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IPCC Fifth Assessment Report: more certainty, not much news

The part of Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report, dealing with the physical basis of climate change, has now been released. The report - released today in Stockholm…

There is still scientific work to do on attributing specific events to climate change, but we know enough to make policy decisions. DeGust/Flickr

The part of Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report, dealing with the physical basis of climate change, has now been released.

The report - released today in Stockholm - is more than 2,000 pages long, has assessed nearly 10,000 peer-reviewed scientific studies, most of them published since the previous assessment in 2007, and (as with previous assessments) went through three rounds of detailed review by 1,089 expert and government reviewers worldwide to ensure balance and accuracy.

So what new does it have to say about our climate problem?

The short answer, at least with respect to the big picture: not much. Despite a recent slowdown of surface ocean warming, the world is still warming and humans are still behind most if not all of the change. Much larger changes loom in the future if business-as-usual continues. If emissions come down, those changes won’t be as bad.

Little progress has been made in narrowing the range of future global warming rates or quantifying the role of aerosols (airborne particles such as soot) in offsetting the warming to date. Confidence in regional predictions of climate remains low. This does not mean, however, that no progress has been made.

First, the report does ratchet up confidence in the basics. Each of the last three decades has been successively warmer that any preceding decade since widespread observations began in 1850. While previous reports already stated that the world is warming, and that human greenhouse gas emissions (mainly carbon dioxide) were causing warming, AR5 expresses 95% certainty that the latter caused more than half of the former.

Indeed human activities can account for all the observed warming, and there is no evidence of a significant contribution from natural causes. This warming is now more clearly evident in the deep ocean. We are also more confident in the positive feedback on global warming by water vapour, clouds, and the net release of CO2 from perturbed ecosystems.

Projected warming by 2100 is still about 3-5C above 2005, under the high-emissions scenario. AR5 takes a longer view than previous reports, noting that the most likely global warming by 2200 under this scenario is a shocking 9C above preindustrial. It also expands its consideration of the palaeoclimate record indicating that the last three decades were likely the warmest of the last 1400 years.

There has been a lot of fuss about the slower warming over the past 10-15 years, which AR5 acknowledges and attributes at least in part to natural variations within the climate system. AR5 also acknowledges that short term trends are a poor indicator of long term changes.

When combined with all other evidence this has a fairly small effect on the conclusions, reflected in a range of 1.5-4.5C per doubling of CO2 for the so-called “equilibrium climate sensitivity”. This is a return to the range in the first three assessment reports but broader than the 2.0-4.5C range assessed in 2007. The upper limit of the “transient climate response,” a related measure, is also down by 0.5C.

New studies have shifted a few conclusions on the question of whether predicted changes can be detected in past observations. It is now clear that both major ice sheets and nearly all glaciers are melting. High-rainfall events (behind disasters such as recent Queensland floods) now seem to be heavier in many places.

But AR5 expresses less confidence that tropical cyclones are on the increase globally or that there are more droughts globally. This does not mean these things aren’t happening but reflects a more nuanced understanding of how difficult it is to confirm them based on the imperfect information available.

Projected future climate changes remain what they have been for years: hotter summers and heat waves, milder winters, heavier extreme rains, and longer periods between rain in most places.

Probably the biggest change since 2007 is that sea level by 2100 in the high-emissions scenario is now expected to be 0.5-1.0 meters.

One new topic not covered in previous IPCC assessments is climate geoengineering, including measures to remove carbon dioxide from the atmosphere or to reflect more sunlight to space in order to offset the impact of emissions. The report is not optimistic about either option. Reflecting additional sunlight to space is possible but carries many risks and does not fully address the impacts of CO2. The IPCC mitigation assessment, due in early 2014, is likely to take this topic up further.

Do we need another blockbuster IPCC report in 2019? Possibly not. As we authors can now attest from personal experience, these reports require a massive investment of time.

Some advocate changing to a system more like the US Climate Change Science Program (CCSP), run about a decade ago, in which smaller and more frequent reports are targeted at key areas of interest to policymakers. This idea, or other possible innovations, deserves serious consideration and was trialled in the IPCC’s SREX (Special Report on Extremes) published in 2011.

The trend in the last several IPCC reports has been growing certainty about the basic things that we already thought we knew. This collectively gives us every reason to think that CO2 emissions are a serious problem—but with little reduction in stubborn projection uncertainties.

The take-home message may simply be that while scientists should continue to strive for improvement, policymakers and the public had best get on with decisions based on the information at hand, rather than hoping for a crystal ball to appear.

Read more IPCC analysis here.

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56 Comments sorted by

Comments on this article are now closed.

  1. Paul Richards

    integral operating system

    Appreciate the article.
    "... policymakers and the public had best get on with decisions based on the information at hand ... " This situation has always been a risk management issue, the clever position is to see opportunity.

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    1. Alice Kelly
      Alice Kelly is a Friend of The Conversation.

      sole parent

      In reply to Paul Richards

      You'd have to wonder why they have ordered the clean energy finance corporation to cease all new loans. Despite the fact that it is illegal for them to do so, until legislation gives them that power. Gerards logic (below) makes no sense. If he did believe his own shouting , he'd be insisting we should not scrap a profit making loan system to ensure we do move away from carbon intensive technology. If more people shouted about both a price on carbon and the clean energy corp., it would make it difficult for weasel words spoken by both Gerard and the Government to have oxygen.

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  2. Comment removed by moderator.

  3. Gerard Dean

    Managing Director

    The authors conclude, "The take-home message may simply be that .... the public had best get on with decisions based on the information at hand, rather than hoping for a crystal ball to appear"

    And what decisions might they be?

    - Stopping installing split system air conditioners.
    - Stopping building ever larger homes with big windows.
    - Stopping buying the Audi 4WD
    - Stopping using the internet and WiFi and IPhones and IPads and PC's
    - Stopping burning fossil jet fuel to fly to Europe for a holiday.
    - Stopping calling for the end of poverty in the third world that can only be achieved by a massive increase in their environmental footprint to match ours.

    No, the authors faith in human nature is misplaced. What most of us will do is keep on consuming and then blaming the government for not acting on Climate Change.

    Gerard Dean

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    1. David Arthur

      resistance gnome

      In reply to Gerard Dean

      Ordinary people will carry on as they do, with their decisions and actions guided and informed by prices. They'll continue choosing the lowest-price option at any moment, so long as fossil fuels and the machines which use them are the lowest-price option, that's what will be used.

      Here's an idea: how about putting a price on that fossil fuels use?

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    2. Steve Hindle

      logged in via email @bigpond.com

      In reply to Tim Bell

      All very sensible answers Tim. Unfortunately though it is human nature to mostly behave like a mob of sheep. We really need broad based support for a price on putting carbon into the atmosphere. Otherwise the general attitude is "my little bit wont make any difference".
      I don't wish for a searing hot summer well beyond the normal extremes, but if we get another one it may make more people realise the seriousness of where our climate is heading.

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    3. Michael Sheehan

      Geographer at Analyst

      In reply to Steve Hindle

      "I don't wish for a searing hot summer well beyond the normal extremes, but if we get another one it may make more people realise the seriousness of where our climate is heading."
      ...And respond by upgrading their air conditioning systems.

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    4. Tim Bell

      logged in via Twitter

      In reply to Steve Hindle

      I absolutely agree that there should be a price on carbon. How that price is set (fixed, or in a market-based system) is not so much of a concern to me, but the price must be such that it captures the externalities of the current fossil-fuel market, so that market forces can begin to operate in non-destructive ways.

      The only reason fossil-fuels and the electricity they generate are so cheap is because they've been allowed to pollute for free – and we're all now paying the price. Fix that with a price on carbon, and people who choose the cheapest electricity will then be helping to stop global warming, because that electricity will be from wind, solar, geothermal, or other green sources.

      In the meantime, those of us who aren't sheep can start taking action ahead of the rest of the flock.

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    5. Mulga Mumblebrain

      Rocket surgeon

      In reply to Wade Macdonald

      Wade, have you reproduced, and, if so, do you think that your attitude will tend to improve or worsen your children's (and everybody else's), chances of living a decent and long life.?

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    6. Mulga Mumblebrain

      Rocket surgeon

      In reply to Tim Bell

      It is quite simple really. Changes to lifestyles and habits must be mandatory, and subsidised. We mandate very many things, proscribing behaviour like murder (denialism will cause more deaths than any other catastrophe in history) paedophilia (what worse abuse of children is there than destroying their world and ensuring their suffering and premature deaths, as the denialists do?). So mandating ecological sustainability and outlawing ecological destruction is simple, just, good and unavoidable if we actually want our descendants to live decently, and not curse our memory.

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    7. Mulga Mumblebrain

      Rocket surgeon

      In reply to David Arthur

      'He knows the price of everything and the value of nothing'. Stop projecting your psychopathology onto the rest of us.

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    8. Mulga Mumblebrain

      Rocket surgeon

      In reply to Steve Hindle

      It won't affect the hardcore denialists. It could be 60 degrees and they will bleat 'Natural variability'. We could see fires rage, but if it is not their houses burning or their families cremated, they will feel nothing, no remorse, no empathy, no concern. That is the nature of the beast.

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    9. David Arthur

      resistance gnome

      In reply to Mulga Mumblebrain

      Mr Mumblebrain, I do not see how your remark about price, value and projections proceeds from anything I've written here. Please expand and expound on your point.

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    10. Michael Sheehan

      Geographer at Analyst

      In reply to Mulga Mumblebrain

      Mulga, what is so frustrating is that a major reason why so many people turned against climate change action, is because climate change advocacy overwhelmingly started sounding like your posts.

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  4. Garry Baker

    researcher

    I think their pronouncements are clear enough. However if there is an expectation they would then go on to recommend a variety of fixes, well that's a bridge too far. Indeed, beyond their remit, given they are funded by their various governments, and have to summarise their work in line with political stances.

    In effect, the public are getting nothing more than a plain vanilla version of climate truths and the really seedy stuff is denied them - hidden in the top end estimates, or dropped…

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    1. Tony Thomas

      Writer for Quadrant Online and Quadrant print monthly

      In reply to Garry Baker

      Hi Lisa, Thanks for the interesting summary.
      Re:
      "While previous reports already stated that the world is warming, and that human greenhouse gas emissions (mainly carbon dioxide) were causing warming, AR5 expresses 95% certainty that the latter caused more than half of the former."

      Could you assist me please with this query: How is the "95% certainty" finding obtained? Is there some objective basis for it, or is it obtained by a show of hands or whatever in a meeting of IPCC authors and/or government reps?
      Thanks again Lisa.

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    2. Alice Kelly
      Alice Kelly is a Friend of The Conversation.

      sole parent

      In reply to Tony Thomas

      For anyone interested in Tonys logic, here is a great read, under "DOOMED PLANET" " todays debate about global warming is essentially a debate about freedom. The environmentalists would like to mastermind each and every possible (and impossible) aspect of our lives" Vaclav Klaus
      "Scaring kids for a greener world" by Tony Thomas.....
      http://www.quadrant.org.au/blogs/doomed-planet/2013/08/scaring-kids-for-a-greener-world
      Another article , also under DOOMED PLANET, the same quote from Vaclav... "The 95% certainty is that the IPCC can't be trusted"
      On the other CC discussion today there's a fan of this notion.
      http://www.quadrant.org.au/blogs/doomed-planet/2013/08/the-95-certainty-is-that-the-ipcc-can-t-be-trusted
      Before I suggest you are a troll and should be ignored. Could you show me a comprehensive list of all donations to Quadrant for the last 10 years??

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    3. Michael Sheehan

      Geographer at Analyst

      In reply to Tony Thomas

      Tony, it seems they've only published the Summary for Policy Makers, so far. The sources for your quote are in Chapter 10 of the WG1 Full Report, which will be published tomorrow.

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    4. roger franklin

      logged in via Twitter

      In reply to Alice Kelly

      Alice Kelly: I edit Quadrant Online and publish Tony Thomas, who has no choice in having his columns appear beneath the Havel quote. It's what is know as "page furniture" and appears above his and every other contributors' work.

      Or rather did appear.

      I've just removed it from the page template, not because I disagree with the sentiment, but because it has been there for two years and should have come down some time ago. I might substitute this video clip in its place, just to remind readers…

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    5. Alice Kelly
      Alice Kelly is a Friend of The Conversation.

      sole parent

      In reply to roger franklin

      I should've been more encouraging Rojer, but it is odd though, because most read quadrant for free, so subscriptions wouldn't go far. I suppose all you few are eagerly waiting for The NIPCC report, and that would give you all something to print. Go ahead, make my day.

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  5. John Newlands

    tree changer

    I have some misgivings about the long term assumptions in the report. I hope to download sections of it when available. My main misgiving is that I think all fossil fuels will be in severe decline by 2050, both the amounts and ease of extraction. Already conventional crude oil has peaked but a fuel volume plateau has been maintained through biofuels. tar sands and fracking. Soon it must decline perhaps taking coal demand with it. Therefore I question scenarios that envisage increased man made CO2 beyond 2050.

    Another issue I hope to see addressed is severity of events. For example can Australian cities expect summer temperatures to crack 50C? That's in this half of the century noting we've already hit 45C a few times. If so it will be hellish.

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  6. Phil Dolan

    Viticulturist

    Hunt on AM this morning. Agrees with the report. What is he gong to do? Nothing.

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    1. Michael Sheehan

      Geographer at Analyst

      In reply to Phil Dolan

      Just as well Phil. Coz there's bugger all that Hunt CAN do about it.

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    2. Mulga Mumblebrain

      Rocket surgeon

      In reply to Phil Dolan

      Empathy zero, indifference stratospheric, ergo psychopathic. I recommend 'Robopaths' by Yablonsky, for a dissection of the type.

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    3. Mulga Mumblebrain

      Rocket surgeon

      In reply to Michael Sheehan

      Denialism in evolution. There is no problem, it is a Communist conspiracy to destroy the ineffable wonder that is Free Market Capitalism. It exists, but it will be wonderful-I'm planting my mango trees, even now. It is going to be tough, and billions will die, but, felicitously, only amongst those Poor World 'useless eaters' that all Right-thinking Westerners fear and despise. There is nothing we can do, because, somehow, it has already gone too far. In any case, soon I will be dead, and will not, therefore, be giving a stuff.

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  7. Geoffrey Henley

    Research Associate

    "AR5 expresses 95% certainty that the latter caused more than half of the former."

    On what basis do they come up with the 95% figure? This is never explained. Do they just sit around a table and someone says "95% sounds good, why don't we use that" and everyone says "sounds good to us, we'll go with that". I think that is how it is done. All very scientific of course.

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    1. Phil Dolan

      Viticulturist

      In reply to Geoffrey Henley

      Eight hundred climate scientists studied ten thousand peer reviewed papers and then 'came up' with 95%.

      That's unlike the few non scientists who look up to the sky and decide that they are 100% right and that the world has not heated up.

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    2. Mike Swinbourne

      logged in via Facebook

      In reply to Geoffrey Henley

      ",...On what basis do they come up with the 95% figure?..."

      Why don't you go away and read it and find out then Geoffrey, instead of commenting from a position of ignorance.

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    3. Geoffrey Henley

      Research Associate

      In reply to Phil Dolan

      I think 'made up' rather than 'came up' would be more appropriate.

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    4. Geoffrey Henley

      Research Associate

      In reply to Mike Swinbourne

      So in other words you have no idea how they came up with the 95% figure.

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    5. Mike Swinbourne

      logged in via Facebook

      In reply to Geoffrey Henley

      Yes Geoffrey, I do know how they came up with the 95% figure.

      But then I - unlike you - actually read science papers for my information, rather than the ignorant rantings on denier blogs.

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  8. James Jenkin

    EFL Teacher Trainer

    What do people think about expressing 'degree of certainty' about a scientific proposition?

    Also, in relation to Cook's paper, in what other areas of science have we tried to quantify 'consensus' to support a proposition?

    I'm genuinely not trying to take any 'side' - I really want to understand.

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    1. Mike Hansen

      Mr.

      In reply to James Jenkin

      Here is an article on scientific certainty and why science, unlike mathematics can never be 100% certain.
      http://www.slate.com/blogs/bad_astronomy/2013/08/05/global_warming_denial_article_says_michael_mann_doesn_t_understand_science.html

      Here is an entry in the Stanford Encyclopedia of Philosophy on the seminal book on the philosophy of science "The Structure of Scientific Revolutions" written in 1962 by Thomas Kuhn. Kuhn uses the term "paradigm" for "consensus". Some of the terminology is a little dense but it dispenses with the notion that consensus in science is a new idea.
      http://plato.stanford.edu/entries/thomas-kuhn/#3

      In science consensus is usually obvious to the scientists involved - as it is in climate science. The reason for the various studies to quantify the consensus in climate science is because of the claim from the "skeptics" that one does not exist and the continual false balance presentation of the issue in the press.

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    2. James Jenkin

      EFL Teacher Trainer

      In reply to Mike Hansen

      Hi Mike, thanks for the response.

      I understand science is never 100% 'certain'. So I'm interested in the effort to quantify the level of certainty. In my field, linguistics, we'd tend to say 'our current understanding is ...' rather than 'we are 95% certain that ...'.

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    3. Michael Sheehan

      Geographer at Analyst

      In reply to James Jenkin

      I wonder how wise the IPCC is in using the word "confidence" at all. The reason being that when we hear "95% confidence", we immediately presume they are using the standard definition, which is an range/interval constructed from actual data, either directly observed, or from simulations.
      While the IPCC's 'consensus' methodology is a perfectly valid methodology, they would be wiser to restrict discussion of results from that methodology to "agreement", leaving the use of "confidence" to describe the data, independent of the more subjective 'polls' taken from groups of scientists.
      This confusion is exacerbated by the number 95%, which also just happens to be the very two standard deviations from the mean, we are used to dealing with when discussing confidence intervals.

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    4. Mulga Mumblebrain

      Rocket surgeon

      In reply to Mike Hansen

      Science is falsifiable. Denialism, being an ideological cult and quasi-religion, is not, being a revealed truth that depends on unquestioning belief, not reason.

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    5. Trevor S

      Jack of all Trades

      In reply to James Jenkin

      "I understand science is never 100% 'certain'. So I'm interested in the effort to quantify the level of certainty. In my field, linguistics,"

      On a slight segway, you may appreciate this article from Asimov on the "Relativity of Wrong", in answering a query from someone with a Lit Major saying the Science was wrong..., a claim you often here repeated here and elsewhere

      http://chem.tufts.edu/answersinscience/relativityofwrong.htm

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  9. Rene Oldenburger

    Haven't got one

    Well they keep saying that deforestation is a main contributor as well, plant more new trees I would say

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    1. Alice Kelly
      Alice Kelly is a Friend of The Conversation.

      sole parent

      In reply to Rene Oldenburger

      Rene, I plant trees, it's good, but when the tree has absorbed enough, the stomates on the leaf shrink, and take in no more. This is a simplistic explanation, there was a UK conversation about this a few months ago which gave a detailed explanation. We have to stop emitting new carbon so that there is something left on the planet in a few hundred years time. A very hard concept for narcissistic thinkers of the world.

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    2. Rene Oldenburger

      Haven't got one

      In reply to Alice Kelly

      Alice I was aware of that, but when I hear these scientist make claim that deforestation is rather a large part of the problem, I actually do not see any Government doing anything about that.

      Personally I would have thought there be several hundred million new trees being planted in Australia alone by now.

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    3. Rene Oldenburger

      Haven't got one

      In reply to Alice Kelly

      Plenty of room to do so, no new housing developments unless the developer plants trees and maintains them etc etc

      Plenty of un employed walking around who can maintain them, here in Adelaide we got a billion dollar water desal plant doing nothing

      Apart from that I like to know what the excuses are of all these scientist and politicians flying around the world going to meetings, when they can use Skype or whatever.

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  10. Theo Pertsinidis

    ALP voter

    The operating system of our world is an incredible tool. It links billions of producers and consumers every day, generating price signals that help people around the world decide what to make and what to buy.

    But when it comes to conserving Earth’s natural environment, our markets are badly broken: we don’t pay the true environmental costs of making, using and getting rid of stuff.

    Are Governments Thinking Of Geoengineering Earth To Adjust To Climate Change?

    National governments more concerned…

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  11. R. Ambrose Raven

    none

    Climate change deniers, by denying the increasing impacts of climate change, thus help deny assistance in crises as well as the big problem of global warming itself.

    After Victoria and other parts of eastern Australia, including Sydney, had just recorded (in '13) their warmest winter on record, was that evidence of climate change, Barrie Cassidy asked Tony Abbott on the ABC's Insiders. Abbott replied that "It is evidence of the variability in our weather."

    Yet, whether or not specific record-breaking…

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