Unit 1

Question 1

what does the climate timeline look like since modern humans evolved

Answer 1

evolved around 200,000 years ago, lived through a warm interglacial period(similar temps to today), glacial advance, glacial retreat, Holocene around 12,000 years ago, Anthropocene starting with the industrial revolution

Question 2

why is climate change a concern

Answer 2

even though we have lived through similar temps about 125,000 years ago, the current rate of increase is much faster so there is less time to adapt. humans also live very differently from how we did during the last period of warmth like this

Question 3

what is the Anthropocene

Answer 3

the current period that has rapid increases in temperatures and is relatively unreversible due to positive feedbacks. argument for Anthropocene is that there is sufficient evidence of changes in planetary conditions to be considered a new epoch

Question 4

what is the greenhouse effect

Answer 4

incoming shortwave radiation from the sun is reflected by water, clouds, ice, snow, etc but the reflected long wave radiation gets trapped by GHG’s warming the atmosphere and earth. more GHG means a warmer earth

Question 5

what are earths GHG by mass

Answer 5

65% water vapour, 25% carbon, 10% other

Question 6

how much does the GHG effect warm earth

Answer 6

about 33 degrees

Question 7

what is the difference between coldest periods and warmest periods on earth

Answer 7

about 20 degrees

Question 8

when did most of earths evolution take place

Answer 8

Cambrian explosion 540m years ago

Question 9

what are the three eras since evolution took place

Answer 9

Palaeozoic, mesozoic, cenozoic

Question 10

how many mass extinction events have happened since the Cambrian explosion

Answer 10

5 with the main one being the extinction of the dinosaurs 66m years ago

Question 11

what are the three parts to the milankovitch cycles

Answer 11

eccentricity, obliquity, precession

Question 12

what is a key difference between todays climate change and past climate changes

Answer 12

atmospheric changes are coming before temperature changes instead of after

Question 13

what are the parts of the atmosphere

Answer 13

troposphere stores 80% of the earth GHG and is 10km above the surface.
Ozone layer stores higher concentrations of ozone and is 20-30km above surface

Question 14

explain the carbon cycle

Answer 14

carbon cycles through different reservoirs including the atmosphere, the ocean, the biosphere, lithosphere, pedisphere. carbon cycles by photosynthesis, respiration, and decomposition. time spend in each reservoir is residence time

Question 15

what are the positive feedbacks in warming periods

Answer 15

less snow and ice means less albedo, increased water vapour(GHG) in atmosphere, permafrost thawing and decomposition lead to increased carbon and methane, more photosynthetic activity means more vwigourous carbon cycle, warmer oceans increase release of dissolved carbon

Question 16

what are the positive feedbacks in cooling periods

Answer 16

increased snow and ice increases albedo, less water vapour in atmosphere, permafrost increasing locks away more methane and carbon, cooler oceans increase absorption of carbon

Question 17

what is the keeling curve

Answer 17

demonstrates the carbon flux by measuring carbon concentrations

Question 18

why does the keeling curve wiggle

Answer 18

due to seasons as well as differing amounts of landmass in different hemispheres. summer in the northern hemisphere will cause higher carbon concentrations due to its higher landmass and vice versa

Question 19

how do scientists know climate change is not just milankovitch cycles

Answer 19

milankovitch cycles happen over much longer periods of time and there has not been a very high increase in solar radiation over the time of increased climate warming.