IPCC Assessment in depth, Part 10: Are there limits to what adaptation can achieve?

The threat that climate change poses to human well-being and the health of the planet is “unequivocal”, says the latest report from the United Nations’ Intergovernmental Panel on Climate Change (IPCC). In this in-depth Q&A series, Carbon Brief unpacks the key findings of the report and the developments since the IPCC’s last assessment. (Read previous section here)

By Carbon Brief

10. Are there limits to what adaptation can achieve?

The report includes lengthy discussions on the limits to adaptation – the points at which it is difficult or even impossible to accommodate the changes the world is undergoing.

This idea of an adaptation limit, first introduced in AR5 in 2014, is defined as “the point at which an actor’s objectives or system’s needs cannot be secured from intolerable risks through adaptive actions”.

Such a concept “strongly affects any appropriate balance among adaptation and mitigation actions” as a failure to cut enough emissions could render adaptation futile, the report says. In other words, if there are numerous limits on adaptation, mitigation efforts will need to be ramped up.

These limits are categorised as either “soft” or “hard’, and are distinguished by the extent to which it is possible to overcome them.

Soft limits tend to be those set by people. Flood defences might not be built because there is not enough money made available, a lack of stable governance or too few people with the skills to construct them, for example.

Hard limits, on the other hand, are largely associated with natural systems. Sea level rise and storms may reach a point where flood defences are no longer sufficient to protect people.

Chapter 2 of the report – which addresses terrestrial and freshwater ecosystems – gives a sense of the magnitude of some of these unadaptable limits, stating:

“In general, adaptation measures can substantially reduce the adverse impacts of 1-2C of global temperature rise, but beyond this losses will increase, including species extinctions and changes, such as major biome shifts which cannot be reversed on human timescales.”

IPCC special reports have delved into these areas, with the ocean and cryosphere report identifying upper limits for ecosystems and communities around coral reefs, urban atoll islands and low-lying Arctic locations, and the land report doing the same for coastal regions and areas affected by thawing permafrost.

Nature-based solutions – such as coral reefs, mangroves and marshes, all of which can help adaptation efforts – will likely reach hard limits of their own as the planet warms beyond 1.5C, the report says.

The report states that understanding where these limits lie gives a sense of the urgency required, noting with high confidence that:

“Adaptation is urgent to the extent that soft adaptation limits are currently being approached or exceeded and that achieving levels of adaptation adequate to address these soft limits requires action at a speed and scale faster than that represented by current trends.”

The report also includes discussions of “residual risk”, a term defined as “the risk that remains after actions have been taken to reduce hazards, exposure and/or vulnerability”. For the most part, this is what remains after the upper limits of adaptation have been reached.

As with climate adaptation more broadly, evidence is somewhat lacking when it comes to adaptation limits. The report says there is high agreement but only medium evidence that there are limits to adaptation across regions and sectors.

The figure below gives a sense of the available evidence on where these limits occur, with darker colours indicating more evidence across a sample of 1,682 studies. It shows that the most detailed picture of future limits on adaptation exists for Latin America and small islands.

The report examines the evidence for limits on adaptation that already exists, in one section zooming in on the examples of agriculture across Asia, livelihoods in Africa and general impacts on small-island states.

Examples of soft limits to adaptation include difficulty preparing for coastal floods in Samoa due to financial, physical and technological constraints, and small-scale farmers in Bangladesh struggling to adapt to riverbank erosion while wealthier farmers have the money to implement responses.

Hard limits include springs running dry in Nepalese farming communities and land scarcity in parts of Africa when organic cotton production is introduced to support more sustainable livelihoods.

The residual risks identified are stark, including “collapse of economies and livelihoods and reduced habitability of islands” and poorer households in Africa “becoming trapped in cycles of poverty”, the report says.

With many parts of the world facing such bleak prospects, the IPCC report has a new focus – a key development since AR5 – on “transformational adaptation”.

Most adaptation is “incremental”, meaning it only modifies existing systems. Transformational adaptation, on the other hand, “changes the fundamental attributes of a social-ecological system”. This relates to the discussion of limits because, as the report explains:

“Transformational adaptation can allow a system to extend beyond its soft limits and prevent soft limits from becoming hard limits.”

One example given is that building a seawall to protect a community is incremental adaptation, while changing land-use regulations in that community and establishing a programme of managed retreat could be transformational adaptation.

The map below shows that, based on the available literature, there is currently little evidence for this kind of adaptation taking place around the world (light colours indicate low evidence for such action).

The report notes that while such changes may be necessary to overcome limits to adaptation, the approach is “not without risks”. This is because changes that impact every level of society can “disturb existing power relationships” within that society, and they can “unfold in difficult to predict and unintended ways”.

All sections:

1. 1. What is the IPCC report?
   2. How is climate change affecting land ecosystems?
   3. What impact is global warming having on marine life?
   4. How is climate change affecting the world’s water?
   5. What does the IPCC report say about impacts on food and agriculture?
   6. What risks does climate change pose to the world’s cities?
   7. What does the report say about public health, conflict and migration?
   8. How does climate change affect poverty and progress towards the sustainable development goals?
   9. How is the world adapting to climate change?
   10. Are there limits to what adaptation can achieve?
   11. What does the report say about ‘loss and damage’?
   12. What the latest IPCC report says about carbon fee and dividend

Authors:

Aruna Chandrasekhar holds an MSc in environmental change and management from the University of Oxford. She previously worked as a freelance journalist for a variety of publications, including the New York Times, Guardian, Scroll and Caravan.

Daisy Dunne holds a BSc in biology from the University of Bristol and a science journalism MA from City, University of London. She was The Independent’s climate correspondent from November 2020 to 2021. Prior to this, she was Carbon Brief’s science writer from 2017 to 2020.

Josh Gabbatiss covers climate and energy policy. Josh holds a BSc in zoology from the University of Bristol. He previously worked as science correspondent at The Independent and prior to that was a freelance journalist for a variety of scientific publications including New Scientist and BBC Earth.