Wednesday, March 08, 2006


Firstly by examining a number of sources climatologists are able to create proxy data therefore giving us insight as to what climatic conditions were, before modern measuring devices were created. This is called palaeoclimate reconstruction. Sources of proxy data include: ice cores in which isotope analysis, physical characteristics as well as trace elements and microparticle concentrations is examined; geological sources include sediments, either marine (inorganic or organic) or terrestrial (aeolian, glacial, preglacial, lacustrine) sediments are determined. Another geological source includes sedimentary rocks, when examining rocks climate is determined by facies, microfossil or fossil, mineral and isotope geochemistry analysis. Biological indicators include tree rings, pollen species and insects; we also look at historical records, for example meteorological, parameteorological and phenological records.


With isotope analysis of ice cores the O18 concentrations determine if polar conditions were warmer or colder as O18H2 freezes in colder polar regions as water ice, therefore having a much lower concentration than in warmer conditions. These findings indicate that we are experiencing higher temperature than in the past hundred years. We also look at the fact that glaciers are drastically retreating causing a rise in sea-level, sea ice shelves are breaking off(Larsen-B ice shelf for example) causing a reduction in ocean salinity, permafrost is melting causing the appearance of potholes and the draining of many lakes as their frozen bases melt away. We also look at the fact that sea temperatures are rising.


We also look at the emission rate of greenhouse gases which has increased drastically over the past 200 years. Greenhouse gases, you could say, play the most important role in climate change as it has a direct influence on temperature. An increase in greenhouse gases then increases global air temperatures due to the greenhouse effect. Examples of greenhouse gases include Carbon dioxide, water vapour, Nitrous dioxide and Methane.


Whether these increases in gases is cause global warming is debated among scientists but anthropogenic influence in global warming is inevitable as proven by records showing an exponential increase in these gases after the industrial revolution.


Reviewed by:Angela Campher

Simone Neethling
BCB Department
University of the Western Cape


Global dimming suggests that although the earth’s temperature is increasing, the rate of evaporation is decreasing. This means that the rays of the sun are not penetrating all the way to the surface.

The evaporation tests were done over years, by farmers out evaporation dishes everyday. Scientists concluded that there is a decrease in the evaporation rate. This could be due various reasons. One of these is the polluted clouds. The suns rays are reflected from the clouds, back into outer space. Pollutants in the clouds are caused by various agents. Fossil fuels are burnt and form by-products that cause the pollution in clouds. It changes the chemistry of the clouds and other aerosols also contribute to the pollution factor.


The only evidence scientist to prove this is after 11 September 1999, when there was an increase of 10C over three days, when the air space above America was not used. This also proved that contrails also contribute to the increase of global dimming. Global dimming is a very serious problem and is linked to various diseases. The only problem we have, is that if we try to fix the problem it could lead to a rapid increase in surface temperature.

Eugene Marinus



Climate change is generally defined as a long term deviation or transformation from the mean and extreme climatic conditions. It has been firmly established that global climate has changed in the past, and more recently through human activities. Climate does vary naturally, with variation in the solar cycle, atmospheric composition and even changes in earth surface features. However change in climate over the last 100 years has shown significant increases in the rate of change, due to mainly burning of fossil fuel and increasing greenhouse gas emissions. A mere 10 000 years ago, marked the end of the 'little ice age' and since then global temperatures has been climbing. Current peaks in atmospheric temperature was last seen during the last interglacial period some 124000years ago. Modeling and signal analysis strongly suggest that or current climatic maximum is indeed anthropogenic.

There are various factors that serve as evidence for climate change. These include atmospheric and oceanic temperature increase, retreating glaciers and melting of sea ice as well as permafrost, rises in sea levels.

Oceanic temperature increase

In the last century there has been an increase in global air temperature of about 0.6 °C. This causes an increase in oceanic temperatures and reduces the solubility of oxygen and carbon dioxide in seawater. Thus global warming is increased because the oceans can't sequester carbon as effectively as in lower temperatures. Increased oceanic temperatures have caused destabilizing in major oceanic currents, for example the North Atlantic thermohaline circulation. The slowing down or total shutdown of this current would prevent heat transfers from the tropics to the poles and the transport of cool water from the poles to the tropics. Not only will the poles significantly decrease, and tropics increase in temperature, but cold nutrient rich bottom waters from the poles will also be unable to surface. Hence, leading to decreased phytoplankton primary productivity. In the last century, warmer temperature has resulted in more frequent and intense El Niño events with reduced La Niña events.

Atmospheric temperature increase

Atmospheric temperatures have shown remarkable increase, directly related to the increase in carbon dioxide emissions by various human activities (mainly fossil fuel burning). The increase in atmospheric temperature is due to the greenhouse effect by which long wavelength radiation (re-radiated from the earth's surface) is prevent from leaving the atmosphere directly. This heat is trapped by what is known as greenhouse gasses (CO2, methane, CFC's etc.).

Retreating glaciers

Almost all glaciers worldwide, except in New Zealand and Norway, are retreating because of increasing atmospheric temperatures. Glacial retreats at the poles, directly contribute to sea level rise. The ice in the Alps hasn't melted for centuries, but recent recession led to the discovery of the 5000 year old "ice man".

Melting of sea ice

Globally, there has been a reduction is sea ice of 13 500 km² to present, due to increasing temperatures. The reduction is clearly visible from satellite data. In 2002, the Larsen B shelf disintegrated, loosing a total of 5700 km² of ice. The melting of sea ice decreases oceanic salinity, and so doing influences oceanic salinity, and so doing influences oceanic deep water currents. Melting of sea ice decreases surface albedo, and so doing causes subsequent oceanic and atmospheric warming.

Sea level rise

Sea level rise is impart due to thermal expansion. When heated, water molecules expand and increase in volume. The main contributor to sea level rise is however glacial melting and subsequent inflows into the oceans.

Melting of permafrost

Large portions of permafrost in the Northern Hemisphere are currently undergoing thawing throughout the year as a result of increasing temperatures.

Changes in rainfall patterns

Globally, terrestrial precipitation has increased with 2% in the last 1000 years. However some isolated areas such as Sub Saharan Africa has actually experienced decreased rainfall. Globally, rainfall patterns are becoming more intense with a deviation from normal precipitation temporal cycles. More frequent, extreme weather events has alo been seen in recent years.

M.van der bank

review: Wynn Haupt


Global dimming is a relatively new phenomenon that is not fully
understood by the general public but has caused some major impacts on
the climate, global dimming is caused by having large particles or
aerosols in the atmosphere that provide sites for water to condense in
clouds, smaller particles, smaller particles can only held small amounts
of water droplets on it but the aerosols and other larger particles
allow more water droplets to form and stay in the atmosphere and reflect
incoming radiant energy from the sun, which causes a cooling affect on
the Earth, pollution particles from the burning of fossil fuels
contribute to global dimming.

Global dimming works oppositely to global warming, which increases the
surface temperature of the earth between 1960 -1990 but recent evidence
indicate that the trend reversed, both these phenomenon is caused by the
burning of fossil fuels, therefore in the theory these two phenomenon
would cancel each other out and the climate of the earth would remain in
constant temperature, but the combustion of fossil fuels releases
harmful gases that threaten human life and most first world countries
have begun to implement strategies to reduce the pollutants in the
atmosphere by using catalytic converters on cars, the use of unleaded
fuels and other methods to reduce CO2 levels and other harmful gases in
the atmosphere.

This improvement on air quality has reduced the amount of aerosols in
the atmosphere and has reduced the affect of global dimming but has
increased the effect of global warming.

It's now believed that global dimming is responsible for the 1984
Ethiopian Famine, which has been called by a BBC reporter as being :
"The closest place to hell on earth", which saw hundreds of
thousands of people dying of starvation, but how does global dimming,
which cools down the earth cause drought and famine?

The answer is that this phenomenon reduces the amount of incoming
photons from the sun to the earth and reduces the PAN evaporation rate
reducing the amount of photons hitting the ocean and replenishing the
water cycle of Ethiopia.

Today many studies are being conducted about global dimming and what
really causes it, some scientists believe that aero planes create a
blanket of aerosols over the earth and therefore creating a cooling
affect which was seen after the September 11th terrorist attacks, where
all air crafts were grounded for a week.

Global dimming is an issue that must be taken seriously because we do
not fully understand climate and the rate at which the climate is
changing over the world and the consequences of the these changes are
going to be disastrous on future generations

Reviewed by: Lee Mervin Mentoor, 2111335

Ashton Mouton
Student Number: 2432509
University of the Western Cape
Private Bag X17
Bellville 7535

E-mail: 2432509@uwc.ac.za


Global dimming is the result of an increase in the amount of light being
reflected out of the earth's atmosphere and thus causing a drop in solar
energy or solar radiation. The main contributors to Global dimming are
thought to be the by-products of fossil fuel use such as sulphur
dioxide, soot, and ash (www.globalissues.org). These pollutants change
the properties of clouds as the excess air-borne particals result in
clouds with larger number of droplets and thereby making them more
reflective (turning the clouds into gaint 'mirrors).
Between 1950 and 1990 there have been recordings of a drop in solar
radiation over various places. The following readings were obtained:
60 % over parts of the British Isles
30 % over Russia
22 % over Israel
10 % over the U.S.A, and
9 % over Antarctica
Although there has been a drop in solar radiation the earth is getting
hotter instead of cooler. This can be attributed to the effects of
Global warming as the trapped CO2 in the atmosphere is making the earth
hotter. The full extent of the warming caused by Global warming is
masked by the cooling effects of Global dimming and thus Global warming
is greatly underestimated.If, however, the problems of global dimming
are only addressed, then the effects of global warming will increase
even more.

Nashreen Williams
University of the Western Cape
E-mail 2318364@uwc.ac.za


What is causing all the shortages problems and what could be done to minimize the problem?

None other than the human species causes all these energy and resources problems. Greed has plaid a big role in it, what has happened is that people wanted to raise their economic growth that they took resources from the earth till there is virtually no more to take. Another major problem that needs to be addressed before coming up with sustainability options is the population bloom, already the world is carrying 4 more billion people than it was intended so you can only imagine just how much shortage of resources we are going to go through. Each country could also initiate a program where each family’s energy resource expenditure is monitored and kept under control e.g. the water restrictions in Cape Town. We will not run out of all our resources in the near future but there will come a time when we will have to purchase air at the rate we are going.



  1. journeytoforever.org/biofuel.html
  2. EAT  statistics on pollution and resources Dr. Richard White



One could always raise solar energy as an alternate source of energy but how possible is this, does it have a future with humans?

Solar energy is another form of clean renewable energy. We already have an advantage that we have a natural reservoir of solar power, which is the ocean. This already cuts out expenses when it comes to the buying of reservoirs. This type of energy could aid us to sustainability but the question then becomes that what would humans do differently that they failed to do to preserve fossil fuel? The disadvantages of this is that it is far too expensive to retrieve for humans to live on it for the rest of humankinds life, secondly when looking at statistics, humans use up as much solar energy a day that it has taken the earth a year to store. The other question then becomes how sustainable is it if humans are already going far above the storage capacity in expenditure


With the use of proxy data such as glacial ice cores, tree rings,
sediments and historical data, scientist are able to determine climate
variation. By looking at something like tree ring thickness for example
you are able to determine the favourability of climatic conditions. We
know from this data that the Earth goes through cycles of extreme heat
and extreme cold. The last ice age occurred 10 000 years ago which is
relatively recent. It is thus highly likely that the increase in
temperature we have been experiencing could just be one of the natural
cycles of the Earth.

Is it possible tha humans might have a hand in it as well? The
naturally occurring greenhouses gases which under normal conditions,
maintain optimal living conditions on Earth, has seen a significant
increase. The increase of these gases means that more and more of it
gets trapped in the atmosphere, heating up the Earth more and more. The
greenhouse gases CO2, methane and CFC's are released through human
activities such as the burning of fossil fuels, from landfills and from
aerosol spray cans. The beginning of the industrial revolution saw the
levels of CO2 increasing from 0.37 in 1900 to . The same could be said
of all the greenhouse gases. The fact that climate change is human
induced can therefore not be argued.
Reviewed by Ashton Mouton and Dane Mcdonald

Ilse Kotzee
Student # 2456349


Global-dimming is the process whereby solar radiation is prevented from reaching the earth's surface by aerosols such as soot and dust. Air transport is a major player in global dimming due to the fact that it releases many aerosols in the troposphere. This was proved when there was a 1ºC increase in the U.S after 9/11 due to the inactivity of airplanes for only three days. Subsequently, reports indicate that the rate of dimming is increasing at 2-3% per decade, worldwide. The aerosols either block or reflect large amounts of sunlight. Hence, in Israel there was a notable decrease in evaporation. Aerosols also affect cloud formation due to excessive precipitation around particles.

Global-dimming is a factor that should be taken very seriously for a number of reasons. It is a factor that counter-balances the effects of global-warming. This means that as climate is warming due to the emission of greenhouse gasses there is the directly proportional effect of global-dimming. An inevitable question is: "What if emissions are decreased? Will the decrease in global dimming, cause excessive warming? Or vice-versa.

The impacts on natural processes (e.g. decreased energy) could be devastating. Excessive drought, which is evident in the Sahel area, is due to the inefficient movement of air from the tropics to temperate regions. This is a death sentence for impoverished people living in that area.

Hence it is clear that various questions and factors concerning global-dimming need to be taken seriously.

Dane McDonald
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535


Hybrid cars have been produced, with the intensions of improving reliability, productivity and environmental awareness. Climatic problems, which have been associated with sub tropical regions, have been taking into consideration as well. Most fossil fueled vehicles consume 10 times more energy above there capital cost each year. Hybrid cars however can save between 15 and 40 percent of electricity without reducing speed or reduce power.



What are biofuels, why are they important to human being?

Bio fuels are a form of renewable energy produced from organic matter, they are basically fuels made from cellulose biomass, and they include ethanol, bio diesel and methanol. What makes them so special is the fact that they are clean sources of energy that everyone can grow themselves from renewable resources. They can be used to power machinery and electricity generators. They are important to human beings because they would somewhat aid in sustainability since they are clean thus less pollution in the air as well as the fact that they are relatively cheap to grow. The major disadvantage though is the fact that we do not have enough land world wide to grow enough of these fuels for at least every family, which means that they could never be our only source of energy other sources still have to be found, another problem is the fact that there is already little crop produce world wide so would people rather eat their produce or generate energy with it?



Biomass is organic matter of recent origin. Biomass, which is also known as biofuels, do not use fossil fuels to produce energy. The carbon dioxide, which is liberated when energy is generated from biomass, is equaled out by that absorbed during the fuels production. Biofuels are produced from organic matter, which can either be from plants directly or indirectly from industries and commercial sectors. Biomass can be used in the home environment; stoves can be 80percent more efficient. Wood burning stoves can be fitted with a boiler to provide domestic hot water and central heating via radiators. Hence producing energy form biomass has both environmental and economic advantages. It is cost effective and it can also contribute to waste management, by harnessing energy from products, which are often disposed of.



Global dimming is a term describing the gradual reduction in the amount of global hemispherical irradiance (or total solar irradiance) at the Earth's surface Global dimming creates a cooling effect that may have led scientists to underestimate the effect of greenhouse gases on global warming.

It is now thought that the effect is probably due to the increased presence of aerosols and other particulates in the atmosphere. It is thought that the water droplets in clouds collect around the particles, resulting in the clouds consisting of a greater number of smaller droplets, which in turn makes them more reflective: bouncing more sunlight back into space.

Clouds intercept both heat from the sun and heat radiated from the Earth. . Usually, during the day the interception of sunlight predominates, giving a cooling effect; however, at night the re-radiation of heat to the Earth slows the earth's heat loss.

Global dimming should be taken seriously as it has negative consequences on our environment. if the amount of energy from the sun decreases, it will affect the rate of photosynthesis of plants and other autotrophic organisms, it will also result in a decrease in global temperature. however global dimming, reduces the amount of sunlight entering the atmosphere, it also keeps out harmful uv rays. After September 11, air travel stopped in America climatologists, found that the air temperature raised by a significant amount, this was because there was a decrease in pollutants in the air, and more sunlight was able to penetrate. it was a clear indicator the pollutants are the major contibutor to global dimming.

Peer reviewer: Celeste Thomas.




The concept of global dimming comes as a counter act to that of global warming. Both are ironically due to pollutants in the atmosphere. Just as much as the earth would be below the freezing point of water without global warming, so it is that without global dimming the earth would be scotching hot. Global dimming is caused by what we know as aerosols. Aerosols are a mixture of dust water or soot that cause turbidity in the atmosphere. These aerosols then cause a cooling of the atmosphere by acting as catalysts in the formation of clouds. Clouds formed by aerosols are more reflective of both heat and light sending the rays back into space. I think that without global dimming the earth would already be in a state whereby it is impossible to live in due to the fact that global warming is a reality and on the increase. In fact the magnitude of global warming is not entirely felt because aerosols mask the whole effect. It is for the above stipulated reason then that I feel we should be concerned, if not I think we will be deceived into thinking the effects of global warming are minor whereas its just global dimming masking it.


Global circulation models is computational models which scientists use to estimate or determine how much climate has changed over a period of time(periods are coarse). They use proxy data which they get from geological time periods (e.g. Holocene) to determine what the climate was at that time and what the atmospheric conditions was during that time scale. The sources they use ranges from ices-cores, tree rings, marine sediments, glacial deposits and many more. The evidence that they get is then used to determine possible climate changes in the future. They also use climate forcings like carbon dioxide, aerosols, etc. to give more accuracy to their predictions.

There are many different circulation models that they use which ranges in complexity and computational density. The accuracy of the predictions depends on how far back proxy data are dating. The further back the less accurate predictions will be. Although the climate models of today are farley accurate, they are constantly replaced by models that give more comprehensive monitoring equipment.

Lee- Mervin Mentoor


University of the Western Cape

reviewed by: Ilse Kotzee


A global climate model is a model that is used to predict climate change
over a period of time. It could be a model of one to three dimensions or
even have no dimensions like that of Energy Balance Models.
These models take into account various forcing- and anthropogenic
"Once historical and climatological data has been collected , we have
some idea of how the climate has changed in the past, and we also know
what atmospheric and biological conditions were associated with this
This allows us to build and test models of the interaction of climatic
variables. These models allow us some capacity to then establish how a
given change in certain factors will affect future climate."

Lucille Radun
University of the Western Cape
E-mail 2362070@uwc.ac.za


In order to determine whether the climate is changing we need to compare
current data with historical data, which will be able to tell us if the
climate has changed and how much. Most climate change has been
attributed to human activity with the environment.

The first piece of evidence which suggest that the climate is changing
is the constant melting of glaciers. This is called glacier retreat,
which is due to an increase of temperature. The melting of the glacier
could contribute to the rise in the sea level.

There has also been an increase in precipitation world wide this is due
to there warming of the earth. Although there are cases where the rate
of precipitation has decreased.

Another concern that indicates climate change or which could be the
cause of climate change is the increase in the greenhouse effect and
increase in green house gases, these gas trap uv radiation intern
heating up the earths surface and possibly increase the ocean
temperature. This increase in temperature due to the greenhouse effect
could be the cause of increase in precipitation, glacier melting and
cause extreme weather conditions such as cyclones.

It seems as if one change induces another change like a ripple effect so
how is it that it got started? The next question should be how are we as
humans going to slow down these changes which are changing our climate
or how are we going to stop it.

Reviewer Megan Van Der Bank