[following is a response to three questions posed by Living
Marxism. The questions are standard denialist stuff,
but they deserve an answer:]
>>Some simple questions anyone who wants to be taken seriously in
>>the discussion of the climate ought to be able to answer:
>>1. Abstracting from the supposed effects of CO2 emissions, what was the
>>trend in average world temperature levels over the last 500 years?
>>
>>2. In natural historical terms do CO2 levels lead or follow temperature
>>levels?
>>
>>3. Is it always the case that CO2 levels move in the same direction as
>>tmperature levels?
james m blaut wrote:
> Evaporation from an open water surface varies with
> the temperature of the air and with air movement. Now, if the avg.
> temperature above the sea surface increases, evaporation will also
> increase.
And so will precipitation, hence the increased rainfall, storms and higher
snowfall over the poles from warm air moving there from the tropics. This
is why the climate models show increased intensity of weather events.
Increased soil temperatures dramatically increase evaporation rates. Most
of the rain falls on the ocean, of course. Freshwater and meltwater from
the icecaps lies on the surface of the northern seas and interferes with
the thermohaline circulation, the so-called 'heat-conveyor' - which conducts
the flow of water right round the planet. It takes a thousand years for the
process to complete itself, the flow is very slow, which is why the oceans
tend to buffer and mask the climate changes which are going on. It's like
pulling a brick away from your face on a piece of elastic, you don't
notice anything at first, until you let go of the brick...
There is no no doubt that something has gone wrong with the north
atlantic thermohaline, which is one of the reasons why no serious
researcher pays attention to James Heartfield's list of questions,
which are familiar from the propaganda activity of the Global
Climate Coalition (a corporate funded entity which does not believe
in global warming, a politics learnt from Nero, Marie Antoinette
and Tsar Nikolai).
In this post I answer Heartfield's questions.
> Has anyone done any quantitative research on this matter?
Yes, oceans of it. NASA, the NOAA, and leading institutes like
Scripps in the US, the UK's Hadley Centre, the University of East
Anglia and many other leading centres.
> An increase in the world's avg. air temperature will ceertainly
> lead to some melting of ice in the Arctic Ocean and on Antarctica.
But how> much?
The question of questions. Will the tendency to thaw prevail, or will
it be over-compensated by increased snowfall, also the result of warming?
But the omens are not good. Last year a chunk of the Antarctic ice-
shelf the size of the English county of Surrey disappeared. The Larsen
"B" shelf recently disintegrated. These are ominous signs.
In 1993 the journal Nature reported that Ice stream 'C', one of
the Ross ice streams that is part of the West Antarctic Ice Sheet,
has come to a halt, and glaciologists are scrambling to find out why,
and what the implications might be. They estimate that the lower,
wide part of the ice stream came to a halt 130 years ago and various
explanations are advanced as to why. The stoppage could be a random
event of the basal topography below ice stream C, or any or all of
the ice streams might experience excessive basal water and cease
moving. It is even possible that this might happen in response to global
warming, potentially counteracting part of the sea level rise due to
thermal expansion of the seas.
More research since then has confirmed both the
existence of counter-tendencies (collapse of the ocean circulation
leaves more stagnant, cold water in the Antarctic ocean floor to
help sustain the ice shelves) and also tendencies (thinning of
the ice-sheets).
In Greenland, the rate of calving of icebergs has increased from a
handful a year to last year more than a 1,000, a deeply-ominous development
since the collapse of the Greenland ice-sheet, which that probably heralds,
will have momentous planet-wide consequences.
If the ocean-circulation stalls, as some models predict, it will cause
a collapse in the ocean eco-systems: the elimination of coral-reefs,
the elimination of fisheries, dramatic changes in phtyoplankton production
and the all-important algae blooms. One problem is that change is likely
to be sudden and stepwise.
The last ice age ended about 15,000 years ago and warmer temperatures
reined. Then 2,000 years later, the climate chilled again, dropping 7
degrees C in the Younger Dryas. Then it appears that the Earth switched
very rapidly, perhaps in as little as three years, to the relatively
warm conditions we have today. If the evidence of these swings is accurate,
the swings may reflect massive shifts in ocean and atmospheric circulation.
The world's climate has more than one equilibrium state...
Warming of the oceans also reduces their ability to trap CO2, and the
further sequestering by phytoplankton which actualy one of the main forms
of carbon draw-down. So ALL the indicators are set to negative. Some
climatologists have taken heart from the idea that increased snowfalls
over the poles may stave off warming, and that sulfate aerosols
(plumes of microscopic particles rising from the world's industrialised
areas) would also stave off warming.
Sulfate aersols are coolants. They reflect heat back into space. They
have mitigated the effects of greenhouse gas emissions in recent
decades, which is one answer to most of James's questions.
But sulfate aersols last only a few years; CO2 is forever. So more
pollution is not really an answer, as more recent research has
conclusively shown. The presence of sulfate aerosols is another
brick in your face; all that happens is that warming is masked
TODAY, allowing rightwing ideologues to pretend nothing is happening,
only to become more catastrophic in the decades ahead.
The journal Nature on 2/11/93, Pages: 497-498 reported that since
the last ice age, high-latitude land areas have been a sink for
carbon dioxide (CO2). New evidence suggests that the Arctic tundra
may now have switched from being a sink to being a source of CO2 to
the atmosphere. In 1990, an additional 0.19 gigatonnes of carbon
were injected into the atmosphere in this way: 'The observed net
production of carbon may be the new status quo for high-latitude
ecosystems as they respond to greenhouse warming.'
The other main thrust of the Three Wise Monkey brigade of know-nothing
doubters -- the last redoubt they have, in the face of overwhelming
and compelling evidence -- is to say that natural climate changes,
both local and short term, and over longer, geological time-spans,
swallow up the allegedely 'marginal' or minor effects of anthropogenic
climate forcing.
Such changes are said to include cosmological factors,
volcanoes, and slow changes in atmospheric composition from a variety of
factors. The Brunt of Heartfield's list of questions is to drag debate
onto this sterile ground. But his questions have been asked before,
and thoroughly answered in ways which give no comfort to the extreme
rightwing and corporate ideological interests which Heartfield follows.
It is true that the earth is swimming in space, and that cosmological
effects resulting from the entire solare system's movement through the
galaxy, as well as from changes in the earth's orbit around the sun,
produce the well-known Milankovitch cycles (Greenfield's 'questions'
concern this).
Milankovitch was the Serbian astronomer, unrecognised in his lifetime,
who first calculated the relationship between cosmological events and
changes in the earth's orbit, and the cycles of ice-ages. The orbital
parameter theory as proposed by Milankovitch and others suggests that
climate changes on Earth, such as glacial and interglacialperiods,
may be the result of a delicate balance in insolation. More
specifically, since insolation varies more at high latitudes, the
changes experienced are a result of net effects at these latitudes.
As the theory goes, glacial periods are the result of cooler than
average summers and warmer than average winters at high latitudes.
Some areas which previously had melted off completely in the summer
months now would remain partially covered with snow and ice. Also,
the increased wintertime temperatures would give the air a greater
capacity to contain more water vapor. This would result in greater
frozen precipitation falling which would enhance the ice/snow coverage
area.
This combined with an increased ice albedo effect would produce a
growth of ice. The argument for interglacial periods is just the
opposite. But what is the cause for the change in insolation? It is
believed that variations in the Earth's eccentricty, precession, and
obliquity through time are the culprits of this climate change.
In addition to the 40,000- and 23,000-year Milankovitch cycles, theere
are now known to be 11,100- and 6100-year cycles previously reported
from marine sediments. Both appear to be higher frequency oscillations
somehow induced as the longer Milankovitch cycles reverberate through
the climate system. For example, the 23,000-year cycle, driven by the
wobbling or precession of Earth's axis, redistributes sunlight so as
to alternatively intensify summer heat in the Northern and Southern
Hemispheres. Land masses straddling the equator might then pick up
temperature maxima from both hemispheres, producing a maximum in the
tropics every 11,000 years or so. Other overtones would appear as
diminishing maxima at successively higher frequencies," according to the
researchers, but pinning down the actual causes is still a matter of some
debate.
But the effect of solar changes are actually much less than those of
anthopogenic climate-forcing. Nature reported in 1992 that there is
' strong circumstantial evidence that there have been intercycle
variations in solar irradiance which have contributed to the observed
temperature change since 1856. However, the authors find that since
the nineteenth century, greenhouse gases, not solar irradiance variations,
have been the dominant contributor to the observed temperature change.'
(Aspen abstracts, Reference Number: 161)
Also in 1992 Nature reported on computer-modelling the effects of a
combination of greenhouse and solar-cycle-length forcing and compared
the results with observed temperatures. They found that this forcing
combination explains many features of the temperature record, but warn
that the results should be interpreted cautiously. Even with optimized
solar forcing, 'most of the recent warming trend is explained by greenhouse
forcing,' they say.
In 1994, Nature (the world's premier science journal) reported a
study evaluating: 'the observed warming trend (0.5 degree C this
century) using a 1000-year time series of global temperatures
obtained from a model of a coupled ocean-atmosphere-land system.
The model reproduces the magnitude of the annual and interdecadal
variation in global mean surface air temperature. Throughout the
simulated time series, no temperature change as large as 0.5 degrees
C per century is sustained for more than a few decades. This suggests
that the currently observed trend is not a natural feature of the
interaction between ocean and atmosphere but rather has been induced
by thermal forcing by greenhouse gases and aerosol loading.
The research is endless, and the more detailed the results are as time
passes, the more frightening they are.
Heartfield wants to know what is the relationship between 'natural'
temperature change and that induced by CO2 emission (humans have
injected 800 billion tonnes of CO2 into the air since 1750, ice-core
analyses show).
Also in 1994 Nature reported research on oscillation, climate change,
greenhouse gases, sulfate aerosols, and sulphate, cycles. This research,
based on temperature records, indicates the presence of a non-random,
oscillatory component in the climate system with a time period of 65-70
years. Further, the authors believe that these oscillations have dominated
the greenhouse gas-anthropogenic sulfate aerosol-induced greenhouse
warming signal in the North Atlantic and North America, obscuring it
and confounding its detection.
In 1995 Nature again reported research about the effect of sulfate
aerosols, as follows: The authors report on the results of a coupled
ocean-atmosphere general circulation model for simulating past and
future climate with the addition of the effects of sulphate aerosols.
By including the effects of these aerosols, the model produces a
better fit to the observed global temperature record since 1860,
particularly in recent decades as sulphate aerosol emissions have
become more pronounced on a global scale. For model runs that do not
include aerosols, the authors find a future global warming
of 0.3 K per decade. When the aerosols are included in the model runs,
the future warming is reduced to 0.2 K per decade.
Since aerosol emissions are not uniformly distributed, but are
concentrated in the Northern Hemisphere over North America, Europe
and Southern Asia, the effect on temperature for specific areas is
varied. The model results show that even though the cooling effect
is strong in some areas, by 2050 all land areas have warmed.
As greenhouse gases continue to build, their forcing of a warmer
climate may dominate more than presently over the cooling effect
of the aerosols.
Future climate model runs were based on emission estimates by
the Intergovernmental Panel on Climate Change in scenario IS92a which
assumes about a 1% per year increase in atmospheric carbon, reflecting
a slowing of economic growth and an incorporation of some conservation
measures.
As Heartfield rightly says, it's complex, a lot of factors are in play.
The main greenhouse gas is actually water vapour, thus one of the self-
reinforcing tendencies which can lead to runaway or enhaced warming
is precisely the extra evaporation, but it is also true that evaporation
produces clouds which reflect heat back into space. Massive reseach is
being done on this.
NASA do most of the sat-observations.Data from the International
Satellite Cloud Climatology Project found that variations in
sunlight reflected by low clouds may offset the higher degree
of warming which had been predicted to occur at the poles, reducing
the variation in warming with latitude. The data indicate that a
positive feedback is operating: at warmer temperatures, cloud
reflectivity dropped, causing the temperature to rise at most times
and in most places. How much it rose depended upon the season, latitude,
and whether the clouds were over land or sea. When this information
was added to the models, a stronger positive feedback was found
at lower latitudes. This would lead to temperature increases near the
equator that would offset the higher warming predicted near the poles.
There are other factors, including even the shape of the earth.
(The weight of ice at the poles compresses them, but there are other
things in play). Changes in the shape of the Earth may have affected
the length and timing of past ice ages, according to new research by
Bruce Bills of NASA/Goddard Space Flight Center. The research,
reported in Geophysical Research Letters, Vol. 21, p. 177),
incorporated the Earth's changing shape in simulations and found that
the axial tilt oscillated by the same amount and with the same cycle
of 41,000 years, but over longer periods the tilt slowly increased.
There appears to be a feedback mechanism involved; not only does axial
tilt affect climate, but climate affects the tilt by changing
the Earth's roundness (during an ice age, ice accumulates in the
polar regions making the Earth more spherical).
Researchers have long known that the oscillation in axial tilt
affects climate: the larger the tilt, the stronger the sunlight
in summer and the weaker in winter. The new puzzle piece here is that
climate can also affect the tilt by altering the planet's shape. This
work may explain why, about 700,000 years ago, the climate shifted
from a cycle lasting 41,000 years to one lasting 100,000 years.
The longer cycle may stem from a periodic change in the shape of the
Earth's orbit around the Sun, from circular to elliptical and back
again.
In assessing anthropogenic forcing, obviously, as Greenfield says,
all this has to be considered, and is being. But the results do not
vary much: anthropogenic forcing now eclipses in intensity of effects
on the climate, all other factors.
In the same way the intensity of human activity is having a more
severe effect on life as it has evolved during four BILLION years than
any previous geological events
In 'Earth's peeling veneer of life, Douglas W. Morris wrote in Nature
in 1995 a long article reporting research into biodiversity, species loss,
terrestrial, deforestation, fish, human population, land use, land cover,
agriculture, soil, forest, habitat, fragmentation, extinction, biological
diversity, and landscape degradation.
Douglas Morris presented results of research relevant to large scale
loss of biodiversity. He points out that there is a lag time between
environmental degradation and species extinctions that result from it,
and that this highlights the value of more immediate and more easily
estimated indicators of human impact. For example, he says that more
than 11% of the world's terrestrial landscape has been converted to
cropland. A further 25% has been occupied by pastureland. The proportion
of Earth's surface covered by forest and woodland has dropped 9% since
1700, much of what remains is becoming increasingly fragmented, and
about 40% of what remains is either plantation or secondary forest.
The rate of soil degradation during the last 45 years corresponds to 17%
of all vegetated land. Biotic functions have been completely destroyed
in 9 million hectares and have been largely destroyed in a further
300 million hectares.
World exploitation of marine fishes has increased by 35% since 1979.
The exploitation of freshwater fisheries has expanded 85% during the
same period. About 60% of the world's main fish stocks may be
exploited beyond their ecological or economic optima. Humans use 8%
of the world's available fresh water each year. Tropical deforestation
continues at a rate of 0.9% per year. Human population size is
increasing at the rate of 1.7% per year, with a parallel increase in
the number of domestic animals. 'The inescapable conclusion,' the author
says, 'is that much of the planet's surface, and its veneer of life,
has already been destroyed. ... We have embarked on a trajectory of
lost biodiversity whose acceleration and direction can, at most,
be controlled but not reversed.'
Again on sea-level rise, Nature reported a correspondence between two
scientists, one a sceptic, the other convinced about anthopogenic effects:
(Nature, 6/23/94, Pages: 615-616, letter by W. Greuell in response to
an article by Sahagian et. al.
The subject is the quantification of the direct anthropogenic
contribution to sea level rise. Sahagian contends that the present rate
of rise caused by anthropogenic factors is 30% and that this is the number
of significance. Greuell seems to say that the more interesting and
important number is the anthropogenic impact on the integrated sea level
rise for the period 1900 to 1994, which he says is 7%.
Sahagian counters that the current rate provides the basis for extrapolation
into the future and also that the rate has increased throughout the century.
The pollution that produces global warming aslo results in the
eutrophication of rivers and destruction of marine life. Two new studies
in the U. S. focus on endangered species. One, carried out by the Nature
Conservancy, suggests that as many as a third of the species in the U. S.
may be at risk. It found that 1.3% of species known from historical records
are now extinct or possibly extinct, another 15.4% are "imperiled" or
"critically imperiled" (fewer than 3000 individuals are left or are
found at fewer than 20 sites), while another 15% are "vulnerable"
(fewer than 10,000 individuals or at 100 sites). "For some groups,
particularly freshwater invertebrates, things are even worse.
More than 20% of crayfish and 26% of freshwater mussel species are
critically imperiled, the report says, and only a third of the species in
either group are considered safe."
Heartfield says of Proyect and myself:
> And what do they
> agree? That the industrial development that gave the West domination
> over the rest of the world should be halted before anyone else gets
> their hands on it; that living standards should be held down; that only
> such development as is "appropriate" (ie low-level, labour intensive)
> should take place in the third world; that civil liberties should be set
> aside for the greater good of 'saving the planet'; that self-
> determination for small nations is an outmoded concept.
>
We do not agree with any of this. But we are waiting for Heartfield to give us a
model of industrial development which can permit the third world to live like
the first world without also destroying the planet, and moreover, how this is to
be accomplished after the next forthcoming and final oil crisis and in the
framework of deepening climate catastrophes. If Heartfield has no
such model, then his politics is a cruel hoax on the very people he
sheds crocodile tears for..
What does he suggest people do in the face of the capitalist rapacity which
has ruined their lives and is wrecking the planet?
What is needed is not ad hominem attacks and personal abuse but a sustained
and serious debate.
[ --- from list marxism-international@lists.village.virginia.edu ---]
MARK JONES