Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.

Settings

Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup

Settings


All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Home Arguments Software Resources Comments The Consensus Project Translations About Donate

Twitter Facebook YouTube Pinterest

RSS Posts RSS Comments Email Subscribe


Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...



Username
Password
Keep me logged in
New? Register here
Forgot your password?

Latest Posts

Archives

Ridley, Murdoch, and Lomborg Attempt to Greenwash Global Warming

Posted on 16 January 2013 by dana1981

Matt Ridley is a businessman, chairman of a failed bank, and science writer who frequently publishes climate contrarian articles in the mainstream media (e.g. see here and here and here  for our previous debunkings of his writings).  His latest foray is an article in the Wall Street Journal, which has a long record of publishing nonsense from climate contrarians (e.g. see here and here and here).

This time around, Ridley's article is factually accurate.  Really there's not much to it - Ridley simply discusses data showing that the planet has become 'greener' over the past few decades as vegetation has increased globally, on average.  You might ask, "so what?".  After all, we're not very concerned about current temperatures and climate change; we're concerned about the global warming yet to come and associated impacts on the climate, including more extreme weather, ocean acidification, sea level rise, species extinctions, etc. 

If plant growth continues to increase, that could be one positive outcome of global warming (depending on what types of plant life thrive), but does the scientific research indicate this will happen?  Unfortunately, Ridley leaves this critical question unanswered, and thus his audience might assume that the correlation between warming and increased vegetation will continue.  Indeed, that appears to be Rupert Murdoch's conclusion from Ridley's article.  On the contrary, as we will see below, continued reliance on fossil fuels will make conditions difficult for global vegetation, and for the rest of the world's ecosystems.

"Greening" Research is a Mixed Bag

Net Primary Production (NPP) is essentially a measurement of plant growth.  Figure 1 shows the results from three studies which sought to measure changes in NPP.

npp

Figure 1: Net primary production change measurements (in petagrams [1015 grams] of carbon per year) from Nemani et al. 2003 (blue), Zhao and Running 2010 (red), and Potter et al. 2012 (green).

As you can see, according to Nemani et al. 2003, global plant growth rose from the early 1980s to the late 1990s.  Zhao and Running 2010 picked up where Nemani left off, and found that this trend had not continued into the 21st century.  According to their estimates, global plant growth had declined, or at the very least the increase had slowedPotter et al. 2012 examined the data and did find an increasing trend from 2000 to 2009, but at a slower rate than the prior two decades.

The Potter results are also consistent with the research that Ridley references in his article (de Jong et al. 2012).  Rather than examining net primary production, de Jong et al. uses the Normalized Difference Vegetation Index (NDVI), which measures plant growth by using satellites to look at the near-infrared part of the light spectrum, where healthy vegetation is very reflective.  Their results showing the net change in NDVI from 1982 to 2008 are illustrated in Figure 2, with green representing a greening, and brown representing a browning.

deJong

Figure 2: Global greening and browning in terms of normalized difference vegetation index changes between 1982 and 2008, from de Jong et al. 2012

The de Jong research finds less overall greening in the southern hemisphere (SH) than the northern hemisphere (NH), which is similar to the Zhao and Potter results, both of which find a decrease in SH plant growth from 2000 to 2009.  Zhao and Running connect this decline to an increase in drought activity.

"Over the past 10 years, large-scale periodic regional droughts and a general drying trend over the SH reduced global terrestrial NPP. Under a changing climate, severe regional droughts have become more frequent, a trend expected to continue for the foreseeable future"

They find a very strong correlation between droughts in the southern hemisphere and decreased plant growth.  This is also consistent with the results of Choat et al. 2012, who find that forests worldwide are becoming increasingly vulnerable to drought.

"We show that 70% of 226 forest species from 81 sites worldwide operate with narrow hydraulic safety margins against injurious levels of drought stress and therefore potentially face long-term reductions in productivity and survival if temperature and aridity increase as predicted for many regions across the globe....These findings provide insight into why drought-induced forest decline is occurring not only in arid regions but also in wet forests not normally considered at drought risk."

Plants Need More than CO2 to Grow

Ultimately Ridley and Murdoch's comments harken back to the oversimplified argument that CO2 is plant food.  Bjorn Lomborg joined this party in an article published by Slate, arguing that CO2 fertilization will increase wheat crop yields.

It's true that when all else is held relatively constant, for example in a greenhouse, adding CO2 to the environment tends to increase plant growth.  However, when we add more CO2 to the atmosphere, it changes the climate.  More extreme weather results, like heat waves, bush fires, droughts, and floods - conditions which are obviously not favorable to plant growth.  And as John Mason recently noted,

"A key constraint of the carbon fertilization effect on the ground (and not in the controlled conditions of a greenhouse or laboratory) is that it would be operating in situations where other variables, essential to plant growth, may not play ball. It's a long list when one includes all the various minerals and trace-elements but key factors are major nutrients such as phosphorus, potassium, nitrogen and so on. CO2 is plant-food but so are these elements and they are essential, as any serious vegetable-grower will tell you."

A new paper in press, Hawkins et al. (2012) examined maize yields in France and found that improved agricultural technology has increased crop yields, but hotter temperatures are taking a toll, and the increase has begun to slow (Figure 3).

"A significant reduction in maize yield is found for each day with a maximum temperature above 32°C, in broad agreement with previous estimates.  The recent increase in such hot days has likely contributed to the observed yield stagnation....We conclude that, to offset the projected increased daily maximum temperatures over France, improved technology will need to increase base level yields by 12% to be confident about maintaining current levels of yield for the period 2016-2035; the current rate of yield technology increase is not sufficient to meet this target."

Hawkins Fig 1c

Figure 3: French maize yields from FAOSTAT (black points) and empirical model predictions for the technology trend (grey shading) and expected yield (red shading) with total uncertainties (red lines), considering both temperature and precipitation.  The black error bar indicates the forecast for 2011, assuming a flat technology trend since 2010.  For the 2016-2035 periods, the boxes show the 25th-75th percentiles and the whiskers indicate the 5th and 95th percentiles.  The yield projections assume a flat technology trend and are shown for both climatological precipitation (left) and precipitation constrained by historical correlations between temperature and precipitation (right).

In particular, note the low maize yield in 2003, associated with the major heat wave that summer.  The projections for 2016—2035 in blue and red demonstrate that climate change is anticipated to decrease crop yields unless technological improvements can offset the effects of increased heat.  Hawkins has also noted that technological improvements have played a much larger role than CO2 fertilization in increasing yields in crops like maize.

Gornall et al. (2010) also examined how climate change will impact agricultural production in the near future, and found that we cannot yet answer the question - it is more complex than Lomborg suggests.

"Perhaps most seriously, there is high uncertainty in the extent to which the direct effects of CO2 rise on plant physiology will interact with climate change in affecting productivity. At present, the aggregate impacts of climate change on global-scale agricultural productivity cannot be reliably quantified."

For those who want more gory details about why 'CO2 is plant food' is a gross oversimplification, we've got you covered.  And we'll have a more detailed post about CO2 plant fertilization research in the near future.

Burning Fossil Fuels Has Many Negative Consequences

Rupert Murdoch also asked why we don't "switch from useless renewable energy investments".  The answer is that continuing to rely on fossil fuels will increase the incidence of heat waves (which Australians are currently experiencing at record levels), ocean acidification, expansion of the subtropical dry zones, exacerbated flooding and drought, mass coral bleaching, the decline of the Great Barrier Reef, further sea level rise, wide-scale species extinctions, etc.  The overall consequences of continuing to rely on fossil fuels will be very bad, regardless of how plant productivity changes.

Greenwashing a Harsh Reality

Ridley, Murdoch, and Lomborg attempt to gloss over this harsh reality by focusing on one consequence of global warming which has so far been a positive one.  Ridley has developed a reputation for this sort of unfounded optimism, always assuming the best case scenario, never preparing for the worst.  This appears to be his approach when it comes to the impact of climate change on plant growth as well.  He only looks at the data which paints a rosy (or in this case, green) picture, and ignores the rest. 

This leaves people like Rupert Murdoch, who desperately want human-caused climate change to be a non-issue and to maintain the status-quo, to assume that the greening trend and increase in crop yields over the past few decades will continue.  In reality, this trend may already be reversing, and the impacts of climate change like droughts and heat waves will not bode well for plant growth in the future.  This greenwashed view also ignores the many other negative impacts of climate change, from ocean acidification to sea level rise to species extinctions.

CO2 may be plant food, but irrational optimism is not.  If we want plant life to continue thriving, we have to do better than ignoring inconvenient science; we have to take steps to stop human-caused climate change and its harsh impacts.

0 0

Bookmark and Share Printable Version  |  Link to this page | Repost this Article Repost This

Comments

Comments 1 to 33:

  1. Ridley is "always assuming the best case scenario, never preparing for the worst."

    Which is why he totally screwed up his bank. Northern Rock was once a fine building society until it became a bank and under Ridley's leadership was then the first to crash when the financial meltdown came along. [This is all referenced in the second link in the article.]

    Note the excuse Ridley made to the Parliamentary inquiry when explaining why his bank went down; "we were subject to a completely unpredicted and unpredictable closing of the world credit markets." Doesn't that say so much about his denial mindset? I can just hear him now using similar words, when he's called to account for denying the changing of the world's climate (well, one can dream, can't one?).
    0 0
  2. John Russell @1 - indeed, failing to account for any but the best possible scenario seems to be a constant problem for Ridley in many different areas. Maybe we'll get lucky - maybe climate sensitivity is on the low end of possible values, maybe the greening trend will continue in the future, etc. But banking (pun intended) on that best case scenario is a fundamental risk management failure. If any but the very best case scenario comes to fruition and we fail to do anything about it, we're in big trouble. Which seems to be basically what happened to Ridley's bank, which probably isn't a coincidence.
    0 0
  3. World is growing greener with CO2? Was it not green enough before?
    0 0
  4. I disagree that Murdoch wants GW to be a non-issue. The topic is an emotional one which sells news. He loves to keep the pot well stirred.
    0 0
  5. An important principle in Agricultural science is Liebig's 'Law of the Minimum'. Essentially that a plant's growth is limited by whichever resource is most restricted. So adding any resource (CO2, Potassium, whatever) may not do much if that resource isn't the limiting factor for that plant.

    So knowing how plants will react in the future is nowhere near as simple as the 'CO2 is Plant Food' meme suggests
    0 0
  6. A correction about Bjorn Lomborg: He's not an economist. His own website says he majored and later a Ph.D. in Political Science.

    Sometimes he's described as a "statician". Not sure how accurate this is.
    0 0
  7. With my serious veg grower head on I was going to comment on different response in C4/C3 plants, increased predation, weeds and nutrition, but I see you have indeed 'got it covered' in the 'gory details' with lots of other interesting stuff I didn't think of ;)

    So if co2 is plant food, can I live on pure sugar? I have tried...
    0 0
  8. Their results showing the net change in NDVI from 1982 to 2008 are illustrated in Figure 2, with green representing a greening, and brown representing a browning
    Oh, these science boffins! Why can't they make these graphics simpler for the rest of us to understand? [/sarc]
    0 0
  9. Regarding Ridley's selective vision and excuse to Parliament, it has for centuries been a financial maxim that to borrow short and lend long is a sure road to bankruptcy. It's not credible that nobody ever pointed this out to Ridley, but he either could not hear or he regaled them with the "new economic paradigm" which comes with every asset bubble, in which old unwelcome maxims no longer applied. What's more the bank was lending long on 125% mortgages, on the understanding that the asset value would inevitably rise (thanks to the new economic paradigm) to fill the gap. None of this was unprecented by a very long way.

    Ridley is a (-snip-), pure and simple.
    0 0
    Moderator Response: [DB] Inflammatory snipped.
  10. We might also mention that plants' reproductive cycles are tuned to a stable or slowly changing climate. With rapidly warming conditions, plants' reproductive mechanisms may not be set in motion--or be set in motion at the wrong time, unable to take advantage of various pollination mechanisms.

    http://news.nationalgeographic.com/news/2013/01/130116-spring-earlier-global-warming-plants-trees-blooming-science/
    0 0
  11. (-Off topic snipped-).
    0 0
    Moderator Response: [DB] Your comment pertains to extreme weather events. As such, it was snipped as off-topic. Please follow up to JasonB's reply to you on the other, more appropriate thread.
  12. Clyde @11 - who are you talking to?
    0 0
  13. Great article! And it may help to understand a strange myth I recently read in a comment at "Klimalounge" [S. Rahmstorfs Blog] and which is not on the myth list. The myth goes like this: "Take that, warmistas! Sahara is getting greener!" and though not explained by the commenter ["Seifert"] it probably means: 1. poorer countries do profit from "good" CO2, 2. models do not predict that (so, models are wrong/bad/evil...). Rahmstorf itself did not pick that up in his explanations and rightly so, I think, because this must be something especially weird.

    Is this WSJ "greening" the root for myths like that? Is that something new within the denialsphere?
    0 0
  14. Clyde: Response posted on a more appropriate thread.
    0 0
  15. Why do you consider increased plant growth to be a positive outcome of global warming? That is a value judgement. Increased plant growth changes ecosystems. For example: According to the latest published results from the satellite based NDVI (Normalized Difference Vegetation Index) instrument, the biomass of the tundra has increased by 20% over the last 30 years. If this continues, large parts of the tundra and alpine ecosystems, including their biodiversity as we know them today, will disappear in a few decades.
    0 0
  16. LRG @7

    " can I live on pure sugar?". Yep,no problem. How long were you planning on living? That's a bit harder.

    Moving on to C3 vs C4. Research programs to try and transpose the C4 gene complex into C3 plants is one of those Big Ideas out there. Big because it isn't about transferring a single gene. Rather an intricate complex of gene's neededto produce the entire architecture of C4.

    Not a small under-taking. RADICALLY not a small under-taking. But a huge pay-off if it can be done.

    Similarly efforts to transfer the capacity for Nitrogen Fixation into other plants. A Doddle surely. Just all the genes needed to provide/support a complete life-support system for a symbiotic organism. No Problemo

    So both really hard. But the pay-off is massive.
    0 0
  17. Lomborg is a more refined denier. He even denies that he denied anything.

    He does not say "global warming is a hoax". He says science is often right, progressing, but you know, CO2 is plant food, and sea level stopped rising, and poor countries rely on fossil fuels to develop themselves, and so on. An articulate obstructionist and public misinformer, this one.

    If you pay enough attention, you can spot the usual bottomline: whatever you do, don't touch the market of fossil fuels.
    0 0
  18. Alexandre@17, you are correct: Lomborg is as tricky and slippery as denialati (lukewarmistas??) come. Howard Friel's book, "The Lomborg Deception," deftly, if not simply, takes apart Lomborg's suppostions better than any other source I've found.
    0 0
  19. A quote, from The New Phytologist, addresses this:

    "Results for predictions of the effects of elevated [CO2] on
    primary production are more mixed, but are generally less
    than a 20% increase in NPP based on the β-factor approach.
    The results from FACE sites suggest that a single β is not
    feasible, at least for global predictive purposes, given differences
    among ecosystems types and differences in plant responses to
    elevated [CO2] in combination with other environmental
    parameters such as water and N availability."

    Google the title below, to find the article: many, *many* other FACE experiments support this finding.

    Functional responses of plants to
    elevated atmospheric CO2 - do
    photosynthetic and productivity data
    from FACE experiments support early
    predictions?
    0 0
  20. Cugel #9,

    You are right. The most dangerous words ever spoken are "This time it's different".

    From a dot.com boom refugee. :)
    0 0
  21. ajki @13 - thanks. I think the 'greening' myth has been around for a while, probably since the Nemani (2003) NPP research.

    prestrud @15 - good point, greening isn't necessarily beneficial, depending on where it happens. Arctic greening will change that ecosystem, but will also add to overall global greening. As the post notes, it's just not nearly as simple as Ridley/Murdoch/Lomborg are trying to make it.
    0 0
  22. A plant is eventually eaten by an animal where its carbon is metabolized to carbon dioxide or else it dies and rots producing methane and organic compounds which get moved into the next generation of plants. Presumably the only thing that really matters then for climate change is if the total global biomass changes since its only while the carbon is locked in living matter that it is out of the atmosphere.
    I can't imagine a hectare of grass contains more carbon than a hectare of rainforest and given the scale of deforestation and desertification over the same period we've been burning our way through our fossil fuels I would have thought that that huge biomass loss would far outstrip any changes in food crop yields.
    What is the research on total global biomass as relates to climate change?
    0 0
  23. prestrud @ 15 - I agree, greening is not necessary a good thing as far as nature is concerned. At the risk of straying into the philosophical, we are not so much concerned with the optimum conditions for life in the most general sense as with the conditions that specific life forms have evolved to live in.

    For example, a desert is a much harsher environment for life in general than a rainforest, but "green" a desert to rainforest conditions and most of its unique plants and animals would surely perish. Would that be a good thing?

    I am reminded of many of the rarest plants of the British Isles that grow on nutrient-poor grasslands: apply artificial fertilisers and instead of flourishing, the rare wildflowers are rapidly out-competed by common, vigorous-growing plants usually thought of as weeds such as coarse grasses, nettles and thistles.
    0 0
  24. jhoyland @22, the total carbon flux from the biosphere due to the direct activities of humans was estimated by Houghton 2005 (revised) as follows:

    "The estimated global total net flux of carbon from changes in land use increased from 500.6 Tg C (1 teragram = 1012 gram) in 1850 to a maximum of 1712.5 Tg C (or 1.7 Pg C, where 1 petagram = 1015 gram) in 1991, then declined to 1409.9 Tg C (1.4 Pg C) in 2000, and rose slightly to 1467.3 Tg C (or 1.46 Pg C) in 2005. The global net flux during the period 1850-2000 was 148.6 Pg C, about 55% of which was from the tropics. During the period 1990-2005, the greatest regional flux was from South and Central America (11.3 Pg C).
    The global total flux averaged 1.5 Pg C yr-1 during the 1980s and 1.56 Pg C yr-1 during the 1990s (but generally declining during that latter decade), dominated by fluxes from tropical deforestation. The global total flux averaged 1.47 Pg C yr-1 during the period from 2000-2005."


    To put that into perspective, one Petagram (Pg = 10^15 grammes) is one billion metric ton, and the equivalent of 0.47 ppmv.

    As it happens, annual emissions from LUC do not drop below the (smoothed) annual atmospheric increase until the 1950s. In recent decades, however, studies in the difference between oxygen depletion and CO2 accumulation have shown that the biosphere is a net sink of carbon (See diagram below). That means total CO2 absorption be regrowth of forests in North America and the old world combined with increased agricultural activity, increased water supply and the CO2 fertilization effect have generated more biomass than deforestation in third world nations has depleted.

    0 0
  25. Did I miss the bit were we found out how much of this greening is actually due to CO2? Rather than changes in land use eg tree planting in uk, Sahel, abandoned farmland in Russia (looking very green there - I hear chernobyl is really beautiful now) etc?
    And what about mycorrhiza? Increases in fungal networks through temp rises (until it gets too hot) surely lead to faster growth of their plants?
    And temp itself in cold places, longer growing season very evident here in uk.
    How do we unpick these?
    0 0
  26. Tom @24. I'm a bit confused - you say the biosphere is a net sink but reading the graphs in Houghton article it looks to me like the flux is positive (carbon to the atmosphere). Am I missing something?
    0 0
  27. jhoyland @26, the Houghton figures are for direct human effects on the biosphere alone. Those include deforestation, reforestation, and agricultural practices. They do not include indirect effects such as CO2 fertilization, increased growth due to increased sunshine, or water etc. Consequently there is no contradiction between Houghton, which shows the net direct human impact on the biosphere is a carbon source, and the O2 data which shows that despite that, net natural and indirect human factors draws down more CO2 from the atmosphere than direct human impacts cause in emissions.
    0 0
  28. I wondered if there might be a connection between temperature and plant growth (greening). So, I went to woodfortrees.org and generated the below graph. I am not skilled enough with graphics to do an overlay, but this looks close enough to make one wonder if there is a link. But, then we would get into the correlation/causation dialogue.


    Image from www.woodfortrees.org

    0 0
    Moderator Response: [RH] Can I ask you to please insert into your links this bit of html: width="500" If you do this it will keep your images from breaking the page formatting.
  29. Terranova - yes, that's correlation, not causation. As noted in the post, Zhao and Running made a convincing case that the causation has more to do with increasing drought.
    0 0
  30. Terranova: You are certainly thinking along the right lines. There is a long literature on the relationship between El Nino and/or temperature and CO2 uptake, e.g. Barcastow 1976. The rate of CO2 change in the atmosphere lags the temperature change, showing that temperature or El Nino are driving the effect.

    This has fooled some skeptics who haven't read this literature (e.g. Humlum) into thinking that temperature is causing CO2 emission, when in fact the emissions have been more steady and the rate of uptake has varied.
    0 0
  31. Excellent article with a lot of good references to follow up on. I'm also looking forward to the follow-up article on carbon fertilization.

    I finally read the Ridley article about which I have a question. He says:

    Dr. Myneni reckons that it is now possible to distinguish between these two effects in the satellite data, and he concludes that 50% is due to "relaxation of climate constraints," i.e., warming or rainfall, and roughly 50% is due to carbon dioxide fertilization itself.

    I noticed that '50% is due to carbon dioxide fertilization' is not a direct quote from Myneni. I was wondering if anyone followed up to see whether Myneni actually said this? I find it hard to believe that any scientist would make such a blanket statement without a large number of caveats. And if by chance Myneni did say this, what in the world is the method by which he came to this conclusion? Is it published or just a wild guess? What's the error bar on that 50%?

    Also, was anyone able to find the "online lecture last July by Ranga Myneni of Boston University, confirms that the greening of the Earth has now been going on for 30 years"? I came up short.
    0 0
  32. Ruppert Murdoch’s transformation from a climate hawk to a climate skeptic Is nicely covered in:

    Has Rupert Murdoch turned into a climate change sceptic? by Ian Burrell, the Independent, Jan 11, 2013

    Like Dana’s excellent OP, this article was precipitated by Murdoch’s recent tweet about Ridley’s op-ed.
    0 0
  33. As a follow-up to my post above, I did a cursory search for papers by Myneni to see if he ever wrote anything suggesting that carbon fertilization is responsible for the greening of the planet as suggested by the Ridley article. I was unsuccessful in finding anything by Myneni, but I did find the following in a paper in which Nemani is a co-author regarding the western Amazon basin:

    "CO2 fertilization effects were evenly distributed over the course of an entire year, but NDVI did not show such an overall increase. Our results do not exclude the possibility that potential gains in productivity resulting from CO2 fertilization effects were not likely distributed to leaf production; however, we suggest that changes in climate rather than CO2 fertilization effects could explain the increasing trend in NDVI. Specifically, a positive trend in shortwave radiation and negative trend in cloud cover most strongly explain the corresponding increase in NDVI, as our simulations showed that these factors drove a simulated increase in NPP for the same months (from August to December) in which the increases in NDVI have been observed."
    0 0

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.



The Consensus Project Website

TEXTBOOK

THE ESCALATOR

(free to republish)

THE DEBUNKING HANDBOOK

BOOK NOW AVAILABLE

The Scientific Guide to
Global Warming Skepticism

Smartphone Apps

iPhone
Android
Nokia

© Copyright 2014 John Cook
Home | Links | Translations | About Us | Contact Us