the average conditions of precipitation, temperature, pressure nad wind measured over a 30 year period
1 of 15
define climate change
any long term trend or shift in climate
2 of 15
give evidence for short term climate change
instrumental records: surface temp has warmed ny 0.74C between 1990-2000, increase in ocean acidification Ice responce: melting greenland ice sheet increased by 16% since 1979, artic sea ice declining 8.5% per decade
3 of 15
give evidence for medium term climate change
Historical records: indicates mini ice age and medieval warm period, Tree rings, Retreating glaciers: most glaciers have retreated since 1850
4 of 15
give evidence for long term climate change
oxygen isotope levels: 200000 ice sheets were @ max means sea levels are lower in glacial periods, CO2 from ice cores: cold ages co2=180ppm, warm periods=280ppm, pollen sequences
5 of 15
name three natural causes of global warming
changes in solar output, milankovitch cycles, cosmic collision&volcanoes
6 of 15
what are the treee milankovitch cycles
orbital eccontricity: every 100000 yrs orbit changes from circular to oliptical, Axial tilt: 41000yrs changes from 22 to 24 degrees, Axial position: earth wobbles every 26000 yrs effecting global temp
7 of 15
define global warming
a recently measured rise in global average surface temperature
8 of 15
name 4 greenhouse gasses
CO2, Nitrous oxide, methane, CFCs
9 of 15
describe the albedo effect
higher temperature redults in less ice meaning more heat is absorbed, then less energy is reflected and more is absorbed resulting in higher temeperatures
10 of 15
describe the posotive feedback loop of permafrost
higher temperature means permafrost will melt realing meathane which will trap heat and casue further temperature rise
11 of 15
what is eustatic sea level change
global sea level change caused by a change in the amount of water in the oceans (from icecaps melting and thermal-expansion)
12 of 15
what is isostatic sea level change
movent of land due to a loss or gain in mass (pressure and weight of a glacier)
13 of 15
what is thermohaline circulation
the flow of warm and cold water that circulates around the wolrds oceans
14 of 15
how can this be affected
fresh water melt= reduced salt water content= lower density= ocean currents stop
Comments
No comments have yet been made