402 Here’s a tweet from the dark side:

1401 Professor Richard Allan, Reader in Climate Science at the Department of Meteorology, University of Reading, UK, on Sky News: It would mean an increase in the frequency of hot extremes,” he said. In 2003, there were extreme temperatures and a lot of people died in France. We can expect a lot more of these events because of warming.

1358 Senator Timothy Wirth, Vice Chair of the UN Foundation’s Board of Directors and lead US negotiator on climate change from 1993 to 1997 as Undersecretary of State for Global Affairs under President Clinton, says:  This updated assessment considered all the new data – and tells us of irreversible and inevitable changes to the land, air, and water we rely on for our lives and livelihoods if we do not take effective and rapid action. This summer in my home in Boulder, Colorado, I heard trees exploding from spreading wildfires, and I saw flooding take away my neighbor’s house. The evidence is very real to me, and millions of Americans have shared similar experiences.

1350 UK youth climate campaigners respond to the IPCC report – Nick Sanderson, spokesperson, says: In the last 30 years…our generation have grown up and scientists the world over have worked tirelessly to explain the problem. World leaders have barely lifted a finger. The UK Youth Climate Coalition is calling for urgent national action on climate change, and for a fair and ambitious global deal in 2015. We can’t afford to lose another lifetime to inaction.

1344 A little more from the report: “Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent ( high confidence)”.

1343  Professor Brian Hoskins on BBC News says: We are performing a very dangerous experiment with our planet, and I don’t want my grandchildren to suffer the consequences of that experiment.

1318 Lunchtime Roundup:

Volcanic eruptions may have caused the “pause” in global warming. (Pic: Alcinoe Calahorrano)

The IPCC report says “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased.”

Breaking it down, what does the report say on:

Global cooling: The observed reduction in surface warming trends over the period 1998–2012 as compared to the period 1951–2012, are as a result of volcanic eruptions and the solar cycle. The IPCC also expresses medium confidence that variability over decades have caused a degree of difference between observations and simulations.

Sea levels: The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia for which the IPCC lays blame on anthropogenic influences that have very likely contributed to Arctic sea ice loss since 1979. However, there is low confidence in the scientific understanding of the small observed increase in Antarctic sea ice extent due to the incomplete and competing scientific explanations for the causes of change and low confidence in estimates of internal variability in that region.

Warming beyond 2100: Under all model scenarios, the IPCC says atmospheric CO2 concentrations will be higher in 2100 compared to the present day. It is virtually certain that there will be more frequent hot and fewer cold temperature extremes over most land areas on daily and seasonal timescales as global mean temperatures increase. It is very likely that heat waves will occur with a higher frequency and duration. Occasional cold winter extremes will continue to occur.

Carbon budgets: The IPCC recommends that in order for the carbon budget to stay below 2C global CO2 levels need to be at 800-880 gigaton carbon. However, 531 GTC had already emitted by 2011; only 350GTC remains to emit. The report notes that a large fraction of anthropogenic climate change resulting from CO2 emissions is irreversible on a multi-century to millennial time scale, except in the case of a large net removal of CO2 from the atmosphere over a sustained period.

1311 A quote from IPCC Scientist Corinne Le Quéré in an article from The Guardian: The recent slowdown in surface warming is one of the many parts of the complex and interconnected puzzle that was discussed last week. Our job is done now and it is time to let the policymakers do theirs. My hope is that they do not ignore the science entirely as they negotiate international climate policy, because climate policy requires a long-term view and the best data available.

Jonathan Grant from PWC says large-scale renewables is the key to making the transition to a low carbon economy. (Pic: SunPower Corporation)

1235 Jonathan Grant, PricewaterhouseCoopers Director of Sustainability & Climate Change tells RTCC: What the IPCC is calling for is a low carbon transition that will limit warming to 2 degrees. That will be a much more fundamental transition than installing a few solar panels on your roof. To achieve this [we need] more carbon capture storage, electric vehicles and nuclear.

1220 Another headline from the IPCC summary: “Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010 ( high confidence ). It is virtually certain that the upper ocean (0 − 700 m) warmed from 1971 to 2010”.

1219 Statement from Dr Saleemul Huq, senior fellow in IIED’s climate change group and coordinating lead author in Working Group II of the IPCC says: People in richer countries are vulnerable too, as recent floods, droughts and storms in Europe, North America and Australia have shown, but because of political inertia and powerful vested interests that have dominated media narratives for decades, they are less aware of the links between these impacts and their carbon emissions. Climate change ignores borders. It is time for national interests to give way to the global good.

Dr Camilla Toulmin, director of the International Institute for Environment and Development also offers a statement: There is also value in what the IPCC report does not say, such as how the climate will change from place to place. This uncertainty about local impacts, coupled with the certainty that impacts will come, is a stark warning that everyone needs to get ready.

1212 Hubert Patricot, executive vice president and president at Coca-Cola Enterprises said: Climate change is something we are already factoring into our long-term strategy. Government and business need to work together to mobilize a concerted and coordinated response to address the most significant environmental issue of our time.

Andrew Bester, Group Director & Chief Executive, Commercial Banking, Lloyds Banking Group said: Those that do take action [against climate change] could see cost, competitive and operational benefits, that could help them steal a march on rivals and contribute to the success of the supply chains in which they operate.

1159 Other members of the UK government are adding their voices to UK climate and energy chief Ed Davey’s earlier comment. Foreign Secretary William Hague says: The longer we delay, the higher the risks and the greater the costs to present and future generations.

“The odds of extreme weather events, which threaten lives and property, have increased”, says UK Foreign Secretary William Hague. (Pic: Chatham House)

1136 Dr Alice Bows-Larkin from the Tyndall Centre and the University of Manchester, UK has this to say: Six years on from the last IPCC report, and little has changed. The big unknown is if, or when, we will manage to break our addiction to fossil fuels, and where that will leave us in terms of future climate impacts. Personally, if investing in my future and that of my family, I would look beyond fossil fuels being mindful of the risk of stranded assets left in a future that whichever path we choose, will certainly be very different from today.

1132 I’m now going to pick out some of the headlines from the 36-page executive summary: “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased.”

1129 Connie Hedegaard, EU Climate Commissioner and one of the key architects behind efforts to develop a global emissions reduction deal in 2015 asks:

1124 A reaction from Christiana Figueres, Executive Secretary of the UN Framework Convention on Climate Change

1118 UK climate and energy chief Ed Davey says the report is a warning that “urgent” cuts to greenhouse gas emissions must now be made: The message of this report is clear – the Earth’s climate has warmed over the last century and man-made greenhouse gases have caused much of that global warming. The gases emitted now are accumulating in the atmosphere and so the solutions must be set in motion today. The risks and costs of doing nothing today are so great, only a deeply irresponsible government would be so negligent.

1114 Over 36 pages of climate science in the IPCC Executive Summary condensed into one Wordcloud. Note how ‘confidence’ features prominently.

A word cloud to sum up the report in full colour.

1048 The press conference is over, but here’s the IPCC AR5 WGI summary for policy makers.

1048 Samantha Smith, leader of WWF’s Global Climate & Energy Initiative says: Whichever facts may be discussed, debated or distorted, we cannot ignore the reality that we must act or face frightening new impacts. We know that most of the pollution that causes climate change comes from burning fossil fuels. WWF calls on governments and investors to stop investing in dirty energy and start an immediate and just transition by investing in renewables.

1044 There is loads of reaction coming in today. Former IPCC chief Bob Watson says the findings indicate that future changes are now inevitable: Many of the other changes observed in the climate system, such as the rate of loss of Arctic sea Ice, melting of mountain glaciers and the Greenland Ice sheet are unprecedented. Without immediate reductions in global emissions of greenhouse gases, the world will not be able to achieve the political target of limiting the increase in global mean surface temperatures to 2°C, but rather we are likely to see an increase of 3-5°C.

1041 Stocker says: I am extremely proud to say we have convinced the policy makers that this is a robust consensus.

1038 Pachauri, IPCC Chair, exits the press conference.

Rajendra Pauchari.


Here’s a comment from the other side of the fence:

Panelists answer questions from journalists.

1028 Stocker says: There is no consensus over high sea levels over the next 100 years. 1026 Qin says: Science is the essence of this working group. China is a very big country and its ecosystem is very vulnerable. If China can protect our own climate system and environment it will be a great contribution to the world.


1015 Journalist question: How much longer will these hiatus continue before you will consider that there is something wrong with the model? Jiraud’s response: This is an ill-posed question. It is based on misunderstanding of how the model works. Stocker answers: The models show agreement with longer term trends which gives us confidence. There is an entire chapter in our assessment that shows models have improved in their performance. 1012 Stocker: The emission of greenhouse gases leads to warming, which causes melting of ice in all parts of the world. We see in the Arctic unprecedented long term trends which will be significantly reduce ice cover in the future.

1009 Stocker: We cannot emit more 1000 billion tons of carbon if we are to keep below 2C but 54% has already been emitted. 1007 Jarraud says: Aggressive action needs to be taken. If we don’t take action quickly now, we’re talking about the [more dangerous] scenario. One of the biggest impacts of climate change will be on water resources. We have a huge responsibility for our children and grandchildren.

1003 Pachauri: The IPCC has to do a lot more in terms of outreach. I hope this will inform the public and heads of government.

1002 Sharan Burrow, General Secretary, International Trade Union Confederation says: “Governments have a responsibility to tackle global unemployment, precarious work and climate change. There are solutions available for governments. Green and decent job promotion in climate-friendly sectors, and building a Just Transition for sectors in hardship can demonstrate that we don’t have to choose between people and the planet.”

1001 Stocker says: Human kind has a choice on which scenario we will fare in the coming 100 years – it depends crucially how much CO2 will be emitted in the future.

0959 Stocker answers questions from journalists: How can we be sure of our predictions if climate models aren’t able to predict warming hiatus?

The scientists have looked at this very carefully. I’m afraid to say that there isn’t a lot of published literature to help us delve into the depths of this observation. Scientists have known for a long time that there is variability. Climate relevant trends should not be calculated for periods of less than around 30 years – these periods are less relevant for the projections of changes in the future. These models do predict variability but is not sufficient for long terms projections.

Piers Forster – Climate Scientist from the University of Leeds:

0954 Stocker concludes his statement: The higher the emissions the warmer it gets. We have concluded that in order to limit climate change it will require sustained reduction of greenhouse gases.

0950 Stocker: Warming will continue under every scenario that is available. This is accepted by governments in the world. We deliver out of this report a clear policy-relevant message.

0948 Stocker: One of the 18 key messages that the 110 governments have adopted in consensus: human influence on the climate system is clear.

0947 Stocker: The ocean has not saved us from global warming.

0946 Stocker presents graph showing changes in average surface temperatures.

Graph shows that warming in climate system is ‘unequivocal’.

0942 Stocker says: Sometimes paragraphs were discussed with policy makers for over an hour. 110 governments have found consensus over 18 short headlines.

0941 Stocker says: An atlas of regional and global climate change maps have been provided in this report.

Thomas Stocker, Co-Chair WGI.

0938 Stocker asks scientists: Give us evidence of climate change and its causes and estimate how it will change in the next 50-100 years.

0937 Thomas Stocker, C0-Chair WGI: presenting the findings says: we have worked during the past 52 hours working incessantly.

Dahe Qin, Co-Chair WGI.

0933 Dahe Qin Co-Chair WGI asks: How can we protect our climate system?

0929  Pauchauri continues: Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850.

0928 Pachauri says: The average person on the street can make use of this report.

0927 Pachauri says: Some of the findings of this report goes far beyond what we were able to provide in the fourth assessment report. I want to pay the highest tribute to the scientists that have worked on this report. This is a very very good report that has come out.

0925 Rajendra Pachauri, IPCC Chair says: I’m happy to inform you that almost 60% of the authors of this assessment are new to the IPCC bringing new knowledge.

0922 Achim Steiner, Director General of the International Union for Conservation of Nature and Natural Resources says: This is not about ideology but our economies and societies.

WMO says more temperature records were broken than in any previous decade, new #ipcc report shows

— Carbon Brief (@carbonbrief) September 27, 2013


Michel Jarraud

0917 Jarraud says: More temperature records were broken than in any other decade. The IPCC report demonstrates that we must reduce global emissions to avoid the worst of climate change.

0915 Michel Jarraud Secretary-General of the World Meteorological Organization since 2004: This report confirms that changes in our climate system are due to human influence – it should serve as another wake up call.

0911 Ban Ki-Moon compliments the IPCC at the opening of the press conference: You are the world’s authority on climate change.

0905 Still no sign of the press conference, so in the meantime take a look at the IPCC AR5 WGI summary for policy makers which is finally available.

0902 The Financial Review talks about how a warming Earth could devastate Australia.

0856 UK scientist Piers Forster, a lead IPCC author on radiative forcing, says the report is now ready for release.

0848 Dr Richard Allan, University of Reading discusses the “pause” in global warming that has been creating a frenzy among climate sceptics:

0846 Incidentally, if you’re interested in why the 2°C warming target (above pre industrial levels) is significant, have a read of this analysis by University of Sussex researcher Chris Shaw

0845 With around 20 minutes to go till the scheduled press conference in Stockholm could start, analysis on the report is already flowing along Twitters wide, entirely rational and polite avenues. Another guy worth following is climate economist Chris Hope – here’s his view on IPCC predictions on when the world could break the 2C barrier

0840 A major issue for the IPCC and participating scientists is to produce a report that can be consumed by both the general public, and also the politicians who will make decisions over future emission pathways. In 2015 countries have agreed to sign a global climate change treaty in Paris. UN climate chief Christiana Figueres says this report will be vital in building political momentum.

0835 A MUST FOLLOW (end caps) today is the BBC’s former environment correspondent Richard Black, never known to shirk a challenge when going in two-footed will do. But in a good way – he’s on myth-busting form this morning…

0830 What are the papers saying? Fiona Harvey on the Guardian has this bleak assessment: “Global warming is likely to surpass the previously recognised danger threshold of a 2C average increase in temperature”. The BBC (ok – not a paper) says ‘scientists are more convinced than ever that the planet is warming’ while the Daily Mail runs the (frankly ludicrous) line that global warming has been put on ice.

0825 But what about the cooling I hear you cry! The world has not warmed in the past 15 years, proof this is all a hoax, that well-paid scientists have colluded with leading institutions, politicians, business, the man from number 45 and my dustbin cleaner to make up global warming. Well, if only that were true. But it’s not that simple, as my colleague Sophie Yeo explains.

0820 So what are headlines we can expect from AR5 WGI? (sorry about the acronyms) Well – scientists are now 95-100% certain humans have caused the bulk of climate change since the 1950s. The three most recent decades have all been warmer than all preceding decades since 1850. The rate of sea level rise is likely to exceed previous scenarios. And the oceans are acidfying – and have been since the start of the industrial revolution.

0815 The Guardian’s Fiona Harvey says journalists in Stockholm are now being ‘locked in’ (in an old brewery) ahead of the release…

0810 10 things you never knew about the IPCC – here’s a useful summary from the AP news agency

0806 Jean Pascal Van Ypersele, the Vice-chair of the IPCC, is worth following on Twitter. He has provided a running commentary of last night’s marathon session involving national delegates and scientists. That concluded four days analysis of the ‘Summary for Policymakers’, and several year’s research.

0803 Today’s report has been created by Working Group I. What’s that I hear you ask? Here’s the IPCC definition: “WG I assesses the physical scientific aspects of the climate system and climate change. The main topics assessed by WG I include: changes in greenhouse gases and aerosols in the atmosphere; observed changes in air, land and ocean temperatures, rainfall, glaciers and ice sheets, oceans and sea level; historical and paleoclimatic perspective on climate change; biogeochemistry, carbon cycle, gases and aerosols; satellite data and other data; climate models; climate projections, causes and attribution of climate change,” – it’s that simple.

0800 BST I’m Nilima Choudhury, and welcome to RTCC’s live blog on what is set to be a day of history for global climate science. In just over an hour the UN’s Intergovernmental Panel on Climate Change will release one of the most eagerly anticipated (and leaked) documents known to man – the Fifth Assessment Report of Working Group I. We’ll bring you the latest news, quotes, tweets, pictures and video throughout the day. Email me at [email protected] or send me a Tweet @rtcc_nilima

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