Guest post by Indur M. Goklany
In this Reuters story (15 December 2009) they report: “Describing a ‘runaway melt’ of the Earth’s ice, rising tree mortality and prospects of severe water scarcities, Gore told a UN audience: ‘In the face of effects like these, clear evidence that only reckless fools would ignore, I feel a sense of frustration’ at the lack of agreement so far.”
Now to most people, “rising tree mortality” raises the specter of a world with less greenery. But how does real world data compare with the virtual modeled world? Is the world getting less greener? Is there any hint of the virtual world in the real world data?
Satellite data for the real world (not the one Mr. Gore lives in) can help give us an idea.
Global
Globally net primary productivity (NPP) has increased. As the IPCC’s WG II report (p. 106) says:
Satellite-derived estimates of global net primary production from satellite data of vegetation indexes indicate a 6% increase from 1982 to 1999, with large increases in tropical ecosystems (Nemani et al., 2003) [Figure 1]. The study by Zhou et al. (2003), also using satellite data, confirm that the Northern Hemisphere vegetation activity has increased in magnitude by 12% in Eurasia and by 8% in NorthAmerica from 1981 to 1999
Figure 1: Climate driven changes in global net primary productivity, 1982-1999. Source: Myneni (2006), p. 5. This is the same figure as in IPCC AR4WGII, p. 106, but with a different color scheme.
Amazonia
In a synthesis of long term ecological monitoring data across old growth Amazonia, Phillips et al (2008) find that from approximately 1988 to 2000 not only that the biomass of these tropical forests increased but that they have become more dynamic, that is, they have more stems, faster recruitment, faster mortality, faster growth and more lianas. These increases have occurred across regions and environmental gradients and through time for the lowland Neotropics and Amazonia. They note that the simplest explanation for this suite of results is that improved resource availability has increased net primary productivity, in turn increasing growth rates, which can all be explained by a long-term increase in a limiting resource. They suggest that this no-longer-limiting resource might be CO2, although other factors (e.g., insolation or diffuse radiation) may also play a role.
Gloor et al. (2009), based on analysis of data from 135 forest plots in old growth Amazonia from 1971 to 2006 show that the observed increase in aboveground biomass is not due to an artifact of limited spatial and temporal monitoring. They conclude that biomass has increased over the past 30 years (p. 2427).
These findings are consistent with satellite data that indicate that the net primary productivity of the Amazon increased substantially from 1982–99, a period that experienced considerable global warming (see Figure 1).
Sahel
Satellite Imagery shows that parts of the Sahara and Sahel are greening up consistent with the trend recorded in Figure 1 (Owen 2009). The United Nations’ Africa Report (Figure 2) notes:
“Greening of the Sahel as observed from satellite images is now well established, confirming that trends in rainfall are the main but not the only driver of change in vegetation cover. For the period 1982-2003, the overall trend in monthly maximum Normalized Difference Vegetation Index (NDVI) is positive over a large portion of the Sahel region, reaching up to 50 per cent increase in parts of Mali, Mauritania and Chad, and confirming previous findings at a regional scale.” (United Nations 2008: 41). Figure 2: Source: United Nations (2008),
Australia
Similarly, an Australia-wide analysis of satellite data for 1981–2006 indicates that vegetation cover has increased average of 8% (Donohue et al. 2009).
Figure 3: Australia, 1981-2006. Change in vegetation cover, as described by the fraction of Photosynthetically Active Radiation absorbed by vegetation (fPAR). Source: Donohue et al. (2009)
Canada
With respect to the northern latitudes, 22% of the vegetated area in Canada was found to have a positive vegetation trend from 1985–2006. Of these, 40% were in northern ecozones (Pouliot et al. 2009; see Figure 4).
Figure 4: Long term changes in vegetation for Canada, 1985-2006. Source: Pouliot, D A; Latifovic, R; Olthof (2009).
References
Donohue, Randall J.; Tim R. McVIcar; and Michael Roderick. (2009). Climate-related trends in Australian vegetation cover as inferred from satellite observations, 1981–2006. Global Change Biology doi: 10.1111/j.1365-2486.2008.01746.x.
Gloor, M.: O. L. Phillips, J. J. Lloyd, et al. (2009). Does the disturbance hypothesis explain the biomass increase in basin-wide Amazon forest plot data? Global Change Biology 15: 2418–2430.
Phillips, Oliver L; Simon L Lewis, Timothy R Baker, Kuo-Jung Chao and Niro Higuchi (2008). The changing Amazon forest. Philosophical Transactions of the Royal Society Series B 2008 363, 1819-1827.
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Further reading
One recent WUWT post that also sheds some light on this issue:
Cosmic Rays and tree growth patterns linked
These next two are particularly relevant, because they show that trees have recently begun to respond positively to increased CO2 in the atmosphere:
EPA about to declare CO2 dangerous – ssshhh! – Don’t tell the trees
Surprise: Earths’ Biosphere is Booming, Satellite Data Suggests CO2 the Cause
Two things:
1 – As an ordinary bloke who learned about graphs over 50 years ago and has since forgotten everything about them, I look at the graphs in this blog and they might as well be in sanskrit. I read the text and it makes sense so I accept the logic of the arguement. I have to trust the presenter.
Gore produces all this pseudo scientific crap and most of his followers look blankly at his graphs (as I do) and pretty pictures and accept his interpretation of the facts (which I don’t) because he seems to know better. More trust. The trouble is, he has had the field to himself for so long, he’s had time to do a lot of brainwashing on young and old. Gore is not stupid, he is a manipulator and a greedy bastard. The public is not stupid, just ignorant of the facts, but that is changing, hopefully, in time.
2 – Gore, Rudd, Obama and Brown don’t have to worry about their children and grandchildren, they’ve been taken care of thanks to taxpayers generosity and personal wealth. It’s the rest of us who should worry. Rudd is allowing dictators and despots to dictate terms and if he accepts them, we are in deep pooh.
Jimbo (13:17:32) :
J Mann (07:17:22) :
“I am not an Al Gore fan, but …
JohnS (07:17:34) :
“Gore is not completely out to lunch …
Neither I nor J Mann (if I may presume) are defending Gore’s linkage of increased tree mortality with climate change. The examples that we (and others) have brought up are fairly dramatic events in which the short-term mortality exceeds growth many fold. In other words, we are looking at negative net growth on a very large scale (i.e., I wouldn’t consider a phenomenon that covers several states and provinces “local”). Negative net growth means that there is a declining amount of growing stock on which the gross growth of the population must occur (think of the declining balance of your 401(k), and the resulting change in earnings). When the mortality event is over, there will likely be positive net growth of the residual population, so it looks positive. However, you are getting the same rate of interest on a much smaller balance, so the net gain may actually smaller.
If you look at the figure above of the Sahel, you will see several “hot spots” (pink) of NDVI. A similar map of the western U.S. and Canada from the late 1990s to present would show many large negative spots such as these. I should also point out that the analysis I have done is based on large-scale, gound-based inventory data, which can detect changes in tree- and stand-level growth that are not possible with remote sensing methods.
So…yes, trees are dying at an alarming rate as compared with “typical” rates. Why they are dying and what the long term impacts are remain to be sorted out.
JohnS
Al Gore…
You are… impossible
Yes so very improbable
That you’re damn near intolerable
Is it even possible
To be so unreasonable
That you’re full on irascible
It is impassable
Totally unbearable
So much so, you’re insufferable
Can you be this unmanageable
So utterly uncontrollable
That reason is unattainable
You are so far from able
Not even particularly stable
Not even to be considered capable
@ur momisugly Dave in Delaware (03:35:41)
Sadly, EPA hears you, oh yeah, they hear you.
But EPA is essentially corporate owned and run. EPA wants plants to be CO2 starved. Want farmer’s to have to buy tons of human-made fertilizers. That is their control. They hate a “free” fertilizer in the atmosphere. Genetic modified plants to reject CO2 enhancements. They hear you alright. The likes of intelligent people like you are their adversary.
Remember, 99+% of all of the carbon in all life forms comes ultimately from CO2 taken up by plants. Plants grow using the carbon in CO2, the cow eats the plants, we humans eat the cow or we eat the cereal and bread directly.
This CO2 control is a hidden taxation on all food, therefore a tax on you and you and you!
J Mann & JohnS
Thank you for the references, I appreciate being pointed to new material. I’ll look them over.
I have no doubt that there are large areas that have seen a loss of trees and vegetation. This seems most obvious by looking at the Australia map. After all there is a lot of variability — some places will have less rainfall, others more, etc. But in the aggregate there has been “greening,” at least in the satellite data so far. I think the problem is that people look at a few areas, and generalize from that. The same is true for looking at small periods — and I would say one would need to see trends over a period at least 2 x the periodicity of various oscillations. [The periodicity of the PDO, for instance, is ~ 50-70 yrs.] Given that, if the trends reversed themselves, I would not be surprised. Nature will play out her rhythms in due course of time and will not be hurried, no matter how impatient we humans are to get a definitive answer.
I think (that is, I hypothesize) that the changes we see are due to a combination of CO2, more rainfall in some areas, higher temps in the northern latitudes, and more nitrogen deposition. Is any of this due to a changed climate? If CO2 and nitrogen have something to do with the trends we’ve seen, then reversing them might be less likely. But I’ll wait and see what the data show.
Finally, note that if the climate is changing and there is a die-off of trees, I am not convinced that one should despair because that may be nature’s way of wiping the slate clean before it starts “re-populating” the area with species that would be more suitable to the “new” climate. Thais, it hastens the transition to new plant assemblies/ecosystems. However, if one is concerned about the loss of carbon, my suggestion would be to harvest the trees and sequester them in long lived products like tables, building materials etc., before the they are gotten by man-made or natural forest fires, insects, disease or whatever.
Bill Tuttle (06:11:08) :
Not a problem in Copenhahahagen
Then after getting “below the neckline,” it’s just a hop skip and a hump to their bank accounts, [as per J.Hansford (04:47:22) ]
Though I’m not sure how repeatable or publishable that would be. An entertaining read, though.
Who writes this buffoons speeches, or is that the problem – he just makes it up as he goes.
Indur M. Goklany (17:46:38) :
J Mann & JohnS
Thank you for the references, I appreciate being pointed to new material….
I agree with your note above. I was trying to make the point that some of the posters should not be so dismissive of the issue of elevated tree mortality (simply based on the fact that AG mentioned it!), especially when it’s a manifestation of weather/climate that is “obvious” to Joe and Jane Public. It’s quite an easy target for the warmists to point to and say “see!”, when we’re talking about the loss of forests that have weathered many droughts (to include the 1500s megadrought for some). Most of the public merely understand that these forests were here long before they were born and, for some forest types, should persist long after they have gone, yet they are being taken out in wholesale fashion by drought and bugs. AGW is a “convenient” explanation for what the public sees!
However, for the bona-fide skeptic, saying “nothing to see here” in relation to the recent mortality events is risking a loss of credibility. There is indeed something to see, and we’re looking very closely.
On a more technical note, I’m assuming that the estimation of NPP integrates all vegetation. If this is the case, it’s perfectly logical to see a positive resonse even in the face of tree mortality. Some of the signal that’s probably been picked up in these types of studies is probably the release of understory vegetation (including young trees), which can respond to overstory mortality quite quickly. So, while net ecosystem productivity might look “OK”, we may be seeing a type converstion (e.g., forest to shrubland) of unknown duration (the slate-wiping you mention above). Again, Joe Public tends to me more attached to trees than NPP!
One hypothesis that comes to mind is that these systems may be ramped up due to moist periods and/or CO2 fertilization effect, and then when a deeper-than-usual drought hits they are particularly susceptible because they are geared up to more favorable conditions. It has also been suggested to me that these “fertilized” trees may actually be more appetizing to the bugs. That is an intriguing hypothesis, especially considering that high CO2 could result in water use efficiency. Trees need water to fend off (many of) the bugs (by generating pitch), so good growth during relative drought could actually lead to higher susceptibility to infestation. There is already some evidence that very slow-growing trees (i.e., on poor sites) may dodge the bullet during these outbreaks. That is contrary to traditional thinking for foresters, because we tend to equate tree vigor with low susceptibility.
Recent events have prompted us to question conventional wisdom, which is exactly how science is supposed to work!
I was somewhat concerned that my comments would get lost in the AG feeding frenzy (it’s been fun to watch the piling-on), but I’m glad you noticed. Feel free to get hold of me directly after you’ve had a chance to digest my 2005 article. There’s quite a rich literature on the die-off issue and a lot more work yet to be done. You’re welcome to all the data I have at my dispoal, should you wish to explore some of the specific cases youself.
JohnS
Someone beat me to mentioning the trees affected by the pine beetle. It is true that parts of the forests are dying because of pine beetle infestation. On top of that the only ways to eradicate the pine beetle are: (1) cold (I cannot remember the cold temperature that it has to reach) and (2) fire. What I do know is that last year around Jasper, Lake Louise and Banff, as well as Kamloops (or rather near Kamloops) trees have been dying and last year the lows were not quite low enough for eradication. I personally do not believe that is evidence of AGW, but would be evidence of a slight shift in temperatures.
What seems important though, is that there is always a need for fire in these regions so that the larch pine trees can begin to regenerate. The pine cones need the heat to be able to open. It is all a part of nature.
Here in Australia, you do have some forest clearing but with the fires we had last year there was also some loss due to the usual bush fire season. Ditto for this year. It will not take long for the plant life to begin the cycle again.
All pine forests are infested with bark beatles. Generally they only attack sick or dieing trees as healthy trees will drown the new grubs with pitch. Pine seedlings are very vigorious and start in large numbers, only a few need to survive and grow large. In a real wild forest, fires kill most of the smaller trees so that the compitition for water does not stress the large trees. If there are too many trees for the available water they are all stressed and become bugged and die.
When I was young I talked to old timers and they claimed when they were young the western forests were very open with few small trees, as if it were a wooded park. The indians and then the settlers would burn out the thickets in the fall to improve the hunting. Wild fires were very rare, mainly just low slow fires.
The great western forest die off is caused by Smokey the bear, as is the infestation of brush on what was once grazing lands.
Al Gore is not too worried about the facts, it is the story that is important.
like Tony Blair stated – “The science doesn’t matter”.
Now the Prince of Wales demonstrats why his mum won’t give him the keys to the family business. At least the longer this takes the more likely it will collapse from the weight of the B S ( bad science)
On top of that the only ways to eradicate the pine beetle are: (1) cold (I cannot remember the cold temperature that it has to reach) and (2) fire.
Woodpeckers work well, too — when they’re not being shredded by wind turbines…
Drs. Golkany and S:
Thanks to both of you. I’ll leave it to you, but am very encouraged by the interchange.
Public comments by Gore’s are a challenge: they need to be fact-checked, but without footnotes, you have to grant him a bit of charity to try to guess what he’s talking about.
If I can summarize (without any expertise) — it sounds like there is some scholarship that may indicate an increase in average tree mortality. However, Gore’s characterization of tree mortality as a component in “clear evidence [of AGW] that only reckless fools would ignore” is probably way off the mark.
http://www.theaustralian.com.au/news/nation/scientists-crying-wolf-over-coral/story-e6frg6nf-1225811910634
I think you should read this article. I think the floodgates are about to open.
regards
If I recall, about 11 years ago I read an extensive UN report sugesting there was and will continue to be a slow increase in rainforest growth/cover going forward. The prime reason cited was the mass immigration of subsistance farmers to the economic ‘advantages’ offered by the urban centres, e.g Sao Paulo.