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Environmental changes > Climate change > Flashcards

Climate change Flashcards

1
Q

Formula Radiative Forcing (with climate sencitivity):

A

dTs = lambda * dRF -> dRF = dTs / lambda

lambda = climate sensitivity [ K/(W/m2) ]

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2
Q

Difference between “climate” and “weather”

A

Weather is short-term (minutes to months) how temperature, winds, clouds are acting and changing at the moment. Caotic and hard to predict. Lots of factors that are changing constantly.

Climate is the weather avarage over time and space. (Typiclally over 30 years.) Descriptions of long-term patterns with the help of statistics.

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3
Q

The 3 mechanisms behind sea level rise:

A
  • Thermal expansion
  • > Melting of ice caps and ice sheets (ice on land)
  • Withdrawal of subsoil water
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4
Q

Paris agreement:

A
  • Holding the increase in the global avarage temperature to well below 2 degC ( above pre-industrial levels).
  • And pursuing efforts to limit the temperature increase to 1.5 degC above pre-industrial levels.
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5
Q

Who discovered the greenhouse effect?

A

Jean-Baptiste-Joseph Fourier (1768-1830)

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6
Q

Who discovered the greenhouse effect of CO2 and water vapor?

A

John Tyndall (1820-1893)

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7
Q

Who did the first calculation/estimation of temperature rise due to CO2?

A

Svante Arrhenius (1859-1927)

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8
Q

Wavelength interval of blackbody ratiation from the Sun?

A

ca 200 - 2000 nm (0.2-2 um) (5800K)

small overlap of Earth in reality

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9
Q

Wavelength interval of blackbody ratiation from the Earth?

A

ca 5000 - 50 000 nm (5-50 um) (288K)

small overlap of Sun in reality

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10
Q

Solar constant S0 (zero)

A

1368 [W/m2]

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11
Q

Earth total albido

A

Albido = 0.3

30% of sun radiation is directly reflected back into space

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12
Q

Avarage sun radiation hitting Earth

A

S0 * 1/4

area of disc hit by the sun / total area of Earth = 1/4

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13
Q

Absorbed energy on Earth (Q_in, E_absorbed)

A

E_absorbed = (1-albido) * S0/4 = 240 [W/m2]

Total income to Earth system, most will be reemitted

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14
Q

Explain Black body

A
  • An idealized physical body that absorbs all incident electromagnetic radiation, regardles of frequency or angle of incidence.
  • Useful asumption in calculations
  • Used for Sun and Earth for specific wavelenth intervals.
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15
Q

Stefan Boltzmann law:

A

E = epsilon * sigma * T^4
sigma = 5.6710^-8 [W/(m2K4)]
epsilon: emessivity/absorptivity
(Black body: epsilon = 1, disappears)

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16
Q

Stefan Boltzmann, two-layer model of radiative balance (in equilibrium):

A

(1-albido)S0/4 = epsigTa^4 + (1-ep)sig*Ts^4
- ep: epsilon atmosphere
Q_in = Q_out_atm + Q_out_surf

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17
Q

3 energy balance equations:

A 
Tot:  Q_in = Q_out_atm + Q_out_surf
(1-albido)*S0/4 = ep*sig*Ta^4 + (1-ep)*sig*Ts^4
Atm: ep*sig*Ts^4 = 2*(ep*sig*Ta^4)
-> Ts = 2^1/4 * Ta
Surf: sig*Ts^4 = Q_in + ep*sig*Ta^4
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18
Q

Most important greenhouse gases

A

Water vapor, followed by CO2

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19
Q

Current result of greenhouse effect

A

About 33 K warmer than without it

20
Q

What would be the result from a uniform temperature in a vertical direction in the atmosphere?

A

No greenhouse effect!

21
Q

What does low respectively high clouds consist of?

A

Liquid water droplets

Ice particles

22
Q

Effect of low clouds

A
  • High reflection (albido), thick cloud
  • Almost same temp as surf, high lw emessivity
  • > Cooling climate effect
23
Q

Effect of high clouds

A
  • Low reflection, thin cloud
  • Lower temperature, low lw emessivity
  • > Warming climate effect
24
Q

Net effect from global cloud cover

A

Cooling

25
Q

Formula for Radiative Forcing (energy balance)

A

RF = Q2in - Q1ut (radiative imbalance, no equilibrium?

reference is usually pre-industrial 1750

26
Q

Why are airplanes extra bad?

A

Clouds from planes contribute to warming

27
Q

Why is NOx a problem?

A

Not a greenhouse gas but causing greenhouse effects through chemical reactions in teh atmosphere.

28
Q

Aerosols lifetime in troposphere

A

Are removed in days or weeks.

29
Q

Radiative forcing CO2 (RF_CO2)

A

RF_CO2 = 5.35*ln(C/C0), (zero)

30
Q

Why is CO2 un important greenhouse gas?

A
  • Very low greenhouse effect compared to other greenhouse gases
  • Very high concentration and therefore it causes a large greenhouse effect anyway
  • Very long lifetime
31
Q

Net radiative forcing from aerosols?

A
  • Very uncertain

- Negative/cooling effect

32
Q

How do we need to reduce our CO2 emissions in order to achive the goals of only 2degC increase?

A

CO2 emissions (more than) halved by 2050 and down to zero by the end of the century.

33
Q

Climate sensitivity formula and value

A

lambda = dT/RF
- Climate sensitivity is sometimes given as S = dTs
equilibrium temperature change due to a doubling of CO2
- without feedbacks: lambda = 0.3
( 1.5 - 4.5 degC )

34
Q

Why is climate sensitivity uncertain?

A

Due to uncertanties in feedbacks. Especially water vapor (exponential) lapse rate.

35
Q

Explain Lapse rate

A

The change in the vertical temperature profile of the atmosphere.

36
Q

Feedback factors for the climate sencitivity (1.5 - 4.5):

A

f = 0.3-0.75 (only fast feedbacks)

37
Q

Fast feedbacks:

A
  • Water vapor +
  • Lapse rate -
  • Clouds (+)
  • Snow and sea ice +
38
Q

Slow feedbacks:

A
  • Albedo change due vegitation change
  • Biochemical feedbacks ( permafrost, oxidation of soil)
  • Ice caps and ice sheets
39
Q

What is the Stefan Boltzmann response?

A

Climate sensitivity will increase proportionally with temperature increase. (Due to changes in tropopause, lapse rate? for example) Sum of feedbacks increase.

40
Q

How is temp transported to deep ocean?

A
  • Turbulence
  • Convective mixing
  • Deep and bottom water formation
41
Q

How long before the ocean has found a new temperature equilibrium?

A

100 - 1000s of years.

42
Q

Why is the ocean heat uptake yet another reason to stop CO2 emissions faster?

A

(- CO2 stays for a very long time in the atmosphere and continues to cause heating.)
- Ocean heat uptake is a very slow process and will also continue for a long time after the atmosphereic temperature has stabilized. That means more sea level rise and more coral bleaching for many many years to come…

43
Q

What is GWP?

A
  • Global Warming Potential
  • Messures the integrated radiative forcing (for ex 100 years) from an instant emission of 1kg of a GHG compared to 1kg of CO2 (how much heat goes into the climate system).
  • Most common alternetive is GTP Global Temperature change Potential. Since GWP is criticised.
44
Q

What are usually the problem with different metric choises?

A

Depending on what metric (model) you choose and for what time span you will get very different results. Makes it hard to compare. Its important to choose the right one for what we are investegating.

45
Q

What fossil fuel resourses are to large to use all of?

A

COAL and Gas!

If we only use the other resourses we will never get to the 2 degree temperature increase. (Only looking at the contribution from fossil fuel combustion.)

Environmental changes (9 decks)

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