Summing up Copenhagen: what we know now

cop_logo_1_r_edited The synthesis report from the Copenhagen climate congress of scientists held in March has been released. It updates the 2007 IPCC report in the light of the latest developments in the science, and means that the UN Copenhagen conference in December will have an overview of the state of our current understanding of climate change.  

The report has six sections. The first deals with climatic trends and is blunt. Greenhouse gas emissions and many aspects of the climate are already changing near the upper boundary of the IPCC range of projections.  In the case of sea level rise the rate is even greater than indicated by the IPCC projections. 

By far the largest amount of heat stored at the Earth’s surface is found in the ocean, not the atmosphere. Although the ocean warms more slowly than  the atmosphere, a change in ocean temperature is a better indicator of change in the climate than changes in air temperature. Current estimates indicate that ocean warming is about 50% greater than had previously been reported by the IPCC. This helps better explain the trend in sea level rise, the rate of which has increased in the period from 1993 to the present.  Looking ahead to 2100,  projections that do not include possible changes in polar ice sheet movement now suggest a sea level rise of around a metre or more.  (The top of the worst scenario IPCC range was 59 cms, though that did not include feedback uncertainties or possible changes in ice sheet flow)

Importantly the report points out that sea level rise will not stop in 2100. Changes in ocean heat content will continue to affect sea-level rise for several centuries at least. Melting and dynamic ice loss in Antarctica and Greenland will also continue for centuries into the future.  In fact, global average surface temperature will hardly drop in the first thousand years after greenhouse gas emissions are cut to zero.

The unexpectedly dramatic reduction in the area of Arctic sea ice cover is important for climate on a large scale because of the feedback effect of the lowering of reflection of the sun’s radiation. Increased water vapour following warmer global temperature is a further amplifying feedback.

Atmospheric CO2 as well as methane and nitrous oxide concentrations have increased dramatically over recent decades because of human activities. Ice core and sediment records show that the concentration of all of these gases in the atmosphere is now higher than it has been since long before modern humans evolved. In fact, the CO2 concentration in the atmosphere has not been substantially higher than it is now for at least the last 20 million years of the Earth’s history. 

At this point the report draws attention to a further amplifying feedback relating to the land and ocean sinks which have so far removed over half the CO2 released into the atmosphere through human activities.  A weakening of the sinks is already occurring and there is likelihood that the decrease in the fraction of CO2 removed from the atmosphere by sinks will become larger under high future emissions scenarios. Several effects contribute to this likelihood, including increasing ocean acidification, ocean circulation changes, and water, temperature, and nutrient constraints on land CO2 uptake. Also, previously inert carbon pools can be mobilised and released into the atmosphere either as CO2 or methane, a more potent greenhouse gas. Two areas of concern are tropical peatland carbon, which is vulnerable to land clearing and drainage, and the large stores of organic carbon in Arctic permafrost, which are vulnerable to warming.

Finally, on smaller scales, the report refers to the observed increase in extreme events.

The congress was not an official UN gathering.  It was organised by the International Alliance of Research Universities with the aim of bringing together the new knowledge that has emerged since the IPCC report.  Open to all, the congress was attended by approximately 2500 people, most of them researchers.  They came from nearly 80 different countries and contributed more than 1400 scientific presentations.  The synthesis report, produced by a writing team of twelve, has been extensively critically reviewed “to ensure that the messages contained in the report are solidly and accurately based on the new research produced since the last IPCC Report, and that they faithfully reflect the most recent work of the international climate change research community.”

The language of the report is fully accessible to a wide audience.  No one can go to Copenhagen in December claiming that the scientific picture is confusing.  

Hot Topic will highlight other sections of the report in further posts.

25 thoughts on “Summing up Copenhagen: what we know now”

  1. “Analyses led by the Potsdam Institute98 also indicate that 12 billion people with 1995 dietary habits could be nourished on less than one third of the present agricultural area – if the best sites were used for the most appropriate crops and if world food trade would operate undistorted by protectionism.” (from the report – page 35)

    This is exactly the point New Zealander’s passionate about climate change need to take on board, the world faces multiple problems, and they need to be addressed together. The UNFCCC should not ask NZ to limit agricultural production, but rather to continue to increase it. This will reduce all the ecological footprints or world agriculture, and aid in feeding the world (I found it comical that NZ wasn’t on the map they produced!).

  2. Hi Bryan

    i’d be very wary of characterising the Copenhagen Climate Congress as “updating” the IPCC. While the Congress did a great job in bringing a lot of scientists together, those attending were struck by the variation in levels of work presented: peer reviewed/not peer reviewed; some were simply hypotheses.

    Mike Hulme summarised the feedback I’ve heard on Prometheus.

  3. sorry, he didn’t post in on Prometheus – but Pielke did… it was originally, i think, a letter to Science magazine.
    of course all the cranks have jumped on Hulme’s comments but I think we need to be careful to label such a thing anything like the IPCC.

  4. Remind me never to step on Hulme’s lawn. And to step on RP Jr. whenever I get the chance. 🙂

    I think the process used for the Copenhagen conference and report was appropriate given experience with the too-conservative IPCC process. I haven’t read the report yet, but I’ll be surprised to see much in the way of ill-supported hypotheses. There may be some that haven’t had a chance to get through formal peer review, but I would expect that any such will have gotten a close vetting (a fair equivalent to peer review, especially given the caliber of the scientists involved) before going into the report. So after all that, the science formally presented to the COP will be *only* nine months out of date.

  5. Cindy, I was perhaps a bit careless in the way I linked the report to the IPCC. I am well aware that it does not have the status of an IPCC report, and intended to make that apparent when I said in the post that the congress was not an official UN gathering.

    That said, the writers of the report say this: “Since the production of the IPCC report, new knowledge has emerged that furthers understanding of the impacts of human influence on the climate and the response options and approaches that are available to tackle this complex issue. To bring this new knowledge together, the International Alliance of Research Universities organised an international scientific congress on climate change…”

    I would imagine that with a congress of that nature there would be a good deal that was messy, but all that I have read about the science suggests that the synthesis report is a fair presentation of where the main body of the science stands today. Policy makers need to know that the IPCC report by its very nature is bound to be somewhat behind the play, yet there seems to be no other way in which it can be updated (for those serious enough about the issue to want an update) than by means such as that employed by the congress.

    Your link didn’t work, and I can’t access Hulme’s letter to Science without a sub. But other references to it I’ve seen seem to fit with his book, the opacity of which I have already commented on in my review . Roger Pielke is bound to find something to snipe at. And when it comes to opacity he’s a master in the bits of his writing that I’ve read. He came into my mind occasionally when I was reading Hulme’s book.

    No doubt negotiators in the lead up to Copenhagen will be wanting to rest on the IPCC report as a commonly recognised authority. The synthesis report in no way undermines the IPCC, but rather indicates that it would be premature to accord the IPCC canonical status, or at least to close the canon. Policy makers have to accept that rapid changes are taking place and need to be taken into account. I welcome any attempt by scientists to bring that fact to their attention.

  6. R2D2, interesting find! I wonder if anyone’s ever tried leveraging that at Doha and the like (obviously unlikely to be a northern hemisphere country).

  7. In the matter of review which Steve touches on I should perhaps add here information I’ve already put in a comment on a different post. I don’t know how this would stand up in terms of “peer review”, but I presume it helps establish the report as representative of a wide body of scientific opinion:

    The synthesis report explains in its preface that it “has been critically reviewed by representatives of the Earth System Science Partnership (explained below), by the parallel session chairs and co-chairs, and by up to four independent researchers from each IARU university (the Universities who organised the congress).”

    (The Earth System Science Partnership is a partnership of the international research programmes World Climate Research Programme, International Geosphere Biosphere Programme , International Human Dimensions Programme for Global Change Research and DIVERSITAS, an international programme of biodiversity science)

  8. Hi Bryan,

    I know I’m probably going to get roasted for posting this but I hope you’ll hear me out.

    It seems that one of the parameters of the IPCC’s range of projections that is not near the upper boundary is temperatures. The atmospheric temperatures for at least this century have been static if not decreasing slightly. There is also a slight downward trend in the Argos SST measurements. The Argos system was put in place in 2003 and is currently our most reliable source for SST readings. I know this period may be too small to be statistically significant but none the less it was not predicted (read: projected) by any of the ensemble of IPCC GCM models and it seems to contradict the reports statements of the rate of current changes.

    The current rate of sea level rise is relatively constant at 3.2 mm/y as measured by TOPIX and Jason at UC boulder and this would indicate another 29 cm of sea level rise by 2100. I agree that sea level rise is unlikely to stop by 2100. As it has been rising for the last 12,000 years it would seem rather unlikely.

    Although atmospheric levels of methane have increased in the past they are not currently increasing according to IPCC AR4 [2007].

    It is also interesting to note that recent research by, Chylek [2007], Douglas and Christy [2009] and Spencer and Bracewell [2008], on climate sensitivity to CO2 appears to indicate that CO2’s feedback mechanism is either zero (i.e. a doubling of CO2 should lead to around a 1 degree rise in global temperatures) or slightly negative. This would indicate positive feed back biases in the IPCCs GCM models.

    Cheers
    Steve

  9. Steve, I am not a scientist, and can only point to my reading in response to your queries. The first point you raise is addressed in this RealClimate post , which includes the obervation that models can only be expected to reproduce the deterministic long-term component. Are you suggesting the graph in figure 4 of the synthesis report is wrong, or just that it hasn’t caught up with a sudden reversal in ocean warming?

    On sea level rise the report acknowledges the problems in model projections and says “an alternative approach is to base projections on the observed relationship between global average temperature rise and sea-level rise over the past 120 years, assuming that this observed relationship will continue into the future. New estimates based on this approach suggest a sea level rise of around a metre or more by 2100.” Your comment about the sea rising since the end of the ice age treats anthropogenic global warming as insignificant, as indeed does the whole tenor of your comment.

    On methane levels, would that they were stabilizing, but you may like to look at this article in Science Daily.

    I’ve run out of energy to look up the work of the people you mention in your final paragraph, though I notice they are enthusiastically hailed on some of the denialist websites. We would all be delighted if it was the case that a doubling of atmospheric CO2 led to only 1 degree rise in temperature. But the vast body of research points to a much higher temperature rise than that. This article in RealClimate may serve as an example. It also serves as a reminder that this is not an academic question. We would be foolish beyond measure to refrain from action because a tiny minority of scientists told us the rest have got it wrong.

  10. Not roasted, lightly grilled.

    Ocean heat content: see graph on page 9 of the synthesis report. It has wiggles. One would expect it to wiggle in the future. Short term fluctuations therefore tell us nothing about long term trends. Same goes for global temperature.

    Current rate of sea level rise tells us nothing about expected future rates of sea level rise. However we know that the rate of mass loss from the world’s ice sheets is increasing, and therefore we can expect sea level rise to speed up. How much is a big question – but up to 2m by the end of this century looks at least possible (see report).

    Methane is currently increasing again (see p11). Odd you should rely on AR4 when this post is about a report that specifically updates it…

    The three papers you reference have found little traction in the field. You will find a better overview of water vapour feedbacks in Dessler and Sherwood (Science, 2009 – here).

    In other words, attempting to downplay the issue cuts no ice here…

  11. Hi Bryan, Gareth

    Thanks for the response and sorry, yes, my comment about sea level rise was a bit sarcastic, yet I still think it is important to remember that there have been natural increases in sea level rise in the past.

    Personally I do believe man is and has had some effect on temperature via anthropogenic GHG emissions but I also believe that nature is also more than capable of experiencing fluctuations in temperature and climate. I guess the key for me is to identify how much is natural and how much man made.

    I believe (could be wrong) there is still a large amount of uncertainty in the field around feedback mechanisms especially in the area of clouds and aerosols and especially in low cloud variability which affects SW radiation.

    I know Mauna Loa has CO2 data available is there an equivalent dataset for Methane? Do they know what caused the spike? I know some effects have been noticed from over fishing of Sardines in Africa (Namibia?) and the resultant effect it had on phytoplankton populations.

    Also I got my Greek mythology mixed up it should have been ARGO not ARGOS :).

    Cool, that wasn’t as bad as I thought it would be.

    1. For methane info, follow the methane tag, and see this post in particular.

      There are certainly uncertainties ( 😉 ) in the ways that clouds are dealt with in models, but the chances of a major negative feedback turning up are small. One good reason: if there were a big negative feedback, how could the climate warm up out of an ice age?

      When thinking about human impacts — specifically that of GHG emissions – you have to remember that they’re cumulative, and started off small. What we’ve seen in the last 30 years is the emergence of that signal from the natural noise in the system.

      Argo/Argos — the same mistake as Wishart made… One of a catalogue of errors. 😉

  12. No doubt Gareth’s selection of “little traction” is due to this being a family blog. 🙂

    Steve, one can demolish those contrarian sensitivity papers in detail (see here for the fate of Chylek and Lohmann 2007), but it’s easier for us amateurs to consider that they all fail to account for the glacial cycles in general and interglacial variability (some with peak temps at least 2C greater than current) in particular, and the even larger problem of things having been warm enough during the mid-Pliocene (about 4 mya) such that permanent ice was reduced to at best a small inland remnant in Antarctica. In principle the problem could be solved with large forcings combined with the postulated low sensitivity, but the complete lack of evidence for such a thing makes it not so plausible.

    Note that the problems with such papers never get discussed on denialist blogs.

  13. Methane……

    First of all, the synthesis report this post is about shows an atmospheric methane graph on page 11. Since 1999 the trend has been flat. Now many on here have posted that 2007 reversed this trend. I find it amusing that the some posters (Bryan Walker post 7) can claim in one post that cold temperature in one year can not end a trend but that a methane rise in one year can. This is called doublethink Brian.

    On the rise, Bryan Walker posted a link to an article that stats, “The amount of methane in Earth’s atmosphere shot up in 2007”, however the article does not quantify the rise, it just relies on its readers to trust it was substantial.

    The full article isn’t available at google scholar, and the abstract also does not include the quantity;

    http://scholar.google.co.nz/scholar?hl=en&lr=&cluster=9694380594515227158

    New Scientist has this to say; “The rise in 2007 was about 10 parts per billion, a significant jump over such a short period.”

    But lets make our own minds up. AR4 shows that between 1984 and 2005 six years had rises over 10ppb, so it is reasonable. It equates to about 0.5% of the atmospheric total. The standard error (1.96) of the measurements are +/- 1.22, so it statistically significant.

    So does this meant that in 2007 the worlds emissions were 1/200 of the historically accumulated methane? ie equivalent to an increase of 2 ppm of CO2?

    No actually it is quite different. Methane lasts in the atmosphere for around 8.5 years

    http://www.ipcc.ch/ipccreports/tar/wg1/134.htm

    So, if the change was driven solely by emissions, it would mean that 2007 emissions must have been 4.2% higher than the average for the last 8.4 years (in a simple world).

    However, as short term concentration levels do not correlate well to estimated anthropogenic emissions (IPCC AR4 Ch2 pg142 “The reasons for the decrease in the atmospheric CH4 growth rate and the implications for future changes in its atmospheric burden are not understood”), it is likely that it is due to a change in the main sink, OH.

    Gareth speculates in his post he linked in comment 10 that perhaps “A possible reduction in OH is also disturbing, because it might indicate that pollution (from all sources, methane, industry, coal burning etc) is beginning to overwhelm the atmosphere’s ability to cleanse itself. “

    However the graphs on page 148 of IPCC AR4 Ch2 do not show any long term trend in OH levels to back this hypothesis up. Section 2.3.5 of AR4 covers the issue, they state that “Prinn et al. (2001) inferred that global OH levels grew between 1979 and 1989, but then declined between 1989 and 2000”. And “In 2003 [concentrations] were comparable to those in 1979”. And “No significant long-term trend between 1989 and 2003 in Southern Hemisphere OH”.

    The IPCC find that “OH minimum coincides with, and is likely caused by, major global wildfires and an intense El Niño”.

    Note: 2007: wild fires in California and Victoria. El Nino year. (Don’t blame the cows people lol).

    So it likely the increase in methane was caused by a decrease in the hydroxyl radical, caused possibly by extreme wildfires or an El Nino or both.

    “For methane info, follow the methane tag, and see this post in particular.” Hmmm maybe just read section 2.3.2 and 2.3.5 of the IPCC AR4 WG1 report.

  14. R2, it’s good to see that you’re beginning to go to reliable sources of info, but AR4 was published in 2007, and reviews work up to (roughly) 2005, so the info in the Copenhagen synthesis report is more recent. FYI (and if I can find the recent item, I will) there are signs that 2008 continued the rise seen the year before, though I wouldn’t expect the final figures for a few months (2007 was released in October 08).

    With respect to the recent rise, no-one is making claims about a new trend, just that after years of relative stability we see a significant increase. In attempting to pin the blame on OH reductions, you are going beyond the data: it’s an interesting thought, and as I said in my post potentially worrying, but we can see bubbles of methane coming out of the Arctic ocean. And, of course, the rise in CH4 could be a bit of both…

  15. Hi Steve,

    Always nice to meet another Steve :). I think we may be talking about different papers here. The one I was referring to was http://pubs.giss.nasa.gov/abstracts/2007/Chylek_etal.html.

    The paper doesn’t really state that CO2’s feedback is zero or negative it just states that because the Aerosol Optical Depth (AOD) has been decreasing aerosols can’t really explain the “missing” temperature rise that should have occurred from the increases in atmospheric CO2. The models have mean 2CO2 forcing around a 3 degree rise in global temperatures.

    The conclusion Christy makes from Chylek et al is that is either 2CO2 forces at most a 1 degree rise in global temperatures or some other forcing is counteracting the effects of the CO2 increase. One possibility he mentions are changes in the ENSO or PDO which could influence low cloud cover over the oceans. There could be others too.

    Sadly there doesn’t seem to be any really reliable scientific measurements of variability in cloud cover, as there is for the PDO and ENSO indexes, and they still remain one of the biggest uncertainties in the models.

    I guess the optimist in me hopes they’re right but I also have that nagging fear they could be wrong. Anyway I still think there is a lot of interesting science to be done in this area.

  16. Gareth, I used info from AR4 and info since. Both are relevant. When have I used unreputable sources? I usually source official policy documents rather than science ones, when I do need to have a science source I usually head to AR4, as it is a summary of scientific literature on the subject.

    Even if 2008 does rise, that does not change the fact that this is a small (0.5%) increase in the forcing from methane. Less if the relationship is non-linear. And it does not change the fact there is no established change in long term trend of OH, so we not expect a change in atmospheric lifetime. Are you aware of research since 2005 that shows OH is decreasing? Because I am not (and this would still not be a long term trend, as it decreased from 79-89 and then recovered).

    “With respect to the recent rise, no-one is making claims about a new trend, just that after years of relative stability we see a significant increase.”

    Right, statistically significant (greater than 95% chance it did increase), but not as dramatic as you imply, 10ppb. We have had other years increase this much (1998), and were then followed by decreasing atmospheric levels 2 years later.

    Why is the change in OH potentially worrying? The 10ppb change is well with in the normal range. The change in OH is probably well within the normal range.

    This statement by nature: “Although atmospheric levels of methane have increased in the past they are not currently increasing according to IPCC AR4 [2007].”, drew criticism, and comments such as “Methane is currently increasing again (see p11)” were posted. But I don’t think this has been proven. Perhaps a retract is in order Gareth? Or maybe you can explain how one and maybe a second year is now a trend for methane concentrations but not for temperature.

    And Steve Bloom, you insult me by calling me stupid and accusing me of lifting my comments. I find this approach degrades the whole AGW community. When someone uses IPCC documents to question your own beliefs you turn to insult – not earning my respect, others can make their own minds up.

  17. Or maybe you can explain how one and maybe a second year is now a trend for methane concentrations but not for temperature.

    There you go again… Two years do not make a trend, and neither I nor anyone else is claiming that it does. The quantum of the increase in methane conc may be small in terms of total atmospheric forcing, but it is the sudden increase after near ten years of more or less stasis that catches the eye – especially when that uptick is set alongside reports of methane releases from Arctic permafrost, lakes and ocean floor hydrates. The concern is straightforward enough. Arctic methane emissions have the potential to be a significant and dangerous positive feedback (more warming, more methane), so it’s a situation we need to watch very closely.

    If you read back through the posts tagged methane you’ll get the picture…

    With respect to temperature, we’re dealing with climate — average weather – and so it makes no sense to talk sbout short term “trends” because they’re the weather we have to average to talk meaningfully about climate. As I’ve said before, wiggles on an underlying trend. The same rationale does not apply GHG emissions, whether caused by warming or man.

  18. Hmm Gareth, I’ll read you back your own coments.

    The quantum of the increase in methane conc may be small in terms of total atmospheric forcing

    but it is the sudden increase after near ten years of more or less stasis that catches the eye

    specially when that uptick is set alongside reports of methane releases from Arctic permafrost, lakes and ocean floor hydrates.

    The concern is straightforward enough.

    How is this logic (that you ridicule on a daily basis), any different to your own?

    Doublethink: The power of holding two contradictory beliefs in one’s mind simultaneously, and accepting both of them.

    You appear to be a master!

  19. Sorry, a little more;

    With respect to temperature, we’re dealing with climate — average weather – and so it makes no sense to talk sbout short term “trends” because they’re the weather we have to average to talk meaningfully about climate.

    As I’ve said before, wiggles on an underlying trend. The same rationale does not apply GHG emissions, whether caused by warming or man.

  20. I have no idea what you did in your comments — all there is is there to read. If you’re trying fancy formatting, be sure to stick to html, as shown in the little box underneath the entry panel.

    If I can read between the lines… 😉 There is no “doublethink” involved. If the recent couple of years uptick in methane conc continues, then it will be a matter for increasing concern because it means (as it said in the post I referred to originally) either the sources of methane are increasing (which we suspect they are based on direct observation), or that the sinks (OH principally) are becoming saturated, or both. But we’ll have to wait and see…

    Climate, on the other hand, is not measured on a few years data. I confidently expect a new global average temperature record in the next five years. I wouldn’t bet on methane, because the underlying mechanisms are nowhere near as well understood.

  21. Sorry, half of my comment is missing. So the point I was making is not made. I was applying logic that you had used to the change in temperature to show the two observations were similar. But I used triangle brackets without realising it would result in lost text.

    (The quantum of the increase in methane conc may be small in terms of total atmospheric forcing, but it is the sudden increase after near ten years of more or less stasis that catches the eye) – The sudden decrease in temp catches the eye

    ( – especially when that uptick is set alongside reports of methane releases from Arctic permafrost, lakes and ocean floor hydrates.) Especially when the down tick is set along side solar minimum and when 2008 showed the early stages of a cool phase of the basin-wide Pacific Decadal Oscillation.

    (With respect to temperature, we’re dealing with climate — average weather – and so it makes no sense to talk sbout short term “trends” because they’re the weather we have to average to talk meaningfully about climate. As I’ve said before, wiggles on an underlying trend.) The methane “spike” is not beyond the normal wiggles of the last 25 years. The last two times methane rose by more than 10ppb in a single year it was followed by a negative movement within 2 years. If you think OH has changed, it makes no sense to talk about single years that may be affected by natural events.

    My point is you apply two different forms of logic to methane data and temperature data. I am not saying we are DEFIANTLY cooling, only that your logic is unbalanced.

  22. And I am saying that the two things are different — different processes completely. There is no methane “climate” (average levels over thirty years), because it’s the effect now that matters…

    But as I said, we have to wait and see.

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