Impacts of Climate Change (Cambridge (CIE) IGCSE Environmental Management): Revision Note

Impacts of climate change on temperature

• Earth's average surface temperature has risen by approximately 1.34 to 1.41 °C since the pre-industrial period

  • The last decade has been the warmest on record

• Climate change is causing:

  • A rise in global average temperatures

  • More frequent and intense heatwaves

  • Fewer cold extremes

• This warming is not uniform, affecting land more than oceans and the Arctic region more than other places

Impacts of climate change on ice sheets & oceans

• The surface temperature of oceans will increase, causing sea level rise as it becomes warmer and expands in volume (thermal expansion)

  • By 2100, global sea levels are predicted to rise between 0.3 and 2 meters

  • As sea levels rise, seawater ingress into underground water supplies reduces fresh water availability, affecting agriculture and drinking water supplies

• As glaciers, ice sheets, and permafrost melt, they flow into the sea, raising the level

  • Average sea levels have risen 23 cm since 1880

  • Sea levels are forecast to increase by a further 30 cm by 2050

• Oceans become more acidic due to increased concentrations of CO₂ in the atmosphere

  • Ocean acidification reduces calcium availability

  • Corals and shellfish will struggle to form and maintain their shells and skeletons

  • This can lead to population decreases

• As sea levels rise, they lead to the loss of low-lying coastal land and increased erosion

  • Low-lying coastal areas and islands are at higher risk of flooding

    • The Maldives may be uninhabitable by 2050 

  • Beach erosion will increase, leading to greater coastal erosion 

Impacts of climate change on ecosystems

• Animals and habitats are adapted to the climate in which they live

• Any changes in the climate will harm ecosystems and animals, reducing biodiversity levels

• As temperatures rise, many species may struggle to live and be forced to relocate

• If suitable habitats are unavailable or species cannot migrate or adapt fast enough, they may become extinct

• Warming can indirectly reduce biodiversity by affecting water availability, intensifying natural disasters, and spreading disease, causing species extinction

Impact of climate change on biodiversity

• Climate change can lead to habitat loss and changes in the food web

• All of these can reduce biodiversity

  • For example, coral bleaching due to increased sea temperatures reduces the variety of species in coral reefs

  • This can reduce the ability of coral reefs to cope with other changes, like ocean acidification or increased tropical storms

• Habitat fragmentation, such as wildfires, separates species, reducing the resilience of ecosystems by isolating and limiting species' ability to adapt to new conditions

• Climate change alters biodiversity distribution, affecting food webs and chains

  • If species richness changes, some species deplete and others thrive

  • However, it may also allow invasive species to take over, affecting the availability of food for existing species

Effect on habitats

• The location of ecosystems and biomes may shift to the north (Northern Hemisphere) and south (Southern Hemisphere) as they rely on specific climate conditions:

  • Polar and tundra biomes are at risk of becoming extinct, as they cannot shift any further north/south

  • Mangrove swamps and coral reefs are already threatened by rising sea levels

• Current ecosystems may change in structure and composition

  • For example, the Arctic tundra is transforming into shrubland as warmer temperatures allow shrubs to grow

  • Rising temperatures are melting the permafrost, or frozen soil, is allowing bacteria and fungi to break down soil that has been frozen for thousands of years

  • As polar ice and glaciers retreat, there may soon be no summer ice in the Arctic if rates of warming there continue

• Seasonal cycles are changing, e.g.

  • Plant species are producing flowers earlier in the year

  • Animals are producing young earlier in the year

  • Bird migratory patterns may lose their synchronisation with their habitats, leading to a change in migration patterns

• Some ecosystems may disappear if conditions become unsuitable for the species that inhabit them

  • For example, alpine regions may lose their unique flora and fauna as temperatures rise and snow cover decreases

  • This can lead to declines in population numbers and even extinction in some cases

Impacts of climate change on migration

Forced migration of animals

• Migration and behaviour patterns of animals affected by changing temperatures

  • Fish species are moving north and south of their usual habitats to seek cooler water

  • Reduced hibernation due to warmer winters

  • Bird migration times have altered

  • Bird nesting is happening earlier

  • Species in mountainous regions might be forced to move to higher altitudes, creating isolated populations

• As species move to new areas or experience changes in their habitats, they may face new competition, predation, or disease

Forced migration of humans

• Almost 32 million people were displaced by weather-related hazards in 2022

  • Over 200 million people may be forced to move by 2050

• There is a loss of land for settlements and agriculture due to extreme weather events such as flooding, drought, desertification, storms and wildfires

• There will be an increase in forced migration as people lose their homes and livelihoods due to rising sea levels

  • People from the south of Bangladesh are relocating to urban areas due to coastal erosion and flooding caused by sea level rise

• Places which are popular with tourists are often reliant on their climate as part of the attraction

• The tourist industry in these areas may be negatively affected by an increase in:

  • Tropical storm frequency and severity

  • Water shortages

  • Melting of snow and ice leading to the closure of ski resorts

Impacts of climate change on weather patterns

• The link between extreme weather events and global warming is complex and it is difficult to link any single event directly

• However, since the 1980s, there has been an increase in extreme weather events

• Particularly floods, storms, and extreme temperatures

• Rising sea levels, together with increased storms, lead to increased flooding risk

• The frequency and length of droughts are increasing

  • As areas become drier, they become more vulnerable

  • In parts of East Africa between 2020 and 2022, there were five failed rainy seasons

    • This displaced over 1.2 million people in Somalia

• Dry conditions lead to an increased risk of wildfires

• Stagnant air during heatwaves leads to increased levels of air pollution

  • Respiratory diseases increase and those suffering from respiratory illnesses such as asthma may be more affected 

• Many countries rely on their climate for tourism and climate change is affecting this attraction

• In the Caribbean, changes to the climate, which are already occurring, include:

  • Average temperature has increased by over 1^°C since the 1950s

  • An increase in water temperatures

  • Drought

  • Changes in coral reefs

  • More severe and frequent storms

• The 2017 hurricane season was particularly severe, with Hurricane Irma and Maria causing destruction over many islands

  • Over 90% of Dominica's buildings were destroyed

• In 2020, there were 30 named storms, many of which caused devastation to people living in the Caribbean

  • These all impacted on the tourist industry

  • Many tourist resorts did not reopen; others took many months, even years to rebuild

Impacts of climate change on agriculture & food production

Change in crop yields

• Wheat and maize yields have been negatively impacted in most regions since 1960

• Crop yields are estimated to continue reducing by over 20% as temperatures increase

• The effects are that rice and soybean yields have been smaller in all major production regions 

• The largest impact has been on the price and production of food for daily consumption

  • Production has decreased

  • Prices have increased

• A changing pattern of rainfall will also threaten crop production

  • Too little rain and crops will fail

  • Too much rain and crops will rot in the fields

• Suitable areas for agriculture will change

  • Farmers may have to change their crops 

  • Areas that could grow certain crops will have to change

    • Wheat grown in the USA will have to be grown in Canada

    • This would negatively affect the USA's economy while boosting Canada's

• Reduced availability of water will mean that irrigation is limited or impossible

• Less reliable food supply and higher prices

• Food shortages will lead to malnutrition and famine

Food shortages

• Food shortages and price spikes following extreme weather events, such as hurricanes or droughts

  • Water rationing in Cape Town, South Africa, during a prolonged drought leading to severe water shortages (2017-2018)

  • Decline in wheat yields in Australia due to heat stress and reduced rainfall

  • Outbreak of coffee leaf rust in Central America, resulting in significant losses for coffee farmers

  • The loss of glacier ice from mountain ranges affect water supplies of many people and the surrounding wildlife

Increased pest outbreaks and invasive species

• Tropical diseases will spread to cooler regions as temperatures rise, as disease carriers, like mosquitoes and ticks, will survive and breed in warmer environments

  • Italy has experienced cases of malaria since 2017, when it was previously a malaria-free area

• Warming will affect the location, number and range of disease-carrying pests (including insects, animals, plants or microbes)

  • This will increase disease transmission rates

• Changes in species distribution and numbers may disrupt ecosystems and increase disease outbreaks due to population density