Mitigation is everything we do to stop the problem getting worse. It works on the cause — greenhouse gases — rather than the symptoms. There are only two ways to do it: put less in, or take more out. Every strategy in this page is one of those two, and knowing which is which makes the whole topic easier to organise.
📚 What you need to know
Mitigation means reducing or stabilising greenhouse gas emissions to limit future climate change.
It splits into two branches: reducing emissions at source and removing greenhouse gases already in the atmosphere.
Source strategies: reduced energy consumption, transport policies, agricultural changes, alternatives to fossil fuels and carbon taxes.
Removal strategies: natural carbon sinks (afforestation, reforestation, rewilding) and carbon capture and storage, including direct air capture.
Geoengineering is sometimes listed as mitigation, but it manages symptoms rather than causes — it gets its own page at HL.
Afforestation is planting where there was no forest. Reforestation is replanting where forest was lost.
The order strategies should come in
Not all mitigation is equally good value. The cheapest and most reliable emission is the one never produced, and the most expensive is the one you have to chase back out of the open air afterwards. That gives a natural order of preference, and using it to structure an answer looks far more thoughtful than listing strategies at random.
Each step only has to deal with what the step before it left behind. That is why efficiency and demand reduction matter so much: they shrink the job for every technology further down the line.
This ladder is my framing, not an IB-defined list, so do not quote it as if it were syllabus wording. Use it as a way to order your answer. Writing “the most effective strategies reduce demand first, because capture and removal technologies are expensive and unproven at scale” is exactly the kind of judgement an evaluation question is looking for.
Mitigation strategies in full
Strategy
How it is put into practice
Source or removal?
Reducing energy consumption
Insulation, efficient lighting and appliances, smart grids, energy management systems and efficient industrial processes
Source
Transport policies
Fuel efficiency standards, incentives for electric and hybrid vehicles, investment in public transport, cycling and walking infrastructure
Source
Reducing agricultural emissions
Better feed quality, methane capture on farms, rotational grazing, and fertiliser management to limit nitrogen oxide release
Source
Alternatives to fossil fuels
Solar, wind, hydro and geothermal generation; charging networks for electric vehicles; research into biofuels, hydrogen and nuclear
Source
Carbon tax
A charge per tonne of carbon dioxide emitted, making pollution a cost on the balance sheet rather than something free
Source
Natural carbon sinks
Afforestation and reforestation, rewilding, restoring degraded ecosystems and protecting existing forests
Removal
Carbon capture and storage
Capturing emissions from power stations and industry, or pulling carbon dioxide from the air by direct air capture, then storing it underground
Removal
How carbon capture and storage works
Depleted oil and gas fields are popular storage sites for a simple reason: they held gas underground for millions of years already, so the geology has proved it can seal.
🧩 How direct air capture differs
CCS at a power station catches carbon dioxide in the exhaust, where it makes up a decent fraction of the gas coming out.
Direct air capture (DAC) pulls it from ordinary outdoor air, where carbon dioxide is only about four molecules in every ten thousand.
That difference in concentration is why DAC needs to move enormous volumes of air to collect the same amount.
Moving that much air takes a lot of energy, which makes DAC expensive and only worthwhile if the energy is itself low-carbon.
But DAC has one advantage CCS does not: it can remove emissions released years ago, and from sources like aviation that have no chimney to fit.
The trap in that last point. CCS reduces new emissions; DAC and forests reduce the existing stock. Questions about reaching net zero usually need both, because you cannot cut aviation or cement emissions to nothing.
Natural carbon sinks
Trees, soils, peatlands and coastal wetlands all absorb carbon dioxide, so protecting and expanding them is mitigation. Afforestation means planting trees on land that was not forest before, creating new forest. Reforestation means replanting an area that was forest until it was cleared by logging, farming or fire. The difference matters because reforestation also restores lost ecological function and biodiversity, not just carbon storage.
Rewilding goes further, letting ecosystems recover their own structure with minimal management, and restoring degraded ecosystems such as drained peatland can be startlingly effective — peat holds enormous quantities of carbon in a small area, and releases it when it dries out.
Do not oversell tree planting. A newly planted tree absorbs very little in its first years, plantations of a single species store less carbon and support far less biodiversity than a recovered natural forest, and a forest that later burns releases everything it stored. Protecting an existing mature forest is usually better value than planting a new one. That nuance regularly separates a good answer from an average one.
Carbon taxes and the price of pollution
A carbon tax puts a price on each tonne of carbon dioxide emitted. The logic is straightforward: while emitting is free, there is no financial reason to stop, and a business that invests in cleaner equipment is at a disadvantage against a competitor that does not. Attaching a cost reverses that, making low-carbon options the cheaper choice and letting each business find its own way to cut, rather than being told exactly what to do.
WORKED EXAMPLE
Outline three strategies that reduce greenhouse gas emissions at their source. [3]
Strategy 1 — energyReducing energy consumption through insulation, efficient appliances and efficient industrial processes lowers the fossil fuel burned to supply that energy.Strategy 2 — transportTransport policies such as fuel efficiency standards, electric vehicle incentives and public transport investment cut emissions per journey.Strategy 3 — agricultureImproved livestock feed, methane capture and better fertiliser management reduce methane and nitrogen oxide emissions from farming.3 / 3Three different sectors, each with a named mechanism. Three versions of “use less energy” would score one.
WORKED EXAMPLE
Evaluate the use of carbon capture and storage as a mitigation strategy. [4]
Strength 1It allows emissions to be cut from industries such as cement and steel where no low-carbon alternative currently exists.Strength 2Suitable geological storage is already proven, since depleted oil and gas fields held hydrocarbons underground for millions of years.Limitation 1It is expensive and energy-intensive, and capturing emissions using fossil-fuelled energy reduces the net benefit.Limitation 2It risks becoming a reason to keep burning fossil fuels rather than replacing them, and long-term storage security is not fully proven.4 / 4Balanced structure. An evaluate answer that only lists advantages caps at half marks.
💡 Exam tip
Sort every strategy into source or removal before you write. It gives your answer instant structure.
Give a mechanism, not just a name. “Rotational grazing” earns little; “rotational grazing improves pasture and cuts methane per animal” earns the mark.
Learn the afforestation versus reforestation definitions word for word. They are easy marks and easy to muddle.
For CCS, remember the three verbs: capture, transport, store.
If a question says evaluate, you need limitations. Cost, energy demand and unproven scale work for almost every technology here.
Keep mitigation and adaptation strictly separate. Mixing them is the single most common error in this sub-topic.
⚠️ Common mix-up
Calling flood defences mitigation. They do nothing to emissions, so they are adaptation.
Treating tree planting as an instant fix. Young trees absorb slowly, and the carbon returns if the forest burns or is cleared.
Confusing CCS with DAC. CCS catches emissions at the source; DAC extracts carbon dioxide already in the atmosphere.
Assuming renewables have zero emissions. Manufacturing panels and turbines has a footprint; it is far smaller, not absent.
Forgetting methane and nitrogen oxides. Agriculture matters because of these gases, not carbon dioxide alone.
Describing a carbon tax as a ban. It changes the price signal; it does not forbid anything.
Up next: Adapting to a Changing Climate — what to do about the warming that is already locked in, no matter how well mitigation goes from here.
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