The causes of climate change can
be divided into two categories, human and natural causes.
It is now a global concern that the
climatic changes occurring today have been speeded up because of man's
activities.
The natural variability and the
climate fluctuations of the climate system have always been part of the
Earth’s history however there have been changes in concentrations of
greenhouse gases in the atmosphere growing at an unprecedented rate and magnitude.
The United Nations, governments and many top scientists around the world
believe that we must act now to stabilise and arrest further changes.
To understand climate change fully, the causes of climate
change must be first identified. Scientists divide the causes into two
categories, natural and human
causes.
Causes of Climate Change
Natural Causes of Climate
Change
The earth’s climate
is influenced and changed through natural causes like volcanic
eruptions, ocean current, the earth’s orbital changes and solar
variations.
Volcanic eruptions
- When a volcano erupts it throws out large volumes of sulphur
dioxide (SO2), water vapour, dust, and ash into the atmosphere.
Large volumes of gases and ash can influence climatic patterns for
years by increasing planetary reflectivity causing atmospheric
cooling.
Ocean current
- The oceans are a major component of the climate system. Ocean
currents move vast amounts of heat across the planet. Winds push
horizontally against the sea surface and drive ocean current
patterns. Interactions between the ocean and atmosphere can also
produce phenomena such as El Niño which occur every 2 to 6 years.
Deep ocean circulation of cold water from the poles towards the
equator and movement of warm water from the equator back towards
the poles. Without this movement the poles would be colder and the
equator warmer. The oceans play an important role in determining the
atmospheric concentration of CO2. Changes in ocean circulation may
affect the climate through the movement of CO2 into or out of the
atmosphere.
Earth orbital changes
- The earth makes one full orbit around the sun each year. It is
tilted at an angle of 23.5° to the perpendicular plane of its
orbital path. Changes in the tilt of the earth can lead to small but
climatically important changes in the strength of the seasons, more
tilt means warmer summers and colder winters; less tilt means cooler
summers and milder winters. Slow changes in the Earth’s orbit lead
to small but climatically important changes in the strength of the
seasons over tens of thousands of years. Climate feedbacks amplify
these small changes, thereby producing ice ages.
Solar variations
- The Sun is the source of energy for the Earth’s climate system.
Although the Sun’s energy output appears constant from an everyday
point of view, small changes over an extended period of time can
lead to climate changes. Some scientists suspect that a portion of
the warming in the first half of the 20th century was due to an
increase in the output of solar energy.
Human Causes of Climate Change
"It has been
demonstrated beyond reasonable doubt that the climate is changing
due to man-made greenhouse gases. We are already committed to future
substantial change over the next 30 years and change is likely to
accelerate over the rest of the 21st century."
The Met Office,
Hadley Centre, UK
"The Hadley Centre
holds an unique position in the world of climate science. No other
single body has a comparable breadth of climate change science and
modelling, or has made the same contribution to global climate
science and current knowledge."
Independent Review
2007
The Industrial Revolution in the 19th century saw the large-scale use of
fossil fuels for industrial activities.
Fossil fuels such as oil, coal and natural gas supply most of the energy
needed to run vehicles, generate electricity for industries and
households. The energy sector is responsible for about ¾ of the carbon
dioxide emissions, 1/5 of the methane emissions and a large quantity of
nitrous oxide.
Carbon dioxide is undoubtedly, the most important greenhouse gas in the
atmosphere. Changes in land use pattern, deforestation, land clearing,
agriculture, and other activities have all led to a rise in the emission
of carbon dioxide.
Methane is another important greenhouse gas in the atmosphere. It is
released from animals such as dairy cows, goats, pigs, buffaloes,
camels, horses and sheep Methane is also emitted during the process of
oil drilling, coal mining, leaking gas pipelines, landfills and waste
dumps.
The certainty of global warming can be seen through some of the natural
phenomenon like the effect on crops and extreme weather conditions
around the world. It is especially clear in the dramatic change of the
polar caps, i.e. the Arctic ice cap is shrinking and the Antarctica ice
shelf is melting.
Main Contributors and Causes of
Climate Change
According to the UK Government the main
contributors of man made causes of climate change in the UK are:
* 4% of carbon emissions come from industrial processes
* 7% come from agriculture – for example methane emissions from
livestock and manure, and nitrous oxide emissions from chemical
fertilisers
21% carbon emissions from transport
65% come from the use of fuel to generate energy (excluding
transport)
About 40% of carbon emissions in the UK are the result of decisions
taken directly by individuals. The biggest sources of emissions for most
people are likely to be:
*
energy use in the home (the main use is heating)
*
driving a car
*
air travel
There other elements of people's homes
that contribute to climate change indirectly.
Everything, from furniture to computers, from clothes to carpets, all
use energy when it is produced and transported – and this causes carbon emissions
to be released.
Want to learn more on the causes
of climate change? Then take a look at the video below.
Agriculture as a Contributor to
the Causes of Climate Change
According to the
Intergovernmental Panel on Climate Change, the three main causes of the
increase in greenhouse gases observed over the past 250 years have been
fossil fuels, land use, and agriculture.
Agriculture has been shown to produce significant effects on climate
change, primarily through the production and release of greenhouse gases
such as carbon dioxide, methane, and nitrous oxide.
Another contributing
cause of climate change is when agriculture alters the Earth's land
cover, which can change its ability to absorb or reflect heat and light.
Land use change such as deforestation and desertification, together with
use of fossil fuels, are the major anthropogenic sources of carbon
dioxide.
Deforestation as a contributor
to the Causes of Climate change
It is important, first to understand what a precious resource
rainforests play in our world. They form part of a delicate ecosystem
that has taken millions of years to evolve.
Rainforests every year
help to absorb almost 20% of man made CO2 emissions therefore
deforestation can be classed as a major contributor to the causes of
climate change. Cutting down rainforests faster than they can be
replaced has a devastating effect on the carbon emission cycle producing
an extra 17% of greenhouse gases. Remember trees absorb CO2. More
deforestation means more CO2 build up in the atmosphere.
Deforestation by means of cutting down and burning these tropical
rainforests usually pave the way for agriculture and industry which
often produce even more CO2.
The causes of climate change
continued
Increase in global temperatures - Inter-government Panel
The most recent
assessment report from the Intergovernmental Panel on Climate Change (IPCC)
says that the earth’s average temperature has risen by 0.74 degrees in
the period from 1906 to 2005, and that the average temperature will
continue to rise.
The greenhouse effect is
a natural mechanism that retains the heat emitted from the earth’s
surface. The earth’s average temperature is at the moment around 14
degrees celsius (57 degrees fahrenheit). If the natural greenhouse
effect did not exist, the average temperature would be around minus 19
degrees celsius (minus 2 degrees fahrenheit).
The greenhouse effect is caused by a range of different gases in the
earth’s atmosphere. Water vapour makes the most significant contribution
to the greenhouse effect, followed by CO2. The atmospheric content of
greenhouse gases – in particular CO2 – and the consequences for the
climate are being discussed because the content of these gases in the
atmosphere has risen precipitously in a period covering approximately
the latest 250 years, and especially the last 50.
At present the concentration of CO2 in the atmosphere is about 385 ppm
(parts per million). Before industrialization it was about 280 ppm.
Analyses of air contained in ice from the Antarctic ice cap show that
there is far more CO2 in the air today than at any time in the last
650,000 years.
The consequence is that the greenhouse effect is becoming stronger, and
therefore the earth is becoming warmer. How much warmer has, however,
been a matter of dispute. The most recent assessment report from the
IPCC is from 2007. It concludes that the earth’s average temperature has
risen by 0.74 degrees in the period from 1906 to 2005. The warming is
stronger over land areas than over the sea, and accordingly it is
strongest in the northern hemisphere. At the same time occurrences of
heat waves and violent downpours have also increased, the oceans have
risen, and the ice at the world’s poles and on its mountains has begun
to melt. All of these effects are predictable in the event of global
warming.
The IPCC’s most recent assessment report concludes that the average
temperature will continue to rise, but that the extent and the duration
of this rise, and the severity of its consequences, depend on how
quickly and how effectively emissions of greenhouse gases can be
restricted and, over time, reduced.
Shattering some of the Green
myths that contribute to the causes of Climate Change
Traditional nappies
(diapers) are as bad as disposables, a study by the Environment Agency
found. While throwaway nappies make up 0.1 per cent of landfill waste,
the cloth variety are a waste of energy, clean water and detergent
Paper bags cause more global warming than plastic. They need much more
space to store so require extra energy to transport them from
manufacturers to shops
Diesel trains in rural Britain are more polluting than 4x4 vehicles.
Douglas Alexander, when Transport Secretary, said: “If ten or fewer
people travel in a Sprinter [train], it would be less environmentally
damaging to give them each a Land Rover Freelander and tell them to
drive”.
Burning wood for fuel is better for the environment than recycling it,
the Department for Environment, Food and Rural Affairs discovered.
Organic dairy cows are worse for the climate. They produce less milk so
their methane emissions per litre are higher.
Someone who installs a “green” light bulb undoes a year’s worth of
energy saving by buying two bags of imported vegetables, as so much
carbon is wasted flying the food to Britain.
Trees, regarded as shields against global warming because they absorb
carbon, were found by German scientists to be major producers of
methane, a much more harmful greenhouse gas.
Sources for
Shattering some of the Green myths that contribute to the causes of
Climate Change: Defra; How to Live a Low-Carbon Life, by Chris Goodall;
Absorbent Hygiene Products Manufacturers Association; The Times; BBC
