Societal impacts of climate change: Sea level rise

By Matt Burdett, 10 April 2018.

On this page, we look at the societal impacts of climate change on people and places, with a special focus on sea level rise, and how Small Island States (SIDs) are responding.

Societal impacts of sea level rise

The IPCC (2014) projected that average sea level rise worldwide would be between 0.44m and 0.74m by 2100. People around the world will be directly affected by sea level rise in two main ways:

  • Those living along low-lying coastlines might experience flooding more often
  • People near the coast may experience more intense storms, including tropical storms like hurricanes

Vulnerable coastal areas

In 2014 The Nature Conservancy released a report called ‘Coasts at Risk’. The report identified that some countries were more exposed to the hazards of sea level rise than others, as shown in the map below.

  • Exposure of the population to coastal hazards (storms, floods, surges, tsunamis, sea level rise). Source: Beck (ed.) 2014.

Currently around 2% of the world’s land area is in a low-lying coastal area, but it is home to more than 600 million people. Of those 600 million, many are in low and middle income countries. None of the top five vulnerable countries is highly economically developed, and all are in Asia: they are Bangladesh, China, Vietnam, India, and Indonesia (IPCC, 2014). People in these countries are especially vulnerable because they are less likely to be able to adapt with infrastructure like sea walls or careful urban planning, and all these five are in areas where tropical storms are a feature of the climate. This means that the vulnerability of the country is not only dependent on being near a low-lying coastline but also whether the local economy is strong enough to prepare for the hazards of sea level rise. The variation in overall vulnerability was calculated in the “Coasts@Risk Index” (Beck (ed.), 2014) shown on the map below.

  • The Coasts At Risk index. Source: Beck (ed.) 2014.

Countries like the UK that have a very high susceptibility to coastal hazards are not actually very high on the index because they have the capacity to cope. But some other countries, such as Ghana, that appear to have very low susceptibility are actually quite vulnerable because, if or when a hazard event occurs in those countries, they would be unable to deal with the problems.

Economic impacts

The IPCC (2014) highlighted a report that estimated the potential costs of coastal flooding for cities. In 2005 the total global cost was about 5% of the global GDP; by 2070 the estimate was for 9%. The cost is for the damage done to infrastructure and property.

The increase in costs is not the same everywhere. The map below shows the cities which will have the biggest increase in economic losses by 2050. Most of these cities are in the ‘middle income’ area. One reason why there are few low-income cities on the map is because the total value of their infrastructure is relatively small compared to the cities shown, so they will lose less. However, those low-income cities will be the least able to afford the losses, so there will be a bigger proportional economic loss. Meanwhile, there are very few high-income cities despite major cities such as London, New York, Hong Kong and Sydney being coastal. It’s likely that these cities will be able to adapt to the changing sea levels by building sea walls and other defences, and therefore they won’t actually have much economic loss.

  • The 20 coastal cities where average annual losses (AALs) increase most. Source: IPCC, 2014 (p382)

Social impacts

The main social impact of sea level rise is forced migration. Some estimates suggest that 2 billion people may have had to migrate by 2100 (Friedlander, 2017). Most of these migrations will be in poorer countries, but there could be impacts everywhere, including the USA where up to 13 million might have to migrate by 2100 (Dunham, 2016).

These headline-grabbing numbers are the upper end of a very wide possible range. The uncertainty about the number of migrants is due to:

  • Uncertainty about the actual sea level change itself
  • Predictions of population growth vary
  • The population growth might not happen in the specific areas predicted, in which case there might be fewer people who need to migrate
  • Migration could happen very gradually so it’s difficult pin down exactly the reason for migration

Response impacts: adaptive capability

Perhaps the most important impact is that countries may need to spend money on coastal defences. The IPCC’s Fifth Assessment Report (IPCC, 2014) identified three possible responses for at-risk areas:

  1. Protection for people and property. This includes ‘hard engineering’ such as building sea walls, soft engineering’ like re-growing mangroves to absorb wave energy
  2. Adaptation. Buildings, infrastructure and emergency shelters are adapted so they can withstand the changing conditions.
  3. Managed retreat. Allow the natural changes to coastal areas and move people and property inland.

The IPCC put these into a diagram in the Fourth Assessment Report (IPCC, 2007):

  • A schematic overview of inter-relationships between adaptation, mitigation and impacts. Source: IPCC, 2007.

The map below shows the results of various studies that have calculated the height that would have to be added to flood protection structures to avoid future flooding. These height increases will be extremely expensive so it’s likely that a combination of all three of the above strategies would be used in most countries, with hard engineering (such as raising the height of sea walls) only used for the most valuable areas like cities.

  • The estimated increase in height (m) that flood protection structures would need to be raised in the 2081–2100 period to preserve the same frequency of exceedances that was experienced for the 1986–2005 period, for selected places. Source: IPCC, 2014 (p371)

Small Island Developing States (SIDS)

Small island states are countries that exist entirely on islands. These countries include low income countries such as Maldives, Fiji, Tuvalu, Tonga as well as some high income countries such as Singapore and Barbados. Some Small Island States have high per capita income levels. However, as a group, they are all vulnerable to climate change. All of them are so small that they cannot make any significant contribution to mitigation. More importantly, they are so small that they cannot move their populations or properties to areas unaffected by sea level rise (IPCC, 2014). Their very existence is threatened by rising seas:

  • Complete loss of land above sea level
  • Contamination of fresh water supplies by sea water
  • More vulnerable to storms
  • Loss of key infrastructure such as port facilities due to erosion

As most of these countries are low or middle income countries, they are grouped together as Small Island Developing States (SIDS). The UN designated SIDS are shown on the map below.

  • Small Island Developing States, as of June 2017. Source: UNCTAD, 2017.

A World Bank (2017) report identified that SIDS have already suffered US$3 billion in damage to property in the Pacific Islands alone. The graphics below identify how these countries have important reasons to want to reduce climate change.

  • The particular concerns of SIDS regarding sea level rise. Source: AOSIS, 2017.

  • Features of the SIDS that are members of the AOSIS. Source: AOSIS, 2017.

Sustainable Development Goals

The United Nations and other organisations recognise the cause of SIDS at the global level, with SIDS specifically mentioned as part of the Sustainable Development Goals. Goal 13, Target B specifically states:

“Promote mechanisms for raising capacity for effective climate change related planning and management in least developed countries and small island developing States….”

Goal 14, Target 7 states:

“By 2030, increase the economic benefits to Small Island Developing States and least developed countries from the sustainable use of marine resources…”

(UN-DESA, 2018)

Political response: Alliance of Small Island States

Many SIDS (and small island states that are not ‘developing’) have joined together as part of the Alliance of Small Island States which was formed in 1989, the ‘Small States Conference’ in Malé in the Maldives. As of 2018, there are 39 member states with 5 observer states (AOSIS, 2017). (Observer states are those that work with the organisation but do not take a full part in decision making. The observer states include those that are territories of other, larger countries such as Puerto Rico which is a territory of the United States. They are not responsible for their own foreign affairs so they cannot become full members.)

  • Global partnerships for climate change in relation to SIDS. Source: AOSIS, 2017.

The work of AOSIS is largely about promoting the agenda of SIDS at the global level. A key success of the AOSIS was the choice of Fiji to hold the presidency of the 2017 UNFCCC Climate Change Conference (COP23), though it was held in Bonn in Germany due to the expense, organizational difficulties and the number of people who need to attend. They have also developed the ‘AOSIS Climate Change Fellowship Programme’ from 2013 onwards which has trained young professionals from various SIDS in policy making, climate change law and so on (AOSIS, 2017).

Adaptation response

The World Bank has a ‘Small Island States Resilience Initiative’ which provides funding of around US$180 million per year to over 20 SIDS (World Bank, 2017). The adaptation that has taken place is mostly on a small scale, with over 1700 individual projects. These projects assume that the global initiatives to mitigate climate change will succeed and include things like building better storm shelters, raising the height of key infrastructure such as medical centres, and educating local people about ways to prepare for severe marine events.


AOSIS, 2017. United Nations Development Programme / Alliance of Small Island States: Rising Tides, Rising Capacity Supporting A Sustainable Future For Small Island Developing States. Accessed 7 April 2018.

Beck (ed.), 2014. Coasts at Risk: An Assessment of Coastal Risks and the Role of Environmental Solutions. The Nature Conservancy. via Accessed 7 April 2018.

Dunham, 2016. Sea level rise projected to displace 13 million in U.S. by 2100. Accessed 7 April 2018.

Friedlander, 2017. Rising seas could result in 2 billion refugees by 2100. Accessed 7 April 2018.

IPCC, 2007. Working Group II: Impacts, Adaptation and Vulnerability. Chapter 18: Inter-Relationships Between Adaptation and Mitigation. Via Accessed 7 April 2018.

IPCC [Intergovernmental Panel on Climate Change], 2014. Fifth Assessment Report. via Accessed 4 April 2018.

World Bank, 2017. Small Island States Resilience Initiative. Accessed 7 April 2018.

UN-DESA [United Nations Department of Economic and Social Affairs], 2018. Sustainable Development Knowledge Platform. Accessed 7 April 2018.

UNCTAD [United Nations Conference on Trade and Development], 2017. Map of SIDS. Accessed 7 April 2018.

Societal impacts of climate change: Sea level rise: Learning activities


  1. What is the projected amount of sea level rise by 2100? [1]
  2. What are the two types of place that will be most affected by sea level rise? [2]
  3. Explain the link between economic development, susceptibility to sea level rise, and the overall vulnerability of a population. [4]
  4. With reference to examples, outline the economic impacts of sea level rise. [4]
  5. Suggest why it is difficult to predict the level of migration that will take place in the future due to sea level rise. [3]
  6. Identify the three possible responses to sea level rise. [2]
  7. Distinguish between hard and soft engineering? [2]
  8. What are SIDS? [1]
  9. Describe the global distribution of SIDS. [3]
  10. Explain why SIDS are particularly at risk from rising sea levels. [4]
  11. Identify the two Sustainable Development Goals that refer to SIDS in relation to climate change. Include both the numbers and the full text of the goal. [2]
  12. What does AOSIS stand for, and what does the organisation do? [2]

Other tasks

Imagine you are the Prime Minister of Fiji. You are welcoming the representatives of countries from around the world to the COP23 in your role as the leader of the presiding government. Give your introductory speech outlining the reasons why your country wanted to preside over the talks.

If you wish, you can include a section that explains why the conference is being held in Germany instead of Fiji. You could try to link these reasons to the particular problems your country faces due to sea level rise.