2.1 Flashcards
2 reasons for climate change
1) changing concentration of GHGs – they allow sunlight to pass through the atmosphere but trap the heat that is radiated back
2) various kinds of external forcing occur, like the amount of sunlight that reaches the earth can change.
GMST
global mean surface temperature
climate change
any long term trend in climate detected by a shift in average value for a climatic element
GHGs
gases in the atmosphere that absorb infrared radiation and cause the world temp to increase
external forcing
precesses that impact earths climate system which originate outside of it (like variations in solar output)
evidence of naturally occuring climatic variations
fossil records
landscape evidence (sea level changes)
tree rings (wider if temp is warmer)
agricultural records (historical harvest dates)
positive feedback loops
effects that amplify any changes that have already occurred. one element changes -> upsets equilibrium -> changes in other elements that reinforce it
negative feedback loops
system adjusts in a way that cancels out the effect. the changes triggered in other elements act in the opposite direction and equilibrium is restored
positive feedback loop example
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negative feedback loop example
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reasons for solar radiation variations
- volcanic emissions, global dimming – short periods of global cooling bcs dust particles from volcano blanket earth. can also happen because of pollution – aerosols released can change reflectivity of clouds
- changes in solar output – 11 year sunspot activity cycle
- changes in earths orbit (Milankovitch cycles): 1) orbit changes from spherical to elliptical every 100 000 yrs
2) the degree to which the earths axis is tilted varies between 22 and 24.5 degrees
3) earths axis wobbles - asteroids colliding w earth – may have caused climate change in the past as it raises a vast dust cloud
- wildfires – smoke adds to global dimming
albedo
how much solar radiation a surface reflects. more solar radiation reflected = higher albedo
terrestrial albedo
the capability of the earths surface to reflect sunlight
2 scenarios w albedo one positive feedback one negative
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insolation
incoming solar radiation
methane
powerful greenhouse gas, much of which is stored in permafrost
permafrost
soil/rock that remains at or below 0 degrees for at least 2 years
how much methane is there currently in permafrost
twice more than there is carbon in the atmosphere
what does climate emergency mean
we’re facing an existential threat and this should be our main focus
proof that humans are to blame for climate change
1) co2 emissions have been rising since 1750, the start of the industrial revolution
2) economic growth, rising consumption, population changes have led to:
fossil fuels w carbon as an energy source; deforestation; methane from livestock – decomposition of organic waste
which countries are the highest polluters
middle and high income countries w large populations (china, usa, germany, japan, russia, india)
what is important to remember when comparing countries in terms of pollution levels
1 data showing per capita footprint reveals a very different pattern (eg china has a relatively small per capita footprint but high total bcs 1.4 billion)
2 current data shows anthropogenic carbon flow, while carbon stock = different pattern
3 think abt globalisation and trade. HICs claim to have reduced their emissions but that doesnt mention that a lot of their goods are imported from other countries – they reduced emissions but increased carbon consumption
per capita carbon footprint
amount of co2 an average person is responsible for in their everyday life in a country
anthropogenic carbon flow
current amount of carbon emission released by a country each year
anthropogenic carbon stock
total size of anthropogenic carbon emissions released into the atmosphere since 1750
deindustrialisation
loss of traditional manufacturing industries in some HICs due to their closure
carbon intensity
amount of co2 emitted per unit of GDP. co2 emissions rise slower than GDP of a country = some action is being taken to reduce emissions
renewable energy
wind, solar, tidal power sources
name 3 ghgs
co2, methane, n2o
natural greenhouse effect
natural process that warms earths surface and is essential for maintaining life on earth, and has been doing so for millions of years
enhanced greenhouse effect
intensification of the natural greenhouse effect due to more ghgs in the atmosphere, primarily bcs of human activity
economic activities causing global warming
fossil fuels – used for energy and when burned release co2
cars are powered by fuels = co2
deforestation – trees absorb co2 so when theres less the effect is reduced + cut down trees release the carbon stored in them
global shipping – fuel
trade growth = urbanisation = higher energy consumption + consumerism which means transport
people w higher incomes = more products that require energy
why do LICs usually have least GHG emissions
bcs lack of industrial development + lower per capita income => less money to spend on high energy products
global energy balance
balance between incoming energy from the sun and outgoing long wave radiation from the earth back into space
global dimming
decrease in sunlight reaching the earths surface bcs of air pollution (particles released - aerosols - can make cloud more reflective) or volcanic eruptions or just more clouds. has a cooling effect
sunspots
dark areas on the sun with magnetic storms that increase solar output
how do TNCs often avoid decreasing their carbon emissions
relocate their manufacturing plants in LICs/MICs which often have less emission regulations to avoid spending more money
