Rising Sea Levels & Bangladesh

RISE IN SEA LEVELS 

AIM:  To investigate how sea level rise may have a disproportionately bigger effect on some countries like Bangladesh.

Modelling the rise in sea levels 

There are various predictions for sea level rise for the future. The mode extreme one predicts a rise in sea level by 15m by 2100. This puts many places including London in peril. But how is this 15m going to be achieved?

  1. Melting of West Arctic ice sheet = 5m rise
  2. Complete melting of Greenland ice sheet  =  7m
  3. Collapse and melting of world’s glacier system = 2m
  4. Continual thermal expansion of oceans = 1m

So all four event equal a 15m rise in sea level.However, most models produce a rise of 1m. Nevertheless, it is important that we act fast because even if the probability is small the risk of sea levels rising is so great. There are 3 key fundamental reasons why it is so difficult to model sea level rise hence the vast set of results.

The first reason is that it is difficult to predict the quantity of future greenhouse gas emissions especially as that isn’t just based on us it is based on nature e.g. volcanic eruptions. The second is based on the concept of ceteris paribus which is the concept that all other things remain the same i.e. ‘business as usual’. Finally, it is difficult to predict the actual impacts of a rise in sea levels.

There are two types of changes involved when we are discussing sea level changes: EUSTATIC & ISOSTATIC. Eustatic changes involve changes in sea level due to the amount of water in oceans and isostatic changes involves movements of land in response to changes in sea levels.

So where are the most vulnerable places?

There are three types of area which are most vulnerable to changes in sea level rise.

  1. Land on river deltas e.g. Bangladesh
  2. Areas that lie close to sea level e.g. Netherlands, Eastern Britain
  3. Small low lying islands in the Pacific oceans e.g. Tebua

CASE STUDY: Bangladesh

Background

  • 70% of the country lies on flood plains, less than 6m above sea level
  • Faced by multiple varieties of hazards
  • Has a growing population 
  • It is an LEDC
  • It is the world’s most densely populated area
  • It is a mega-delta filtering 57 river including Ganges, Meghna and Brahmaputra. In addition it filters snowmelt from Himalayas, monsoon rains and high tides.

What happens if sea levels rise

  • It could loose up to 20% of its land
  • Displace 40 million people
  • Threaten food supply, drinking water and agricultural land
  • Increasing water temperatures can lead to increased number of water borne diseases such as Cholera
  • The biggest risk is being lost like Tebue which means that tens of millions of environmental refugees will have to seek livelihood in other countries.
  • Damage to coral reefs 
  • More risk of cyclones
  • Malnutrition
  • Child development and education will be negatively affected 
  • Loss of properties 

So how are Bangladesh acting right now?

  1. Technological solutions – In the 1990s, Dhaka the capital city – cleared 102km of drains and constructed 144km of drains. They also opened 633 channels to improve drainage
  2. Early warning/ flood predictions – This includes preparing people especially the vulnerable of floods e.g. allowing people to be evacuated to safer grounds quickly and effectively
  3. Behavioural – Changing land uses and food choices e.g. increase fishing more than arable farming. Bans have also been put in place to slow down urbanisation
  4. Managerial – e.g. improve sanitation and water management to prevent water-borne diseases.

The solutions presented in this post are one thing but Bangladesh only has limited funds and there is a limit to how much they can borrow or rely on international aid. They also have a large vulnerable population and protecting every single citizen isn’t easy. Bangladesh has to think ahead as climate change provide more extreme situations of flooding etc then they have prepared for.

REVIEW QUESTIONS

  1. Define Eustatic changes.
  2. Define Isostatic changes.
  3. What are the three reasons that make modelling difficult?
  4. What is extreme quantity of sea level rise predicted?
  5. What are three most vulnerable places in regards to rising sea levels
  6. State two facts about Bangladesh
  7. Name three impacts of rising sea levels in Bangladesh
  8. Name two solutions Bangladesh plans
  9. What are the two fundamental  problems with these solutions?
  10. What are the three main rivers of the 57 that make Bangladesh a mega-delta?

Suggested Answers

  1. Eustatic changes are changes caused by changes in the amount of water in oceans
  2. Isostatic changes are the responses of land to changes in sea levels
  3. It is based on the concept of ceteris paribus, it is hard to predict future greenhouse gas emissions and we do not accurately know the impacts of rising sea levels
  4. 15m 
  5. Large river delta e.g. Bangladesh, the Nile, places with low lying land such as Netherlands or Eastern Britain, small low lying islands in the Pacific or Indian ocean
  6. Almost 70% is a flood plain which lies on less than 6m above sea level and  has the world’s most densely populated area
  7. 40 million people will have to be displaced, risk of water borne diseases such as Cholera and risk to properties and livelihoods 
  8. Technological 633 channels to improve drainage and managerial improve sanitation and waste management
  9. Bangladesh does not have the funds and has a large vulnerable population
  10. Ganges, Meghna and Brahmaputra
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