Global population futures

How has ozone depletion impacted global health?

Depletion of ozone in the upper atmosphere means that more ultraviolet radiation reaches the earth’s surface. This depletion is caused by chlorofluorocarbons and halocarbons, the main sources of which are heavy industry, fridges and aerosol sprays.

Increased exposes to ultraviolet radiation can increase risk of:

- Skin cancer

- Skin cancer is the 17th most common cancer worldwide

- Cataracts

- Cataracts cause the lens of the eye to become cloudy and can cause blurred vision

- Cataracts causes blindness in approximately 20 million people worldwide each year

The Montreal Protocol 1987 limited the release of chlorofluorocarbons and halocarbons into the atmosphere, reducing CFC emissions by 99%.

- A summit in Copenhagen 1992 then tightened restrictions further

How has climate change impacted global health

Climate change is having negative impacts on human health in three ways:

Direct impacts of more extreme weather, such as flooding and tropical storms

Indirect impacts of reduced environmental quality, such as air and water pollution and infectious diseases

Indirect impacts of reduced levels of mental health, such as increased trauma from climate-induced natural disasters

Nutritional standards:

• Food shortages leading to malnutrition and famine

• Increase in vitamin deficiency and diseases such as rickets

• Rise in food prices caused by lack of supply in some areas

Thermal stress:

• Heatwaves increase risk of cardiovascular disease and respiratory disease

• Extreme cold can increase mortality rate amongst the young and elderly

Vector borne diseases:

• Hotter and wetter conditions lead to increased growth and survival of vectors such as mosquitoes

Agricultural productivity:

• Changes in precipitation patterns and temperatures change which crops can be grown where

• Extreme and unpredictable weather makes income from agriculture more unpredictable

• Increase in pests and diseases that destroy crops

• Sea level rise can cause saline intrusion into crop lands

The World Health Organisation (WHO) predicts that by 2050 climate change will be responsible for an extra 250,000 deaths worldwide each year

There are some positive health impacts too, such as increased food supply in some parts of the world.

Describe and explain the predicted global population change

• Although global population growth rates are in decline, UN predictions suggest total global population will continue to rise for some time

  • Expected to increase from current 8 billion to 9.7 billion in 2050

  • Could peak at nearly 10.4 billion by 2085

  • Possible decline after from 2085 onwards

• These trends are due to:

  • A decline in fertility rate

    • Predicted to decline from a global average of 2.5 today to 2 children per woman in 2100

    • The fertility replacement rate is 2.1 to allow for infant mortality, so a rate below that means population will fall

  • An increase in life expectancy

    • Better healthcare and standard of living mean more people are living for longer

What are the limitations of current predictions for future population growth?

• Future total population predictions are problematic

  • They rely on current trends continuing

  • Political agendas in some areas might bring in anti- or pro-natalist policies which impact birth rates

    • E.g. Singapore and Japan currently have policies in place to encourage people to have more children to lower their dependency ratios

  • They don’t take into account external factors, such as war and pandemics, that can increase death rates significantly