The greenhouse effect and global warmingWhat are they?The causes, effects, impacts and responses

Key Idea only the oneEnvironmental abuse has serious consequences. Its causes need to be tackled to ensure a more sustainable future.But there are still 3 sections to study ..

Section 3 part 1Causes of global warming and climate change: deforestation; use of fossil fuels; air pollution; agricultural change; CFCs.Consequences: rising sea levels; more hazards; ecosystem changes; new employment opportunities; changing settlement patterns; health and well being.A case study of the threats posed by global warming and climate change to one country (eg Bangladesh, the Maldives).

Please visithttp://news.bbc.co.uk/1/shared/spl/hi/sci_nat/04/climate_change/html/greenhouse.stm

THE NATURAL GREENHOUSE EFFECTThe atmosphere has a number of gases, often in tiny amounts, which trap the heat given out by the Earth.To make sure that the Earth's temperature remains constant, the balance of these gases in the atmosphere must not be upset.

The GREENHOUSE GASES are very important and are mainly:

water vapour occurs naturally in the atmosphere.carbon dioxide produced naturally when people and animals breathe. Plants and trees absorb carbon dioxide to live. Volcanoes also produce this gas. Carbon dioxide is not the same as carbon monoxide methane comes from cattle as they digest their food. The gas also comes from fields where rice is grown in paddy fields.nitrous oxide when plants die and rot, nitrous oxide is produced. ozone occurs naturally in the atmosphere.

THE ENHANCED GREENHOUSE EFFECT Because there are more and more greenhouse gases in the atmosphere, more heat is trapped which makes the Earth warmer. This is known as global warming. A lot of scientists agree that man's activities are making the natural greenhouse effect stronger. If we carry on polluting the atmosphere with greenhouse gases, it will have very dangerous effects on the Earth.

What are the causes of rises in Greenhouse gases

THE ENHANCED GREENHOUSE EFFECTSome of the activities of man also produce greenhouse gases. These gases keep increasing in the atmosphere. The balance of the greenhouse gases changes and this has effects on the whole of the planet. Burning fossil fuels - coal, oil and natural gas - releases carbon dioxide into the atmosphere. Cutting down and burning trees also produces a lot of carbon dioxide. A group of greenhouse gases called the chlorofluorocarbons, - which are usually called CFCs, because the other word is much too long! - have been used in aerosols, such as hairspray cans, fridges and in making foam plastics. They are found in small amounts in the atmosphere. They are dangerous greenhouse gases because small amounts can trap large amounts of heat.

Some greenhouse gasesX 300 more effect on global warming than CO2 Man-made sources of nitrous oxide include nylon and nitric acid production, the use of fertilisers in agriculture, cars with catalytic converters and the burning of organic matter. Methane is x 30 more effective than CO2 Where does methane come from? (3 places)

CO2 and temperature rise

Two ways of looking at causes

The effects

Global Warming some effectsSince 1970, rise in:Decrease in: Global surface temperatures Snow extent Tropospheric temperatures Arctic sea ice(air closest to ground level) Global Sea Surface Temperatures Glaciers Global sea level Cold temperatures Water vapor Rainfall intensity Precipitation Hurricane intensity Drought Extreme high temperatures Heat waves

Global mean temperatures are rising faster with timePeriod Rate

Years /decadeWarmest 12 years: 1998,2005,2003,2002,2004,2006,2001,1997,1995,1999,1990,2000

Global mean temperatures are rising faster with timePeriod Rate

Years /decade

Global mean temperatures are rising faster with timePeriod Rate

Years /decade

Annual anomalies of global average SST and land surface air temperature Sea Surface TLand

Land surface temperatures are rising faster than SSTs

Smoothed annual anomalies for precipitation (%) over land from 1900 to 2005; other regions are dominated by variability.Land precipitation is changing significantly over broad areas

Regions of disproportionate changes in heavy (95th) and very heavy (99th) precipitation Proportion of heavy rainfalls: increasing in most land areas

Projected Patterns of Precipitation Change2090-2100 Precipitation increases very likely in high latitudesDecreases likely in most subtropical land regionsThis continues the observed patterns in recent trends

Sea level is rising: from ocean expansion and melting glaciersSince 1993 Global sea level has risen 41 mm (1.6 inches) 60% from expansion as ocean temperatures rise, 40% from melting glaciers

Steve Nerem

Evidence for reality of climate changeGlaciers melting1900 2003 Alpine glacier, Austria1909

TobogganGlacierAlaska

2000Muir Glacier, Alaska

Global mean temperatures are rising faster with timePeriod Rate

Years /decade

The impacts

Impacts on living thingsIf the sea-levels are rising then what might the effects be? And on people and the ecosystems?If there are more climatic hazards what might they be? What is the impact? Where might be affected the most?Changes in rainfall what might be the effects on the earth? On the human welfare?Rises in temperature what would be the effects? What are the impacts on the different groups? That is the sea as well? Warming seas with more CO2 in ( that is an acid by the way)?

Impacts on living thingsEcosystem changes which would be most affected? What would be the impacts on the world as a whole? On people? On ecosystem populations? Agricultural production: all bad or maybe some good?

One of the impacts is on human health why?

Case study: BangladeshNotice all the rivers that come down from the Himalayas when is there the highest flow in these?

75% of Bangladesh is at or below just 10 metres in height.

Projected climate change impacts Many of the projected impacts of climate change will reinforce the baseline environmental, socio-economic and demographic stresses already faced by Bangladesh. Climate change is likely to result in: i. Increased flooding, both in terms of extent and frequency, associated with sea level rise, greater monsoon precipitation and increased glacial melt ii. Increased vulnerability to cyclone and storm surges iii. Increased moisture stress during dry periods leading to increased drought iv. Increased salinity intrusion v. Greater temperature extremes

So what are the issues?The ice caps in the Himalayas are melting so the spring flood carrying sediments to re-enrich the soils are slowly reducing.The storms seem to be becoming more intenseThe sea level is rising due to snow melt and thermal expansion.The mangrove swamps, the Sundarbans, are the largest in the world, will disappear is the sea levels rise by a mere 45cm.Without mangroves to protect the coastal behind them, much land will be washed away in storms, leaving millions homeless.

So what are the issues?More salt water infiltration is likely, which will make more of the land that is still above sea level, useless for growing rice, so putting more pressure on more to people to migrate.Saltwater from the Bay of Bengal already penetrates 100 kilometres inland during the dry season , and climate change is likely to exacerbate this. Pressure from an increasing population (rising at 2% pa) and rising demand for groundwater further reduces the availability of freshwater supplies for domestic and industrial purposes If sea levels rises up to one metre this century, Bangladesh could lose up to 15 per cent of its landmass and up to 30 million Bangladeshis could become climate refugees . In these areas, agriculture, industry, infrastructure, livelihoods, marine resources, forestry and biodiversity, human health, and utility services will all suffer. Such a scenario could lead to a decline in GDP of between 27 and 57 per cent . ( It is currently US$ 641 )Given the high population density (954 per sq km) of the country as a whole, this could lead to mass climate emigration where could they go?