Adaptation: reducing vulnerability to climate change

Overview

Mitigation and adaptation, main coastal adaptation options and why mangroves and saltmarsh are often preferred to hard engineering.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is adaptation?

   Model answer

   Adaptation means adjusting to the climate change that occurs, in order to reduce vulnerability to its impacts and to take advantage of any opportunities. It does not attempt to reduce greenhouse gas concentrations or to slow warming; it accepts that a certain amount of change will happen and acts to limit the harm that change causes to people, property, economies and ecosystems. Examples include building coastal defences, breeding drought-tolerant crop varieties, installing flood warning systems and revising building regulations. Its benefits are local and accrue to whoever pays for it, and they appear quickly, which makes it politically easier to fund than mitigation.

2. 2

   Why is adaptation necessary even if all emissions stopped tomorrow?

   Model answer

   Because of inertia in the climate system. A large fraction of the carbon dioxide already emitted will remain in the atmosphere for centuries, so the enhanced greenhouse effect does not switch off when emissions do. The ocean has enormous heat capacity and has not yet finished warming in response to the greenhouse gases already present, so surface temperatures would continue adjusting for decades. Ice sheets and glaciers respond over centuries, so sea level would keep rising long after temperatures stabilised. And more than one degree of warming has already occurred, with its impacts already being felt. Some further change is therefore unavoidable regardless of future mitigation, and adaptation is the only means of dealing with it.

3. 3

   Distinguish between mitigation and adaptation.

   Model answer

   Mitigation acts on the cause and adaptation acts on the consequences. Mitigation reduces greenhouse gas emissions or removes greenhouse gases from the atmosphere, thereby limiting how much warming eventually happens; its benefit is global, shared by everyone regardless of who paid, and delayed by decades because of the inertia in the system. Adaptation reduces vulnerability and exposure to the impacts of the warming that occurs anyway; its benefit is local, accrues directly to whoever funded it, appears quickly, and does not depend on what any other country does. Mitigation therefore suffers from the free-rider problem while adaptation does not, but only mitigation can prevent the problem growing without limit. They are complements, not alternatives.

4. 4

   Classify each of these as mitigation or adaptation, and say why: a sea wall, an offshore wind farm, a drought-tolerant seed variety, a carbon tax, planting mangroves.

   Model answer

   A sea wall is adaptation: it reduces the harm from sea-level rise and storm surge but does nothing about the greenhouse gases causing them. An offshore wind farm is mitigation: it displaces fossil fuel generation and so reduces emissions. A drought-tolerant seed variety is adaptation: it protects yields under conditions that occur regardless. A carbon tax is mitigation: it raises the cost of emitting and so reduces emissions across the economy. Planting mangroves is both, which is worth noting - the trees and their sediments store carbon, which is mitigation, while the belt of vegetation absorbs wave and surge energy and traps sediment, which is adaptation. Measures that do both are particularly attractive, and are usually called win-win or co-benefit measures. That is a different idea from a no-regrets option, which is one worth doing for its other benefits even if the climate were not changing at all.

5. 5

   What is vulnerability, and what determines how vulnerable a place or group is?

   Model answer

   Vulnerability is the degree to which a system, place or group is likely to be harmed by climate change, and it is determined by three components. Exposure is whether the hazard reaches them at all - living on a low-lying delta, an atoll, a floodplain or in a semi-arid region raises it. Sensitivity is how much damage a given hazard does - an economy dependent on rain-fed agriculture or on coral reef tourism is more sensitive than a diversified service economy. Adaptive capacity is the ability to prepare, cope and recover, and it depends on wealth, technology, infrastructure, education, health services, insurance, governance and social networks. Reducing any of the three reduces vulnerability, and adaptation policy works mainly on exposure and adaptive capacity.

6. 6

   What are the main coastal adaptation options?

   Model answer

   Hard engineering: sea walls, revetments, embankments and large storm-surge barriers such as those protecting London and Rotterdam, which give a high standard of protection but are costly, need maintenance and can shift erosion elsewhere along the coast. Soft engineering: beach nourishment, dune stabilisation and the restoration of mangroves, saltmarsh and reefs, which are cheaper, adjust themselves and provide habitat, but offer a lower and less certain standard. Accommodation: raising buildings on stilts or on earth plinths, raising road and rail levels, building flood-resilient structures and cyclone shelters, and improving warning and evacuation. And retreat: managed realignment of defences inland and, at the extreme, planned relocation of communities. Most coasts require a combination chosen according to what is being protected and what it is worth.

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