The term Global Warming that is often associated with the cumulative impact
of the buildup of greenhouse gases in the atmosphere does not accurately
describe the nature of the consequences of this change in climatic conditions
arising from human activity. The more
appropriate term is Climate Change. The reason for this distinction is that the
near term effect of this phenomenon is not necessarily warming on all parts of
the globe. However, dramatic changes in
climate including temperature are predictable within this model.
Our first order of business is to
examine the science that is the underpinnings of Global Warming. This necessitates an examination of the
earth’s atmosphere. The major components
of the Earth’s Atmosphere are shown in the following table.
*Carbon Dioxide (CO2)
*Water Vapor (H2O)
*Nitrous Oxide (N2O)
Table 1 – Major
constituents of the earth’s atmosphere are reported in percentage and parts per
million (ppm) where * indicates the greenhouse gases.
Chart 1 – Pie chart showing distribution of major components
in the atmosphere and the greenhouse gases (*)
The current level of CO2 in
the atmosphere is 390ppm (as shown below in Chart 2). CO2 is a by-product of respiration
of all living things on the planet.
However, this is normally balanced by the uptake of CO2 by
the world’s oceans and by green plants that are capable of photosynthesis –
these interactions are collectively referred to as the carbon cycle. In this regard, CO2 is the carbon
source for all of life.
Human activity since the dawn of
the machine and the use of oil (hydrocarbon) as a cheap and plentiful source of
energy has resulted in a continuous upward climb of this gas in the atmosphere. The reason for this is that when fossil fuels
are burned for energy, the by-products are CO2 and water.
The following chart shows the increase in the concentration
of CO2 in the atmosphere over time.
Chart 2 –
Concentration of CO2 in the Atmosphere over Time where 1790 represents
the beginning of the industrial age – the steam engine was invented in
The following chart shows these values as a change in
percentage of CO2 per year.
Chart 3 – Change
in Percentage of CO2 per Year.
As can clearly be seen from this
representation, the increase of CO2 in recent times correlates well
with the introduction of industrialization to human societies. This change might not seem dramatic, but a
doubling of the concentration of CO2 from pre-industrial levels is
expected to increase the average global temperature by 2.5 degrees C. From the data shown in Chart 3 it can be
estimated that if the current rate of increase remains constant (0.63%/year)
this doubling would be reached in approximately 100 years. This is an extremely significant increase
with horrendous implications for the earth’s climate. Given the current political and economic
situation throughout the world, it is unlikely that this increase in the rate
of CO2 accumulation will remain static; unless more sustainable
sources of energy are actively pursued.
In addition, even if the human production of this gas were to halt
today, it would take a few hundred years for the current levels to decrease
CO2 is referred to as
a greenhouse gas based on its molecular structure. This gas has the ability to absorb heat and
retain it much like the glass of a greenhouse allows heat from sunlight to pass
freely through it from the outside but prevents some of it from leaving. Therefore, some of the heat that would
normally be reflected back from the earth’s surface and dissipate into space is
retained. The net effect is a general
increase in temperature at the lower part of the atmosphere. The science regarding this property of CO2
is irrefutable. CO2 is
not the only greenhouse gas in the atmosphere; the others as Table 1 demonstrates
are water vapor, methane, nitrous oxide and chlorofluorohydrocarbons (CFC). Increases in CO2, methane and CFC
- synthetic compounds that used to be used widely in refrigerants - are a
direct consequence of human activity; whereas, the amount of water vapor in the
air is not.
There are predominantly two
different processes through which heat is transferred throughout the
atmosphere. One is through radiant
energy as mentioned earlier and the other is through what is referred to as
convection. In this process as air is
heated near the surface of the earth it rises as it becomes less dense and is
replaced by the colder and denser air from above. This process is continuous with the net
effect of transferring heat from the surface to higher reaches of the
atmosphere. It is the greenhouse gases
that trap some of the heat, effectively warming the air in the lower
The planet Venus is a striking
example of the ultimate impact of CO2 on temperature. Scientific probes of the planet have shown
that it has an atmosphere very high in CO2, a dense cloud cover and
a surface temperature of over 500 degrees C.
Although Venus is considerably closer to the sun than the earth, the
thick and nearly impermeable cloud cover would be expected to cool the planet
considerably. However, the exceedingly
high concentration of CO2 in the Venetian atmosphere would explain
most the heat trapped at the planet’s surface.
There are additional processes
contributing to climate change that are important to consider in addition to
the direct greenhouse effect. These are:
The impact that increased CO2 concentrations
has on the oceans including increasing ocean temperature. This gas dissolves to some extent in water
and increased concentrations of dissolved CO2 increases the acidity
of the oceans. This has a significant
impact on marine life and ocean-based ecological systems.
Increased surface temperature in the northern
climes can lead to the enhanced release of methane into the atmosphere from
melting permafrost. Methane is not only
a potent greenhouse gas, it also possesses toxic properties.
An increase in the frequency and intensity of
extreme weather conditions.
Increased melting of land-based ice in the form
of glaciers and especially in regards to Iceland and Antarctica. This can have powerful implications in regards
to sea-level rise. As a matter of fact,
it has been estimated that should all of Greenland’s ice melt, it would cause a
rise of sea level by about twenty-five feet.
Climate change is a very real
phenomenon and, in my opinion, is the greatest challenge faced by all of
humanity. The manner in which this issue
is addressed will have serious repercussions for the future of the human race.