2.4 The Human Impact Flashcards
how do rising sea levels give evidence of climate change?
- IPCC: average sea lvl increased 10-20 cm in past 100 years
1. higher T, freshwater ice melts, more water in seas
2. thermal expansion
3. CO2 dissolved increasing volume
how do temperature records give evidence of climate change?
- average surface air increased about 1 C over past 100 years
-last three decades warmer than any other instrumental record since 1880 - 10 warmest years in 194 year record occurred since 2000s, and 1998
how does glacial retreat and melting ice give evidence of climate change?
-IPCC: global scale decline
- glaciers shrinking and retreating worldwide
- estimated some completely disappear by 2035
- artic sea ice thinned by 65% since 1975, 2014 was all time low
how do ice cores as historical records give evidence of climate change?
- cylinders of ice enclose small bubbles of air that contain samples of atm - measure cc
- cc of CO2 stable until 19th century, 40% up after industrial revolution
-low cc of CO2 during cool times: consistent hypothesis of T and CO2 intimately linked and amplify changes of other
what is the greenhouse effect?
- CO2 emissions have risen from around 280 ppm in 1750 to 367 ppm in 1999
- in 2020 the lvl are 415 ppm and expected to rise to 685 ppm by 2050
-methane: 2nd largest contributor - CFCs and N2O are less significant in proportion, warming potential still high
- cattle and paddy fields: methane
- CFCs are synthetically created, react with O3, 6% increase per annum
- 4 tonnes of CO2/ 1 tonne of C burned, since 1980: 5Gt/year burned
what are natural causes of climate change?
- variations in Earth’s orbit around the sun
- variations in tilt of axis
- changes in aspect of poles from towards to sun to away
- changes in amount of dust in atm
- changes in ocean currents due to continental drift
why is climate change complex?
- scale
-global interactions - natural and anthropogenic forces
- feedback mechanisms
-long term processes: impact and consequences might not yet have occurred
what are the impacts of climate change?
-rise in sea level - flooding in low-lying areas (Netherlands, Egypt) (200M people displaced by 2050 in Bangladesh)
- increased storm activity
- shorter USA grain belt, longer Canada’s growing season
- USA, SEU, CIS : reduced rainfall, drought
if T rises by 2: - 4B ppl water shortage
- 35% drop crop yield
(Africa, ME)
- 200 M exposed to world
hunger
- 60 M Africans exposed to
Malaria
- 40% of wildlife species
extinction
what are positive impacts of climate change in the UK?
- more timber yields (25% by 2050)
- Northwards shifting farming 200-300km
- more pastural farming in NW
- more tourism as higher temperature and less precipitation in summer
what are negative impacts of climate change in the UK?
- increased soil drought, erosion, shrinkage of clay
-more insects
what does the Stern Review state? (2006)
- cheaper to address problem than deal with consequences: BAU: 5-20% blow to GDP, dealing: 1% GDP= 184 B pounds
- CO2 increased global T by more than 0.5 C
- 2-3 C in 50 years if no cut
- poorest countries suffer earliest and most
- 45 pound damage / CO2 tonne
- level limit should be 450-550 ppm
- action should include carbon pricing, new tech and robust international agreements
define microclimate
the small-scale variations in T, ppt, humidity, wind speed, evap that occur in a particular environment
what is a climactic dome?
term to refer to the different weather patterns found above urban areas that differ significantly from surrounding areas
what is the urban heat island?
a metropolitan area which is significantly warmer than surrounding rural areas
- The urban heat island creates the urban boundary layer, which is a dome of rising warm air and low pressure. As ground surfaces are heated, rapid evapotranspiration takes place. This evapotranspiration, although lower compared to rural areas, occurs more rapidly and can result in cumulus cloud and convectional weather patterns.
what impacts the urban heat island?
- bare earth and vegetation
- water
- albedo
-building and ground store heat - anthropogenic sources of heat
- cityscapes v landscapes
- energy in-out
