Climate Change and Its Effects

First homework due this weekend.
- Worth approximately 10 points.
- Content is manageable, with three homework assignments throughout the semester.
Homework submission will be done via HuskyCT.
The first assignment will be released tomorrow at 9 AM.
- The assignment will consist of a worksheet based on a video watched.
Deadline for completion: Monday at 9 AM.
Deadlines are strict; extensions are not typically granted except for technical issues.
- Students should contact the instructor via email if submission issues arise.
Submissions must be in .doc or .pdf format.
- Links to documents will not be accepted.
Multiple options for completing homework:
1. Handwriting, scanning via phone (most modern phones can scan documents).
2. Typing responses directly in a document editor.
Emphasis on personal input over AI-generated responses:
- Students are encouraged to reflect on their learning without relying on AI tools like ChatGPT.
- If AI usage is suspected, students may receive a zero.
- Students can discuss any discrepancies if they believe they did not use AI.

Today's lecture will cover the scientific aspects of climate change, connected to global change concepts.
Objective of the course:
- To build an understanding of climate change causes, consequences, and impacts.
- To simplify scientific concepts so all students can understand.

Definitions:
- Weather: Refers to short-term atmospheric conditions.
- Example: Snow one day and sun the next in Connecticut.
- Climate: Describes long-term average weather patterns in a specific area.
- Climate includes statistical properties like average temperature and variance over long periods (years).
Importance of distinguishing weather from climate:
- Weather represents immediate atmospheric conditions and is difficult to predict accurately.
- Climate is easier to model due to the long-term data available.

The atmosphere's thickness:
- Measures approximately 100 kilometers (60 miles) from Earth's surface.
Dense with various gases that contribute to climate dynamics.

Oceans cover 71% of Earth's surface and significantly influence climate.
- Average depth of the oceans: 2.3 miles.
- Ocean conditions affect global climate through water vapor and temperature exchanges.

Land accounts for approximately 29% of Earth's surface, influencing weather and climate through its absorption and reflection properties.
Freshwater is less than 1% and is critical in land ecosystems.

The sun's role is significant:
- Its energy drives atmospheric circulation and weather patterns.
- Solar variations and Earth's position also affect climate conditions over time.

Air circulation is crucial in climate regulation:
- Warm air is less dense and rises.
- Cold air is denser and sinks.
Hadley Cells: Air movement around the equator creates large-scale air circulation patterns termed Hadley cells.
Trade winds are produced by the interaction of these air cells with Earth's rotation.
Circulation impacts weather and climatic conditions worldwide.
- At the equator, warm air creates a lot of precipitation due to its rise and cooling.

The greenhouse gas effect explains how certain gases warm the Earth's atmosphere:
- Solar radiation hits Earth, with some energy reflected back into space.
- Greenhouse gases absorb and radiate heat back towards Earth's surface, maintaining temperate conditions for life.
Key greenhouse gases include:
- Carbon dioxide (CO$_2$)
- Methane (CH$_4$)
- Nitrous oxide (N$_2$O)
Increased concentrations of these gases enhance the greenhouse effect, leading to global warming.

Clouds can cool Earth's surface by reflecting solar radiation.
- Albedo Effect: Measurement of reflectivity of different surfaces.
- Lower clouds reflect about 90% of sunlight, cooling the surface.
Day vs. Night Effects:
- During the day, clouds tend to cool the surface; at night, they trap heat and keep the surface warmer.

Oceans are essential for:
- Providing water vapor, a major greenhouse gas.
- Absorbing and storing carbon dioxide, impacting atmospheric levels.
Evaporation from oceans contributes significantly to greenhouse gas concentrations.

Upwellings bring nutrients to the ocean surface, promoting marine biodiversity:
- Nutrient-rich areas lead to higher biological productivity.

Involves geological processes and long-term weathering of rocks.
Operates over millions of years, balancing CO$_2$ levels through sedimentation and volcanic activity.

Driven by biological processes like photosynthesis and respiration.
Carbon moves rapidly through ecosystems and the atmosphere; significantly faster than the slow cycle.

El Niño Southern Oscillation (ENSO) significantly affects global climate variability:
- Characterized by fluctuations in wind patterns and sea temperatures.
- Alters weather scenarios, causing extremes like droughts and heavy rainfall events.

Volcanic eruptions, plate tectonics, and carbon cycling have historically altered climates:
- Different periods of icehouse (cold) and greenhouse (warm) phases.
- Current climate is warming in an icehouse phase, driven by anthropogenic emissions.
Scientific records show an increase in global temperatures and CO$_2$ concentrations since the 1800s, significantly correlating with human activities.
Historical data from the Mid-Miocene reflects potential consequences of current temperature increases.

Homework assignment #1 involves analyzing changes impacting food systems in the context of climate change and will dive deeper into the Anthropocene.
Assignment reference: Video “In Solving the Maze: A Big History of Food Complexity.”