Mitigate or Adapt?

Two responses, and why the difference matters

Global average surface temperature is now around 1.1 degrees Celsius above where it sat in the second half of the nineteenth century. Carbon dioxide in the atmosphere has gone from roughly 280 parts per million before industrialisation to over 420 today. Global sea level has risen about 20 cm since 1900 and is currently climbing around 3.7 mm a year, with something like 0.3 to 1.0 m more expected by 2100 depending on what happens to emissions. Arctic sea ice at its September minimum is shrinking on the order of 13 per cent per decade. Those are effects, and effects reach people unevenly. The Maldives averages about 1.5 m above sea level. Around a quarter of Bangladesh lies under about 2.2 m. Meanwhile the UK recorded its first temperature above 40 degrees Celsius in 2022, when Coningsby in Lincolnshire reached 40.3 degrees on 19 July, and the Thames Barrier, built to close a handful of times a decade when it opened in 1982, now closes far more often than its designers expected. There are exactly two ways to respond, and AQA cares enormously that you keep them apart. Mitigation attacks the cause: it reduces the greenhouse gases going into the atmosphere, or takes them back out. Adaptation accepts that some change is already locked in and adjusts to live with the effects. Planting a forest is mitigation. Building a sea wall is adaptation. Both are sensible, they are not alternatives in practice, and putting them in the same list in an exam answer is one of the most reliable ways to lose marks in this topic. This module is about telling them apart and then judging between them.

Five climate response terms

The first two are the distinction the whole topic rests on. The other three are specific strategies precise enough to name in an answer.

Order the chain from fuel to flood

These six stages connect burning fossil fuels to a flooded coastline. Put them in order.

• Fossil fuels are burned and carbon dioxide is released
• The concentration of greenhouse gases in the atmosphere rises
• More of the heat radiating from the Earth is absorbed rather than escaping to space
• Air and ocean temperatures rise
• Seawater expands as it warms, and glaciers and ice sheets on land shed water into the ocean
• Sea level rises and low-lying coasts flood more often and more deeply

What actually raises sea level?

Global sea level has risen about 20 cm since 1900. Which answer gives the correct causes?

• Two things, roughly comparable in size. Water expands as it warms, so the existing ocean occupies more space without a drop being added, and ice that has been sitting on land, meaning mountain glaciers and the Greenland and Antarctic ice sheets, is melting and running into the sea. Floating sea ice is not a cause at all: it already displaces its own weight, so when it melts the level does not change.
• Melting Arctic sea ice is adding its water to the ocean.
• Increased rainfall is putting more water into the oceans.
• Rivers are carrying more sediment, which is displacing seawater upwards.

Four of each, with real schemes attached

Read across the rows and ask the same question of every entry: does this change how much greenhouse gas is in the atmosphere, or does it change how much damage a given amount does? That question is all you need to sort any strategy you are given.

Match each scheme to what it does

The one-question test, and the 9-mark structure

Sorting any strategy takes one question: does it change the amount of greenhouse gas in the atmosphere? If yes, it is mitigation. If no, but it reduces the harm, it is adaptation. A sea wall does not remove a single molecule of carbon dioxide, so however useful it is, it is adaptation. Planting a forest does not stop a single flood this winter, but it removes carbon, so it is mitigation. Watch for the two that trip people up. Solar panels on a roof are mitigation, because they displace generation that would have burned fuel. Air conditioning is adaptation, and it is the awkward kind, because the electricity it uses may itself cause emissions: an adaptation that worsens the cause is worth a sentence in a good answer. For a 9-mark question such as "Assess the extent to which mitigation is more effective than adaptation in responding to climate change.", the shape is: define both so the examiner can see you know the difference, make the case for each with a named scheme and a figure, then judge on a stated criterion. Two criteria work well here. On timescale, adaptation wins, because a barrier protects a city this winter while emissions cuts take decades to alter the temperature. On permanence, mitigation wins, because adaptation has a ceiling: there is no sea wall that makes a 2 m rise survivable for the Maldives, whose land averages about 1.5 m above the sea. The strongest conclusions say that the two are not really rivals, since some warming is already locked in and must be adapted to while further warming can still be prevented, and then still answer the question by saying which matters more and on what measure.

Complete the climate response facts

Carbon dioxide has risen from about _____ parts per million before industrialisation to over 420 today, and global average temperature is now around 1.1 degrees Celsius above the later nineteenth century. Sea level has climbed roughly 20 cm since 1900, driven by the thermal _____ of warming water and by ice melting from the land, not by floating sea ice. Responses divide in two. Storing carbon dioxide underground, as at Sleipner since 1996, is _____, because it changes how much gas reaches the atmosphere. Closing the Thames _____ against a surge tide is adaptation, because it changes only how much harm the water does. The UK has legislated for net zero by _____, which is a mitigation target.

Spot the three accurate climate claims

Select the THREE statements that are true.

• Air conditioning is adaptation rather than mitigation, and it is an awkward case, because the electricity it consumes may itself produce the emissions that are driving the warming it protects against.
• Some further warming is already locked in by gases that have been emitted, which is why adaptation is necessary regardless of how successful mitigation turns out to be.
• The Paris Agreement of 2015 is mitigation: it commits its signatories to holding warming well below 2 degrees Celsius above pre-industrial levels, with efforts towards 1.5.
• Building a sea wall is a form of mitigation because it reduces the effects of climate change.
• Most of the sea level rise observed so far has come from melting Arctic sea ice.
• If emissions stopped tomorrow, sea levels would return to their 1900 level within a few years.

A 9-mark assessment, marked

"Mitigation is more effective than adaptation as a response to climate change." Assess this view. [9 marks] Mitigation attacks the causes of climate change and adaptation adjusts to its effects, so the two are effective in different ways and over different timescales. The case for mitigation is that it is the only response that addresses the problem itself. Carbon dioxide has risen from around 280 parts per million before industrialisation to over 420, and the Paris Agreement of 2015 commits almost every country to holding warming well below 2 degrees Celsius; specific measures already work, since the UK has removed coal from its electricity supply while wind has grown to more than a quarter of generation, and the Sleipner project has stored roughly a million tonnes of carbon dioxide a year beneath the North Sea since 1996. This meant that emissions cuts, unlike defences, reduce the harm everywhere at once rather than in one protected place. However, mitigation is slow and depends on agreement between countries with very different interests, and some warming is already locked in by gases emitted decades ago, so adaptation is not optional. The Thames Barrier has protected London since 1982 and closes far more often than its designers expected, salt-tolerant and drought-tolerant crops keep farms productive on ground that has already changed, and raised flood shelters save lives in Bangladesh, where around a quarter of the country lies under about 2.2 m. Adaptation works now, locally, and without needing anyone else to cooperate. Judged on timescale, adaptation is more effective, because it protects people this winter while emissions cuts take decades to change the temperature. Judged on permanence, mitigation is decisively more effective, because adaptation has a ceiling: no sea wall makes a 2 m rise survivable for the Maldives, which averages about 1.5 m above sea level. I therefore partly agree. Mitigation is the only response that can eventually stop the problem, but it cannot help those already exposed, which is why the realistic answer is that both are required and mitigation determines how much adaptation will eventually be needed. What earned the marks: both terms defined at the start, so the distinction is visible; both cases made with named schemes, dates and figures rather than generalities; two stated criteria, timescale and permanence, doing the judging; and a conclusion that answers the question rather than declaring the two equally important and stopping.

Find the two that are mitigation

Five real responses to climate change. Only two of them reduce or remove the causes. Tap those TWO.

• Restoring drained peat bogs so that they absorb and hold carbon instead of releasing it.
• Building raised concrete shelters on high ground so that villagers have somewhere to go when the water comes.
• Insulating the housing stock so that far less fuel is burned to keep homes warm.
• Constructing a new reservoir to secure the water supply through longer, drier summers.
• Deciding to stop maintaining a sea defence and allowing the coastline to move inland.

Build the sea level sentence

Assemble a sentence that states the cause of sea level rise accurately.

Four responses, four places

Each stage is a real decision. Choose the response that fits the situation, and note whether it attacks the cause or manages the effect.

• You advise the Maldives, where the land averages about 1.5 m above sea level and the sea is rising. Your own emissions are negligible, so cutting them would change nothing measurable.
• The Thames Barrier is closing far more often than when it opened in 1982. It has a finite design life and the surges it defends against are growing.
• You farm in a delta where seawater is pushing further up the river each year and salt is reaching fields that used to grow ordinary rice.
• You advise a government on its electricity supply. The existing coal stations are old, demand is rising, and the country has strong offshore wind resources and a net zero target in law.

Assess the two responses

Assess the extent to which adaptation is a more effective response to climate change than mitigation. [9 marks]

• The distinction between cause and effect
• Adaptation: the Thames Barrier since 1982, salt-tolerant crops in a named delta
• Mitigation: the Paris Agreement of 2015, a net zero target in law, carbon storage at Sleipner since 1996
• Criteria such as timescale or permanence
• Some warming is already locked in