Download Atmosphere and Change 2

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Climate is cyclic. Throughout the ages, the
Earth’s climate has changed often;
Figure 3.7 shows some examples of climate
changes in Greenland;
Even though the number of humans in some
of the eras and ages shown in those charts
was far smaller than what it is now,
Greenland was never a much populated place
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Global Climate Change is due to both
antropic/human causes and natural causes:
Less/more solar activity (e.g. due to sun
storms);
Impact of volcanic activity (excessive dust can
cool off the atmosphere);
Variations in the Earth’s orbit (Chile’s and
Haiti’s earthquakes both changed the axis of
the Earth, which changes its orbit) with
changing distances from the Sun;
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Other phenomena that explicit different
trends in global temperature are:
Excessive melting of the Arctic Sea (40%
thinner now than in 1970s);
All major non-polar glacial systems are in
rapid retreat;
The timing of egg-laying for animals and the
flowering for plants has changed as the
climates have warmed, changing the
distribution of life species as well;
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Precipitation has increased in the northern
hemisphere, especially destructive rain
storms;
Last, but not least, El Niño and La Niña
events; the waters of the Southern Pacific
warm up causing a reverse whirlpool which
affects climate on Earth in the form of extra
thunderstorms, heat waves, tsunamis,
typhoons etc.
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The scale of changes in global temperatures
since the 1980s are unprecedented, which
leads many researchers and geographers to
hypothesise that human activity may be a
significant part of the cause.
“There seems little doubt that global warming
is occuring, although some researchers
question whether it is due to natural
processes or human activities such as the
consumption of fossil fuels”.
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Nevertheless, global warming is a very much
present and ongoing issue on Earth today,
and it is of great importance for us to
understand its behaviour.
Events that may possibly occur, as a
consequence of climate change:
Reduced crop yields;
Less availability of water (especially in dry
areas);
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Land degradation;
Rising sea levels;
Reduced biodiversity;
Deforestation;
Tropical cyclones (Typhoons in northwestern
Pacific - Asia/ Hurricanes in Northeastern
Pacific – North America)
Destructive thunderstorms (increasing
flooding problems)
Serious financial costs.
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There is also concern that global warming might
cause tropical cyclones (typhoons/hurricanes) to
become more frequent and much more intense;
Typhoons are low pressure atmospheric particle cells
(from dust/vapor/gases) that cause winds to exceed
speed of 120 km/h.
They exist over the warm oceanic waters from which
they draw their energy and moisture
When they move over cool water, they lose strenght;
however, when they move over warm or hot water (a
direct consequence of global warming) they can gain
strenght, size, intensity and speed, becoming
devastating to nature and to mankind (one good
example is the Hurricane Katrina, which killed almost
2 thousand people in 2005)
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We have already seen that the greenhouse effect
is, in fact, important for life to exhist on Earth;
However, if the concentration of gases that make
the greenhouse effect possible – gases that retain
heat (i.e. Carbon Dioxide, Nitrous Oxide and
Methane) gets too high, things start to turn ugly
Researchers say that, since the Industrial
Revolution in the late 18th century, the
concentration of these gases in the atmosphere
have been growing, which, in turn, is making the
global temperature rise an average of 0.8 ºC
since 1880
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Since the late 1950s, however, the trend of
global climate change has accelerated, given
to an increase of 17,5% in the annual average
concentration of atmospheric CO2 (carbon
dioxide)
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Have you ever heard of the Kyoto Protocol?
K.P. is a world treaty, created in 1997, which
aims to restrict emissions of greenhouse
gases, especially Carbon dioxide (CO2)
[Ten years earlier, in 1987, the Montreal
Protocol was a treaty to reduce the use of CFC
(Chlorofluorocarbon), which helps to destroy
the Ozone layer]
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In Kyoto, however, it was agreed that:
◦ a) CO2 levels had increased substantially since the
Industrial Revolution (1750-1850) and that this trend
was expected to continue;
◦ Humans had been responsible for much of this increase;
Nevertheless, there was a disagreement regarding how
much of the increase in temperature was due to higher
CO2 concentrations;
There’s a controversy regarding how bad x how good CO2
levels can be to nature: Some say it is vital to plants and
the Flora (and, thus, to the Fauna also); Others say it’s
harmful and it would raise the Earth’s temperature and
melt polar ice caps.
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It is agreed by people from all points of view
that the greenhouse effect is *real*.
Greenhouse gases such as H20 (water vapor)
and CO2 in the atmosphere reduce the escape
of long-wave (emitted from cooler bodies)
infrared radiation (heat) from the Earth into
space.
Therefore, when we increase the
concentration of CO2, we effectively increase
the energy input to the earth.
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At the end of the Kyoto meeting, 38
industrialized countries (including Brazil)
decided to cut their emissions of six
greenhouse gases that were linked to global
warming (CO2/CH4 – methane/N20 – nitrous
oxide/ SF6 - sulfur hexafluoride/HFC –
hidrofluorocarbon/PFC – perfluorocarbon)
By 2005, when the Protocol was made
official, 191 countries had ratified it.
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The countries that have agreed to sign the
Protocol are obliged to reduce emissions of
CO2 to na average of 5,2% below 1990 levels
during the five-year period of 2008-2012
Compared to not doing anything, this
initiative represents a reduction of almost
30% in greenhouse gas emissions
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Significant work on the issue of climate
change has been undertaken by a group
known as the Intergovernmental Panel on
Climate Change, or IPCC, established jointly
by two UN (United Nations) bodies, UNEP
(PNUMA) and WMO (OMM);
The IPCC comprises the elite of the world’s
leading scientists and researchers on
Climatology, Biogeography, Metereology and
Geography
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Several reports have been published by the
IPCC on Global Climate Change;
Each report consists of 4 large volumes that
were finalized at conferences held in
Shanghai (CN), Geneva (CH) and Accra (GH) in
late 2000 and early 2001.
The report suggests that humanity stands on
the edge of a cataclysm as a consequence of
global warming
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How do they reached this conclusion?
By means of extensive measurements
undertaken in the upper atmosphere
(Thermosphere), under the sea, on tundra
and desert, on ice caps, in pollen sediments
and bird nesting records, with satellites and
weather balloons.
The preliminary finding made in 1995
concluded that the balance of evidence
suggests a discernible human influence on
global climate
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The conclusion reached in a further report
was far more alarming: using 6 different
projections about how economies would grow
and how they’d make the transition to noncarbon forms of energy, it was concluded that
the global average temperature would rise
1,7°C to 6,1°C before the year 2100; which
means that, since the current average
temperature on Earth is 15°C, by the
beginning of next century it’ll be 21°C!
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This temperature would mean a huge rise in
the amount of energy trapped in the lower
atmosphere (troposphere) increasing the rate
of almost every natural process except the
volcanic (eruptions) and the tectonic (quakes);
The IPCC states that there’s no doubt that the
climate is warming. The organism notes that
the biggest increases in temperature have
been in the lowest 8 km of the atmosphere,
which is where human impacts are greatest