Only 10% of global carbon emissions come from tropical deforestation

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“How much carbon is emitted from tropical deforestation?” asks Daniel J. Zarin of the Climate and Land Use Alliance in the most recent issue of Science magazine. The answer may be considerably less than previously thought.

A study, also in Science, based on satellite data finds that emissions from deforestation account for 10% of global carbon emissions.

While greenhouse gas emissions continue to increase, the scientific estimates of how much tropical deforestation contributes to the total are falling. REDD, it seems, is becoming less relevant either as a mechanism to prevent the destruction of the tropical forests or as a means of addressing climate change. (Of course, as a carbon trading mechanism, REDD is in any case hopeless as a means of addressing climate change because carbon trading does not reduce emissions, it just moves them from one place to another.) This does not mean that addressing deforestation and climate change are not important. Both are important. They just happen to be less related to each other than previously thought.

The new study, which was funded by a World Bank grant to Winrock International, is is titled, “Baseline Map of Carbon Emissions from Deforestation in Tropical Regions”. The lead author of the research was Nancy Harris of Winrock International. Other members of the research team are from Applied GeoSolutions, NASA’s Jet Propulsion Laboratory, the University of California and the World Bank.

In 2007, the Intergovernmental Panel on Climate Change (IPCC) came up with a “best estimate” of net carbon emissions from tropical land use change in the 1990s of 1.6 ± 0.6 petagrams of carbon per year. That amounts to about 20% of greenhouse gas emissions from human activity during the 1990s. Harris et al. produced a figure of gross carbon emissions in the tropics of 0.81 petagrams of carbon per year (with a 90% prediction interval of 0.57 to 1.22) between 2000 and 2005. “This comprises 7 to 14% of total global anthropogenic CO2 emissions over the time period analyzed,” write Harris et al.. So that’s approximately half of the IPCC estimate.

The difference between net emissions and gross emissions is that net emissions include forest regrowth. Harris et al. note that,

[A] policy mechanism that proposes to compensate developing countries for reducing emissions from deforestation and forest degradation (REDD) will benefit from estimates of emissions from gross deforestation that are disaggregated from the forest regrowth term and that do not use a priori assumptions about the fate of vegetation carbon stocks after clearing.

The Winrock International team used satellite data rather than relying on the UN Food and Agriculture Organisation’s figures for deforestation. In a press release about the Science paper, one of the co-authors, Winrock’s Sandra Brown, points out that,

“It’s time to acknowledge the problems with the FAO data and accept that we can now do much better. We have the ability, at last, to match the areas of forest clearing with their carbon stocks before clearing in much greater detail, allowing us to pinpoint more precisely where the highest emissions are occurring.”

The change from using FAO data is certainly to be welcomed. The FAO is far from a neutral collector of data on the world’s forests. Among other problems, the FAO’s Global Forest Resources Assessment includes industrial tree plantations as forests (on planet FAO, monocultures are “planted forests“). And FAO doesn’t include logging as deforestation (on planet FAO, clearcuts are “temporarily unstocked areas”).

Harris et al. found that 55% of emissions from tropical deforestation between 2000 and 2005 came from Brazil and Indonesia. They produced a map that highlights where the most deforestation was taking place (click on the image for a larger version):

Nearly 40% of total forest loss between 2000 and 2005 in our study region was concentrated in the dry tropics, but these losses accounted for only 17% of total carbon emissions, reflecting the low carbon density of these forests compared with tropical moist forests. Emissions are high in the Brazilian Amazon, but other areas of high emissions include Peninsular Malaysia, Laos, Sarawak (Malaysia), and Sumatra and Kalimantan (Indonesia) in Southeast Asia and, to a lesser extent, the Congo Basin in Africa.

CLUA’s Dan Zarin points out that Harris et al. are not the only ones to have taken another look at emissions from tropical deforestation. In January 2012, a study by Alessandro Baccini and colleagues was published in Nature Climate Change. They came up with a figure of 2.22 petagrams of carbon per year. Zarin notes drily that the difference is “cause for concern in climate policy circles”. He suggests that,

it would benefit both the science and policy communities if the two research groups could determine the reasons for the 1.41 Pg C year−1 difference in their results soon, and do so with sufficient transparency for others to evaluate.

True, that would probably benefit the science and policy communities. But there are at least two other important observations to be made. First, measuring emissions from deforestation is complex and it’s going to be a while before we can do so accurately on this sort of scale. Harris el al. point out that, “emissions from land-use change … are the most uncertain component of the global carbon cycle”. Second, as a percentage of global carbon emissions, tropical deforestation emissions are decreasing because emissions from fossil fuels are increasing rapidly, while emissions from deforestation remain comparatively steady. We need to reduce deforestation urgently. But let’s not pretend that doing so is going to stop runaway climate change. If we are serious about addressing climate change we need to reduce emissions from burning fossil fuels.


UPDATE – 28 June 2012: Daniel Zarin contacted REDD-Monitor requesting that the following “factual clarifications” be provided:

  • The Harris et al. (2012)* estimate of 0.81 petagrams of carbon emissions per year from tropical deforestation (equivalent to 3 gigatonnes of CO2 emissions per year) does not include peatland conversion, which would add at least an additional gigatonne of CO2 emissions per year to the estimate.
  • Emissions from forest degradation (the second “D” in REDD) are also not included and are likely to be significant.
  • Differences in recent estimates of emissions from deforestation referenced in my essay and cited in your post (Baccini et al 2012**; Harris et al. 2012*) are not because “measuring emissions from deforestation is complex” as stated in your post, but rather because they use different methodologies and definitions. Unpacking and explaining those differences should not take long for these talented scientists to do, and would provide a clearer understanding of what the numbers mean and how they relate to REDD+ policymaking, particularly the setting of reference levels.
  • *N.L. Harris et al., Science 336:1573 (2012)
    **A. Baccini et al., Nat. Clim. Change 2:182 (2012)

 

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10 Comments

  1. Your commentator has interesting comments…these are additional ones to address fundamentally.

    * Runaway fossil fuel usage particularly by the newly emerging G8 nations is particularly relevant; this will only reinforce Scheer’s analysis of the economic extinction of such a resource within the lifetime of our children! Irrespective of the sham declared by the FF Brigadiers!
    * Many in the green economic arena of study are horrified at the direction that all deforestation and carbon emissions from the “sunset” logging industry and burning of vegetation is centred on the tropical realms only. Whilst this has some truth and very relevant there are large gaps in our knowledge to identify how much carbon in the tropical realms are actually sources for carbon (and of course other carbohydrate compounds). Seeking to identify forests…one has only to examine what hierarchical level of definition of how we determine “forests”; (cf FAO/World Bank/UNEP/WCMC et al). Are we doing this through the science of ecology or as a growing crop for the gluttony of G20 nations? Here the difficulty begins. Forests by succession are the only vegetations types in over 90% of the tropical realms.
    * Often misleading and being mislead are the areas of the tropical realms such as peatland/wetland forests which contain vast sources of carbon both here and temperate realms too. The amount of carbon sourced is still under investigation; but it has been postulated that this is many factors above direct deforestation and degradation within humid forest regions. And global warming in northern and southern Siberia too is having a vast carbon sourcing effect.
    * So called Dry Forests (a vague ecological term) again are misrepresented. These are the forests where human alienation and impact are often (the African continent in particular) of much greater importance than is currently recognised; even though sources are lower per hectare may be lower quantifiably, the distribution of and disturbance is much higher. Therefore as sources of carbon et al compounds, again we have to be very careful at interpreting data of actual carbon sources released globally into the atmosphere. To suggest that areas here are reducing is a gross misunderstanding of the socio-ecological-economic realities which occur. Especially from your enclosed diagrams those forests which do occur in Australia have suddenly vanished, which would have injected a source of carbon so high we can understand why Australia is being ravaged by such regional weather calamities!
    * Quantities of carbon et al compounds released. Official levels of deforestation and degradation vary depending on one’s references. Satellite photography at resolutions down to 150 meters would provide some evidence and monitoring the levels of carbon as carbon dioxide and methane (et al) would help resolve this but again it depends on whether or not there is the political will for this. In an official manner the Government of Indonesia and its so called monitorium on logging in new areas of concession is one of the only governments to make such applauded proclamation. But not surprising as it is in the global top five of nations as carbon et al sources! Guyana has made such proclamations as long as bilateral support can be and quite correctly so, supported, in this case by the UK Government into promoting negative deforestation. Time (what is left of this) will only tell….but
    *What the reality becomes depends on the support the G8 nations provide not only in REDD Plus finances but local community and biodiversity fillips as indicated by UNEP’s, IPBES.
    * In temperate realms, we understand that in alienated realms that carbon sources and sinks may be in balance. This again has to be examined much more closely; not only in highly alienated realms of Europe, but those the temperate Americas and the temperate and boreal Americas and Russian Federation where rampant deforestation is occurring in areas of central and eastern Siberian and the Pacific Ring areas; fires in Western N.America and in the eastern rocky realms too are often under-reported and researched. As your commentator has made mention we need much more investigation into this science on a global level before making pronouncements of decreasing carbon sources from deforestation. Indeed it is the G8 and its G20 associates in many non tropical realm nations which are the cause for the so called sunset products of deforestation in the first place.
    *It is our addiction to consumption, our increasing human population all wishing to consume as G8 nation citizens and using destructive technology to accomplish such acts. Added to which are the totally inappropriate irresponsibility of governments to promote such consumption when their advisors, many green economists have for over a decade advised them to redirect their economic policies to development and not even “growth”
    *There is only “one larder”, our biosphere. Every day the natural capital it contains is diminishing. Growing consumption will not alter this fundamental reality. Whether deforestation is 10% (highly unlikely) as a source of carbon et al compounds or nearer 40% (more scientifically realistically on a global survey)…they are only symptoms of a reality we have to address….and do so quickly in a manner unrelated to the recent debacle at Rio 20 plus!

  2. Thanks for sharing this article. I assume this study might legitimize that REDD+ would not happen. Is that right? I might be wrong.

  3. Presumably, because the emissions from industrial sources have continued to grow rapidly since 2005, whilst the emissions from deforestation have remained stable or possibly declined (due to reductions in burning in the Amazon, if nowhere else), then the CURRENT proportion of total emissions from deforestation is even lower than 10%?

    Does anyone have that figure?

  4. @TreeFellas (#3) – I think you’re right. Guido van der Werf and colleagues made this point in their 2009 paper. A graph from their paper illustrates the point:

    The estimates of carbon emissions from deforestation are the various (more or less horizontal) lines at the bottom of the graph. The red line represents emissions from fossil fuel. Every year, the proportion of emissions from deforestation gets smaller. Obviously, this is not good news.

    Harris et al. are now looking at the satellite data for the period 2006-2010. For the sake of argument, let’s assume that emissions from deforestation remained at 0.81 billion tonnes carbon per year (I don’t know whether or not this is a reasonable assumption).

    According to the US Energy Information Administration, emissions from energy consumption in 2010 were 31.8 billion tonnes CO2. To convert from CO2 to carbon we have to multiply by the ratio of molecular weights 12/44. (CO2 is heavier than carbon, because of the attached oxygen atoms.) This gives a figure of 8.67 billion tonnes of carbon emissions from energy consumption in 2010.

    Based on the assumption that emissions from deforestation remain steady, in 2010 deforestation would be 9.34% of emissions from energy consumption.

    If anyone has more accurate figures for emissions from deforestation in 2010, please let me know!

  5. A few hours after I made this post, Dan Zarin from CLUA got in touch, requesting that I post some “factual clarifications”. I’ve added these as an update to the post. I’d like to thank Zarin for his comments. I agree with all three of them, but I think there’s more to say about each of them. Zarin makes three points summarised in bold, followed by my comments:

    1. Harris et al. exclude emissions from peat conversion.
    Yes, peat emissions are excluded, but it’s worth quoting what Harris et al. say about emissions from peat in their paper:

    Peat emissions are excluded from most estimates of emissions from land-use change (4–7, 9–12), although peat drainage and burning in Southeast Asia have been shown to contribute a substantial portion of carbon emissions in past decades (22). Emissions from peat fire (23) and peat drainage (24) add another 0.099 and 0.173 Pg C yr−1, respectively, which increases our total emissions estimate by approximately 25% but keeps the estimate within the uncertainty bounds of our analysis (Fig. 1).

    4. R. A. Houghton et al., Ecol. Monogr. 53, 235 (1983).
    5. R. A. Houghton et al., Nature 316, 617 (1985).
    6. R. A. Houghton, Tellus 51B, 298 (1999).
    7. R. A. Houghton, Tellus 55B, 378 (2003).

    9. R. S. DeFries et al., Proc. Natl. Acad. Sci. U.S.A. 99, 14256 (2002).
    10. F. Achard, H. D. Eva, P. Mayaux, H.-J. Stibig, A. Belward, Global Biogeochem. Cycles 18, GB2008 (2004).
    11. Y. Pan et al., Science 333, 988 (2011).
    12. A. Baccini et al., Nature Clim. Change 2, 182 (2012).

    22. S. E. Page et al., Nature 420, 61 (2002).
    23. G. R. van der Werf et al., Proc. Natl. Acad. Sci. U.S.A. 105, 20350 (2008).
    24. 24. A. Hooijer et al., Biogeosciences 7, 1505 (2010).

    2. Harris et al. omit emissions from degradation.
    True. In fact the word “degradation” occurs only once in the paper and there is no discussion about emissions from degradation. Zarin is probably correct to say that emissions from degradation are “likely to be significant”. But has the definition of forest degradation been agreed at the UNFCCC level? As far as I’m aware, it hasn’t.

    The FAO uses the following definition: “the reduction of the capacity of a forest to provide goods and services”. In November 2011, the Collaborative Partnership on Forests put out a report titled, “Assessing forest degradation: towards the development of globally applicable guidelines”. This is work in progress. Measuring emissions from forest degradation on a global scale to a meaningful degree of accuracy is still a long way off.

    3. Differences in estimates of emissions from deforestation are not because measuring is complex, but because different methods and definitions are used.
    Again, I agree, but I think that the complexity of measuring emissions from deforestation includes the difficulty of agreeing methods and definitions. Zarin’s first two points illustrate part of this complexity. I agree with Zarin that “Unpacking and explaining those differences should not take long for these talented scientists to do.”

    Incidentally, mongabay.com produced an illustration showing that it’s not only Harris et al. and Baccini et al. that need to reach agreement:

    But once the scientists have reached agreement, that’s where the fun starts. At that point, the UNFCCC has to agree with the scientists. That may or may not be a straightforward, non-political, technical process carried out with good will on all sides. Based on what we’ve seen so far at the UNFCCC, I’m not holding my breath.

  6. Thanks for all of you as above who have made a tremendous input into the original argument and my response which in the main has either been agreed upon or the continued dispute has been about statistical variations and not necessarily the science. Even though I feel that Pan et al (2011) above is nearer to the reality than the other researchers based upon arguments I made in my original input recently.

    In my wildest hopes and I feel we would all like to realise that ONLY 810 mtonnes of carbon is sourced by “deforestation”, which is global; the reforestation which occurs in non tropical realms is as much harmful as it is in the tropical realm to biodiversity sustainability to maintain the norms in evolution. Natural succession to all natural forests within their associations/biotypes and biomes is far more ecologically productive than “man made reforestation”. Innumerable references across the litany of biodiversity ecology will establish this reality. The subsequent interactions on ecological and ecosystems associated strategies on sinks for carbon based compounds cannot and fundamentally will not be totally understood…there are two many gene-ecological interaction to accurately assess their affect on biodiversity-ecological dynamics let alone affects on micro-regional nor global climate. We have only “statistical analysis” again to associate this with climate change, noble as this is. So back to the original dilemma, but a rational has be added to ensure an understanding of aspects of statistics.

    Are some of us suggesting that in reality global deforestation and degradation is reducing due to our understanding of the nature of forests and deforestation? Again we have to look globally and not just within the humid tropical realm. With respect no response was made to this. Maybe because readers on this site only relate to the remit within the guidelines of where REDD operates. This is both misleading and scientific folly. This I found out when providing attention to a junior researcher at the University in Oxford who on gaining their MSc in Forest Management and working with the World Bank attempted to inform me that the area located in the vicinity of Ayres Rock in central Australia was an area of closed sub-moist forest. As you will realise her lack of understanding is one reason why many such inaccuracies are made in such profound ways to others who attended her REDD seminar at Mansfield College.

    My aim in my original response was to bring to the attention of those who are not that experienced in global ecological systems is that you cannot take a programme such as REDD and localise its promotion when effective measures by humanity which are in the main destructive to the viable function of the biosphere are being addressed in ways which do not respond to the greater need for our commonwealth. We are on this site to save the forests of our world because they have an innate right to exist as a function of their own biodiversity and to maintain the process of evolution. The fact that they are useful to humanity at times of our current global warming emergency can only strengthen our resolve to enquire to more deeper levels of investigation on their perpetuity as biome systems. With respect this has to be addressed at a higher philosophical level in relationship to any progress which may or may not have been achieved in lowering deforestation and degradation, which to all intents and purposes from a scientific viewpoint, globally, is not reducing as I did make mention why in my first letter earlier this week.

    By the way, the simplest method of converting C02 to C is to multiply the former by 27.272% and you arrive at the latters quantity!

    Thank you for your attention.

    Nigel Miles
    Green Economic Institute/UN-IPBES.

  7. There was an article in the Washington Post last week about this study: “The mystery of tropical deforestation — in two maps”. Here’s the conclusion:

    So why does any of this matter? It’s not terribly important for our understanding of global warming per se — climate scientists are able to measure the increase in carbon dioxide in the air directly, at observatories like the one in Mauna Loa, even if it’s not clear whether 10 percent or 20 percent is coming from deforestation.

    But it is important for climate policy. Currently, the U.N. is trying to set up various programs to reduce deforestation, under which wealthier nations would pay tropical countries such as Brazil or Indonesia or Congo to protect their forests. In theory, this could prove one of the cheaper ways for the world to reduce carbon emissions (though it won’t be simple). But the program won’t work as well unless scientists can create an accurate picture of where deforestation is actually occurring — and has a solid baseline to measure progress.

  8. Thanks for this Chris. The % figures cannot be accurately measured as is mentiond in the conclusion of the Post’s article, but it is possible to gain an understanding globally about “deforestation and degradation” when forested landscapes are altered.

    One aspect of my initiative I will eventually promote for the IPBES is the factor of restoration and revival. Purest may mock such actions but realists understand that an evolved understanding of forest succession can be an valuable tool in assessing and promotinig strategies for natural forest succession, and an integration with aspects of choice acheivable sustainable development. UNEP and the WCMC suggest that up to 900 million hectares are available for restoration. This is a huge area where both natural forests and development can be promoted and it as such this should be promoted globally with the support of IPBES.

    Best regards

  9. without those trees. humans wont be able to breathe…..so the cut down the rainforest and replant if with other species of trees not usuauly native to that undergrowth epiphites tubers etc nematodes.. all these are required for our ecology.. There should be a ban on logging natural forests worldwide . stick to logging the forests that are man made which have been prepared for logging.. personally i hope some natives grab those carbon cowboys n toss them in the river for the crocodiles to feed on..not all trees breath in carbon dioxide.. many breathe in oxygen .. the trees can survive without us/ humans.. transferance mainly occurs when teh temperatures are low.. so be careful.. when the temperatures get too high.. then you;ll all be needed help to breathe

  10. those peat emissions… perhaps somebody also might like to paay attention to the permafrost in alaka/canada area.. when the ice melts.. more methane let into the skies above. another thing is that the gas fracking also lets out tremendous amounts of methane into the water supply and eaths atmosphere… lets not mention gas fracking..

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