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7.2 Climate change - causes and impacts - Coggle Diagram
7.2 Climate change - causes and impacts
Weather vs climate
Weather: Result of daily changes of temperature, pressure and precipitation; Varies from place to place; Fluctuates wildly on a daily basis but doesn’t affect overall average
Climate: Average weather pattern over many years; Specific for a location on Earth; Different from weather because of the timescale it is measured on
Weather AND climate
Both affected by:
Ocean and atmospheric circulatory systems
Clouds – may trap heat underneath or reflect sunlight away from Earth
Forest fires – release CO2, a greenhouse gas (GHG) but regrowth traps it in carbon stores
Volcanic eruptions – release huge quantities of ash which circulate in atmosphere cooling the Earth
Human activities – burn fossil fuels and keep livestock (both release GHGs)
What is climate change?
The Earth's average temperature is about 15ºC but has been much higher and lower in the past.
There are natural fluctuations in the climate but scientists say temperatures are now rising faster than at many other times.
Greenhouse gases
CO2, H2O vapour methane, but also CFC’s and HCFC’s, nitrous oxide, and ozone. Many of them have increased because of human activities enhancing greenhouse effect.
Carbon Dioxide in Earth’s atmosphere has risen by about 30% since the beginning of the industrial revolution. Most of the increase is due to the combustion of fossil fuels, which releases the long-stored CO2 back into the atmosphere.
Human contribution:
Burning of fossil fuel which release carbon dioxide
deforestation affects earth's ability to absorb carbon dioxide
use of fertilizers lead to higher nitrous oxide
Gases: carbon dioxide CO2, methane CH4, Nitrogen Oxides NOx, Chlorofluorocarbons CFC
Source: combustion, decomposition or respiration, anaerobic decomposition in rice fields and landfill, cow and stores under the arctic permafrost and oceans, internal combustion engines, from fridge coolants and aerosol cans.
Evidence for a correlation between atmospheric carbon dioxide (CO2) and average global temperatures
global temperatures show large variations (for various reasons)
(despite this) there is strong support for correlation between atmospheric carbon dioxide and global temperatures
Global warming potential (GWP)
Looking at the example below, methane traps 23 times more heat for 1 CO2 molecule, so has a higher GWP.
Water vapour has the highest GWP but it’s not taken into account as in is condensing.
CFC’s and HCFC’s have the highest values.
Methane as a greenhouse gas
Tundra (Bogs and swamps of tundra have methane produced by decomposition in waterlogged soils. With the melting of permafrost, this methane is released)
Cattle (have a bacteria in their stomach that break down the cellulose from grass releasing methane as a waste)
Impacts on climate change
Melting polar ice caps will cause sea levels to rise as it flows into the ocean.
Also, water expands as it heats up increasing the volume of sea water. Up to 40 nations will be affected. Low lying states will loose land, and others will disappear.
Oceans will absorb more CO2 so the ocean will be more acidic (affecting coral reefs etc…)
There will be a change on weather patterns: More heat means more energy in the climate, and so weather will be more violent and sporadic, with bigger storms, droughts, soil erosion, precipitation, hurricanes… Therefore there will also be an effect on food production.
On biodiversity and ecosystems: Animals can move to cooler places but plants cannot. The distribution of plants can shift as they disperse seeds which germinate in more favourable places.
Polar species would become extinct.
Plants are breaking their winter dormancy earlier
On human health: Heatwaves; insect disease vectors will spread to more regions (malaria, yellow fever could spread to higher latitudes); Algal bloom may be more common as seas and lakes warm up; Warmer temperatures at higher latitudes would reduce number of people dying of cold.
What next on climate change?
Humans are resourceful and climate change will not make the human species extint, but it will change our lifestyle and possibilities (just as our grandparents were concerned about Cold War, nuclear proliferation…)
There is an ethical question for governments of MEDCs whose people mostly have a high standard of living and why should they deny this to people of LEDCs?
Philosophies
Fossil fuels:
ecocentric view: carbon dioxide emissions need to be reduced; there is a need for alternative energy sources but there is also a role for initiatives such as carbon credits and carbon trading.
Technocentric view: we can continue to develop a high standard of living; greener technologies can be developed so that there is no effect on industrial production; these technologies will include ways to sequester existing carbon from the atmosphere and the exploitation of low carbon alternatives; fossil fuels may continue to play a role
Ecological footprint:
ecocentric view: humans need to reduce their reliance on fossil fuels and reduce actions which cause pollution or other harm to the biosphere; to achieve this a change in lifestyle (certainly in MEDCs) is required.
Technocentric view: there is no need to charge our lifestyle; we can all aspire to better standards of living; economic growth, prosperity and scientific advances will achieve this
Climate change:
ecocentric view: limits should be imposed on the consumption of fossil fuels; farming methods need to be modified to reduce our dependence on meat; reforestation is necessary; we need to switch to greener source of energy. (There is some cross-over here with technocentrism)
Technocentrisc view: technologies can be employed such as 'artificial trees' to sequester carbon or fleets of unmanned ships spraying salt water into the atmosphere to increase the Earth's albedo