AO1 v. AO2
Feedback mechanisms and the carbon cycle
[It is a while since I did such a post, and in response to being copied into a tweet recently, (my account is @jmbgeog) here is another. I think the essay title is appropriate for all of the specs..
There are over 950 subscribers to this Substack now – will it get to 1k??]
Question: To what extent does an understanding of feedback systems in the carbon cycle help with attempts to mitigate the impacts of climate change? (20)
A reminder: for A level Geography, there are two key Assessment Objectives (AOs):
AO1: demonstrate knowledge and understanding of places, environments, concepts, processes, interactions and change, at a variety of scales.
AO2: apply knowledge and understanding in different contexts to interpret, analyse, and evaluate geographical information and issues.
So, as on previous occasions, here are two versions of the answer.
The first answer is unannotated.
The second answer is in three formats:
(a) Normal font – no AO indicated or addressed as the answer is restating the question
(b) AOs indicated: AO1 in italics; AO2 in bold.
NB. A key parameter is that the answer can be no more than 600 words within the 30-minute time frame of the exam context.
Answer – no AOs indicated
Feedback occurs when one element of the Earth’s natural system changes because of an outside influence. This will upset the dynamic equilibrium and affect other components in that system. Negative feedback is when a system acts by lessening the effect of the original change and ultimately reversing it. Positive feedback occurs within a system where a change causes a further effect, continuing or even accelerating the original change. Mitigation, in the context of climate change, refers to a reduction in the output of greenhouse gases (GHGs) and/or the increase of carbon stores (or sinks). To what extent these concepts are interconnected will be addressed in the context of mitigating the impacts of climate change.
One positive feedback loop involves an increase in evaporation due to warmer temperatures which enhances the greenhouse effect and therefore provides more warming and hence further increased evaporation. This is a clear way in which an understanding of feedback systems points to the fact that something needs to be done to counter a warming world. The increased level of cloud cover created (due to more water in the atmosphere) results in more outgoing longwave radiation being trapped, hence more warming and continuing increases in evaporation. As temperatures rise there is a decreased albedo in polar regions (due to ice and snowmelt) with the result that more solar radiation is absorbed at the Earth’s surface resulting in yet more warming, and a further decreased albedo. This is another example of a positive feedback loop that helps to explain that the climate crisis of global warming is occurring.
Perhaps the most worrying positive feedback loop is that of the thawing of the permafrost in Arctic areas. This thawing is releasing vast amounts of CH4 and CO2 stored in previously frozen permafrost. These GHGs increase the climate warming that is happening now and will happen more into the future. Linked to this is the increase in methane hydrates being released from ocean sediments as the oceans warm. In both the permafrost and the oceans, methane is a potent GHG which will create more warming.
All of these positive feedback systems create difficulty in attempts to mitigate the impacts of climate change as they are acting now whilst world leaders continue to meet to discuss whether climate change is a reality (some such as former President Trump do not accept it) and before they even decide what actions to take to counter it. But, it could be argued that they do help explain the issue as the world dallies.
Negative feedback loops also operate and include increased cloud cover (due to more water in atmosphere) resulting in more incoming solar radiation being reflected back into space, hence lowering temperatures. Climate warming encourages forest growth, and indeed one major mitigation strategy is to re-afforest or reforest areas that have been cleared of trees either naturally or by human actions. These processes will result in more CO2 being stored in biomass, as a carbon sink, and therefore countering the impacts of climate change. This is another example of where the understanding of feedback mechanisms helps understand attempts to mitigate against climate change.
It is clear therefore that an understanding of feedback systems in the carbon cycle does help greatly with attempts to mitigate the impacts of climate change. The majority of feedback systems appear to be positive, worsening the situation, but at least they help understand what is causing the problem. Similarly, an understanding of negative feedback systems helps us to understand what we can do to address the climate change problem. (590)
Answer – with AOs indicated
Feedback occurs when one element of the Earth’s natural system changes because of an outside influence. This will upset the dynamic equilibrium and affect other components in that system. Negative feedback is when a system acts by lessening the effect of the original change and ultimately reversing it. Positive feedback occurs within a system where a change causes a further effect, continuing or even accelerating the original change. Mitigation, in the context of climate change, refers to a reduction in the output of greenhouse gases (GHGs) and/or the increase of carbon stores (or sinks). To what extent these concepts are interconnected will be addressed in the context of mitigating the impacts of climate change.
One positive feedback loop involves an increase in evaporation due to warmer temperatures which enhances the greenhouse effect and therefore provides more warming and hence further increased evaporation. This is a clear way in which an understanding of feedback systems points to the fact that something needs to be done to counter a warming world. The increased level of cloud cover created (due to more water in the atmosphere) results in more outgoing longwave radiation being trapped, hence more warming and continuing increases in evaporation. As temperatures rise there is a decreased albedo in polar regions (due to ice and snowmelt) with the result that more solar radiation is absorbed at the Earth’s surface resulting in yet more warming, and a further decreased albedo. This is another example of a positive feedback loop that helps to explain that the climate crisis of global warming is occurring.
Perhaps the most worrying positive feedback loop is that of the thawing of the permafrost in Arctic areas. This thawing is releasing vast amounts of CH4 and CO2 stored in previously frozen permafrost. These GHGs increase the climate warming that is happening now and will happen more into the future. Linked to this is the increase in methane hydrates being released from ocean sediments as the oceans warm. In both the permafrost and the oceans, methane is a potent GHG which will create more warming.
All of these positive feedback systems create difficulty in attempts to mitigate the impacts of climate change as they are acting now whilst world leaders continue to meet to discuss whether climate change is a reality (some such as former President Trump do not accept it) and before they even decide what actions to take to counter it. But, it could be argued that they do help explain the issue as the world dallies.
Negative feedback loops also operate and include increased cloud cover (due to more water in atmosphere) resulting in more incoming solar radiation being reflected back into space, hence lowering temperatures. Climate warming encourages forest growth, and indeed one major mitigation strategy is to re-afforest or reforest areas that have been cleared of trees either naturally or by human actions. These processes will result in more CO2 being stored in biomass, as a carbon sink, and therefore countering the impacts of climate change. This is another example of where the understanding of feedback mechanisms helps understand attempts to mitigate against climate change.
It is clear therefore that an understanding of feedback systems in the carbon cycle does help greatly with attempts to mitigate the impacts of climate change. The majority of feedback systems appear to be positive, worsening the situation, but at least they help understand what is causing the problem. Similarly, an understanding of negative feedback systems helps us to understand what we can do to address the climate change problem. (590)