How Climate Change Affects Species

• Enzyme Activity and Temperature: Biological reactions are governed by enzymes that have specific optimum temperatures. Increasing ambient heat initially raises kinetic energy, leading to more frequent successful collisions between substrates and active sites, thereby accelerating metabolic rates.

• Thermal Denaturation: Beyond the optimum temperature, the excessive kinetic energy breaks the weak hydrogen and ionic bonds maintaining the enzyme's tertiary structure. This leads to denaturation, where the active site loses its complementary shape, effectively halting essential metabolic processes like photosynthesis or development.

• The Temperature Coefficient ($Q_{10}$): This value represents the factor by which a reaction rate increases when temperature is raised by $10^\circ C$. It is calculated as:

$Q_{10} = \frac{\text{Rate at } (T + 10)^\circ C}{\text{Rate at } T^\circ C}$

• Impact on Development: Fluctuating temperatures can alter hatching rates in invertebrates and even determine the sex ratios in certain reptiles, such as alligators, where incubation temperature dictates the gender of offspring.

• Retreat of Polar Ice and Glaciers: Rising temperatures lead to the rapid melting of Arctic summer ice and mountain glaciers. This loss of physical structure directly destroys the habitats of ice-dependent species and threatens the seasonal water supplies of ecosystems downstream.

• Sea Level Elevation: Global sea levels are rising due to two primary factors: the thermal expansion of warming ocean water and the addition of water from melting land-based ice (glaciers). This results in the flooding of coastal habitats and the salinization of freshwater ecosystems.

• Distinguish Mechanisms: Always distinguish between the greenhouse effect (the mechanism), global warming (the rise in temperature), and climate change (the long-term shift in weather patterns). Examiners often penalize the interchangeable use of these terms in technical explanations.

• Verify Rate vs. Total: When analyzing $Q_{10}$ data, check if the question provides the rate of reaction or the total volume produced. If given the time taken for a reaction, remember that $\text{Rate} = \frac{1}{\text{time}}$.

• Connect to Selection Pressures: When discussing species movement, frame it as a response to a changing selection pressure. Use the terminology of natural selection to explain why certain alleles become advantageous in new climates.

• Data Interpretation: If provided with a graph showing correlation, explicitly state that "correlation does not equal causation" unless further evidence of a biological mechanism is provided.