Climate change: physical

Question 1

anthropocene

Answer 1

a human-dominated geological epoch

Question 2

global radiation balance

Answer 2

solar radiation is the primary energy source of r the ocean-atm system
averaged over a year, the energy balance at the top of the atm is 0
incident energy that comes from the sun is reflected, absorbed, returned to space

Question 3

greenhouse effect

Answer 3

trapping of heat in the atm

Question 4

enhanced greenhouse effect

Answer 4

addition of GHGs to the atm results in an intensification of the greenhouse effect
atm conc of CO2 is higher than it has been for at least the last 800,000 years

Question 5

weather vs. climate

Answer 5

state of the atmosphere at a specific time and place

vs. long-term statistical sum of weather in an area

Question 6

climate system

Answer 6

the many elements that contribute to creating a climate in a region

Question 7

natural variability

Answer 7

the variability driven by natural processes (e.g. seasons)

Question 8

forced variability

Answer 8

variability originating from anthropogenic sources (e.g. increase in CO2 emissions)

Question 9

climate model

Answer 9

A mathematical representation of the climate system based on physical, biological
and chemical principles that includes atmosphere, ocean, land, and sea ice components

Question 10

IPCC

Answer 10

scientific and intergovernmental body under the auspices of the United Nations created in 1988

established to assess periodically the science, impacts and socio-economics of climate change and of adaptation and mitigation options

Question 11

effects of energy imbalance on ocean

Answer 11

Around 93% of the excess heat has been absorbed by the ocean

Involvement of all water column in this uptake

Volcanic eruptions are evident as temporary slow-down of heat uptake

some ocean regions warm faster (e.g. North Atlantic) and the upper ocean warms faster at air-sea interface - transfers heat to interior, but overall increases temp strat in ocean due to surface warming

a smaller warming is detected at depth

Question 12

circulation slowdown (general)

Answer 12

Hints of a negative trend in the meridional overturning circulation (MOC) strength (0.5 Sv/year)
Would be associated with an increase stratification and decrease in deep water formation
large uncertainties
Observation-based timeseries are too short
The natural variability of the MOC is poorly known and poorly understood

Question 13

circulation slowdown (thermohaline)

Answer 13

MOC is mainly responsible for carrying excess heat from the tropics to higher latitudes

MOC slowdown would have large consequences on climate in many regions

large consequences on the sequestration of carbon

Question 14

sea level rise

Answer 14

has increased 1.7 mm/year accelerating to 3 mm/year for last 20 years
total sea level rise since approx 1700 is 30 cm

large variability within basins but relatively consistent across basins, from year to year and decade to decade

Question 15

2 main causes of sea level rise

Answer 15

thermal expansion of the ocean (thermosteric effect)

land ice melting

Question 16

melting sea ice

Answer 16

NOT a contributor to sea level rise
The Arctic sea ice extent has been declining at a rate of 3.8 % year, 1.5% INCREASE in Antarctic

effects on ocean circ, albedo, gas exchange

Arctic
- A sea ice thickness decrease (-0.62 m decade), multi-year ice (-17% decade)
increase in the mean sea ice drift speed
- increase in the average length of the melt season (+6 days decade)

Question 17

land ice melting

Answer 17

West Antarctica and Greenland huge ice mass losses

huge freshwater storage (90% in Antarctica, 9% in Arctic

Question 18

sea ice increase in Antarctica

Answer 18

1.5% / year
decreases in W Antarctica

hypotheses:

• Intensification of winds and shift in wind pattern affecting sea ice drift
• Ocean surface cooling
• Increase in land ice melting
• Natural variability