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20 November 2009
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Climate change, global warming and the
greenhouse effect are all names used more or less interchangeably for
the same thing, often incorrectly.
How many times have we heard people
say during a warm spell, "Must be global warming" or during a
cold snap, "Where is this global warming?"? I must have heard
them a hundred times or more, yet it is all wrong. Yes, all
wrong! Weather has nothing to do with climate and climate has
nothing to do with weather. So, let's define them, to try and
make the issue clear:
| Climate: |
The prevailing atmospheric
phenomena (sun, rain, wind, humidity etc.) of a region,
averaged over many years, and creating the biota of that
region.
|
|
Weather:
|
The instantaneous atmospheric phenomena (sun, rain,
wind, humidity etc.) at one given place and time. |
Let me emphasise the difference by
an analogy; a very rich man, with all his wealth invested
wisely, may not have much cash in his pocket, while a very poor
man, living on the vital minimum, may have a lot more money in
his pocket on the day he collects his benefits. The wealth of
these two men is their financial climate, while the cash in hand
is their weather. It can be a cold day in Central Africa, or it
may be a warm day in Antarctica. It can rain in the Sahara
desert or there can be a drought in Central Borneo.
Global climate is the climate of
the whole planet or the averaged climate of all regions. A heat wave over
Cyprus in early August is "normal weather", just as much as snow in the
Troodos mountains in winter. Even if the heat wave, one year, hits record
daytime maxima of 47°C or more, it is still weather and it is unlikely to
show any change in the climate and it certainly will have almost no effect
on the average global temperature and, even less, on the global climate.
If the earth had an inert
atmosphere, it would be a very cold, inhospitable place, with a
global average air temperature of about -18°C. In fact, the
global average temperature is between 14° and 15°C. Why? The
answer is global warming. In the hypothetical first case, all
the energy in the sun's rays striking the earth's surface would
heat it up (if the earth did not have a hot core and there were
no sun, its temperature would be close to absolute zero).
However, much of this energy would be radiated straight out
again and equilibrium would be reached at -18°C. In reality, it
is not like that, because of global warming, without which life
as we know it could not exist. In fact, global warming has
existed for many millions of years.
To explain this, let us take the
analogy of a greenhouse. All the sun's energy passes almost
uninhibited through the glass and heats up the inside surfaces
to above ambient temperature. However, glass will not allow the
long wavelength energy which the warmed surfaces could radiate
to escape, so the air inside the greenhouse also increases in
temperature. So it is with the earth, except that we are not
surrounded by glass but by certain gases which have the same
effect of not allowing the energy stored in the earth's surface
to escape into outer space. The average global temperature is in
a careful equilibrium dependent on many factors and parameters.
The concentration of these "greenhouse gases" (GHGs) is
one such factor, and a very important one at that.
What are these
greenhouse gases? The most important one is water vapour, which
averages about 1 per cent by volume over the planet. In terms of
weather, the concentration is extremely variable from the dry
air of a sirocco wind to a dank Scotch mist, but the average
over time is very constant and is governed largely by
evaporation from the oceans and vegetation. The quantity of
water in the atmosphere is so great that man cannot change the
overall global amount, not even by his worst efforts, so that a
natural equilibrium pertains. The next greenhouse gas and the
most important from the point of view of climate change is
carbon dioxide. The concentration of this has increased from 280
to 360 ppm in the last 125 years and this change is due to human
activities, mostly burning extracted minerals, such as coal and
oil, from where they have resided for millions of years under
the earth's surface (for a further treatment on this subject,
see the essay on Sequestration). However, carbon dioxide and water vapour are
not the only greenhouse gases, nor even the worst ones. If
carbon dioxide is given an index of 1, called the Global Warming
Potential (GWP), representing the rise in resultant temperature
for a given mass, methane has a GWP of about 40, meaning it is
40 times worse. Fortunately, there is only about 0.00017 per
cent of methane in the atmosphere, but that has more than
doubled in the last 150 years, again because of man's
activities. This is largely because of leaks of natural gas
(increasing yearly), waste gases in petroleum refining,
increased areas of rice paddies and increases in the numbers of
cattle (enteric fermentation within a single cow will produce
several litres of methane per day!), all of them resulting from
human activities (on the other hand, draining wetlands would
cause a slight reduction of natural methane). Nitrous oxide has
increased from 280 to 312 ppbv (parts per billion by volume) in
the same period, relatively modest, in comparison. However, the
worst of the lot are all man-made compounds, mostly containing
fluorine. Hydrofluorocarbons (HFCs) often have GWPs between 500
and 2000, while perfluorocarbons (PFCs) may even exceed 10,000.
Happily, the concentrations of these gases is still very low, a
fraction of 1 ppbv. However, HFC production has increased
enormously over the past two decades as a result of using them
as substitutes for CFCs, banned by the
Montreal Protocol. In particular, HFC-134a is a very popular gas for
refrigeration and air conditioning.
It can be seen from
the above graph that the average temperature in Cyprus has
increased by a little over 1°C in the past century. The red line
is the mean annual temperature and the blue line is the average
over the five preceding years, which tends to smooth the curve.
This does show that we are suffering from a small climate
change.
Over the same period,
we can see that the rainfall has dropped by as much as about 100
mm or 20 per cent, although the fluctuations are much greater,
even as much as in a ratio of almost 4:1. This is serious,
because the population, and thus water demand, has increased by
about 50 per cent since 1950, not counting an increased usage
because of better hygiene.
Although the observations and the
theory closely correlate, there is still no absolute scientific
proof that the increase of greenhouse gases due to human
activities is a contributory cause of climate change. The
evidence is circumstantial, but very strong (many murderers have
been executed on much weaker evidence!). It is therefore
reasonable to discuss the ramifications of this, as if it were
proven. In the unlikely event of it being proved wrong, no harm
will have resulted, only good, so it's a double-whammy in favour
of action being taken.
As can be seen from
the above graphs, Cyprus has a hotter, drier climate than it had
a century ago, even if we cannot prove that the cause is
man-made. This is serious because it means changes to our
nature, especially as we are taking more out of the land than
ever before.
Recent research
(2004-2005) is tending to show the correlation between the
emissions of man-made GHGs and the resultant effect on global
climate is becoming stronger. Worse, a study by scientists at
Oxford University is predicting a greater effect on climate than
hitherto believed possible, with global temperature rises of up
to a maximum of 11°C by the end of this century. This is based
on the fact that polar and oro-glacial ice is already melting at
a much faster rate that was previously forecast. If this extreme
prediction came to pass, then life on earth, as we know it
today, will become very precarious and the human population
decline may become much greater, because of famine and disease.
Personally, I think that there is much more research necessary
to be able to subscribe to the worst doomsday scenario, but we
must not discount the possibility, either.
The earth's climate and weather is
the result of a delicate balance between a host of different
natural phenomena:
-
the "greenhouse effect"
-
solar radiation
-
the sunspot cycle
-
elliptical orbits of the earth
and moon
-
wobble of the earth's axis
-
the earth's magnetic field and
positional polar changes
-
ocean currents
-
continental drift
-
atmospheric convection cells,
notably the Hadley cell
-
photolysis and hydrolysis of
organic matter
-
volcanoes
-
sulfate aerosols and other dust
sources
-
transpiration of living
organisms
-
forestation
-
the size of the ice caps
-
and many others...
A modification of any one of these
may induce rapid changes of weather or slower changes of
climate, depending on how and the length of time of the
modification. Some changes may involve negative feedback, which
will tend to restore the status quo while others may
involve positive feedback which may tend to cause a runaway
effect. As a hypothetical example of negative feedback, let us
assume that the sun's radiation increases, causing a small rise
of the temperature of the surface oceanic water; evaporation
will increase, causing a heavier water vapour loading and more
clouds form; the clouds have a high albedo and more radiation is
reflected back into space, so the ocean water will tend to cool
down again. An equally hypothetical example of positive feedback
is that if a large tract of tropical rain forest were cut down
for timber or to claim farm land, there will be a very reduced
mass of vegetable matter and less transpiration will occur,
resulting in lower regional rainfall; this will result in an
inability of the remaining forest to sustain itself and it will
slowly die off from the edges, causing desertification which
will encroach continually and more rapidly until no rain forest
is left.
What is sure is that the earth's
regional climates do change, as is shown by the ice ages and by
evident changes of vegetation over time. This is a perfectly
natural phenomenon, usually taking many thousands of years.
What is equally sure is that the
earth's average temperature, throughout the world, has increased
by nearly 1°C over the past century or so. Never has such a
change occurred in so short a length of time, since we have been
able to follow the evolution of the earth's climate, dating back
a few thousand years. As this is coincident with the increase of
greenhouse gases caused by man's activities, the hypothesis of
the latter being causal becomes inevitable. This has caused many
of the world's most eminent atmospheric scientists to attempt to
determine whether the observations result from the supposed
cause. The main way that this has been tackled is to calculate
mathematically all the potential identified causes, outlined in
the above list, and their probable effect on the global
temperature. Their results have been published in many
scientific assessments and can be summarised by:
These graphs were published by the
Intergovernmental Panel on Climate Change (IPCC) under the
auspices of the United Nations Environmental Programme (UNEP),
which instigated this research. It can be seen, in graph (a)
that natural phenomena alone cannot explain the observed rise in
temperatures, especially since 1950. Man-made greenhouse gases
alone do not fit the observations, either, especially between
1930 and 1980, as shown in (b). Combine the two, producing graph
(c), and the fit is visibly very good. Note that the model
results take into account potential tolerances, due to
incomplete knowledge (e.g., the tonnage of dust reaching the
stratosphere from a violent volcanic explosion). The models take
into account the minimum and maximum values, where there are
uncertainties, therefore the grey lines in these graphs are
broader than the observations line.
Note that the red line in graph
(c), between 1900 and 2000, is similar in shape and amplitude to
the blue line in the average temperature curve for Cyprus. This
shows that the changes we are experiencing are probably the same
as in the rest of the world.
I don't believe it is necessary to
say much more than that the average climate change is causing
several effects, some of them potentially severe. It does not
really matter whether the change is caused by human activities,
it is happening. The obvious ones have been mentioned in the
press that we are all sick and tired of hearing them: ice cap
meltings, atolls and low-lying land disappearing, increased
desertification, biota changes, increasing violent weather
phenomena etc.
The only statement that can result
from this is:
if the changes are due partially to human activity, as
seems most probable, then we should do everything in our power
to reduce their effect as quickly as possible; if they are not
due to this, then it will do no harm if we try to reduce their
effect. In other words, we should do our best to restore
the average climate to what it was over a century ago.
If we wait for formal scientific
proof before doing anything, then it will be too late. The only
reasonable time scale to reduce GHG emissions is immediate
or sooner.
For me, this is the most telling
argument to act rapidly. If carbon dioxide were the only
problem, then the urgency would be less. The problem is that
every vehicle exhaust pipe, every power station stack, every
domestic chimney, if these are all using fossil fuels directly
or indirectly, is emitting other pollutants. These are causing
diseases of epidemic proportions. Skin and lung diseases,
including cancer, emphysema and asthma are just the tip of the
iceberg, the visible results. The invisible results are damage
to the body's immune system and a whole host of other new and
old diseases find it even easier to gain a strong foothold.
These indirect costs of our fossil-fuel economy are swingeing
and are bleeding health services dry in most countries. If we
reduce carbon dioxide emissions by 20 per cent, the cost may be
high but the collectivity would save far more than it would
cost.
I ask all those who are over about
50 to think back to how many kids in your class suffered from
asthma. Then ask how many kids in a class of 30 have an inhaler
in their pocket today.
This report shows that, in the USA, school absence days due
to asthma in 1980-82 were 6.6 million, rising to 14.0 million in
1994-1996. Other reports evoke a 160 percent increase in the
last ten years. Other juvenile diseases, such as severe
migraines, rheumatoid arthritis and diabetes have been following
similar progressions. I am not saying that these are all
directly due to pollution from burning fossil fuels, but I am
sure that it is contributory.
Over the past few years, we have
seen outbreaks of a number of apparently new diseases or an
increase in the apparent virulence of previously known diseases.
These include bird 'flu, SARS, ebola, Creutzfeldt-Jakob disease
and a number of others. Have you not thought that the reason why
these are becoming serious is not because they are new (they
have always been around in other species) but that the human
immune system is weakened and cannot fight against trans-species
transmission? I have no proof of this hypothesis, but neither
can I rule it out. What we do know is that immune system is
weaker, partly because improved hygiene does not expose us to as
many pathogens as in the past and partly as a result of
pollution-related effects.
I therefore state, quite
categorically, that we cannot afford NOT to act against
fossil fuels for fear that the cost of health care will be out
of the reach of ordinary people. Health care and
insurance is the biggest economic inflationary influence in most
countries, developed and developing alike.
The Kyoto Protocol, which is
designed to reduce GHG emissions, has now entered into force.
The adoption by the USA is very unlikely, as the Bush
administration has pronounced an opposition to it, for purely
selfish reasons; it is aberrant that 5 percent of the world's
population emits 28 per cent of the GHGs that cause such
problems and literally intends to do nothing to improve the
situation, other than lip service. Cyprus ratified the Protocol
in 1999.
The EU has unilaterally agreed to
reduce GHG emissions by an average of 8 percent from 1990 levels
by 2008 - 2012. Within member-states, this will vary according
to a number of factors and Cyprus will benefit from some relief.
In addition to this, if one state exceeds its reduction "quota",
it can sell the difference to other member-states that have not
reached their's, so there is some degree of flexibility, albeit
costly.
Can Cyprus make any significant
reduction from its 1990 levels? I'm afraid that the answer is
probably negative for the following reasons:
-
The expanding tourist industry
since 1990
-
The increased per capita
electricity demand (especially for air conditioning)
-
Desalination plants
-
The increased numbers of cars
and HGVs (doubled since 1983)
-
The increased use of fossil
fuels (LPGs and light heating oils) for house heating
Cyprus can make a contribution to reducing
its GHG emissions, even below 1990 levels, but it will require a strong
will and sacrifices from its population. The means of doing so are
outlined in a number of the other essays on this web site. It will
depend on a mix of improved public transport, changes in fuel types,
especially for electricity generation, renewable energy sources and,
above all, the will to do so by the people.
Climate change
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