The UN Intergovernmental Panel on Climate Change (IPCC) has confirmed the climate is changing and that it is linked to human action (2007 Assessment Report).
The central factor is increasing global temperatures. This affects all natural systems – changing rainfall patterns, timing of seasons, water reservoirs, storm frequency, patterns of coastal erosion, location of flora and fauna, and food chains. It threatens extinctions, rising sea levels and loss of land used for agriculture. See the IPCC website for more on the science of climate change and its impacts on the planet.
The effects on people will be dramatic. The IPCC warns that if average global temperatures rise 2°C by 2050:
• 250 million people will be forced to leave their homes
• 1-3 billion people will face acute water shortages.
• 30 million more people will go hungry as agricultural yields fall and food prices rise
• Sea levels will increase up to 95cm by the end of the century. This would submerge 18% of Bangladesh alone, creating 35 million environmental refugees.
Why is the climate changing and what is the impact on people’s health| homes| access to food |access to water |vulnerability to disasters?
CO2 emissions from fossil fuels and deforestation are the key causes of human-led climate change. Both have spearheaded development and economic growth for industrialised countries.
Greenhouse gases are emitted when fossil fuels like coal, oil and natural gas are burned. They block heat energy escaping into the atmosphere, trapping the earth’s infrared radiation. Deforestation means there are fewer trees to absorb greenhouse gases, and the felling of trees releases more of the gasses. As a result of these factors, the earth’s mean surface temperature is rising.
Scientists have shown that warming observed during the twentieth century is unprecedented in the past 1000 years. The trend is continuing. The IPCC projects increases of 1.4 to 5.8 ºC by 2100 in comparison to 1990.
The world faces an average temperature rise of around 3°C this century if greenhouse gas emissions continue to rise at their current pace and are allowed to double from their pre-industrial level.
Some impacts include:
• Melting of permafrost and ice
• Rising sea levels
• Increased drought
• Earlier timing of spring events, such as leaf-unfolding, bird migration and insect hatching
These changes will cause:
• Increased water shortages in some areas (up to 250 million people in Africa at increased risk of water stress by 2020)
• Reductions in the area suitable for agriculture
• More damaging storm surges and coastal erosion
• Increased flooding in coastal and delta areas
• Increases in the frequency of droughts and floods diminishing crop production.
• Changing weather patterns which will bring more hurricanes and storms
• Increased risk of extinction among 20-30% of plant and animal species
• A major decline of most corals, which are critical to fish breeding.
The World Health Organisation warns the health and lives of millions of people are at risk from climate variability and change.
• Malnutrition will increase as food production decreases
• Supplies of fresh water will be compromised, bringing an increase in water-borne diseases. Already rising sea levels are causing salination of ground water reducing access to drinking water.
• An additional 220-440 million people could be exposed to malaria. Warmer, wetter weather will see malaria, which currently kills up to 3 million people a year, spread to new territories – there is evidence that it has already encroached into previously cool highland areas of Rwanda and Tanzania. Other insect borne and infectious diseases are expected to increase
• Natural disasters such as heatwaves, floods and droughts will occur more frequently
An estimated 150,000 more people are already dying annually from diseases that are increasing because of climate change.
One impact of global warming is rising sea levels. This is a significant threat to people who will lose their homes and land or be at greater risk of flooding.
• It is estimated that 10% of the world’s population live less than 10 metres above sea level. (UN population division)
• One hundred million people live within one metre of mean sea level
• If the temperature rises by 3°C, 330 million people will be permanently or temporarily displaced through flooding, including 70 million people in Bangladesh, six million in Lower Egypt and 22 million in Vietnam.
• The Carteret Islands, in PNG, have already become uninhabitable as high tides rise and flooding increases. The islanders are being formally relocated to the mainland.
The number of people at risk of hunger is projected to increase as crop yields and fish stocks decline and food prices rise.
• An additional 600 million people worldwide (9 percent of the world’s current population) may face malnutrition.
• A decrease in rain-fed agriculture yields of up to 50% are predicted for parts of Africa by 2020, which will exacerbate malnutrition. Already in east Africa, 11 million people are at risk of hunger by years of unprecedented drought.
• Extreme weather events will destroy food production.
• Rising sea levels and increased coastal flooding and erosion is contaminating ground water. In Tuvalu, people have already been forced to plant in pots instead of soil.
• Coastal erosion, coral bleaching and changing sea currents are all impacting on the breeding and location of fish stocks. 200 million people and their families worldwide depend on fishing and aquaculture for their food and income.
• Plants, livestock and fish will be exposed to new pests and diseases that flourish only at specific temperatures and humidity.
The number of people impacted by water scarcity is projected to increase from about 1.7 billion people today to around 5 billion people by 2025,independent of climate change (OECD).
Climate change will further reduce water availability due to increased frequency of drought, increased evaporation and changes in rainfall patterns.
• Between 75 and 250 million more people in Africa will experience water scarcity.
• Millions in Asia and South America depend on melting snow and glaciers for water. Thanks to rising temperatures, they are vanishing – since 1995 more than 90% of glaciers have been in retreat. Once they are gone, they cannot be replaced.
• If the glaciers of the Tibetan Plateau melt, then four of South East Asia’s major rivers could dry up, endangering the lives of one third of the world’s population.
• An additional 1.8 billion people (more than the population of China and the USA together) may face water shortages.
In other regions and areas too much rain will be the problem. Precipitation is expected to increase in equatorial, middle, and high latitude regions. Greater intensity of rainfall will lead to increased flooding, jeopardizing human settlements, livelihoods, crops and infrastructure.
Climate change will increase the incidence of extreme weather patterns:
• 90% of the victims of weather-related natural disasters during the 1990s lived in poor countries.
• Over the past 35 years, storms of the force of Hurricane Katrina have almost doubled. Meteorologists say rises in the temperature of the sea surface are the most likely cause.
• Bangladesh could experience 15% more rainfall by 2030, putting 20-40% more of its land at risk of flooding.