Lecture Twenty - Atmosphere and climate change Flashcards
What is the green house effect?
Sunlight warms Earth’s surface.
Land & oceans release heat (infrared radiation) into atmosphere.
H2O vapour, CO2 & trace gases* in lower atmosphere absorb some of this radiation.
Earth’s surface remains warm.
* Concentrations of Greenhouse gases are increasing.
Simply put, short wave radiation comes in, longer wave length radiation leaves.
By how much as the CO2 concentrations increased?
• 30% greater than 18th century.
• Increased trapping of infrared - warms lower atmosphere, and changes weather.
Is there a relationship between atmospheric CO2 and temperature?
Close link between atmospheric CO2 and temperature
–>
High surface temperatures when CO2 concentrations high.
Where have changes been observed as a result of climate change?
Observed changes in:
(a) global average surface temp;
(b) global average SL from tide gauge and satellite data
(c) North Hemisphere spring snow cover.
How has CO2, methane, nitrous oxide and CFC concentrates changed over time?
CO2, methane and nitrous oxide have all increased since before the industrial revolution.
CFCs are decreasing.
CO2 stays in the atmosphere for 50-200 years.
Methane stays in the atmosphere for 12 years.
Nitrous oxides stays in the atmosphere for 120 years.
CFCs stay in the atmosphere for 50 years.
What are sources of green house gasses?
CO2
• fossil fuel burning (7 billion tonnes p.a.)
• deforestation burning (1-2 billion tonnes p.a.)
Methane
• ruminant animals (cows, sheep) - fermentation of cellulose
• rice paddies - bacteria
• land fill, natural gas fields + other
Nitrous oxide
• biomass burning
• microbial breakdown of nitrogen (fertiliser)
in soil and oceans • industry
CFCs
• industrial chemicals : coolants, propellants, foam
• no longer used in developed count
What are the predicted impacts of green house gasses?
Warming of earth surface.
Australia hotter and drier - 1-2 degreed C greater in 2030 then 1990.
What is happening to glaciers due to global warming?
Most are receding at high rates.
What effect with the melting ice sheets have on the climate?
- Ice reflects solar energy away from the Earth - acts as a natural refrigerator for the planet.
- Ice (+ melt water) have profound affects on ocean circulation patterns in the North Atlantic and therefore on ocean and climate systems over the entire planet.
What is occurring due tot he loss of the arctic sea ice?
Ice algae cling to dark underside of ice pack - winter
–> a dense mat under ice. In summer, phytoplankton bloom develops beneath the ice.
As ice breaks up, bloom spreads into a 20- 80 km belt surrounding the ice.
Habitat for huge range of crustaceans & other inverts eaten by fish (e.g. Arctic cod), & these by seals, birds and polar bears.
What are some records which have been broken (weather wise) which serve as evidence for climate change?
- 20th century - warmest for 1000 years.
- 2000-2010 - warmest recorded decade
- 2010 - the warmest year.
- Greenhouse gas increases - main factor contributing to global warming in the 20th – early 21st centuries.
What are the impacts of climate change (weather wise)?
• Climate more extreme e.g. rain, floods, storms, cyclones, drought.
• E.g. cyclone Katrina –> cyclones gain strength ex heat in surface water –> warmer waters generate more powerful hurricanes.
*Hurricane intensity also increasing (the number of hurricanes is actually not increasing).
• Raised sea levels.
What are climate changes impacts on the biota?
Temperature increase.
Changes in distributions of plants and animals.
i) treeline at higher altitudes in Europe & NZ
ii) expansion of mosses in Antarctica
iii) northwards extension of red fox in Canada
iv) coldwater fish depend on mix of spring and glacial water. e.g. in the USA, estimated that trout will lose 75% of habitat.
v) Extinction of Australian alpine fauna and flora
- Aus alps only 11500km^2.
- By 2020, alpine daisies sand other snow patch species will be extinct.
–> Cascade to insects, birds and other animals.
- Weeds, feral animals and rabbits will become more abundant = extra pressure on native taxa.
vi. Melting of permafrost in Sweden and west Siberiadisappearance of 00s of pools and lakes (drained into thawed soil)total loss of flora and fauna.
vii. Forests sensitive to drought adversely affected by global warming.
viii. Impacts on insect populations. e.g. outbreaks of spruce bark beetles (formerly limited by cold) killed 2.3 x 106 acres of Alaskan forest since 1992. Largest loss of trees to insects ever recorded in North America.
What impacts on human health will be experienced?
Increases in spread of some diseases; e.g. malaria could reach parts of Europe (incl. UK).
Urban air pollution will worsen –> exacerbation of ill-health.
Increase in heat-induced deaths, especially among elderly.
Adverse weather conditions, e.g. storms and floods –> human (death, injury) and economic (rebuilding, insurance) costs.
What is the Kyoto protocol?
Requirements:
Developed countries reduce emissions of six key greenhouse gases by at least 5%.
Achieved through cuts of:
• 8% by Switzerland, most Central & E European states, and the EU;
• 7% by the US; 6% by Canada, Hungary, Japan, Poland & Russia.
NZ, Ukraine to stabilize their emissions.
Norway may increase emissions up to 1%, Australia by up to 8%, and Iceland 10%.
