Full IPCC AR4 report now available

The complete WG1 IPCC 4th Assessment report (AR4) is now available online. It’s missing the index and some supplemental data, but all should be available by May 7.

Over the next few weeks we’ll try and go through the report chapter by chapter, but since this is likely to the key reference for a number of years, we can take a little time to do it properly. Happy reading!

205 comments on this post.
  1. Nancy Rutman:

    I apologize if this subject has been covered elsewhere on this site, but when it comes to mitigation of AGW, I think people minimize the importance of agriculture. According to David R. Montgomery in his book Soil: The Erosion of Civilizations, “No-till agriculture has the potential to increase the organic matter contect of the top few inches of soil by about 1 percent a decade. [O]ver twenty to thirty years that can add up to about 10 tons of carbon per acre. … A third of the total carbon dioxide buildup in the atmosphere since the industrial revolution has come not from fossil fuels but from degradation of soil organic matter. … If every farmer in the United States were to adopt no-till practices and plant cover crops, American agriculture could squirrel away as much as 300 million tons of carbon in the soil each year.” Montgomery estimates the carbon sequestration potential of the world’s cropland at 25 percent of the current carbon emissions.

    I find this news encouraging, and yet… Farmers are now in a race to produce crops for biofuels, and in the usual American fashion, are further degrading the soil to do so. The production of crops specifically to burn in our vehicles may in fact ADD carbon to the atmosphere by bringing more land under cultivation. Solution: End ag-fuel subsidies and increase soil-conservation (no-till, organic) subsidies.


  2. Thomas Lee Elifritz:

    American agriculture could

    We need to bioengineer a carbon to compost cycle. Any specific suggestions? It takes energy. There is only so much land and sunlight available. Plus you need other nutrients. Clearly reducing emissions and soil conservation and enhancement practices are the key.

  3. Adrianne:

    Re Burt & Hank: Being an open forum, I feel that everyone is free to sustain their beliefs. As you can see, I am very into the Naval War theory, as it explains various climatic events, such as Spitsbergen Big Warming, ald other climatic trends. I don’t agree to the IPCC report because it has other focus parts, together with climate: political, financial, etc. This is why it has faults. If it had been just climate-oriented, I am sure that it would look alot different.

    I am interested in debating the global warming issue, because it is one of the biggest problems that we are facing and I think everybody should care. I have found Bernaerts’ thesis on the internet and I followed the links from there, I read more and more on it and I find it logical for me to understand. I accept the fact that others have other opinions, I can also accept that maybe my opinion is not good, but I would like to see arguments that contradict me, as I am always open to a constructive debate.

  4. Lorenzo:

    The IPCC AR4 report has an FAQ aimed, I assume, at the educated reader who doesn’t necessarily have a science background.

    FAQ 10.3 says-
    “Stabilisation of CO2 emissions at current levels would result in a continuous increase of atmospheric CO2 over the 21st century and beyond,
    In fact, only in the case of essentially complete elimination of emissions can the atmospheric concentration of CO2 ultimately be stabilised at a constant level.”

    Is this true, or just badly written?

    The bulk of the IPCC report seems based on models are extrapolating forward the trajectory of temperatures where CO2 emmissions are stabilised at varying concentrations, such as 450ppm.

    My mind is led (as is, I suspect, the public mind)to the idea that if we reduce use of fossil fuels (as fossil fuels contribute ~75% of the CO2), it is possible to reach a dynamic equilibrium at (say) 450ppm.

    And there it will stay. Things are a bit warmer, bit sea level rise, but oh well, that was a close call!

    BUT the wording in the FAQ seems to say that unless ALL emmissions of CO2 are eliminated – no oil burnt, no gas burnt, no coal burnt – then it is literally impossible to stablilise CO2 levels. Impossible.

    That is, I assume, the ocean CO2 ‘sump’ is full, the ‘modern’ carbon cycle is roughly in balance, the earth can absorb no further fossil carbon. It is sated. Couldn’t take another atom. Not a crumb. And therefore every fossil carbon atom emitted from ~now on has ‘nowhere to go’, and is in effect cumulative in the atmosphere. With no way back out for millions of years (when phytoplankton may ultimately remove CO2 as they die and are buried deep in ocean sediment).

    The uneasy feeling that yes, this is exactly what the reported words mean is reinforced when the FAQ goes on to say:

    “All other cases of moderate CO2 emission reductions show increasing concentrations because of the characteristic exchange processes associated with the cycling of carbon in the climate system.

    More specifically, the rate of emission of CO2 currently greatly exceeds its rate of removal, and the slow and incomplete removal implies that small to moderate reductions in its emissions would not result in stabilisation of CO2 concentrations, but rather would only reduce the rate of its growth in coming decades.”

    Are they really saying that CO2 will accumulate in the atmosphere in (broadly speaking) direct proportion to the rate at which fossil fuels are burnt?

    What is the ‘conversion’ between x tonnes of emitted carbon (in coal, oil, gas)and an increase of 1 ppm in the atmosphere?

    We roughly know the tonnage coal, oil, and gas likely to be recoverd. It is very likely is will all, over human existance on earth (i.e. beyond 2100), be burnt.

    Is it not possible to therefore estimate the ultimate level of permanent atmospheric CO2 ppm once all available fossil fuel is burnt?

    I have tried to think how all fossil fuel use could be agreed to be left in the ground. By all nations. For all time. It is utterly impossible.

    If it it true that even 450ppm can only be “attained” if NO MORE fossil fuels are burnt, why bother to model the temperature trajectory and sea level consequences of an atmosphere with CO2 “stabilised” at 450ppm?

    Why not simply model the ppm rise with burning of available fuels, and THEN model thousands of years hence to the point of a stable hot climate, less land, more sea, and with no ice on earth?

    Surely that would be the truth. The idea that CO2 levels can be stabilised at all, given the structure of our society and in what volume we depend on coal and oil, is little more than a convenient fiction.

    I sincerely hope I have utterly misunderstood the true meaning of the sections of the report quoted!

    Thank you for your work and time,

  5. Barton Paul Levenson:

    [[What is the ‘conversion’ between x tonnes of emitted carbon (in coal, oil, gas)and an increase of 1 ppm in the atmosphere? ]]

    As I understand it, the sinks take up about half of human emissions. That’s about to change, though. There are signs the biggest sink — the upper ocean — is becoming saturated.