AP Environmental Science Study Guide: Climate Change and Ocean Impacts

AP Testing Logistics and Protocol

• College Board Account Information: Students are required to bring their College Board account login credentials, including the student account email and password. It is explicitly noted that saved passwords on devices will not work for the testing process.

• Identification Requirements: A physical ID is mandatory for admission to the exam. Digital IDs are not accepted under any circumstances.

• Punctuality and Attendance:     - Late students will not be admitted to the testing room.     - Being late does not qualify a student for a late exam reschedule.     - Students must double-check the specific date and time of their exam and are advised to arrive at least half an hour (30 minutes) early.

Off-Campus Departure Procedures

• Documentation for Leaving Early: If a student needs to leave campus after a test, they must provide a physical note. Phone calls or emails are not accepted for this purpose.

• Note Details: the note must state the specific day and the specific time the off-campus pass is requested for.

• Submission: Notes must be given directly to Eren.

Sea Level Rise: Thermal Expansion and Oxygen Depletion

• Mechanism of Thermal Expansion: As liquid water warms due to climate change, the molecules expand and spread out, which increases the total volume of the water and takes up more space.

• Impact on Marine Life: Warm water has a lower capacity to hold dissolved oxygen ($\text{O}_2$). This leads to several biological consequences:     - Fish populations may decline significantly.     - Species may migrate to cooler waters to maintain respiration levels.

Sea Level Rise: Melting of Land-Based Ice and Albedo Feedback

• Land-Based Ice vs. Sea Ice:     - Land ice includes glaciers and land-based ice sheets.     - Sea ice is already in the water; its melting does not contribute directly to sea level rise in the same way land ice does.

• Atmospheric Warming and Glacial Melt: As the atmosphere warms, glaciers and land ice melt, and the runoff flows from the land into the ocean, adding new volume to the sea and causing levels to rise.

• Albedo Effect and Positive Feedback Loop:     - Ice has a high albedo, meaning it reflects a large portion of light and heat.     - As ice melts, it exposes darker land or water surfaces, which have a lower albedo. These surfaces reflect less light/heat and instead absorb more.     - This increased absorption raises temperatures further, leading to more ice melting.     - This cycle is characterized as a Positive Feedback Loop.

Greenland Ice Mass Change Observations

• GRACE Data: Gravity Recovery and Climate Experiment (GRACE) satellite observations provide data on ice mass changes.

• Greenland Statistics:     - The average mass loss in Greenland is approximately $281\,\text{gigatons/year}$.     - Monitoring shows a consistent downward trend in ice mass from April 2002 through 2016.     - Data from NOAA (National Oceanic and Atmospheric Administration) Climate.gov and the 2016 Arctic Report Card indicate the ice mass has decreased by nearly $4000\,\text{gigatonnes}$ between 2002 and 2016.

• Atmospheric Conditions: $\text{CO}_2$ levels are currently 1.5 times higher than they were 400,000 years ago.

• Potential for Disastrous Rise: If the Greenland ice sheet were to melt completely, global sea levels would rise by approximately $7\,\text{meters}$ ($23\,\text{feet}$), causing devastation to billions of people living in coastal regions.

Future Sea Level Rise Pathways and Projections

• Representative Concentration Pathways (RCP):     - Current Pathway (RCP 8.5): A high-emissions scenario leading to significant sea level rise by the years 2100 and 3000.     - Lower Emissions Scenario (RCP 2.6): A scenario with reduced greenhouse gas concentrations leading to more stabilized sea levels.

• NOAA Projections for 2100: Future pathways differ based on emission rates and ice sheet loss:     - High: Reaching nearly $7\,\text{feet}$ above 2000 levels.     - Intermediate-High: Between $4\text{ and }5\,\text{feet}$.     - Intermediate: Around $3\text{ to }4\,\text{feet}$.     - Intermediate-Low: Approximately $1.5\,\text{feet}$.     - Low: Approximately $1\,\text{foot}$.

• At-Risk Locations: Specific coastal cities identified with varying risk levels (Low to Very High) include:     - Tampa     - New Orleans     - Virginia Beach     - Charleston     - Miami

Regional Case Studies: Maldives and Florida

• The Maldives:     - Comprised of a group of approximately 200 small islands.     - The islands average only $6\,\text{feet}$ above sea level.     - Response: An artificial island was constructed by pumping sand from the sea floor onto an existing coral reef. This was done to accommodate housing and industrial demands and to mitigate the threat of rising seas. Settlement on this artificial island was officially declared in 2004.

• Florida:     - Sea levels around Florida are up to $8\,\text{inches}$ higher than they were in 1950.     - The state's geology is composed of porous limestone, which complicates flooding issues.     - There are roughly $120,000\,\text{properties}$ currently at risk from frequent tidal flooding.     - Infrastructure solutions (raising roads, stormwater system protections, sewage protection) are projected to cost over $4\,\text{billion dollars}$.

Impacts on Species and Coastal Communities

• Loss of Habitat: Species that depend on land ice for food and habitat in polar regions are severely affected.

• Coastal Community Property Damage: Rising seas lead to property loss and relocation. Seawalls and barriers provide only a temporary delay to eventual flooding.

• Barrier Islands: These natural buffers protect coastal ecosystems from wind and waves; their loss increases the vulnerability of inland communities.

• Coastal Ecosystems: Rising sea levels threaten the existence of salt marshes and mangrove forests.

Melting Permafrost and Greenhouse Gas Release

• Definition: Permafrost is frozen ground found in the tundra.

• Carbon Sink: It holds massive quantities of stored methane ($\text{CH}_4$) and carbon dioxide ($\text{CO}_2$).

• Impact: As it melts, these greenhouse gases are released into the atmosphere, which accelerates global warming. This acceleration causes more permafrost to melt, creating another Positive Feedback Loop.

Changes in Thermohaline Circulation

• Function: The thermohaline circulation is a global ocean current that redistributes heat from the equator, along with salt and nutrients, by mixing ocean waters.

• Disruption: Melting ice from Greenland introduces large amounts of fresh water into the North Atlantic.

• Mechanism: Fresh water decreases the salt concentration (salinity). Since saltier water is denser and drives the sinking motion of the pump, a decrease in salinity could slow or completely stop the thermohaline circulation.

Extreme Weather and Biological Consequences

• Precipitation Changes: Increased water vapor in the atmosphere leads to greater rainfall and more intense storms in some areas, while causing drought in others.

• Climatic Shifts:     - More intense storms and flooding.     - More intense cold weather events.     - Severe droughts and heat waves lead to soil moisture loss, resulting in desertification and erosion.

• Wildfires: Increased heat and drought lead to more frequent and intense forest fires.

• Vegetation: Reduced plant growth means less $\text{CO}_2$ is removed from the atmosphere via photosynthesis, further driving warming.

• Energy Demands: Extreme temperatures increase the energy required for heating and cooling.

• Disease and Ecology:     - The range and transmission season length of infectious diseases, pathogens, and vectors (such as mosquitoes) are expanding from the tropics toward the poles.     - Climate instability provides a competitive advantage to invasive and r-selected (generalist) species.

Ocean Warming and Coral Bleaching

• Heat Absorption: The oceans absorb a significant portion of the heat trapped in the atmosphere.

• Metabolic Changes: Marine species experience loss of habitat and changes in metabolism and reproduction as they are pushed out of their physiological range of tolerance.

• Coral Bleaching: As the ocean warms, the symbiotic algae living inside coral tissues die or are expelled. This causes the coral to lose its color and turn white, a process known as bleaching.

Ocean Acidification: Chemistry and Causes

• Anthropogenic Causes:     - Fossil fuel combustion (releases $\text{CO}_2$).     - Deforestation (reduces $\text{CO}_2$ sequestration).     - Coal and gas combustion (releases $\text{NO}_x$ and $\text{SO}_x$, contributing to acid precipitation).

• Chemical Process:     1. Human activity increases atmospheric $\text{CO}_2$.     2. $\text{CO}_2$ reacts with seawater to create carbonic acid ($\text{H}_2\text{CO}_3$):        $\text{CO}_2 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{CO}_3$     3. Carbonic acid dissociates into a hydrogen proton ($\text{H}^+$) and a bicarbonate ion ($\text{HCO}_3^-$), effectively lowering the water's pH:        $\text{H}_2\text{CO}_3 \rightarrow \text{H}^+ + \text{HCO}_3^-$     4. The free $\text{H}^+$ proton combines with a dissolved carbonate ion ($\text{CO}_3^{2-}$) to form another bicarbonate ion:        $\text{H}^+ + \text{CO}_3^{2-} \rightarrow \text{HCO}_3^-$     5. This reduces the concentration of available carbonate ions ($\text{CO}_3^{2-}$) that marine organisms need to build calcium carbonate ($\text{CaCO}_3$) shells and exoskeletons.

• Biological Impact: Organisms such as coral, clams, mussels, sea urchins, and oysters struggle to maintain or build their shells, resulting in weaker structures.

• Historical and Projected pH Change:     - Standard ocean water is mildly alkaline (pH around $8.2$).     - pH has decreased from $8.2$ to $8.1$ in the past 150 years.     - pH could decrease to $7.8$ by 2100, representing a $150\,\%$ increase in acidity.     - There is an inverse relationship: as $\text{CO}_2$ increases, pH decreases.

Academic Schedule and Unit 9 Review

• Review Materials: Students should be working on the Unit 9 Review Packet and the AP progress check.

• Practice Exams: Computers will be required on Monday for Practice Tests #2, #3, #5, and #7. No stamp is needed.

• Upcoming Schedule (May 4 - May 8):     - Monday: Practice Exam.     - Tuesday: Finish Unit 9; Review and correct practice exam; Unit 9 packet and progress check are due.     - Wednesday: Day 1 Final Multiple Choice Questions (MCQ).     - Thursday: Day 2 Final MCQ and Free Response Questions (FRQ).     - Friday: Notebooks for Units 8 and 9 are due.