Understanding climate change
Climate change questions and answers
What is global warming?
Earth has been slowly getting warmer over the last 50 years
most likely because of an increase in human-caused greenhouse
gas emissions in Earth's atmosphere (especially since the
industrial revolution). Scientists believe that the average
temperature could rise between 1.4 and 5.8 degrees centigrade
in the next 100 years. This effect is called global warming.
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Why is Earth getting warmer?
Scientists believe that Earth is getting warmer because of
the way humans live. All over the world, people use a lot
of electricity in their daily lives. Also our factories use
a lot of energy, more and more people drive around in bigger
cars (which use lots of petrol), and lots of trees are chopped
down everyday. These activities are increasing the amount
of greenhouse gases in the atmosphere.
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What is a greenhouse gas?
There are six main greenhouse gases, the most common of which
are carbon dioxide (C02), methane (CH4)
and nitrous oxide (N20). These are all produced
from human activity - C02 from transport and energy;
CH4 mainly from animals burping out the gas as
they digest their food; N20 mainly from agriculture
such as the use of fertiliser and when animals urinate. The
three other main gases are hydrofluorocarbons (HFCs - used
in refrigerants), sulphur hexafluoride (SF6 - used
in the electricity industry) and perfluorocarbons (PFCs -
from aluminum production).
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How do the greenhouse gases work to make Earth warmer?
Greenhouse gases trap heat from the sun and act like an invisible
blanket around Earth which makes Earth's surface warmer. If
we put more greenhouse gases into the air (from such things
as cars, cutting down trees, electricity generation and farming)
the blanket becomes thicker causing Earth to become warmer
and the climate to change.
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Where does the greenhouse gas carbon dioxide come from?
C02 is naturally released into the air from rotting
or burning trees and plants. When it is released, some C02
stays in the air for a long time and some is stored in plants,
plankton and seashells. Some C02 also dissolves
in seawater.
Human activity is adding to the amount of C02
in the air. People burn fossil fuels like coal, oil and gas
to power factories and make electricity to heat our homes.
Fossil fuels come from buried forests from long ago: trees
soak up C02 from the air and store it as carbon
- when trees are cut down and burnt, C02 is released
back into the air. Cars and trucks engines also release large
quantities of C02 into the air - the more fuel
that is burnt, the more C02 is released.
What is happening is that C02 is being released
faster than it is being stored again, so lots of it stays
in Earth's atmosphere.
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Where does the greenhouse gas methane come from?
Every day millions of cows and sheep in New Zealand are
burping the greenhouse gas methane (CH4) into the
air as they digest their food. CH4 is also released
when these animals chew cud. It is produced by the bacteria
that live inside their stomachs - these bacteria are essential
for the animals to digest the grass they eat. Methane from
farm animals is an important issue because of the increasing
number of such livestock being farmed worldwide.
Methane is also produced when organic rubbish (such as food
scraps and grass clippings) decay in rubbish dumps. Rice and
other crop production release methane too.
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Where does the greenhouse gas nitrous oxide come from?
Nitrous oxide (N2O), is released into the air
when animals urinate and when fertilisers are applied to the
soil.
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Are all greenhouse gases bad?
No, we do need some greenhouse gases. Greenhouse gases help
the sun's heat from escaping Earth's atmosphere. If we didn't
have any greenhouse gases, Earth would be too cold to live
on, like Mars. But if we don't do anything to reduce the amounts
of human-created greenhouse gases we're putting into the air,
Earth's whole climate will change - eventually with very serious
consequences.
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Why do we need to do something about this?
Every year, there are larger amounts of greenhouse gases
being put into the air. The number of cars, factories and
people keep on growing. In 50 years time there may be twice
as much C02 in the air as there was 300 years ago.
The world's leading climate scientists believe that the average
temperature could rise between 1.4 and 5.8 degrees centigrade
in the next 100 years. This increase in air temperature has
already started to affect our weather patterns and climate
(for example, there are more droughts and floods in some countries,
and rainfall patterns are changing in many regions). Sea levels
are also likely to rise by 9 to 88cm by 2100 because as water
gets warmer it takes up more room. Also some ice caps and
glaciers could melt, increasing sea levels (this is likely
to erode coastlines and flood low-lying areas). Sea levels
will continue to rise for many more centuries, even after
atmospheric temperatures have reached a new stable level.
In the short term in New Zealand, there could be some benefits
from climate change: for example, warmer winters are likely
to reduce winter illnesses and the amount of electricity needed
to heat homes, there could be increased agricultural production
in some areas, and there are likely to be opportunities to
create new technology and services to address climate change.
However, most scientists say that worldwide, more people will
be worse off if we keep releasing large amounts of greenhouse
gas emissions into the air and causing the climate to change.
In the long run, climate change will have severe impacts on
many parts of the world if we do nothing to reduce our emissions.
We need to think about what climate change might mean for
our grandchildren and great grandchildren.
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What could happen to New Zealand's climate in the future?
New Zealand probably won't be as affected by climate change
as some other countries, but our weather is likely to become
more extreme.
Some places could have more droughts while other places could
have heavier rainfall. Heavy rainfall could flood towns and
cities in some areas. Floods in low-lying river valleys could
also damage homes, farm animals and food crops. The sea level
is likely to rise and some of our beaches could be damaged
or lost. There are likely to be more water shortages in eastern
parts of New Zealand such as Hawke's Bay, Malborough and Canterbury.
There could also be more pest and disease problems for our
animals, plants and even ourselves. Diseases may spread from
more tropical climates - mosquitoes carrying dengue fever
may become established in a warmer New Zealand. Warmer winters
are likely to reduce winter illnesses such as colds and flu,
but hotter summers could cause people and animals heat stress
and facial eczema on sheep and cattle.
A warmer climate could be better for growing some crops but
worse for others. Plants are used to the climate they live
in now - perhaps they won't survive if the climate changes.
What will happen to the birds and insects that depend on them
as a source of food?v Warmer winters will reduce the amount
of electricity needed to heat homes, but warmer summers may
increase the need to cool homes with air conditioning.
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What can be done about this?
New Zealand needs a stable climate for farming animals,
growing crops, and other money-earning activities. We also
want to protect our natural heritage. We need to decrease
the amount of greenhouse gases in the atmosphere to reduce
the effects of climate change. If we work with other countries
to help reduce the amount of global greenhouse gases in the
air, we will be helping to keep the climate stable all over
the world.
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What can I do to help?
The biggest amount of carbon dioxide in New Zealand comes
from transport and from making electricity to use in homes
and businesses. Think of all the ways you use transport and
electricity each day. Can you use other forms of transport
and less electricity? This will save your family money on
power bills and petrol use. Can you use cars less often -
travel with friends, take a bus, ride a bike, or walk? And
make sure you service your car regularly, keep its tyres inflated,
drive as smoothly as possible and keep to the speed limit
- these measures will reduce the fuel your car uses.
Can you reduce waste such as packaging? Can you reuse containers
and bags (e.g. bring your own bag to the supermarket), recycle
as much of your waste as possible and compost food scraps?
Can you use less electricity? Some ways you can do this is
to turn the light off when you leave a room, turn off appliances
(such as your TV, computer and microwave) at the wall when
nor in use, put on a sweatshirt and turn off/down the heater,
and pull curtains, shut doors and close windows to keep heat
in. You could also ask at your supermarket for energy efficient
lightbulbs. And plant more trees - trees remove C02
from the air while they are growing and store it as carbon
in their trunk, branches, leaves and roots.
For more ideas and information on how you can help reduce
greenhouse gas emissions see .
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What is New Zealand doing now?
The Government is putting in place ways that people and
businesses can address climate change. In December 2002, it
ratified (formally signed) an agreement with other governments
around the world to reduce the amount of greenhouse gases
in Earth's atmosphere. This agreement is called the Kyoto
Protocol. Formally signing this Protocol is an important first
step for countries to reduce their greenhouse gas emissions.
There will be further steps taken by all the countries who
participate in the Protocol in future years.
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How does the Kyoto Protocol work?
The Kyoto Protocol will give each country, like New Zealand,
a greenhouse gas 'reduction' target. This is like a goal to
aim for. New Zealand's target is to get greenhouse gases released
from cars, factories, and farm animals back down to 1990 levels
by 2012. Every country can choose how it reduces its greenhouse
gas emissions, but if New Zealand or any other member of the
Kyoto Protocol fails to get their emissions down to the level
they've promised by 2012, then they have to be responsible
for not meeting their goal. That means they either have to
pay for all the extra greenhouse gas emissions they've produced
(an international market will be set up for this purpose)
or trade them off against carbon sinks (carbon sinks are explained
in another question below).
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How do the Kyoto Protocol targets work?
To reach our reduction target by 2012, we would need to reduce
the amount of greenhouse gases in the atmosphere to the level
they were in 1990 or take other action to make up for being
over our target. Scientists in New Zealand predict that if
we do nothing to reduce our greenhouse gas emissions, we will
be about 24% above our 1990 levels by 2010.
Trees soak up C02 from the air, so planting more
forests would be one way to help us achieve our target. But
planting trees is only part of what we need to do. Ratifying
the Protocol would mean that people would also be encouraged
to be more aware of what they do to produce greenhouse gases,
and what they can do differently to help New Zealand reduce
greenhouse gas emissions (e.g. look at how often they use
their cars, reduce, re-use, recycle and compost, and how energy
efficient they are in their homes, at school and at work).
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