Reference no: EM133194728 , Length: Word count: 3 Pages

Question 1: Essentials of Systems Thinking - Feedback Loops in the Climate System

[Refer to Meadows Ch.1 & 2, and Climate Science 101 video on Complex Systems from SFSU.]

Briefly describe (i) a balancing (negative) feedback loop, and (ii) a reinforcing (positive) feedback loop, in Earth's climate system. Be sure to note the main variable involved in the feedback loop (i.e. what is being balanced or intensified). Also clearly indicate the forces or fluxes affecting that variable.

(i)

(ii)

Question 2: Earth's Atmosphere

[Refer to IPCC WG1 AR5 SPM for this question.]

The concentrations of CO₂, CH₄ , and N₂O have risen dramatically in Earth's atmosphere since the Industrial Revolution (since the mid-1800s in the US).

(i) What is the mathematical shape of the graphs plotting GHG concentration over time (the 'hockey-stick' graphs)? ______________.

(ii) The concentrations of these gases in the atmosphere is unprecedented in the past _________ years.

Question 3: Radiative Forcing, GWP, CO₂eq

[Refer to IPCC WG1 AR5 SPM for this question.]

(i) Define radiative forcing. In what unit of measurement is it expressed?

(ii) Based on both its GWP and atmospheric concentration, which GHG has the largest radiative forcing? [Refer to IPCC WG1 AR5 Fig. SPM.5 / TS.7]

(iii) Calculate the 20-year CO₂-equivalent values of the following amounts of greenhouse gasses, based on their Global Warming Potential (GWP). Show your calculations. CO₂-e for a gas is derived by multiplying the tonnes of the gas by the associated GWP: CO₂-e

(MtCO2) = Mt (million metric tonnes of a gas) * (GWP of the gas).

For example, 5 Mt SF₆ * 16,300 GWP = 81,500 Mt CO₂-e

(a) 120 Mt N₂O = _____ CO₂ -e

(b) 12,300 Mt CH₄ = _____ CO₂ -e

Question 4: Paleoclimate

"Lords of the Water Mountains" (Ch.8 in Brian Fagan's book The Great Warming) gives a climatological history of Mayan civilization in the lowlands of present-day Mexico and Central America.

(i) Give two specific examples of how the ancient climate of the Maya is indirectly measured. [see pp.139-141]

(ii) Briefly discuss what specific impact of climatic change during the Medieval Warm Period -and what socio-political response to it - likely led to the demise of Tikal and the scattering of the Maya. [1 paragraph]

Question 5: IPCC WG1 AR5 SPM: Climate Change: Current Trends [1 pt]

[Refer to the IPCC report and video]

[Fall 2021 note: The recently released AR6 report finds that climate disruption is worse, faster, and more dangerously close to tipping points than previously reported]

Briefly, what are the three (3) main messages from the findings of IPCC Working Group I (WG1) in their Fifth Assessment Report (AR5)?

(i)

(ii)

(iii)

Question 6: Future Climate Scenarios

While there is much uncertainty about how quickly high-emitting countries will reduce their GHG emissions, scientists have a clearer picture about how long elevated temperatures and climate impacts will last. Based on IPCC WG1 AR5 SPM, answer the following:

(i) What proportion of anthropogenic CO2 emissions will remain in the atmosphere for >1000 years? (Give a range) ___% to ___%

(ii) For how long will surface temperatures remain elevated after a complete stop of anthropogenic CO₂ emissions? (Order of magnitude) ____________

(iii) How long will sea level rise and ocean warming continue after the year 2100? (order of magnitude) ____________

Question 7: The Oceans: Climatic Role

Provide brief answers to the following questions, based reading, and discussion (1-2 sentences each, or fill in the blanks).

(i) Briefly describe one or two connections amongst the components of this oceanic shoreline climate system. How are heat and water moved around? How is the moon connected?

(ii) What is the connection between the strong winds at the shore and inland temperatures?

Why do we tend to see more fog at the coast when there are heat waves and fires inland? (Explain in terms of the hydrological cycle and heat balance.)

Also see these sites on ocean acidification: US EPA, NOAA, Smithsonian.

(iii) The dissolution of CO₂ from the atmosphere into the ocean is influenced by Henry's Law of partial pressures. What happens to CO₂ when it dissolves in the ocean - and how does this relate to ocean pH and acidification?

(iv) The average ocean pH is currently 8.1, a drop of 0.1 on the logarithmic pH scale since the 1800s. By what percentage has pH changed during this time period? ____%

The Smithsonian Institute notes that deep ocean sediment cores reveal past CO₂ levels.

During the Paleocene-Eocene Thermal Maximum, about 55.8 million years ago, CO₂ levels jumped, global average temperatures rose by 5 C (9 F), and ocean pH dropped rapidly, causing "a sudden "dissolution event" in which so much of the shelled sea life disappeared that the sediment changed from primarily white calcium carbonate "chalk" to red-brown mud." How does our present rate of ocean acidification compare with the Paleocene-Eocene Thermal Maximum?