Day15_iceageFeedbacks_post

pdf

School

University of British Columbia *

*We aren’t endorsed by this school

Course

340

Subject

Geography

Date

Dec 6, 2023

Type

pdf

Pages

51

Uploaded by ChiefStarling1535

Report
Day 15: Ice age cycle feedbacks Class learning goals: CG1. Derive the climate sensitivity associated with orbital forcing and ice age cycles CG2. Describe how the ice-albedo feedback helps explain the mismatch between the amplitude of insolation forcing and the climate response. CG3. Describe the two main pathways by which CO 2 gets from the atmosphere to the deep ocean (solubility pump and biological pump) CG4. Explain how feedbacks between CO 2 and temperature can amplify glacial- interglacial climate cycles
Upcoming deadlines Prairie-Learn Quiz 3: Nov 1st at 11.59pm Assignment 4 (paleoclimates and isotopes): Nov 6 th at 11.59pm (Extra credit) Mid-term survey: Let me know what helps you learn in this course, what could be better – I’ll try to implement some of your suggestions and feedback into the rest of the course. Anonymized survey on canvas, due Nov 1 st at 11.59pm
Isotopes and temperature: summary In Ice Cores: - Heavier d 18 O (less negative/more positive) = warmer temperatures over the ice sheet WHY? If the air over the ice sheet is warmer, there is a smaller temperature difference between evaporation in the tropics and precipitation over the ice sheet, so less condensation, so less fractionation (and fractionation makes the remaining water vapour, and thus the precipitation from that water vapour, lighter) In Sediment Cores: 1. Heavier d 18 O (less negative/more positive) relative to the ocean d 18 O = colder ocean temperatures that the foram grew in WHY? Fractionation during shell formation (colder temperatures, less energy available, heavier isotope stronger preference for most condensed format, in this case solid in shells)* AND/OR… 2. Heavier d 18 O (less negative/more positive) = heavier d 18 O of sea water = lower sea levels (and thus we infer a colder climate generally as we’re forming large ice sheets) WHY? Snow in high latitudes is lighter than ocean water due to fractionation. If we have large ice sheets, we have a lot of light isotopes locked up in the ice and so a higher ratio of heavy isotopes in the sea. More ice on land = lower sea levels. * You don’t need to know the text in purple, but the reasoning might help you remember the direction warmer heavier colder heavier (difference) d 18 O ice = -30 ‰ More ice Heavier ocean water
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
CLICKER: What orbital conditions would MOST FAVOR growth of an ice sheet over Canada? A. Low tilt angle, June 21 st at perihelion B. Low tilt angle, June 21 st at aphelion C. High tilt angle, June 21 st at perihelion D. High tilt angle, June 21 st at aphelion Let “June 21” = summer solstice for the northern hemisphere
CLICKER: What orbital conditions would MOST FAVOR growth of an ice sheet over Canada? A. Low tilt angle, June 21 st at perihelion B. Low tilt angle, June 21 st at aphelion C. High tilt angle, June 21 st at perihelion D. High tilt angle, June 21 st at aphelion LOW seasonal contrast: cool summers (and warmer winters) Greater tilt = greater seasonal contrast, so want low tilt Cooler NH summers when NH summer is when the Earth is furthest away from the sun, i.e. aphelion: June 21st at apheliion
Recap on climate sensitivity: How much is the planet warming for a given change in radiative forcing? The climate sensitivity ( ! ) is defined as the equilibrium temperature change per unit forcing (either 1W/m 2 or a doubling of CO2 = 3.8W/m 2 ) Current best estimates are that ! = 3°C (2.5 to 5 °C) for a doubling of CO 2 Converting units: " = 3.0/3.8 = 0.8K/(Wm -2 ) " = ∆$ ∆% Recall that the climate sensitivity is related to the feedback parameter, f : " = − ∆& ∆' = −1/! CG1
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Estimates of climate sensitivity: How much is the planet warming for a given change in radiative forcing? IPCC AR6 fig 7.18 The climate sensitivity ( l ) is the equilibrium temperature change per unit forcing. Estimates are: ! = 3°C (2.5 to 5 °C) for a doubling of CO 2 or ! = 0/8°C/Wm -2 Where do we get these estimates from? CG1
Climate sensitivity: How much is the planet warming for a given change in radiative forcing? The climate sensitivity ( ! ) is defined as the equilibrium temperature change per unit forcing (either 1W/m 2 or a doubling of CO2 (= 3.8W/m 2 ) We distinguish between : - Transient climate response (TCR) - Equilibrium climate sensitivity (ECS) THINK PAIR SHARE: Why is this distinction relevant for the modern context? " = ∆$ ∆% CG1
Groups of 2-4 Insolation DISTRIBUTION in JUNE T = tilt P = precession Worksheet: climate sensitivity and feedbacks associated with ice ages CG1 + 2 ! = ∆# ∆$
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Worksheet Q1 Estimate the maximum global temperature change possible, if ALL temperature changes were due to eccentricity-driven changes in incoming solar radiation l =0.8 ° C/(W/m 2 ) D F = 0.5W/m 2 A. 5 °C B. 0.75 °C C. 0.4 °C D. 0.025 °C E. Did not manage to answer it. CG1
Worksheet Q1 Estimate the maximum global temperature change possible, if ALL temperature changes were due to eccentricity-driven changes in incoming solar radiation l =0.8 ° C/(W/m 2 ) D F = 0.5W/m 2 A. 5 °C B. 0.75 °C C. 0.4 °C = ∆" = l * D F D. 0.025C CG1
Worksheet Q2 The temperature change was actually D T = 5°C. If D F = 0.4W/m 2 , calculate the effective climate sensitivity: l = DT / D F = 5/0.4 = 12.5 ° C/(W/m 2 ) Our current climate forcing due to anthropogenic greenhouse gases is about 2.7W/m 2 . If the climate sensitivity was 12.5C/(W/m 2 ), what would be the final equilibrium temperature of Earth if we kept the forcing at D F = 2.72W/m 2 ? A. 1.5C B. 2C C. 5C. D. 11C E. 34C CG1
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Worksheet Q2 The temperature change was actually D T = 5°C. If D F = 0.4W/m 2 , calculate the effective climate sensitivity: l = DT / D F = 5/0.4 = 12.5 ° C/(W/m 2 ) Our current climate forcing due to anthropogenic greenhouse gases is about 2.7W/m 2 . If the climate sensitivity was 12.5C/(W/m 2 ), what would be the final equilibrium temperature of Earth if we kept the forcing at D F = 2.72W/m 2 ? A. 1.5C B. 2C C. 5C. D. 11C E. 34C DT = D F x ! = 2.7 W/m 2 x 12.5 C/(W/m 2 ) = 34C ! = 12.5 ° C/(W/m 2 ) is much larger than our best estimates for climate sensitivity (thankfully!). So what’s going on in ice ages? CG1
Worksheet Q4 Given the magnitude of the forcing in the figure above, what kinds of feedbacks are needed in order to get a 5K glacial-interglacial temperature change? (A) Amplifying (B) Stabilizing CG2
Worksheet Q4 Given the magnitude of the forcing in the figure above, what kinds of feedbacks are needed in order to get a 5K glacial-interglacial temperature change? (A) Amplifying (B) Stabilizing CG2
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Worksheet Q5 T = tilt P = precession A key latitude and season is 65°N in summer. Using the figure, approximate the maximum change in incoming solar radiation over time at this latitude and season. A. 0.5 W/m 2 B. 1 W/m 2 C. 10 W/m 2 D. 30 W/m 2 E. 60 W/m 2 CG2
Worksheet Q5 A key latitude and season is 65°N in summer. Using the figure, approximate the maximum change in incoming solar radiation over time at this latitude and season. A. 0.5 W/m 2 B. 1 W/m 2 C. 10 W/m 2 D. 30 W/m 2 E. 60 W/m 2 Seasonally and locally, the insolation forcing can be quite large, and explain the large response, but it needs to be transmitted to the whole planet. CG2
Worksheet Q6: Feedbacks Starting with a change in the incoming solar radiation (insolation) at this latitude and season (65°N in summer), construct at least one feedback loop you think would help Earth’s climate system get from a glacial state to an interglacial state CG2
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Worksheet Q6: Feedbacks Starting with a change in the incoming solar radiation (insolation) at this latitude and season (65°N in summer), construct at least one feedback loop you think would help Earth’s climate system get from a glacial state to an interglacial state CG2 Forcing: Increase in solar radiation at 65N Increased temperatures in Arctic Melting of sea ice in Arctic Reduced albedo and increased absorbed radiation
Conclusions about orbital forcing • Periodicities of these orbital cycles match the periodicities of cycles measured in climate records. • Amplitudes of the orbital cycles do NOT match the amplitudes measured in climate records. • The global orbital forcing is very small, but regionally/seasonally it can be large. • The relationship between forcing and temperature during ice age cycles informs us on the climate sensitivity, and thus the feedbacks in the climate system In order to understand the climate response, we need to find the feedbacks amplifying the orbital forcing. 1. ice-albedo feedback 2. Carbon cycle feedback
Modified from NASA and Trenberth et al., 2009 ALBEDO = fraction of incoming solar radiation that is directly reflected back to space • depends on the reflectivity of the surface • Earth’s average (today) = 30% Albedo - definition CG2
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
A. Sea level B. Position of the continents C.Amount of forested areas D.Earth’s temperature E. All four factors above can potentially affect Earth’s albedo Clicker Question: Which of these factors does NOT influence Earth’s albedo and climate evolution? CG2
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
A. Sea level B. Position of the continents C.Amount of forested areas D.Earth’s temperature E. All four factors above can potentially affect Earth’s albedo Clicker Question: Which of these factors does NOT influence Earth’s albedo and climate evolution? CG2
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
• Ice sheets replace tundra and forests • Sea ice replaces water • Land replaces ocean (sea level decrease) Higher albedo Feedback 1. The Ice-Albedo Feedback CG2
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Ice-albedo feedbacks are local, and ice ages are forced by insolation changes at 65N, but… THINK-PAIR-SHARE: What types of feedback could also influence the southern hemisphere and lead to near-global cooling in response to 65N forcing? CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Feedback 2. Greenhouse Gas Feedbacks Polar ice cores contain tiny (1mm) bubbles of air. They can give us a direct record of the past atmosphere. CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Feedback 2. Greenhouse Gas Feedbacks Ice age cycles in temperature over the past 800,000 years CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Feedback 2. Greenhouse Gas Feedbacks There is a remarkable correspondence between atmospheric CO 2 and temperature It supports the idea of a direct link between greenhouse gas concentrations & climate in this period CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Clicker Q: Which statement correctly describes the lead/lag of these two time series? A. 1 leads 2 by about 10 thousand years B. 1 leads 2 by about 50 thousand years C. 2 leads 1 by about 10 thousand years D. 2 leads 1 by about 50 thousand years 1 2 Age (kya or “thousands of years ago”) CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Clicker Q: Which statement correctly describes the lead/lag of these two time series? A. 1 leads 2 by about 10 thousand years B. 1 leads 2 by about 50 thousand years C. 2 leads 1 by about 10 thousand years D. 2 leads 1 by about 50 thousand years 1 2 Age (kya or “thousands of years ago”) CG3 Time 2 decreases About 10,000 years later, 1 decreases
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
CO 2 and temperature from ice cores Vostok data (Antarctica). Temperature estimated from deuterium Age (kya or “thousands of years ago”) CLICKER: Based on this graph (hint: look at the decreases in temperature for a clearer signal) A. Temperature leads CO 2 B. CO 2 leads temperature C. CO 2 and temperature change at exactly the same time CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
CO 2 and temperature from ice cores Vostok data (Antarctica). Temperature estimated from deuterium CO 2 lags temperature by several 100 years Does CO 2 drive temperature? Does temperature drive CO 2 ? CO 2 can be both a forcing (current) AND a feedback (past) Age (kya or “thousands of years ago”) CLICKER: Based on this graph (hint: look at the decreases in temperature for a clearer signal) A. Temperature leads CO 2 B. CO 2 leads temperature C. CO 2 and temperature change at exactly the same time CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
The Carbon Cycle Fast timescales (0-100s years): Photosynthesis-respiration Exchange with surface ocean CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
The Carbon Cycle Reservoirs (stocks) Fluxes Fast timescales (0-100s years): Photosynthesis-respiration Exchange with surface ocean Medium timescales(1kyr-1Myr): Ocean-atmosphere exchanges Also with deep ocean CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
The Carbon Cycle Reservoirs (stocks) Fluxes Fast timescales (0-100s years): Photosynthesis-respiration Exchange with surface ocean Medium timescales(1kyr-1Myr): Ocean-atmosphere exchanges Also with deep ocean Long timescales(>1My): Rock weathering, volcanism CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
The Carbon Cycle : important ice age feedback Reservoirs (stocks) Fluxes Fast timescales (0-100s years): Photosynthesis-respiration Exchange with surface ocean Medium timescales(1kyr-1Myr): Ocean-atmosphere exchanges Also with deep ocean Long timescales(>1My): Rock weathering, volcanism CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
The Carbon Cycle Reservoirs (stocks) Fluxes Fast timescales (0-100s years): Photosynthesis-respiration Exchange with surface ocean THINK-PAIR-SHARE: The anthropogenic contribution is relatively small compared to the natural fluxes. So why does it matter so much for modern climate change? CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Carbon cycle timescales CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Modulation is through CO 2 exchanges between atmosphere and ocean Greenhouse gas feedbacks amplify the effects of variations in incoming solar radiation produced by orbital forcing: Feedback 2. Greenhouse Gas Feedbacks This exchange can happen in two ways: 1. The solubility pump (or physical pump) 2. The biological pump CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Modulation is through CO 2 exchanges between atmosphere and ocean Greenhouse gas feedbacks amplify the effects of variations in incoming solar radiation produced by orbital forcing: Feedback 2. Greenhouse Gas Feedbacks This exchange can happen in two ways: 1. The solubility pump (or physical pump) 2. The biological pump CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Solubility ‘Henry’s Law’: The solubility of a gas in a liquid is directly proportional to the partial pressure of the gas in the atmosphere above the liquid. The concentration of CO 2 in the ocean, C(CO 2 ) = p(CO 2 ) Hs(T) where p(CO2) is the partial pressure of the CO 2 above the ocean, and Hs(T) is a constant that depends on temperature (called the ‘Henry solubility’) CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
http://earthobservatory.nasa.gov/Features/OceanCarbon/page1.php A. Lower atmospheric CO 2 concentrations B. Higher atmospheric CO 2 concentrations C.It’s independent of atmospheric CO 2 concentrations Clicker Q: For a fixed temperature, the CO 2 concentration in the ocean will be higher with: CO 2 concentration in water Low High Temperature (°C) Pre-industrial atmospheric CO 2 Current atmospheric CO 2 2 x atmospheric CO 2 CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
http://earthobservatory.nasa.gov/Features/OceanCarbon/page1.php Clicker Q: For a fixed temperature, the CO 2 concentration in the ocean will be higher with: A. Lower atmospheric CO 2 concentrations B.Higher atmospheric CO 2 concentrations C.It’s independent of atmospheric CO 2 concentrations CO 2 concentration in water Low High Temperature (°C) Pre-industrial atmospheric CO 2 Current atmospheric CO 2 2 x atmospheric CO 2 Solubility CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
http://earthobservatory.nasa.gov/Features/OceanCarbon/page1.php CO 2 concentration in water Low High Temperature (°C) Clicker Q: What relative temperature of water can dissolve more CO 2 ? A.Colder water B.Warmer water CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
http://earthobservatory.nasa.gov/Features/OceanCarbon/page1.php CO 2 concentration in water Low High Temperature (°C) Clicker Q: What relative temperature of water can dissolve more CO 2 ? A.Colder water B.Warmer water Hs(T), the Henry solubility: Hs(T) = C(CO 2 ) water /P(CO 2 ) air decreases with temperature . CG3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Feedback 2. Greenhouse Gas Feedbacks a. The solubility pump When temperatures gets colder, CO 2 becomes more soluble, and more CO 2 can dissolve into the Ocean Cooling More CO 2 dissolve in the ocean Less CO 2 in atmosphere, less greenhouse effect The solubility Hs(T) = C(CO 2 ) water /P(CO 2 ) air decreases with temperature . CG4
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Clicker Q: Based solely on sea surface temperatures (shown in the map below), where would you expect CO 2 to dissolve into surface ocean water the most? Sea surface temperature: Red=warmer; blue-colder 1 5 3 2 4 A. 1 & 2 B. 1 & 5 C. 3 & 4 D. 2, 3, & 4 E. 1, 2, & 5 CG4
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
D A E B C Sea – air CO 2 fluxes CO 2 is moving from atmosphere to ocean where the sea-air CO 2 flux is negative, i.e. in the blue/purple regions in this map. CO 2 is moving from ocean to atmosphere in the positive (red) regions. CG4
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
D A E B C Sea – air CO 2 fluxes If we’re increasing atmospheric CO 2 , then why is CO 2 coming OUT of the ocean in some places? (mostly the tropics) CG4
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help

Related Documents

4-2 Worksheet.docx
01-1_Latitude_and_Longitude (1).pdf
Exercise 8 (2).docx
Iceland Tourism.docx
M10 Quiz_ East Asian Realm.pdf
DAT 223 Project Three Status Report Western Forest.docx
ENV 305 Milestone Two.docx
IT242_FinalProject.pdf
ENV305 2_2 Special Feature Assignment.docx
Continental Drift Q&A.docx
The Sand Story Q&A.docx
Homework_08.pdf