Project #31390 - Important Homework

Please answer  following questions in your own words. Answer all parts of

each question for full credit. Use illustrations/figures to help explain your answers.

You may use your class notes, lecture pdfs, readings and articles to help answer these questions.

This is intended to be your effort, so please do not work with others on this test.

Fully reference any source of information from outside of class readings and lectures.



1. Sea level rise is of specific concern for residents of New York City. (i.) Describe the

two main processes that directly contribute to changes in the global sea level. In your

answer specifically refer to both sea ice and glaciers on land. (ii.) How much has sea

level increased since 1900, since 1980 and how much is sea level supposed to rise by

2100 according to the IPCC WG1 AR5 summary? (iii.) Explain how and why the oxygen

isotope enrichment (i.e., ä18O) of the water in the ocean will shift as sea level rises; (iv.)

explain how NYC is most likely to experience the effects of sea level rise during the next

30 years.


2. The recent 2013 IPCC Assessment Report (AR5) outlines 4 scenarios (i.e., RCP 2.6

to 8.5), which provide model predictions of future climate including specific predictions

of sea level rise, global air temperature, etc. (i.) Please describe each of these 4 model

scenarios and include the main assumptions for each scenario, including the predicted

global emissions of CO2eq from 2012 to 2100, and for each scenario describe the

expected concentrations of CO2 in the atmosphere and the expected global air

temperature in 2100; (ii.) Explain the 2 main approaches you would suggest to reduce

GHG emissions to meet the RCP 4.5 scenario and how each approach would result in

the intended emissions/temperature changes; (iii.) Explain which scenario you expect

to occur and two reasons why that scenario is most likely to occur compared with the

other 3.


3. Many of the future scenarios for climate could be more precise if we better

understand feedbacks within and among the terrestrial, marine and atmosphere

spheres. For the following 2 feedbacks, illustrate (and describe) the nature of the

couplings and the overall effect of each feedback loop. You must illustrate your answer

with component notation.

Feedback A:

Pools: Atmospheric carbon dioxide concentration, terrestrial plant NPP (C3 pathway),

and air temperature.

Initial exterior effect - rising CO2


For feedback A: What would be the effect, if the photosynthesis pathways were C4, not


Feedback B:

Pools: Atmospheric methane concentration, methanogens, and air temperature.

Initial exterior effect- rising temperature

For feedback B: what if methanotrophs replaced methanogens? Hint: both groups of

organisms will increase their metabolism with increasing temperature


4. There is concern that rising air and water temperatures may significantly affect deep

ocean circulation rates and patterns. Explain deep ocean circulation, its main

mechanisms that establish the gradient and this concern in terms of the underlying

Earth Systems Science mechanisms of deep ocean formation and circulation. In your

answer explain the effects of rising temperature on the rate of deepwater formation, and

consider sea and land ice levels, water density, and water salinity. Also explain how this

predicted change in deep ocean circulation could affect atmospheric CO2 levels and

marine NPP in the future. Finally, briefly comment on the main effects of a prolonged

stoppage of deep water circulation on climate and on marine life.


5. Geologic records indicate that there have been 2 main patterns in global air

temperature during our recent past. These include: (i.) a general trend downward in the

average global temperature during the last 60 million years; and (ii.) an oscillation (up

and down) pattern of air temperature on ~100,000 yr cycle, which is clearly evident in

the past few million years. Please explain the main causes of each of these 2 patterns.

(iii.) Also provide some evidence from the marine record to support these temperature

patterns on each of 3 scales: (a.) 100 yrs, (b.) 1000 yrs and (c.) 500,000 yrs.


6. The evolution of the atmosphere during the Earth’s 4.5 billion year history is marked

by a large change in the concentration of atmospheric oxygen (O2) from < 1% to close

to today’s 21%. Describe this change in troposphere O2 quantitatively during the past 4

billion years, with special attention to the rise. Explain why this change occurred. In your

answer include the following: (i.) The organisms responsible for this change developed

2 processes and why this was important for O2 on Earth; (ii.) explain how the change in

O2 affected evolutionary change and the development of life on land; (iii.) explain the

evidence that exists in both the marine and terrestrial sedimentary record that supports

this change in O2; (iv.) explain what is regulating O2 in the atmosphere today (i.e.,


keeping it relatively constant).

Subject Science
Due By (Pacific Time) 05/21/2014 05:00 pm
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