Anti-Environmentalist gets shredded by experts:
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Check out how he fudges data:
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Not Seeing the Forest for the Trees
On Bjorn Lomborg and deforestation
by Emily Matthews
12 Dec 2001
In The Skeptical Environmentalist, Bjorn Lomborg writes that "basically,
the world's forests are not under threat." A charitable reader could
attribute this flawed conclusion to errors of omission and ignorance;
perhaps the author simply doesn't know the sources well enough to
interpret them properly. Less charitably, one might reasonably conclude
that Lomborg intentionally selects his data and citations to distort or
even reverse the truth. His interpretations of data on global forest cover
and Indonesian forest fires aptly illustrate both failings.
Lomborg scorns an analysis by the
World Wildlife Fund that found that
nearly two-thirds of the world's original
forests, dating to the pre-agricultural
period (defined as 6000 BC), have at
one time been cut. He challenges it by
stating that, "Most sources estimate
about 20 percent." Whatever the
merits of WWF's claim, Lomborg
confusingly contrasts net loss of
forest cover (that is, his figure of
loss of natural forest offset by
regrowth and new plantations)
with loss of original forest (WWF's
figure).
Moreover, the sources Lomborg cites in the relevant footnote do not
support his claim. The first, a 1993 college textbook by Andrew Goudie,
indeed gives a figure of 20 percent net loss in forest cover since
pre-agricultural times. However, its author provides no reference or
authority for this number. The second source, by Michael Williams, is
stated in the footnote as giving the (amazingly) low figure of 7.5 percent
loss, but a review of the source itself reveals that Lomborg has misread
7.5 million square kilometers as though it were a percentage.
The last two sources mentioned in the footnote, which give figures of 19
and 20 percent, do not purport to measure forest loss during the entire
8,000-year period for which Lomborg cites them. On the contrary, these
two sources cover only tiny fractions of the relevant time period -- less
than 4 percent (300 years) and 2 percent (140 years), respectively --
and even so, each registers roughly a 20 percent loss of forest.
Barking Up the Wrong Tree
Another claim by Lomborg -- that global forest cover has remained
remarkably stable over the past 50 years -- is based on two acts of
statistical conjuring. First, he expresses changes in forest cover as a
percentage of the total land area of the world, a technique that reduces
changes of millions of hectares to fractions of 1 percent. Second, he
cobbles together a variety of different data sources compiled using
different definitions of forest and different methodologies. These
different data sets cannot be strung together to form a consistent time
series. The United Nation's Food and Agriculture Organization, the
"official source" on which Lomborg proudly claims to rely, does not
attempt to construct such a time series. Yet the first graph in Lomborg's
chapter on forests prominently features an FAO data series of forest
cover that was generated for agricultural purposes and discontinued by
FAO precisely because it considered the data unreliable for assessing
forests.
FAO forestry data can be difficult to
understand, as Lomborg's notes make
amusingly clear. In Note 767, he defines
closed forest as 20 percent of forest cover
rather than forest where the tree canopy
covers 20 percent or more of the ground.
More seriously, he appears to believe that
the U.N. carried out two global forest
surveys in 1995 and 1997. In fact, the U.N.
surveys forests only once per decade. The
1990 survey was updated with a
mathematical model to the year 1995 and
these results were published in the 1997
State of the Forest report.
Are the world's forests "basically not
under threat," as Lomborg claims?
Lomborg quotes the FAO's most recent survey, the Forest Resources
Assessment 2000, which states that, "Tropical forests are being
deforested...at an annual rate of 0.46 percent." Lomborg claims this
figure is "much below the feared 1.5-4.6 percent" rate, although he
provides no clue as to who feared such extraordinary rates. But there is
a serious error here: Lomborg is quoting the FAO's figure for global
deforestation, not tropical deforestation. The vast majority of forest
clearance is occurring in the tropics -- forest area is actually expanding
in most of the temperate zone -- so this error grossly distorts the rate of
tropical deforestation.
According to the 2000 report, about 161 million hectares of natural
forest were lost during the 1990s, of which 152 million hectares (about
94 percent) were in the tropical world. The 2000 report puts total global
forest cover at about 3.9 billion hectares, 95 percent of which is "natural
forest," meaning that there are about 3.7 billion hectares of natural
forest. Of this, 47 percent, or 1.74 billion hectares, is in the tropics. Thus
if 152 million hectares of natural tropical forests were lost during the
1990s, from a total natural tropical forest area of 1.74 billion hectares,
then tropical forests shrank by 8.7 percent over the decade -- an annual
average rate of 0.87 percent.
In the Line of Fire
Lomborg devotes an entire page to Indonesia's fires of 1997-1998,
acknowledging that they were serious but also claiming that they were
not out of the ordinary. He criticizes WWF for estimating that 2 million
hectares burned and contrasts this claim with the "official Indonesian
estimate" of 165,000-219,000 hectares. He notes that the WWF
estimate included both forest and non-forestland, but does not point out
that the official Indonesian estimate he quotes was for forestland only.
He then claims, citing a 1999 United Nations Environment Programme
report, that subsequent "satellite-aided counting" indicated that
upwards of 1.3 million hectares of forest and timberlands may have
burned.
The official Indonesian estimate of 520,000
burned hectares of forest and non-forest land
was based on reports by plantation owners --
who were responsible for much of the
deliberate fire-setting and had no incentive to
report accurately. This estimate was quickly
challenged by the German-supported
Integrated Forest Fires Management Project,
which, using satellite data and ground checks,
produced convincing evidence that fires had
actually burned some 5.2 million hectares in
1998 alone -- 10 times the Indonesian
government's estimate. Informed of this data gap, the Indonesian
Ministry of Forestry and Estate Crops effectively instructed the governor
of East Kalimantan (the province that suffered the worst fires) not to
allow the new data to be made public, citing the need "to protect
national stability." Despite strong official protests from the German
government, the Indonesians never retracted their original estimate or
made the new data public.
Regarding estimates of how much forest actually burned, Lomborg
cites a UNEP report, which in turn refers to an analysis, "A Study of the
1997 Fires in Southeast Asia Using SPOT Quicklook Mosaics," that
was based on 766 satellite images. These images covered the islands
of Kalimantan and Sumatra only, for just August to December 1997.
The study did not examine burn areas for 1998, nor did it take into
account fires on other islands. The UNEP report states that this
estimate represents "only a lower limit estimate of the area burned,"
although Lomborg's readers are not so informed.
An analysis by the Singapore Centre of Remote Imaging, Sensing, and
Processing using the same satellite images yielded a total burn area
estimate for 1997 and 1998 of nearly 8 million hectares. In 1999, a
technical team funded by the Asian Development Bank and working
through the Indonesian National Development Planning Agency
aggregated and analyzed all available data sources and estimated that
the area burned during 1997-1998 totaled more than 9.7 million
hectares, of which some 4.6 million hectares were forest.
Thus, the most authoritative consensus estimate of the extent of forests
burned during the Indonesian fires of 1997-1998 is more than twice the
WWF estimate that is derided by Lomborg.
Lomborg's interpretation of global
forest cover and Indonesian forest
fires are just two examples of the
incomplete and superficial analyses that underpin too much of this
book. In his introduction, the statistician tells us that his skills lie in
"knowing how to handle international statistics." A few paragraphs later,
he confesses that, "I am not myself an expert as regards environmental
problems." Unfortunately, statistical prowess by itself does not
guarantee accuracy, insight, or understanding. A little more expert
knowledge would have significantly diluted this book's glib optimism.
Indeed, the book would probably never have been written.
- - - - - - - - -
Emily Matthews is a senior associate at the World Resources Institute.
She is the lead author of the Pilot Analysis of Global Ecosystems:
Forest Ecosystems (WRI, 2000) and Understanding the Forest
Resources Assessment 2000 (WRI, 2001). Her latest report, The State
of the Forest: Indonesia, will be released in January 2002 by WRI's
Global Forest Watch. |
