Geo 5/5

Midterm 2 Results and Logistics

• Midterm 2 Grading Summary:     * The mean grade for Midterm 2 was $84\%$, which includes $2$ points of extra credit.     * The grade distribution showed the highest frequency of students scoring in the $(86.625, 95.825]$ and $(95.825, 105.025]$ ranges.     * Specific frequency bins observed include:         * $[40.625, 49.825]$         * $(49.825, 59.025]$         * $(59.025, 68.225]$         * $(68.225, 77.425]$         * $(77.425, 86.625]$         * $(86.625, 95.825]$         * $(95.825, 105.025]$         * $(105.025, 114.225]$

• Announcements:     * Grades are currently posted.     * The answer key for Midterm 2 will be posted soon.     * Class will be asynchronous on Thursday, and potentially on Tuesday the 5th as well.

Concept Review: Emissions and Ocean Impacts

• Clicker Question 10: A decrease in annual emissions rates from $40$ to $37\,Gt\,CO_2/yr$ during the COVID-19 pandemic resulted in:     * Correct Answer: An increase in cumulative emissions and an increase in atmospheric $pCO_2$.     * Reasoning: Even though the rate of emission decreased, $\text{CO}_2$ was still being added to the atmosphere, thereby increasing the total cumulative amount and the partial pressure of $CO_2$.

• Clicker Question 20: Which of the following is not true about the impacts of ocean acidification on ocean ecosystems?     * Statements that ARE true:         * It impacts many organisms low in the food chain.         * It reduces the available carbonate ($CO_3^{2-}$) that many organisms use to make their shells.         * Even with organisms that can continue to make shells, it may harm their physiology.     * Correct Answer (The False Statement): It is the main mechanism behind coral bleaching.     * Clarification: Thermal stress (warming), not acidification, is the primary driver of coral bleaching.

Defining Adaptation and Mitigation

• Adaptation: Strategies designed to offset the effects of increased $\text{CO}_2$ and subsequent climate change. This includes addressing:     * Environmental impacts.     * Social and economic impacts.

• Mitigation: Actions taken to reduce or remove the excess buildup of $\text{CO}_2$ in the atmosphere to reduce climate change itself, thereby reducing environmental, social, and economic impacts.

• Scales of Adaptation:     * Individual level.     * Local level (e.g., City Hall initiatives like those in Northampton).     * State/Regional level.     * National level.

• General Categories of Adaptation:     * Structural/Physical.     * Social.     * Institutional.

Structural and Physical Adaptation Strategies

• Sea Level Rise (SLR) Projections:     * Projections vary by scenario ($SSP1-1.9$ to $SSP5-8.5$).     * Under $SSP5-8.5$, low confidence estimates for the $83rd$ and $95th$ percentiles suggest sea level rise could exceed $2.0\,m$ by $2150$.     * Historical data starting from $1950$ shows a steady increase in sea level.

• Specific Structural Interventions for Sea Level Rise:     * Sea Walls:         * Purpose: Protect coastal beaches from erosion and allow for more stable development.         * Benefit: Can protect against storm surges.         * Constraint: Requires continuous maintenance and eventual replacement.     * Levees:         * Purpose: Walls specifically directed toward preventing flooding.         * Application: Applied to coastal areas and the banks of river systems.         * Historical Failure: Levees failed during Hurricane Katrina ($2005$), leading to the catastrophic flooding of New Orleans.     * Tidal Basin:         * Purpose: A man-made reservoir that fills during high tide or flooding events.         * Benefit: Reduces tidal flooding in developed areas.         * Constraint: Significant engineering undertaking; difficult to implement in already heavily developed areas.     * Marsh Restoration:         * Purpose: A natural solution that absorbs high-energy waves.         * Benefit: Reduces storm surge, flooding, and erosion.         * Constraint: Not effective if urban development reaches all the way to the beach line.     * Aquifer Recharge:         * Mechanism: Pumps water into the near-coastal subsurface.         * Benefit: Prevents saltwater intrusion into the freshwater groundwater table by maintaining the salt-water interface.

Social and Institutional Adaptation Strategies

• Social Adaptation Categories:     * Education: Ensuring the public knows what to expect; raising awareness of adaptation options via high school education and environmental outreach.     * Mapping and Informational: Utilizing hazard mapping and early warning systems.         * Example: Modeling Boston after a $5\,ft$ Sea Level Rise.         * Resource: NOAA Sea Level Rise Viewer ($\text{https://coast.noaa.gov/slr/}$).     * Behavioral: Personal decisions regarding purchasing or developing property.         * Key Action: Migration (fleeing) or retreat, which may be the only option for some coastal/island communities and requires geopolitical solutions.         * Livelihood diversification and training.

• Institutional Adaptation Categories:     * Economic Policies: Incentives, taxes, subsidies, insurance, ecosystem service payments, water tariffs, and microfinancing.     * Laws and Regulations:         * Zoning Laws: Preventing future development in hazardous areas.         * Building Codes: Increasing resilience to floods and storms.         * Water rights and catch/harvest quotas.     * Programs: Adaptation plans, disaster planning, and watershed management.

• National Flood Insurance Program (NFIP):     * A federal program created because private insurance companies cannot afford to cover disaster relief.     * Currently unsustainable and has racked up massive debt due to "severe repetitive loss properties."     * Severe Repetitive Loss Data ($1978-2015$):         1. Louisiana: $7,223$ properties; $\$1.22$ billion in damage.         2. Texas: $4,889$ properties; $\$960$ million in damage.         3. New Jersey: $3,246$ properties; $\$660$ million in damage.         4. New York: $1,802$ properties; $\$400$ million in damage.         5. Florida: $1,601$ properties; $\$370$ million in damage.         6. Missouri: $1,526$ properties; $\$190$ million in damage.

Economics and Barriers to Adaptation

• Economic Goal: Minimize the total costs of adaptation plus climate impacts.     * The optimal balance is found where adaptation costs and residual impacts are minimized relative to each other.     * Avoided impacts represent the difference between the cost of climate change with no adaptation and the cost with adaptation.

• Regional Economic Damages: Hundreds of billions of dollars annually. Damages impact:     * Coastal property.     * Labor productivity.     * Extreme temperature mortality ($0-12.3$ deaths per $100,000$).     * Air quality (Ozone).     * Road repairs.

• Case Study: California Power Outages: Planned outages to over $2\,million$ people across California to prevent wildfires during extreme weather events.

• Barriers to Economic Basis for Adaptation:     * Some items (ecosystem services, loss of life, communities) cannot have a price tag easily applied.     * Equity issues: Where do the costs fall? Impact on poor communities and government spending.     * Externalities that market prices do not capture.

• Adaptation Activity in the US ($2018-2022$): Documentation of activities varies by state, with numbers ranging from $1$ to over $311$ documented activities per state.

Introduction to Climate Mitigation

• Identifying Emission Sources: Mitigation requires knowing the source of greenhouse gases ($\text{GHG}$).     * Direct Emissions: Result from direct fuel consumption.     * Indirect Emissions: Associated with purchases such as electricity, heat, and waste disposal.

• Global Electricity Sources ($1985-2023$):     * Primary sources include Coal, Gas, Nuclear, Hydropower, Wind, and Solar.     * Growth Trends ($2015-2020$): Solar PV grew by $170\%$, and Wind grew by $70\%$.

• Global Fossil $CO_2$ Emissions:     * $1990-1999$: $+1.0\%/yr$     * $2000-2009$: $+2.8\%/yr$     * $2010-2019$: $+0.9\%/yr$     * $2024$ Projection: $37.4\,Gt\,CO_2$ ($0.8\%$ increase from previous year).     * Major Historical Declines: Dissolution of Soviet Union ($\downarrow 3.1\%$), Global Financial Crisis ($\downarrow 1.5\%$), COVID-19 Pandemic ($\downarrow 5.7\%$).

• Total Global Energy Consumption (In-class Question):     * Energy from non-fossil fuels (nuclear, hydro, biofuels, wind, tides, geothermal) represents approximately $27\%$ (Option C) of total global energy consumption.

• Mitigation Benefits ($2090$ Projections): Annual economic damages under $RCP8.5$ are significantly higher than $RCP4.5$, particularly regarding labor and air quality costs.

Mitigation Strategies and Cap and Trade

• Seven Major Mitigation Strategies:     1. Greenhouse Gas targets, caps, and pricing.     2. Increased energy efficiency standards.     3. Shift to renewable or nuclear energy sources.     4. Reduced non-$CO_2$ GHG emissions.     5. Reduce energy consumed for transportation.     6. Improved forest management and land-use practices.     7. Carbon Capture.

• Cap and Trade Mechanics:     * The government sets an emissions cap (which may decrease over time).     * Companies receive or auction limited "allowances."     * Companies reducing emissions below their allowance can sell unused credits.     * Goal: Use market mechanisms to find the cheapest way to cut emissions.

• Cap and Trade Case Studies:     * China: Launched the largest system in $2017$ but was initially timid to avoid limiting economic growth.     * California: Strongest US legislation; goal was $1990$ emission rates by $2020$. It reached these levels in $2016$ ($4$ years early) without damping the economy.     * United States: A policy similar to the EU's passed the House in $2009$ but failed in the Senate.

• Pricing Examples:     * California: $\$15$ per metric ton of $CO_2$ ($85\%$ share of emissions covered).     * Northeastern US: $\$5$ per metric ton of $CO_2$ ($18\%$ share of emissions covered).