Topic 5: On the Wild Side
Climate Change
Climate change
Climate change describes the gradual change in weather patterns in a region over a long period of
time. It happens naturally (such as the increase in temperature after the last ice age) but is
accelerating due to human activities. Global warming is a type of climate change caused by the
release of greenhouse gases, such as carbon dioxide and methane. These gases trap heat
energy that is radiating back from the Earth’s surface, trapping the heat in the Earth’s atmosphere.
This causes the global temperature to increase and can lead to severe weather conditions such as
draught, flooding and typhoons.
Since the Industrial Revolution, carbon dioxide concentration in the atmosphere has been increasing
due to increased use of fossil fuels and deforestation. Trees are able to absorb carbon dioxide and
store it as organic compounds, so we refer to them as carbon sinks. Cutting down trees destroys
these natural carbon sinks.
, Levels of methane in the atmosphere have also increased due to the burning of fossil fuels and
cattle farming. Methane is also trapped in ice so as the Earth’s temperature increases and icy
ground and glaciers begin to melt, natural stores of methane are released into the atmosphere.
Evidence for climate change
Scientists have collected data to support the fact that climate change is happening from three main
sources: temperature records, dendrochronology and pollen in peat bogs.
• Temperature records - data for global temperature has been recorded since 1850. The
records show that global
temperatures remained fairly stable
until around 1910. From 1910 to the
present day, global temperatures
have been gradually and steadily
increasing. It is a reliable source of
data but only concerns a relatively
short time period.
• Dendrochronology -
dendrochronology is the study of
tree rings. Trees usually produce one ring each year. Tree rings provide evidence that the
Earth’s temperature is increasing because the tree grows faster in warmer temperatures
which causes the tree rings to become thicker. Scientists can take cores through the tree
trunks and prove that climate change is happening by showing that the tree rings are getting
thicker over time.
• Pollen in peat bogs - peat bogs are marshy, wetland areas which often trap pollen. Peat
bogs accumulate in layers so the age of the pollen in the peat bog can be determined by its
depth. Cores can be taken of the peat bog and used to show that the species of plants that
has been growing nearby has changed over time. If we see a drop in plant species which
grow best in colder temperatures or an increase in plants which prefer warmer
conditions, this indicates that climate change has taken place.
Models of climate change
The Intergovernmental Panel on Climate Change (IPCC) has used data about greenhouse gas
concentrations to create models of global warming and make predictions about what may happen in
the future. They have proposed different scenarios as to what might happen:
• Scenario 1: this is the best case scenario - greenhouse gas emissions are significantly reduced
• Scenarios 2 and 3: greenhouse gas emissions continue to increase but eventually level off
Climate Change
Climate change
Climate change describes the gradual change in weather patterns in a region over a long period of
time. It happens naturally (such as the increase in temperature after the last ice age) but is
accelerating due to human activities. Global warming is a type of climate change caused by the
release of greenhouse gases, such as carbon dioxide and methane. These gases trap heat
energy that is radiating back from the Earth’s surface, trapping the heat in the Earth’s atmosphere.
This causes the global temperature to increase and can lead to severe weather conditions such as
draught, flooding and typhoons.
Since the Industrial Revolution, carbon dioxide concentration in the atmosphere has been increasing
due to increased use of fossil fuels and deforestation. Trees are able to absorb carbon dioxide and
store it as organic compounds, so we refer to them as carbon sinks. Cutting down trees destroys
these natural carbon sinks.
, Levels of methane in the atmosphere have also increased due to the burning of fossil fuels and
cattle farming. Methane is also trapped in ice so as the Earth’s temperature increases and icy
ground and glaciers begin to melt, natural stores of methane are released into the atmosphere.
Evidence for climate change
Scientists have collected data to support the fact that climate change is happening from three main
sources: temperature records, dendrochronology and pollen in peat bogs.
• Temperature records - data for global temperature has been recorded since 1850. The
records show that global
temperatures remained fairly stable
until around 1910. From 1910 to the
present day, global temperatures
have been gradually and steadily
increasing. It is a reliable source of
data but only concerns a relatively
short time period.
• Dendrochronology -
dendrochronology is the study of
tree rings. Trees usually produce one ring each year. Tree rings provide evidence that the
Earth’s temperature is increasing because the tree grows faster in warmer temperatures
which causes the tree rings to become thicker. Scientists can take cores through the tree
trunks and prove that climate change is happening by showing that the tree rings are getting
thicker over time.
• Pollen in peat bogs - peat bogs are marshy, wetland areas which often trap pollen. Peat
bogs accumulate in layers so the age of the pollen in the peat bog can be determined by its
depth. Cores can be taken of the peat bog and used to show that the species of plants that
has been growing nearby has changed over time. If we see a drop in plant species which
grow best in colder temperatures or an increase in plants which prefer warmer
conditions, this indicates that climate change has taken place.
Models of climate change
The Intergovernmental Panel on Climate Change (IPCC) has used data about greenhouse gas
concentrations to create models of global warming and make predictions about what may happen in
the future. They have proposed different scenarios as to what might happen:
• Scenario 1: this is the best case scenario - greenhouse gas emissions are significantly reduced
• Scenarios 2 and 3: greenhouse gas emissions continue to increase but eventually level off
