The Biology of Climate Change

Introduction to Climate Change and the Biosphere

• Climate Definition: Climate refers to the average weather patterns in a specific geographic area over a long period. The primary characteristics used to define a climate are temperature and rainfall.

  • Seasonal Variations: Local seasonal changes are caused by the tilt of the Earth on its axis ($23^{\circ}$). For instance, in the spring, a region may be cool and rainy, whereas in the summer, it may be hot and humid.
  • Global Manifestation: Climate is considered a global phenomenon. While regional climates vary due to the amount of solar radiation striking the surface, these factors cumulatively affect the entire planet.

• The Biosphere: The biosphere represents the sum of all regions on Earth where life exists. This includes the deepest parts of the oceans and extends high into the atmosphere.

  • Dependence: All components of the biosphere depend on the planet's climate to maintain the conditions necessary for life.

• Ecological Levels of Biological Organization:

  • Population: A group of organisms belonging to the same species that live in a specific area.
  • Species: The collection of all populations of organisms that are similar in appearance and possess the ability to interbreed.
  • Community: Multiple populations of different species interacting within a specific area.
  • Ecosystem: The interaction between a biological community and its physical environment (abiotic factors), such as the climate.
  • Biosphere: The sum of all regions on Earth—water, surface, and atmosphere—where living organisms are found.

Distinguishing Global Warming and Climate Change

• Historical Context: The term "Global Warming" was first utilized by scientists in the 1980s to describe a discovered upward trend in global temperatures.

• Definitions and Differences:

  • Global Warming: Primarily refers to the increase in the Earth's average surface temperature.
  • Climate Change: A broader term referring to changes in the average weather patterns in an area over time, typically recorded through temperature and precipitation. While often used interchangeably with global warming, climate change encompasses a wider range of phenomena.

• Correlated Weather Events: Climate change is correlated with several specific weather phenomena, including:

  • Extreme precipitation events.
  • Heat waves.
  • Coastal flooding.
  • Severe droughts.
  • Hurricanes.
  • Note: The connection between climate change and tornadoes is still under active scientific investigation.

Greenhouse Gases and the Greenhouse Effect

• The Greenhouse Effect: This is a phenomenon where certain gases in the lower atmosphere retain heat near the Earth's surface. These gases play a vital role in maintaining the planet's climate within a range suitable for life.

• Major Greenhouse Gases:

  • Carbon Dioxide ($CO_2$):
    • Found in small concentrations measured in parts per million (ppm).
    • Critical due to its ability to absorb infrared energy (heat).
    • Produced naturally by fires, volcanic activity, and the breakdown of food in living organisms.
    • Used by plants to produce carbohydrates, which form the base of most food chains.
  • Methane ($CH_4$):
    • A rare gas found in concentrations measured in parts per billion (ppb).
    • Relatively unstable, remaining in the atmosphere for only about a decade.
    • Considered powerful because it can retain and release nearly 30 times the heat of $CO_2$.
  • Water Vapor ($H_2O$): Produced through natural processes in the water cycle.
  • Nitrous Oxides ($N_2O$): Result from agricultural practices (fertilizer use) and burning fossil fuels.
  • Ozone ($O_3$): Produced through natural processes and the interaction of solar energy with pollutants in the lower atmosphere.
  • Chlorofluorocarbons ($CFCs$): Synthetic compounds used in refrigerants and spray propellants.

Evidence of a Changing Climate

• Temperature Observations: Since the 1980s, the average temperature of the planet has shown a consistent increase. In the United States, average temperatures have risen by $1.3^{\circ}F$ to $1.9^{\circ}F$, with a projected increase of $2^{\circ}F$ to $4^{\circ}F$ by the year 2050.

• Evidence from Oceans:

  • Ocean Acidification: As $CO_2$ enters the ocean, it reacts with water to produce carbonic acid ($H_2CO_3$). This increase in acidity lowers pH levels.
  • Impact on Carbonate: Acidification reduces the availability of carbonate ($CO_3^{2-}$), which is essential for organisms like crabs, lobsters, and clams to form their shells.
  • Heat Sinks: Oceans act as temporary storage locations for heat energy. While heat sinks (like those near Florida) can moderate local winter temperatures, long-term heat storage in oceans influences global climate.

• Evidence from Glaciers and Sea Ice:

  • Glacial Loss: Glaciers naturally expand and contract, but a global loss of ice mass has been recorded by scientists since the 1970s.
  • Arctic Sea Ice: The extent of sea ice in the Arctic has been steadily decreasing since the late 1970s.

• General Statistical Trends (Climate Indicators):

  • Increasing Factors: Temperature over land, ocean heat content, sea level, temperature over oceans, humidity, air temperature near surface (troposphere), and sea surface temperature.
  • Decreasing Factors: Glaciers, snow cover, and sea ice.

The Global Carbon Cycle

• The Carbon Atom:

  • Nucleus: Contains positively charged protons and neutral neutrons.
  • Atomic Number: The number of protons (6 for Carbon).
  • Atomic Mass: The sum of protons and neutrons.
  • Bonding: Carbon can form bonds with four other elements, allowing for long chains or rings.

• Organic Chemistry: The study of hydrocarbon chains (molecules containing both carbon and hydrogen) in living organisms.

• Carbon Reservoirs and Sinks:

  • Reservoirs: Large storage areas for carbon, including the atmosphere, the oceans, and underground fossil fuels.
  • Carbon Sinks: Regions that absorb more carbon than they release.
  • Carbon Sources: Processes that release $CO_2$ into the atmosphere, such as cellular respiration or the combustion of fossil fuels.

Photosynthesis and the Carbon Cycle

• Autotrophs: Organisms that produce their own food. Most life on Earth relies on energy captured by photosynthetic autotrophs (e.g., plants, trees).

• The Process of Photosynthesis: Plants use sunlight, water ($H_2O$), and atmospheric carbon dioxide ($CO_2$) to produce carbohydrates ($CH_2O$).

• Chloroplast Structure:

  • Mesophyll Cells: Specialized cells in leaves that conduct photosynthesis.
  • Chloroplasts: Organelles specialized for photosynthesis.
  • Thylakoids: Plate-like structures within the chloroplast.
  • Grana: Stacks of thylakoids.
  • Stroma: The fluid-filled space between the grana.

• The Role of Light: Solar energy travels as particles called photons at various wavelengths. Photosynthesis primarily uses the visible spectrum of light.

• Stages of Photosynthesis:

  1. Light-Dependent Reactions:
     • Occur in the thylakoid membrane.
     • Chlorophyll absorbs solar energy to energize electrons.
     • $H_2O$ is broken down, releasing electrons, $H^+$ ions, and $O_2$ (released as waste).
     • Energized electrons are used to produce $ATP$ from $ADP + P$ and $NADPH$ from $NADP^+$.
  2. Calvin Cycle (Light-Independent Reactions):
     • Occurs in the stroma.
     • Carbon Fixation: $CO_2$ is taken up from the atmosphere and attached to a starting molecule ($RuBP$).
     • CO2 Reduction: $ATP$ and $NADPH$ provide energy and electrons to convert the fixed carbon into $G3P$ (glyceraldehyde 3-phosphate), which then forms carbohydrates.
     • The starting materials are recycled for the next cycle.

• Relationship with Cellular Respiration: Photosynthetic organisms convert $CO_2$ into carbohydrates and $O_2$. Heterotrophs (consumers) and autotrophs use these to power cellular activities via respiration, which releases $CO_2$ back into the cycle.

Fossil Fuels: Formation and Role

• Definition: Fuel sources formed within the Earth from the remains of plants and animals. Examples: Oil, natural gas, coal, and shale.

• Formation Process: Submerging organic material over long periods and subjecting it to intense heat and pressure from the Earth's crust.

• Current Status: Fossil fuels account for approximately $79\%$ of United States energy production. While renewable energy is increasing in the US, global fossil fuel emissions continue to rise, with Asia (specifically China and India) showing significant increases.

Impacts on Individuals, Species, and Communities

• Human Disease and Vectors: Climate change facilitates the spread of vectors (organisms like mosquitoes and ticks that transmit bacteria or viruses). Examples include the spread of Zika virus and West Nile virus.

• Heat and Drought: Droughts and heat waves are increasing in severity. Heat waves cause more deaths annually in the United States than any other climate-associated factor. They also disrupt agriculture and forestry.

• Habitat Loss and Extinction:

  • Bramble Cay Melomys: Recognized as the first mammal to go extinct due to climate change.
  • Ocean Biomes: Warming and acidification threaten aquatic communities.

• Invasive Species: Organisms introduced outside their natural range, often by human migration. They negatively impact native biodiversity, community structure, and ecosystem functioning.

• Community Level Shifts: A community is a stable group of species evolved to interact (e.g., a coral reef). Climate change disrupts these interactions, such as the loss of shellfish impacting the entire aquatic food web.

Global Ecosystems and Biomes

• Biome Definition: A term used to describe the general characteristics (climate and types of organisms) of similar ecosystems globally.

• U.S. Weather Pattern Changes:

  • Average temperatures have increased $2.12^{\circ}F$ ($1.18^{\circ}C$) above the 20th-century average.
  • Average precipitation has increased by $4\%$ in the past century. This change is regional: the West and Southeast are becoming drier, while the Central and Northeast are becoming wetter.

• Desertification: The conversion of grasslands to deserts, caused by increased temperatures, decreased precipitation, deforestation, and poor agricultural practices (cattle farming).

• Coral Bleaching: Coral are symbiotic organisms requiring relationships with algae. Global warming and invasive species threaten these reefs.

Addressing Climate Change

• Carbon Footprint: A calculation of the amount of carbon (usually measured in tons of $CO_2$) released directly or indirectly by the actions of an entity (individual, company, or country).

• Personal Choices:

  • Diet: Fruits and vegetables contribute less to a carbon footprint than red meat or dairy products.
  • Energy Source: Choosing wind or solar power reduces carbon emissions compared to fossil fuels.

• Alternative Energy Sources (Renewables):

  • Solar Power: Constantly renewable resource; clean energy option.
  • Wind Power: Mechanical generation via turbines (onshore or offshore).
  • Geothermal: Energy from the Earth's internal heat.
  • Other options: Biofuel, natural gas, and hydroelectricity.
  • Nuclear Power: Considered "alternative" because it does not use fossil fuels (it splits the nucleus of atoms like uranium), but it is not generally classified as "clean" due to potential environmental impacts.

• Technology and Geoengineering:

  • Carbon Dioxide Removal (CDR): Technologies focused on stripping $CO_2$ from the atmosphere.
  • Solar Radiation Management (SRM): Technologies designed to reflect a portion of solar energy away from Earth before it is trapped.
  • Genetic Engineering: Developing plant varieties that can survive in drought and higher temperatures.

• Barriers to Implementation: These include significant funding requirements, public acceptance of large-scale changes, and the higher cost of adapting to "climate safe" technologies compared to traditional sources.

Questions & Discussion

• Question 1: Which of the following levels of biological organization represents the sum of all of the locations where life may be found on the planet?
  • Answer: a. The biosphere.
• Question 2: The average temperature and precipitation of an area are referred to as its:
  • Answer: a. climate.
• Question 3: Which of the following are considered to be greenhouse gases? (Select all that apply)
  • Answer: a. Carbon dioxide, c. Methane, d. Water vapor.
• Question 4: The major sources of this greenhouse gas are agriculture and the decay of organic material.
  • Answer: a. Methane.
• Question 5: The production of carbonic acid occurs as a result of increased carbon dioxide concentrations in which of the following?
  • Answer: a. Oceans.
• Question 6: Which of the following is not directly associated with an increase in global temperatures?
  • Answer: c. Increases in the frequency of tornadoes.
• Question 7: Which of the following carbon reservoirs do members of the biosphere exchange carbon with regularly?
  • Answer: d. All of the above (Oceans, Atmosphere, Fossil fuels below ground).
• Question 8: Which of the following statements are correct regarding the element carbon? (Select all that apply)
  • Answer: a. It is involved in the formation of organic molecules, b. It forms long chains called hydrocarbons, d. It is absorbed from the atmosphere via the process of photosynthesis in plants.
• Question 9: In which of the following processes does atmospheric carbon get combined with energy to form carbohydrates?
  • Answer: a. Calvin cycle.
• Question 10: In the carbon cycle, where does atmospheric carbon dioxide get combined with energy to form carbohydrates?
  • Answer: c. Chloroplasts.
• Question 11: Which of the following is required for the formation of a fossil fuel? (Select all that apply)
  • Answer: b. Organic remains of plants and animals, d. High temperatures.
• Question 12: Mosquitoes and ticks are called vectors because they have the ability to transmit a disease between individuals.
  • Answer: a. True.
• Question 13: Climate change has already caused which of the following at the individual and species levels? (Select all that apply)
  • Answer: a. Increased extinction rates, c. Increased exposure to diseases from mosquito vectors.
• Question 14: Invasive species:
  • Answer: d. All of the above (may be introduced accidentally by humans, disrupt local biological communities, can adapt to changing environmental conditions).
• Question 15: Refer to the biome graph. An increase in the temperature of a grassland, with no change in the precipitation patterns, would result in it changing into which type of biome?
  • Answer: c. Savanna.
• Question 16: Evidence suggests that currently the climate of the United States is stable, and will not change until the year 2050.
  • Answer: b. False.
• Question 17: Which of the following contribute to your individual carbon footprint? (Select all that apply)
  • Answer: a. Transportation choices, b. Energy choices, c. Recycling options, d. Food choices.
• Question 18: With regard to food choices, a diet that contains more locally grown vegetables would do what to your carbon footprint?
  • Answer: a. Reduce your overall footprint.
• Question 19: Which of the following sources of alternative energy have the ability to be used almost anywhere on the planet? (Select all that apply)
  • Answer: b. Wind, d. Solar.
• Question 20: Which of the following is not considered to be a clean form of alternative energy?
  • Answer: b. Nuclear power.
• Question 21: Which of the following forms of geoengineering proposes increasing the reflectivity of the planet so that more solar radiation is reflected back into space?
  • Answer: b. SRM.
• Question 22: The consequences of global climate change may be completely eliminated solely through the development of new technologies.
  • Answer: b. False.