Challenges for the planet Flashcards
What is weather?
the state of atmosphere at any given time and place
What is climate?
the average weather conditions over a long period of time
How has the climate changed since the last ice age (8000BC)?
- after the last ice age there was a warmer period which caused the climate to fluctuate to a warmer temperature (6800 BC - 5 degreesC change)
- there was then a cool period causing a dip before it warmed up again in a warmer period (5000 BC - 1 degreesC decrease to 4000 BC - 2 degreesC increase)
- afterwards there was another cooler period before the medieval warm period at 0 AD (1500 BC - 2 degreesC to 0 AD - 1 degreesC approx increase)
- there was a little ice age from 1200 to 1800 AD with about a 1 degreesC decrease in temperature
How much is the temperature projected to increase?
projected to increase to a 7 degreesC temperature change which is 2 more degreesC than currently (2000 AD to 2300 AD)
What are the external and internal factors affecting the world’s climate?
External)
- solar output
- orbital geometry (shape and tilt)
Internal)
- volcanic activity
- surface reflection
- change in atmospheric gases
- tectonic activity
Explain how solar output affects the world’s climate:
- this is the energy that comes from the sun which changes over time
- in the 1980s, the total amount reaching earth had decreased by 0.1%
- if the trend continue then it could greatly influence global climate
- a 1% change in solar output could make the temperature rise or fall by 0.5-1 degreesC
- it is thought to be influenced by activity of sunspots on the sun’s surface
- there was a period of drastically reduced sunspot activity between 1645 to 1715 which may have been the cause of the little ice age
Explain how orbital geometry affects the world’s climate:
1) Shape
- the shape of the earth’s orbit around the sun varies from circular to elliptical and back every 95000 years
- cold glacial periods occur when the earth’s orbit is circular and warmer periods when it is more elliptical
2) Tilt
- the tilt of the earth’s axis varies over time from 21.5 to 24.5 degreesC
- this variation occurs over a 41000 year time span
- the greater the tilt, the hotter the summers are and the colder the winters are
- when the angle is greater the earth usually experiences warmer peiods
Explain how volcanic activity affects the world’s climate:
- volcanic eruptions release large amounts of sulfur dioxide and ash into the atmosphere
- these act like a cloak reducing the amount of solar radiation energy reaching the earth’s surface
- in 1815, mt. Tambora erupted - the following year it was unusually cold and 1816 was known as the year without summer
Explain how surface reflection affects the world’s climate:
- during cooler periods when there is a larger amount of snow and ice on earth, global temperature will drop due to it reflecting sunlight back to space
- if the planet warms up, snow and ice will diminish and the earth will continue to get warmer
Explain how change in atmospheric gas affects the world’s climate:
- there is a clear relationship between amount of CO2 and temperature variations in the atmosphere
- CO2 is primarily responsible for the greenhouse effect which keeps heat within the earth’s atmosphere by absorbing long-wave radiation
- without it, the average global temperature would be -18 degreesC rather than 15 degreesC
Explain how tectonic activity affects the world’s climate:
- movement of continents caused by plate tectonics affects the global pattern of atmospheric and ocean circulation
- the changing shape of the earth’s surface causes wind and ocean currents to change
- this process is too slow to have much effect on climate over the relatively short geological time span of 10000
What are the causes of current climate change (on a local and global scale)?
- burning of fossil fuels
- increase of methane in the atmosphere
How does the burning of fossil fuels affect climate change?
- produced from coal, oil and natural gas
- used to produce energy in power stations and to supply fuel to vehicles
- in China, 75% of energy is produced from coal
- when fossil fuels are burnt they release gases such as CO2 that build up in the atmosphere
- CO2 contributes to the greenhouse effect and the generation of power accounts for 25% of global CO2 emissions
How does the increase of methane in the atmosphere affect climate change?
- methane is a greenhouse gas so it can trap heat in the earth’s atmosphere
- makes up 20% of greenhouse gases in the atmosphere and is 20x more potent than CO2
- comes from organisms that were alive many years ago, recently dead rotting organisms and those which are alive today
- 30% released into atmosphere was formed underground many years ago and comes to the surface when fossil fuels are mined
What are examples of modern methan sources?
- wetlands (including marshes and swamps)
- the growing of rice
- landfills containing rotting vegetable matter
- burning vegetation
- the bowels of animals
Why have the levels of methane in the atmosphere been rising by 1.5% a year for the past decade?
- an increase in the mining of fossil fuels
- rising temperature, which causes an increase in bacteria emissions from wetlands
- an increase in rice production due to growing populations in rice growing countries
- an increase in the number of cattle and sheep for meat reflecting an increase in western-style diets
Explain the greenhouse effect?
1 heat energy from the sun beams down onto the earth- some of it passes through a blanket of gases in our atmosphere
2 some of the heat energy escapes back into space
3 greenhouse gases form a blanket around the earth which traps the heat energy in the atmosphere
4 the energy which does not escape back into space is reflected back to earth
5 the main greenhouse gases are carbon dioxide, methane and nitrous oxide