GEOG 401 Climate Change. Discussion. Discussion of Readings Earth s Energy Balance. Readings 2/17/14

Transcription

1 GEOG 401 Climate Change Discussion of Readings Earth s Energy Balance Discussion Readings 1. Diagnosis Earth: The Climate Change Debate, by William Anderegg 2. The Silver Bullet of Climate Change Policy 3. Climate Change: Who s the biggest emiler of them all? 1

2 Diagnosis Earth: The Climate Change Debate, by William Anderegg What problem was invespgated in the study reported here? What methodology was used? What were the results? What are the implicapons of those results? Were there any significant flaws in the methodology that might have biased the results? When the corporate media presents the issue of climate change, do you think they fairly represent the scienpfic consensus on global warming? The Silver Bullet of Climate Change Policy What problem does this arpcle address? What is the silver bullet of climate change policy according to this arpcle? Do you agree or disagree with the conclusions of this arpcle? 2

3 Climate Change: Who s the biggest emiler of them all? What problem does this arpcle address? Who are the biggest emilers? What is the fairest way to allocate the costs of addressing climate change? 3

4 Intercepted Solar Energy = solar constant x disk area of Earth Intercepted Solar Energy = 1366 [W m - 2 ] x πr 2 [m 2 ] Radius of Earth = 6,378,100 meters Intercepted Solar Energy = x WaLs Intercepted Solar Energy Averaged Over the Whole Earth = Intercepted Solar Energy Surface Area of Earth = 1366 [W m - 2 ] x πr 2 [m 2 ] 4 πr 2 [m 2 ] = 1366/4 [W m - 2 ] = W m - 2 4

5 Absorbed Solar Energy Averaged Over the Whole Earth = Intercepted Solar Energy x (1 Earth Albedo) Earth Albedo = 0.3 Absorbed Solar Energy = x 0.7 [W m - 2 ] Absorbed Solar Energy = 239 W m - 2 To maintain energy equilibrium, the Earth must emit an amount of longwave radiaaon equal to the absorbed solar energy. Earth Longwave EmiDed RadiaAon = Absorbed Solar Energy = 239 W m - 2 5

6 What is the mean equilibrium temperature of the Earth? Use the Stefan- Boltzmann equapon: Rearranging I = σt 4 we get: T = (I/σ) 0.25 T = (239 / 5.67 x 10-8 ) 0.25 = K = C C ß RadiaAve Equilibrium Temperature of Earth RadiaAve Equilibrium Temperature of Earth = C Actual mean surface temperature of earth: 20 th Century Mean: 13.9 C (57.0 F) 2012 Mean: 14.5 C (58.03 F) QuesAon 1: Why is the actual surface temperature 32.8 C higher than the radiapve equilibrium temperature? QuesAon 2: Is the radiapve equilibrium temperature of the earth changing due to increasing greenhouse gases? QuesAon 3: Why is the surface temperature of the earth increasing? 6

7 On the following slide is a diagram showing the present- day, globally- averaged veracal energy fluxes for planet earth. Look carefully at the diagram and answer these quesaons: QuesAon 1: How much energy is entering at the earth system at the top of the atmosphere (TOA)? Use the mean espmates. QuesAon 2: How much energy is leaving at the TOA? QuesAon 3: Are the incoming and outgoing energy at the TOA equal? QuesAon 4: Do the same comparison for (a) the atmosphere, and (b) the earth s surface. Do the comparison using radiapon only and then do it using all energy fluxes. QuesAon 5: What will happen to this picture if greenhouse gas concentrapons (a) keep on increasing; (b) level off; (c) decline? AR5 WG1 Drap report (2013, Chapter 2) 7