Download Al Gore`s An Inconvenient Truth: unscientific? It has been a week

Al Gore's An Inconvenient Truth: unscientific?
It has been a week of contrasts for Al Gore. No doubt he has spent much of
it wondering if he should prepare champagne for breakfast on Friday, with rumors running wild over
whether or not he should and would win the 2007 Nobel Peace Prize. Just this morning, the
announcement was made: the prize is his - or at least half of it. The other half goes to the
Intergovernmental Panel on Climate Change.
Meanwhile, over in the UK, a judge criticised Al Gore's Oscar-winning movie An Inconvenient Truth
for a series of inaccuracies. The ruling concludes a case brought to the UK High Court by Stuart
Dimmock, a parent of two who was concerned to find that the UK Department for Education and
Skills had distributed a copy of Gore's film to every state secondary school in the UK.
He argued that the film was political material, had no place in the classroom, and that its distribution
to schools should be made illegal. Moreover, his legal team pointed out a list of alleged scientifically
inaccuracies in the film.
The judge, Justice Burton, declined to make it illegal. In his ruling, however, he says Gore
committed nine counts of scientific inaccuracy.
But was the judge right?
Sea level rise of up to 7 metres will be caused by melting of either west Antarctica or
Greenland in the near future.
Burton: This is distinctly alarmist... It is common ground that if indeed Greenland melted, it would
release this amount of water, but only after, and over, millennia, so that the Armageddon scenario
he predicts, insofar as it suggests that sea level rises of 7 metres might occur in the immediate
future, is not in line with the scientific consensus.
Gore does not explicitly say that Greenland’s ice will disappear in the immediate future, merely that
coastal areas will be dramatically flooded very soon. That point aside, there is, as Burton says,
some debate over how quickly the ice caps – and Greenland in particular – could melt.
The Intergovernmental Panel on Climate Change 2007 report predicts a sea-rise of up to 59
centimetres by 2100, but explicitly states that this excludes any water contributed by melting in
Greenland and Antarctica because of the huge uncertainties involved. Many scientists agree that
neither is likely to melt significantly before the end of the century. One exception is James Hansen,
head of NASA's Goddard Institute for Space Studies in New York, US. Hansen strongly believes we
may see several metres of sea level rise by 2100.
Low-lying inhabited Pacific atolls are being inundated because of global warming.
Burton: Mr Gore states "that's why the citizens of these Pacific nations have all had to evacuate to
New Zealand". There is no evidence of any such evacuation having yet happened.
In 2005, the people of the Carteret atoll in Papua New Guinea announced their imminent
evacuation. See this article for more details. According to this Greenpeace blog, the evacuation is
due to begin in 2008.
The "Ocean Conveyor" in the North Atlantic will shut down
Burton: According to the IPCC, it is very unlikely that the Ocean Conveyor (known technically as the
Meridional Overturning Circulation or thermohaline circulation) will shut down in the future.
Gore suggests that this density-driven ocean circulation system could collapse in the North Atlantic
if it were to receive a large influx of cold water. The 2007 assessment of the IPCC states that it is
very unlikely that the ocean conveyor belt will shut down, but very likely that it will slow down by
2100 (p. 16 of WGI summary for policymakers).
Gore implies that this could happen if the Greenland ice sheet melts. In 2006, a team of
researchers led by Kirsten Zickfeld of the University of Victoria in Canada carried out a poll of 12
scientists on this question. Eight said they believed there was a 40% chance the conveyor belt
would collapse if global average temperature rose by more than 4°C above pre-industrial levels.
How much temperatures rise depends entirely on how society evolves and on our future energy
supply.
There is a direct relationship between historic rise in CO2 in the atmosphere and in
temperature
Burton: Mr Gore shows two graphs relating to a period of 650,000 years, one showing rise in CO2
and one showing rise in temperature, and asserts (by ridiculing the opposite view) that they show
an exact fit. Although there is general scientific agreement that there is a connection, the two
graphs do not establish what Mr Gore asserts.
Historically, global warming events at the end of ice ages have not been triggered by rises in
atmospheric CO2 concentrations. However, as explained in Climate myths: Ice cores show CO2
increases lag behind temperature rises, disproving the link to global warming, this does not
disprove that CO2 warms the atmosphere and that rising CO2 emissions have cause warming
since the 20th century.
The receding snows of Kilimanjaro are due to global warming
Burton: Mr Gore asserts that the disappearance of snow on Mt Kilimanjaro is expressly attributable
to global warming. However… the scientific consensus is that it cannot be established that the
recession of snows on Mt Kilimanjaro is mainly attributable to human-induced climate change.
Only 21% of the 1912 ice cover on Kilimanjaro was still around in 2003. Whether or not the melting
of Kilimanjaro's snow and ice cap is a symptom of global warming has long been a subject of
debate. In 2006, a team of scientists apparently put the controversy to bed with a 2006 study led by
Nicolas Cullen of the Tropical Glaciology Group at the University of Innsbruck. Using recent highresolution satellite images, Cullen's team came to the conclusion that "rather than changes in 20th
century climate being responsible for their demise, glaciers on Kilimanjaro appear to be remnants of
a past climate that was once able to sustain them".
Read more about the study here.
There is, however, uncontested evidence that the world’s mountain glaciers are melting fast.
Lake Chad's disappearance is due to global warming
Burton: The drying up of Lake Chad is used as a prime example of a catastrophic result of global
warming. However, it is apparently considered to be far more likely to result from other factors, such
as population increase and over-grazing, and regional climate variability.
According to NASA: "Using model and climate data, Coe and Foley calculate that a 30% decrease
took place in the lake between 1966 and 1975. Irrigation only accounted for 5% of that decrease,
with drier conditions accounting for the remainder. They noticed that irrigation demands increased
four-fold between 1983 and 1994, accounting for 50% of the additional decrease in the size of the
lake." Read more here.
The impact of Hurricane Katrina was due to global warming
Burton: Hurricane Katrina and the consequent devastation in New Orleans is ascribed to global
warming. It is common ground that there is insufficient evidence to show that.
There is still considerable debate over the link between the strength of hurricanes and climate
change, yet given that hurricanes collect their power from the temperature of surface water, there is
a plausible physical link. One paper published recently comes down more strongly in favour of a
link than any other previous study. I recently discussed this finding with a hurricane specialist at the
UK Met Office and according to him the debate is still not resolved.
Certainly, when Gore’s film came out there was no definitive evidence for a link. Also, very few
scientists would try to link a single weather event to climate change. Studies can say whether the
probability of an event happening increases with global warming, though, so far as I know, none
has yet been carried out on Katrina.
To get a flavour of the debate, see Global warming link to hurricanes likely but unproven and Coral
reveals increased hurricanes may be the norm.
Polar bears are dying due to disappearing ice
Burton: Mr Gore says: "A new scientific study shows that for the first time they are finding polar
bears that have actually drowned swimming long distances up to 60 miles to find the ice. They did
not find that before." The only scientific study that either side before me can find is one which
indicates that four polar bears have recently been found drowned because of a storm. That is not to
say that there may not in the future be drowning-related deaths of polar bears if the trend continues.
In September 2004, four polar bears were found dead, floating in Arctic waters - an unprecedented
observation. The authors of the report in Polar Biology speculate that they may have died of
exhaustion and this might have been a result of shrinking sea ice. They propose that polar bears
may increasingly meet an untimely death for this reason.
Charles Monnet, first author on the paper, told New Scientist that "he doubts this was simply the
result of exhaustion from having to swim further from ice to shore. More likely, weather conditions
are becoming more severe in the growing expanses of open water, making swimming more
difficult." Read more about the fate of polar bears and other animals here.
Coral reef bleaching events are due to global warming
Burton: Mr Gore says: "Coral reefs all over the world because of global warming and other factors
are bleaching." [According to] the IPCC report, if the temperature were to rise by 1 °C to 3 °C, there
would be increased coral bleaching and widespread coral mortality, unless corals could adopt or
acclimatise, but that separating the impacts of climate change-related stresses from other stresses,
such as over-fishing and polluting, is difficult.
The IPCC states that most corals will bleach if temperatures rise by more than 1 °C over what they
were in the 1980s and 1990s (Table SPM-1 in IPCC's WGI - pdf). Temperatures over the past 50
years have warmed by 0.13°C per decade (p 5 of WGI summary for policy makers).
Many scientists agree that limiting warming to 2°C above 1900 temperatures will need CO2
emissions to be cut by more than half from their 2006 levels by 2050. So unless drastic, world-wide
policy measures are agreed, increased coral bleaching looks pretty likely.
Bleaching is caused by other factors as well, namely disease. There is some evidence warming will
also increase the incidence of disease.