“The destruction of the worlds rainforests will have a greater impact on the carbon cycle
than the water cycle” With reference to a rainforest area, to what extent do you agree with
this view? (20 marks)
A rainforest is an area of dense forest rich in biodiversity, found in tropical areas. The
Amazon rainforest is the biggest rainforest in the world, it spreads across 4 countries and
contains 300 billion trees. The destruction of this rainforest can have a massive impact on
both the water cycle and carbon cycle. The carbon cycle is a series of processes by which
carbon compounds are interconverted in the environment, and the water cycle is the cycle
of processes by which water circulates between the earth’s oceans, atmosphere, and land.
These are cycles are important in the Amazon as it is a major carbon sink and is home to
20% of the world’s river water.
Deforestation is happening at large in rainforests shown by the 20% of the Amazon that has
already been deforested. One impact of this is the negative effect it will have/ has had on
the carbon cycle. The Amazon rainforest is a crucial part of modern-day life and plays a key
role in mitigating climate change due to storing between 80-120 billion tonnes of carbon.
Deforestation leads to lots of these trees which hold the carbon being destroyed causing a
sudden increase in CO2 levels, at first this may be seen as a good thing as an increase in CO2
causes a surge in photosynthesis which means that growth rates increase, and more CO2 is
absorbed by vegetation. However, we now know that trees that grow quicker due to the
increased amount of CO2 die a lot sooner too. The Amazonian soils are also a great store for
carbon and contain 4-5kg in the upper 50 cm of soil, although these soils are also releasing
carbon due to the deforestation that occurs. Cutting down the trees in a rainforest means
that less interception of rain occurs (usually 50% of the rain is intercepted), this means that
the heavy rain is causing the soil to wash away into nearby rivers meaning that carbon is
entering the rivers which could cause eutrophication to occur killing animals and plants. Not
only does the deforestation mean that more greenhouse gases go into the atmosphere, but
the replacement land also causes an increase in greenhouse gases for example 60% of
deforested land is turned into cattle ranching which releases huge amounts of methane into
the environment. Land replaced with soya farms absorbs much less CO2 than the trees that
have been destroyed. Overall, the destruction of the rainforest is having a massive impact
on the carbon cycle.
Some people would disagree with the statement and say that the destruction of the
rainforest has a larger impact on the water cycle. The Average rainfall across the basin in the
Amazon is 2300 mm per year, half of this never reaches the ground as its intercepted and
re-evaporates. However, deforestation has a massive impact on interception and
completely stops it, this causes more surface runoff meaning the water reaches the river
more quickly increasing flood risk in nearby settlements, this can have many economic and
social impacts. Furthermore, the heavy rainfall causes soil erosion and means that the soils
have less nutrients than the low levels that they currently do have. Another consequence of
deforestation is that it leads to a decrease in the amount of transpiration which then leads
to a lower atmospheric humidity which reduces precipitation levels in the Amazon basin and
can even reduce precipitation levels thousands of miles downwind and total deforestation
would affect precipitation levels worldwide which could cause things such as plants to
struggle.
than the water cycle” With reference to a rainforest area, to what extent do you agree with
this view? (20 marks)
A rainforest is an area of dense forest rich in biodiversity, found in tropical areas. The
Amazon rainforest is the biggest rainforest in the world, it spreads across 4 countries and
contains 300 billion trees. The destruction of this rainforest can have a massive impact on
both the water cycle and carbon cycle. The carbon cycle is a series of processes by which
carbon compounds are interconverted in the environment, and the water cycle is the cycle
of processes by which water circulates between the earth’s oceans, atmosphere, and land.
These are cycles are important in the Amazon as it is a major carbon sink and is home to
20% of the world’s river water.
Deforestation is happening at large in rainforests shown by the 20% of the Amazon that has
already been deforested. One impact of this is the negative effect it will have/ has had on
the carbon cycle. The Amazon rainforest is a crucial part of modern-day life and plays a key
role in mitigating climate change due to storing between 80-120 billion tonnes of carbon.
Deforestation leads to lots of these trees which hold the carbon being destroyed causing a
sudden increase in CO2 levels, at first this may be seen as a good thing as an increase in CO2
causes a surge in photosynthesis which means that growth rates increase, and more CO2 is
absorbed by vegetation. However, we now know that trees that grow quicker due to the
increased amount of CO2 die a lot sooner too. The Amazonian soils are also a great store for
carbon and contain 4-5kg in the upper 50 cm of soil, although these soils are also releasing
carbon due to the deforestation that occurs. Cutting down the trees in a rainforest means
that less interception of rain occurs (usually 50% of the rain is intercepted), this means that
the heavy rain is causing the soil to wash away into nearby rivers meaning that carbon is
entering the rivers which could cause eutrophication to occur killing animals and plants. Not
only does the deforestation mean that more greenhouse gases go into the atmosphere, but
the replacement land also causes an increase in greenhouse gases for example 60% of
deforested land is turned into cattle ranching which releases huge amounts of methane into
the environment. Land replaced with soya farms absorbs much less CO2 than the trees that
have been destroyed. Overall, the destruction of the rainforest is having a massive impact
on the carbon cycle.
Some people would disagree with the statement and say that the destruction of the
rainforest has a larger impact on the water cycle. The Average rainfall across the basin in the
Amazon is 2300 mm per year, half of this never reaches the ground as its intercepted and
re-evaporates. However, deforestation has a massive impact on interception and
completely stops it, this causes more surface runoff meaning the water reaches the river
more quickly increasing flood risk in nearby settlements, this can have many economic and
social impacts. Furthermore, the heavy rainfall causes soil erosion and means that the soils
have less nutrients than the low levels that they currently do have. Another consequence of
deforestation is that it leads to a decrease in the amount of transpiration which then leads
to a lower atmospheric humidity which reduces precipitation levels in the Amazon basin and
can even reduce precipitation levels thousands of miles downwind and total deforestation
would affect precipitation levels worldwide which could cause things such as plants to
struggle.
