Glaciological and Geological Evidence
- Glaciers - The advance and retreat of glaciers us a clear response to variations in climate. Most glaciers have shown a descrease in size.
- Ice cores - Drilling through ice can give us a detailed picture of greenlands past climate.
- e.g the extent and size of ancient drainage patterns and fluvial deposits in parts of N.Africa
- Geologists use radio carbon dating to find the age of fossils, rocks and sediment
- Dendrochronology - Involves the study of the annual growth of rings of trees that reflect the climate of the area.
- Pollen Analysis - The characteristics of plants including rate of growth and flowering and the production of pollen are influenced by climate change. Pollen preserved in peat and sediment can be very useful to reconstruct past climatic condition.
Is climate change natural or human induced?
- Not all areas of the world are warming at the same rates (Fastest - Arctic)
- Some areas have not warmed at all in recent decades
- Industrial areas are not warming as fast as more remote areas.
The natural greenhouse effect
- The driving force for weather and climate is the sun and its radiation
- The earths atmosphere intercepts the radiation and 30% reflected back into space by reflective surfaces such as snow.
- If this was the only factor the earths surface would be 33 degrees cooler and human life would be impossible.
- Some radiation is absorbed by the earths surface and some is re-emitted by greenhouse gases which warm the earths atmosphere by 33 degrees.
- The process is completely natural.
- The main greenhouse gases have increased from the pre-industrialised concentration of 280 ppmv to 367 ppmv.
- CO2 - The main reasons for increase is combustion of fossil fuels and deforestation.
- Nitrous Oxide - Agricultural fertilisers. burning fossil fuels. It traps infrared radiation in the atmosphere, changing to nitric acid which destroys ozone and allows harmful ultraviolet rays into the earths atmosphere.
- chloroflurocarbons(CFCs now band so ozone hall closing) - used in 1960s in spray cans. they abssorb solar radiation and contribute to global warming.
- Ozone - Plays a vital role in dispersing harmful ultraviolet rays.
- Methane - very effective at retaining heat. Annual emissions have increased four times faster than the increase in CO2. Causes are rice production, coal mining and livestock flactulance.
Changing the salinity
- Oceans and winds help to distribute heat between its warmest and coldest parts.
- The current of warm water in the atlantic is known as the gulf stream. This makes the UK's climate warmer than it would otherwise be for its latitude and as it flows the ocean releases heat into the atmosphere.
- As the ocean cools it becomes denser and sinks to the ocean floor.
- This helps to form an ocean circulation called thermohaline circulation.
- This is a flow of warm and cold water that circulates around the world's oceans.
The enhanced greenhouse effect
- The increase in the natural greenhouse effect is said to be caused by human activities whcih increase he quantity of greenhouse gases in the atmosphere.
- The quantities of several greenhouse gases have increased by 25% since 1750.
- 75% of CO2 emissions have come from burning fossil fuels.
- They believe it leads to increasing global temepratures.
- Human activities such as burning fossil fuels and deforestation which releases natural stores of carbon and nitrogen which combines with oxygen to form greenhouse gases such as carbon dioxide and nitrous oxide.
Thermohaline circulation - The way it works
- The water is both cold and very saline whih makes it denser heavier and causes it to sink.
- By sinking it draws warmer water in from the ocean surface above. This in turn draws water across the ocean surface from the tropics.
- Eventually this movement from the tropics draws cold water up from the ocean bottom ready to be warmed again.
- This pattern is being disturbed and more freshwater is entering the arctic oncean as a result of global warming which melts the ice and increases rainfall.
- Melt water lowers the salinity which decreases the density of the ocean and slows down the rate at which the ocean sinks.
- Global warmiong could turn off the North Atlantic Drift which supplies Europe with warm water and air.
- It this is stopped january temperatures in Western Europe would drop by at least 5 degrees creating bitter winters.
Evidence for global warming in Africa
- Africa is steadily warming as a continent as a whole it is 0.5 degrees warmer than it was in 1900.
- Temperatures have increased more in the interior as coastal areas are cooled by the sea. Some inland areas have experienced double the global increase. e.g kenya increased by 3.5 degrees since 1985.
- Droughts have become more common
- Rainy seasons are now more unreliable and overall is decreasing. 40% decrease expected.
- Rains are more localised
What are the causes of Africas vulnerability?
- Most African economies are heavily dependent on famring and agriculture is rain fed and vulnerable to rainfall shortages.
- The united nations environmental programme reported in 2007 that 14 countries in Africa were suffering from water shortages and 11 more will join them by 2032.
- Rainfall is declining in the areas that need it most - areas with high annual totals are likely to maintain or increase them but the edge of the Sahara ( Sahel region) is likely to see reductions.
- Competition for water is likely to arise between countries such as the Nile (Egypt, Sudan and Ethiopia)
- As scarcity increases so does dependence on poor quality sources. This leads to increase in water-bourne diseases like cholera (particulaly you and old) putting pressure on health care systems and therefore on giverment budgets.
Physical and Human Impacts
- The main impacts in africa are human but in the arctic they are physical.
- The changes in rainfall can reduce the period in which crops grow
- Malaria is also on the increase as increased humidity and rainfall causes the mosquito to spread over wider areas. Its estimated that the area will double and that 7.2 million people will be at risk which is an increase of 5.2 million.
Debt and Global Warming - Africa
- One of the main reasons Africa is vulnerable to global warming is because of its debt crisis.
- Many countries have had the dept written off because the worlds richest countries (G8) decided to cancel them in 2005. (18 countries)
- However the burden of debt still affects the majority of African countries.
- The Debt crisis - African countries have become so heavily indebted that repayments sometimes exceed their entire GNP.
- Case crops - Crops sold for income, rather than their own food supply.
- Desertification - The way climate change and over grazing turn previously fertile land into desert.
- Food security - The extent to which a country can rely upon food supplies e.g upon the weather, or, if unable to grow all its food, the extent to which it can pay for imports to feed itself.
Impacts of projected change
- The impacts can be classified as direct or indirect.
- The arctic is vulnerable environmentally and ecologically.
- The African continent is most vulnerable economically as it is home to many of the world most vulnerable people.
- These case studies demonstrate the concept of an unfair world, whereby the poor areas suffer most despite having contributed very little to greenhouse emissions.
The indirect effects of global warming
- Equally important are the indirect affects resulting from the eustatic rise of sea level. These will have a global impact, particulaly on low lying areas e.g 80% of the lanf and coral atolls such as the Maldives.
- The rate of climate change may reach the tipping point at which catastrophic and irreversible changes can occur.
- e.g changes in albedo (reflectivity) over the arctic ocean as ice cover is lost - less sunlight being reflected off darker coloured waters - will accelerate warming further).
- Melting of premafrost - if sea level rises methane hydrates will be given off
Impact of global warming on Africa
- Some areas will get drier e.s S.Africa and Sahara
- Snow fields shrinking - Mt Kilimanjaro - reduced more than 80%.
- 2.5 degrees temp rise will result in a 4% increase in GDP(drought, crop failure, floods).
- 1190 easy water availability but by 2025 many people will have water scarcity/ stress/vulnerability)
- Rainfall decrease by 40%
- Temp increase by 4%
- Extreme events increase by 20%
- Malaria increase due to increase in stagnant water
- Sahel region by 2050 will have 50% less cereal production
- 1/3 of Africa will have 50% less cereal
- Increase in dust storms and animal deaths
- The point in which we reach the peak of the hill so the temp will just keep increasing.
- Albedo effect, warm acidic water in ocean (acidification), plants become less effective, carbon sink to carbon source, forests dry out causing fires.
- Permafrost melts and releases methane - 20% more powerful than CO2, methane under sea can be released raising global temps by 10 degrees.
How to prevent this
- Need to consume less
- Reduce greenhouse gases
- Reduce air travel
- Use renewable energy
- Use public transport
- Diversify from fossil fuels to renewable
Mitigation and Adaptation
- Mitigation - Policies that are meant to delay, reduce or prevent climate changes caused by global warming - e.g cutting co2 emissions, increasing carbon sinks (afforestation), wind turbines, hydroelectric, tidal, solar, nuclear
- cutting greenhouse gas emissions in developing countries is essential as economic growth leads to increase in emissions, environmentalists believe that adaptation policies waste time when the world should concentrate on reducing emissions.
- Adaptation - Policies that are designed to reduce the existing impacts of global warming such as sea defences, flood protection and manage retreat.
- It will take time to get all the countries to agree let alone cease them e.g Kyoto, the time taken to persuade countries to agree to reductions means that climate change will worsen before it improves.
- The world must therefore adapt because mitigation may not be achieved in time.
- They collected evidence suring the 1990s to show that global warming was really happening by collecting data about the atmosphere, observing sea levels, measuring greenhouse gas concentrations and used supercomputers to predict the impacts of global warming.
- The fear is a sequence of events leasing to irreversible change.
- It could be so great that it causes shifts in climate belts which would be irreversible.
Rising sea level
- Greenpeace estimates that the melting of the ice caps causes a rise in sea level of 10-25cm during the twentieth century.
- In the twenty-first they predict further rises of 15-95cm.
- 95cm would result in large scale coral bleaching, killing off hundreds of coral reefs. It would also flood large areas.
Shutting down the Atlantic thermohaline circulatio
- The TC is driven by cold dense arctic water and dense salty/saline water
- With global warming arctic sea water warms and becomes less dense. Melt water in rivers dilute the salinity of the arctic ocean making it less dense.
- The consequences of this is the gulf stream switching off or reversing causing the UK to freeze.
- There's a 50% chance it will shut down within 200 years.
Falling agriculture yields and water shortages
- The rain forest of northern Australia contain 255,000 species .
- If global warming leads to reductions in rainfall according to the stern review 40% would become extinct.
- The stagnation of the worlds oceans would mean mass extinction in the sea.
The Stern Review
- It focuses on the impacts of global warming and the actions needed to deal with them.
- Environmental impacts - increasing global flood risk, declining crop yields, rising sea levels, 40% extinction of worlds species %.
- options for change - reduce consumer demand, make global energy more efficient and prevent further deforestation, promote cleaner energy technology,
- UK government response - set targets to reduce carbon emissions byt 30% by 2020 and 60% by 2050, pass laws to set carbon reduction, invest in green technology, create a $20 billion world bank fund to help poor countries adjust to climate change.
European Emissions Trading Scheme (ETS)
- Aims to cut emissions by placing a limit of the total amount emitted, get polluters to pay for the damage by introducing credits for the gases they emit, create incentives for companies to invest in cleaner technology.
- Reduce the available number of credits to below the levels of demand to encourage the sale price and encourage companies to seal the credits and pay for cleaner technology.
- Manufacturing companies are moving out of Europe , polluters are not absorbing the price of the credits and the low cost of carbon credits are not leading to investment in green technology.
- The name given to a credit system called carbon credits which aims to reduce greenhouse gas emissions. It allows companies to pollute but at a cost. The cost encourages companies to look for other ways of production.
- Eg Shell - They pump waste co2 from an oil refinery into 500 greenhouses growing fruits and veg which avoids annual emissions by 170,000 tonnes.
- Londons congestion charge - drivers charged £8 a day to drive in central london congestion times - reduced levels by 15%, 12% reduction in emissions of NOx and co2.
- Congestion charging for New York - conjestion charging raising $380 million to fund public transport, new transport authority to fund public transport projects, planting 1 million trees by 2017, cutting greenhouse gas emissions by 30% improving power plants.
- Its a global agreement setting targets for reducing greenhouse gas emissions (175 countries signed up)
- Industrialized countries are to cut their overall greenhouse gas emissions to 5% below their 1990 levels by 2008-12.
- Australia and the USA are not signed up which are 2 main emitters.
- They cut emissions by 3% below their 1990 levels.
- Many countries believe the targets are too low.
Combined heat and power in Copenhagen
- Its a CHP system that supplies 97% of the city with clean, reliable and affordable heating.
- It supplies 15% of Denmark's total heating needs.
- uses a combination of;
- - Waste heat from electricity production
- - Surplus heat from waste incineration
- - Geothermal energy
- - Bio-fuels
- - Small amounts of natural gas, oil and coal.
- By 2005 annual heating bills were 1400 euros less than if oil had been used.
- Between 1995 and 2000 the citys annual co2 emissions dropped from 3.5 to 2.5 million tonnes.
- so2 emissions cut by 33%
CHP system is successful because ....
- It is clean; there are low co2 emissions from natural gas and bio fuels.
- It is cheap; costs have barely risen in 20 years and annual costs for consumers are 50% less than with oil heating.
- It is efficient - It wastes only 68% of the energy generated and is computer controlled so that excess heat in one area can be redirected to another area which needs it more.
- Tax incentives given to producers - The danish government gave tax incentives to the energycompanies involved so they pay less tax if they use CHP.
- It is the most controversial of all energy sources.
- Concerns about radioactivity from uranium
- the cost of dismantlingnuclear power stations is £30 billion.
- It involves a nuclear reaction which heats water and turns a turbine which generates electricity.
- It is very clean and lowers greenhouse gas emissions.
- Nuclear waste is radioactive for thousands of years and there is no known way of storing it making transportation difficult.
BedZED - local energy conservation project
- A new housing development in South London which attempts to be carbon-neutral.
- They were built in 2004 and use heat-efficient natural, recycled or reclaimed materials which absorb and release heat when needed.
- It has its own CHP plant, fed by waste wood from tree surgery that would otherwise go to landfill.
- The system provides hot water, distributed via insulated pipes
- The CHP system failed in 2005 and the houses are not cheap and new technology is expensive.
- Carbon neutrality is hard to achieve as most people drive there own cars although there is a car-sharing scheme.
- But..... the houses are so well insulated there is little need for heating, it uses 33% less water, they emit 40% less carbon than the average UK household and the houses are in demand at 15% above local house prices.
- The worlds most densely populated country (142 million)
- It lies on the flood plains of three major rivers
- Almost every year huge areas of the country flood as Himalayansnow-melt adds to monsoon rains and high tides of the Bay of Bengal.
- 60% of the country lies one metre or less above sea level
- Some of the worlds poorest and most vulnerable people live there.
The flood risk - Bangladesh
- They receive 2000mm of rainfall a year mainly between April and September
- Coastal flooding is a major problem as violent thunderstorms produce strong winds of up to 160km per hour which create 6 metre high waves from the Bay of Bengal to swamp coastal areas.
- Also during tropical cyclones low pressure reduces pressure on seawater in the Bay of Bengal which causes it to rise.
- The high tides and storms then surge inland.
- In 1998 2/3 of Bangladesh experienced flood damage eroding riverbanks and flooding vast areas.
Bangladesh and global warming
- The IPCC predicts that the snow-melt from the Himalayas will increase flooding in Bangladesh by 2030.
- Increased water temps will increase bacteria and diseases such as cholera.
- Coastal areas will be at risk from flooding and seawater inundation. This will destroy crops and increase the hunger risk
Adapting to global warming
- Technological solution - sea walls, river embankments, drainage systems.
- Early warning/flood prediction enables people to be evacuated quickly.
- Behavioural such as changing land uses and therefore food choices e.g fish farming.
- Managerial - improve sanitation, waste management and slum improvements so that water infections from disease during flooding is reduced.
- They are adapting as a cyclone 16 years ago killed over 140,000 but in 1970 a similar cyclone killed 500,000.
- Indonesia has over 17,500 islands with a population of 225 million.
- It is one of the worlds hazardous countries as its situated of the pacific ring of fire and has frequent earthquakes and volcanic eruptions.
- It has over 129 active volcanoes.
- It has 2 monsoon seasons annually causing flash floods.
- During El Nino season the country suffers drought
Management is hard because;
- The country has a low GDP and is ranked lowest with 114th out of 179 countries.
- Government corruption
- Economy being drained by dept.
- Political instability
- Terrorist attacks
- Asian economy crisis.
What is the future? - Indonesia
- Rising sea levels will increase the wave energy in tsunamis
- Much of the population live on low lying coastal areas so are at high risk.
- Greater climatic extremes may worsen the impacts of El Nino resulting in more and worse drought and forest fires.
- The tourist and fishing industries will deteriorate sharply
- Coral reefs are vulnerable and are likely to result in coral bleaching and death.
- The volcano Krakatau shows evidence of erupting in the next 20-30 years.