Time for a new
paradigm on climate change?
There are two alternative ways to look at how science
progresses. In one corner is the concept of the falsifiable hypothesis,
credited to Karl Popper .
Popper argued that all science is based on hypotheses, which must
be tested to destruction. Sound evidence which does not fit with the hypothesis
must logically cause it to be rejected. However, the other side of the same
coin is that no hypothesis can ever be said to be proven. Over time, the body of evidence consistent with a
successful hypothesis builds up to the extent that it becomes regarded as a theory, for example the theory of
General Relativity, or Tectonic Plate theory.
At this stage, theories are treated, to all intents and
purposes, as fact. However, even then, quite basic knowledge may, with time, be
seen as merely provisional. A classic example is Newtonian mechanics, which
fully describes the motion of bodies on the scale we are familiar with, but
which breaks down both at the level of elementary particles (hence the
development of quantum mechanics) and at a cosmological scale (where relativity
comes into play).
Popper used the concept of falsifiability
as his criterion for whether something is genuinely scientific or not. Thomas
Kuhn , in the other corner of this contest,
contributed a different view of how scientists work. He introduced the concept
of "normal science" to cover the situation where scientists work on
various topics within a central paradigm. In contrast to Popper, the Kuhnian
view is that "wrong" results (ie, those which are in conflict with
the prevailing paradigm) are considered to be due to errors on the part of the
researcher rather than findings which jeopardise the consensus view. However,
as conflicting evidence increases, a crisis point is reached where a new
consensus view is arrived at: a so-called paradigm shift.
These two philosophical approaches represent the extremes of
a spectrum. Popper is the purist, who describes how scientific
progress ought to work in an ideal
world. On the other hand, Kuhn 's description is more pragmatic
and a more realistic view of what actually happens. When a hypothesis is first
put forward, it would be quite easy to discard it if early experimental results
falsified it. However, when a consensus builds up over time that a particular
view is "correct", it takes plenty of hard evidence to convince
people they have been wrong. After all, scientists are only human.
The example often used of this happening in the fairly
recent past was the derision which was directed at Wegener 's
hypothesis of continental drift, when the prevailing scientific view was that
land masses were immobile. Although there were some supporters of this view
during the first half of the twentieth century, it was only in the 1950s that
an understanding of plate tectonics led to the general acceptance that
continents are not static. This was a revolutionary shift in thinking, but the
paradigm took many years to change.
But Popper's description was more nearly correct in the case
of cosmology. In the 1950s, there were two competing primary models of the
Universe: the Big Bang and the Steady State. By the mid-60s, the accumulation
of evidence led most astronomers to accept that the Big Bang was the hypothesis
which gave the better explanation of how the Universe behaves.
Coming now to the more topical and contentious case of
climate change, it is clear that science is operating in a Kuhnian fashion.
There are a number of observations which would apparently serve to falsify the
hypothesised enhanced greenhouse effect. Not least of these are the missing
signature of CO2-driven warming (an enhanced rate of warming in the
upper troposphere relative to the Earth's surface) and the lack of warming
across the greater part of Antarctica . The response to
this - from those who do not simply dismiss the evidence out of hand - is to
point instead to evidence which is
consistent with the AGW hypothesis and to introduce a range of fudge factors
such as aerosols to account for the observed lack of correlation between
atmospheric carbon dioxide level and average temperatures.
The behaviour of a great many researchers involved in
climate change is far from Popperian. Rather than test their hypothesis by
trying to falsify it, they look instead for evidence which supports it and, in
a deeply unscientific manner, will often simply dismiss contrary evidence on
the basis of minor flaws or criticism. This is research done according to
prejudice rather than with an open mind. To compound the error, and because
evidence can only be gathered by observation rather than experiment, increasing
reliance has been placed on computer models.
Making headlines in the Guardian last week was a study not
yet even published. Jointly written by Judith Lean of the US Naval Research
Laboratory and David Rind of the NASA Goddard Institute for Space Studies and
due to appear in Geophysical Research Letters, this is billed as the first
analysis of the combined impact of human influences (including CO2
and aerosols), solar radiation, volcanic eruptions and ENSO
(the El Nino Southern Oscillation) on global temperatures.
Their main conclusions are that anthropogenic global warming
has been masked in recent years by reduced solar activity and a lack of a
strong positive El Nino, but that a projected increase in solar activity will
cause temperatures to rise at a rate 50% faster than projected by the IPCC. Many
readers will of course remember that mainstream researchers have generally
downplayed the role of variations in the Sun's output as insignificant in terms
of global temperatures, but there now seems to have been a reinterpretation to
fit the facts.
But the main criticism of this paper (or at least, what has
been reported prior to publication) is that it is not a scientific study but
the output of a computer model. The study smacks of damage limitation, of a
desire to find some rational explanation for the lack of temperature rise over
the past seven or more years. The explanation is that well, yes, natural
variation can be important, but that this is only creating a temporary masking
effect, soon to disappear. Suspicions about the motivation for the paper are
only increased by the Guardian headline: "New estimate based on the forthcoming
upturn in solar activity and El Niño southern oscillation cycles is expected to
silence global warming sceptics".
Highly unlikely, as this is merely hypothesis and,
crucially, it is not directly falsifiable. But what is important is that the
authors are predicting the return of global warming in the next few years, and
that the upward trend will be higher than before. If this does not occur, then
we must conclude that their analysis is wrong. If they are wrong, it may be
because the coming solar cycle will be a weak one, as many people are
predicting. And, if so, the logical conclusion may be that natural cycles are
more important than carbon dioxide emissions.
In the meantime, Henrik Svensmark and colleagues from the
Danish National Space Centre have published a paper in the same journal which
gives support for the hypothesis that cosmic rays, modulated by the solar wind,
can indeed alter the degree of cloud cover and hence affect temperature
(Svensmark et al; Cosmic ray decreases affect atmospheric aerosols and clouds;
Geophysical Research Letters; Vol 36, L15101, doi:10.1029/2009GL038429, 2009).
Their measurements indicate that cloud cover measured over oceans decreases to
a minimum approximately a week after cosmic ray minima. The effect can take
large quantities of liquid water out of the atmosphere. This hypothesis may or
may not be right, but it remains a working possibility and should certainly not
be dismissed lightly.
So, climate science, heavily influenced by global warming
politics, continues to adhere to a central paradigm as described by Kuhn .
Contrary evidence is clearly not going to be accepted as falsification. It will
be fascinating to see what trends there actually are in climate over coming
years and, if the predictions of renewed (and faster) global warming come to
nothing, then what else will be necessary to cause the crisis which will lead
to a paradigm shift. In the meantime, we have to hope that politicians do not
take us too far down the road of trying to control the climate based on the
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