Study unit 11 LONG-TERM CLIMATE CHANGE AND THE IMPACT OF HUMANS ON THE ENVIRONMENT IN AFRICA Flashcards
What is climate change?
Climate change is a long-term shift in the climate of a specific location or region. The
shift is measured by changes in features associated with weather, such as temperature,
wind patterns and precipitation
explain what the greenhouse effect is
A natural system known as the “greenhouse effect” regulates temperature on earthour atmosphere traps the sun’s heat near earth’s
surface, primarily through the heat-trapping properties of certain “greenhouse gases”.
Earth is heated by sunlight. Most of the sun’s energy passes through the atmosphere, to
warm the earth’s surface, oceans and atmosphere. However, in order to keep the energy
of the atmosphere in balance, the warmed earth also emits heat energy back to space
as infrared radiation. As this energy radiates upward, most is absorbed by clouds and
molecules of greenhouse gases in the lower atmosphere. These re-radiate the energy in
all directions, some back towards the surface and some upward, where other molecules
higher up can absorb the energy again. This process of absorption and re-emission is
repeated until, finally, the energy does escape from the atmosphere to space
what is the combination of greenhouse gases
• water vapour, which is the most common greenhouse gas. Some occurs naturally
and some comes from human activity.
• Carbon dioxide (CO2), which is the most significant greenhouse gas released by
human activities, mostly through the burning of fossil fuels such as coal, oil and
natural gas. It is the main contributor to climate change.
• Methane, which is produced when vegetation is burned, digested or rotted with no
oxygen present. Rubbish dumps, rice paddies, and grazing cows and other livestock
release lots of methane.
• Nitrous oxide, which can be found naturally in the environment; human activities,
however, are increasing the amounts. Nitrous oxide is released when chemical
fertilizers and manure are used in agriculture.
• Halocarbons, which are a family of chemicals that include CFCs or
chlorofluorocarbons (which also damage the ozone layer), and other human-made
chemicals that contain chlorine and fluorine.
what are The causes of climate change
Earth’s climate changes naturally
Other natural causes of climate change include variations in ocean currents (which can
alter the distribution of heat and precipitation) and large eruptions of volcanoes (which
can sporadically increase the concentration of atmospheric particles, blocking out more
sunlight).
Because we burn fossil fuels to heat our homes, run our cars, produce electricity,
and manufacture all sorts of products, we are adding more greenhouse gases to the
atmosphere. By increasing the amount of these gases, we have enhanced the warming
capability of the natural greenhouse effect. It is the human-induced enhanced
greenhouse effect that causes environmental concern, because it has the potential to
warm the planet at a rate that has never been experienced in human history.
What could happen if the climate changes
Increasing
temperatures will lead to changes in many aspects of weather, such as wind patterns, the
amount and type of precipitation, and the types and frequency of severe weather events.
Such climate change could have far-reaching and/or unpredictable environmental, social
and economic consequences
The global sea level could rise due to a number of factors, including melting ice and
glaciers. Rising sea levels could damage coastal regions through flooding and erosion.
The climate of various regions could change too quickly to allow many plant and animal
species to adjust. Harsh weather conditions, such as heat waves and droughts, could also
be experienced more often and be more severe.
Climate change could also affect health and wellbeing. Many large cities could
experience a significant rise in the number of very hot days. Air pollution problems
would increase, placing children, the elderly and people suffering from respiratory
problems at risk. Increases in pollens due to warmer temperatures could also cause
respiratory problems such as asthma for some people
Climate change occurs when the climate of a specific area is altered between two
different time periods. This usually occurs when something changes the total amount of
the sun’s energy absorbed by the earth’s atmosphere and surface. It also happens when
something alters the amount of heat energy from the earth’s surface and atmosphere that
escapes to space over an extended period
what causes these changes
• Natural processes include things such as volcanic eruptions, variations in the sun’s
intensity, or very slow changes in ocean circulation or land surfaces which occur over
decades, centuries or longer.
• Humans can cause climates to change by releasing greenhouse gases and aerosols into
the atmosphere, by changing land surfaces, and by depleting the stratospheric ozone
layer.
What could happen if the climate changes
Increasing
temperatures will lead to changes in many aspects of weather, such as wind patterns, the
amount and type of precipitation, and the types and frequency of severe weather events.
Such climate change could have far-reaching and/or unpredictable environmental, social
and economic consequences
The global sea level could rise due to a number of factors, including melting ice and
glaciers. Rising sea levels could damage coastal regions through flooding and erosion.
The climate of various regions could change too quickly to allow many plant and animal
species to adjust. Harsh weather conditions, such as heat waves and droughts, could also
be experienced more often and be more severe.
Climate change could also affect health and wellbeing. Many large cities could
experience a significant rise in the number of very hot days. Air pollution problems
would increase, placing children, the elderly and people suffering from respiratory
problems at risk. Increases in pollens due to warmer temperatures could also cause
respiratory problems such as asthma for some people
identify 12 major environmental
problems facing society.
(1) We are destroying natural habitats, such as forests, wetlands, coral reefs and
the oceans, and converting them into human-made habitats (for example, cities,
farmlands, road and transport infrastructure) or exploiting them at unsustainable
rates for the resources they offer.
(2) Wild foods, particularly fish, which contribute a large proportion of the protein
that humans consume, are in steep decline, as the ocean’s resources become
seriously depleted. Some two billion people, or one-third of the world’s population,
rely on the oceans for protein; the great majority of these people are poor.
(3) Some wild species and genetic diversity of the planet are under threat, and a
fraction has already been lost. This fraction is likely to grow significantly in the
next 50 years.
(4) Soils of farmlands used for growing crops are being carried away by water and
wind erosion at between 10 and 40 times the rates of soil formation. This means a
serious net loss of soil.
(5) The world’s major energy sources, particularly for industrial societies, are fossil
fuels: oil, natural gas and coal. Except for coal, which will last for a considerable
time still, reserves of the other fossil fuels are likely to last for no more than three
or four more decades, and their extraction will place ever-growing demands on
the environment because of the need for deeper mining or drilling, making them
increasingly expensive and occurring at greater and greater environmental cost.
(6) Increasing pressure is being placed on fresh water resources on the planet. The
majority of these resources is used for irrigation purposes, for industry and for
domestic consumption, as well as for transport, and underground water resources
are being depleted at a greater rate than they are being naturally replenished.
(7) Plants need to photosynthesise in order to grow. In the process of photosynthesis,
they use sunlight to manufacture energy. Even though the supply of sunlight
appears infinite, and therefore the earth’s capacity to grow crops and wild plants
is also seemingly infinite, this is in fact not the case: As human populations grow,
humans will use more and more of the sunlight used in photosynthesis for crops,
leaving less to support the growth of natural plant communities.
(8) Industries, particularly the chemical industry but also many others, manufacture
or release many toxic chemicals into the air, soil and waters of the planet.
Insecticides and pesticides have long been known to be negatively affecting birds
and fish, but more recently other chemicals, such as detergents, the components of
plastic and coolants have come to affect humans too. They affect the quality of air,
water and food, and evidence of their effects on the health of human populations is
growing.
(9) “Alien species” are those species which we transfer, intentionally or unwittingly,
from a part of the planet where they occur naturally to places where they do
not. Some are valuable to us (as crops, for instance), but others are not, because
the natural environment of the new area has no resistance to them, and is
consequently placed under severe threat.
(10) The issues relating to global warming remain a grave concern. As gases such as
carbon dioxide and methane escape in ever greater quantities into the atmosphere,
there may well be winners and losers. Some cooler areas may be able to increase
their crop yields, but other warmer or drier areas will probably see theirs decrease.
Sea levels will rise, seriously affecting many parts of the world, and the full
impact, though uncertain, is likely to be very serious for the majority of the planet.
(11) The human population of the planet is growing, although percentage increases
are beginning to slow. More people require more food, space, water, energy and
resources. There remains disagreement about how population growth will project
in the next 30 to 50 years, but that it will continue to expand seems to be in little
doubt.
(12) The per capita impact of the human population on resources consumed and the
waste generated varies greatly around the world. On average, each person in the
United States, western Europe and Japan consumes 32 times more resources and
puts out 32 times more wastage than inhabitants of the developing world. Many
people in the developing world aspire to higher standards of living and it is clear
that this is not possible or sustainable. This leaves a really difficult problem:
How does one encourage and help all people achieve a higher standard of living,
without undermining that standard through over-stressing global resources?
how has africa been affected by climate change from history
Over past eons of geological time,
the climate of Africa has alternated between cold and dry phases and warm and wet
phases. Sea levels also rose as ice caps melted when temperatures rose, and fell again
during colder periods. Rivers and lakes rapidly filled valleys during wet periods, and
dried out again during the next period of prolonged drought, with some lakes even
vanishing completely. Vegetation responded in kind, with forests plentiful at times,
but deserts dominating large parts of the continent when colder and drier conditions prevailed. Plants and animals, as well as hominids, responded to these climatic changes
mainly by migrating to regions where conditions for survival were easier
how did different farming practises affect the relationships and societal construction in Africa,
Agricultural farming took place mainly in coastal areas due to the reliable sources of water used for irrigation while in the highveld lifestock farming was dominant and this also influenced distribution of wealth and status.
what effect did colonisation have on Africa
Colonial systems of authority and law, new taxation burdens on Africans, and new
demands for African labour all played an important role in altering traditional modes
of existence, but these were exacerbated by the fact that the colonial powers allowed
mainly private enterprises to begin to exploit African countries for resources and for
new crops for export
