Climate change Flashcards
(45 cards)
Formula Radiative Forcing (with climate sencitivity):
dTs = lambda * dRF -> dRF = dTs / lambda
lambda = climate sensitivity [ K/(W/m2) ]
Difference between “climate” and “weather”
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.
The 3 mechanisms behind sea level rise:
- Thermal expansion
- > Melting of ice caps and ice sheets (ice on land)
- Withdrawal of subsoil water
Paris agreement:
- 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.
Who discovered the greenhouse effect?
Jean-Baptiste-Joseph Fourier (1768-1830)
Who discovered the greenhouse effect of CO2 and water vapor?
John Tyndall (1820-1893)
Who did the first calculation/estimation of temperature rise due to CO2?
Svante Arrhenius (1859-1927)
Wavelength interval of blackbody ratiation from the Sun?
ca 200 - 2000 nm (0.2-2 um) (5800K)
small overlap of Earth in reality
Wavelength interval of blackbody ratiation from the Earth?
ca 5000 - 50 000 nm (5-50 um) (288K)
small overlap of Sun in reality
Solar constant S0 (zero)
1368 [W/m2]
Earth total albido
Albido = 0.3
30% of sun radiation is directly reflected back into space
Avarage sun radiation hitting Earth
S0 * 1/4
area of disc hit by the sun / total area of Earth = 1/4
Absorbed energy on Earth (Q_in, E_absorbed)
E_absorbed = (1-albido) * S0/4 = 240 [W/m2]
Total income to Earth system, most will be reemitted
Explain Black body
- 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.
Stefan Boltzmann law:
E = epsilon * sigma * T^4
sigma = 5.6710^-8 [W/(m2K4)]
epsilon: emessivity/absorptivity
(Black body: epsilon = 1, disappears)
Stefan Boltzmann, two-layer model of radiative balance (in equilibrium):
(1-albido)S0/4 = epsigTa^4 + (1-ep)sig*Ts^4
- ep: epsilon atmosphere
Q_in = Q_out_atm + Q_out_surf
3 energy balance equations:
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
Most important greenhouse gases
Water vapor, followed by CO2
Current result of greenhouse effect
About 33 K warmer than without it
What would be the result from a uniform temperature in a vertical direction in the atmosphere?
No greenhouse effect!
What does low respectively high clouds consist of?
Liquid water droplets
Ice particles
Effect of low clouds
- High reflection (albido), thick cloud
- Almost same temp as surf, high lw emessivity
- > Cooling climate effect
Effect of high clouds
- Low reflection, thin cloud
- Lower temperature, low lw emessivity
- > Warming climate effect
Net effect from global cloud cover
Cooling
