Impact on biodiversity, biomedicines and the global food supply

Introduction: Why This Matters

Hi there! Welcome to one of the most important chapters in your H2 Biology journey. While climate change often feels like a "Geography" topic, it is actually a massive biological crisis. Why? Because every living thing—from the rice on your plate to the rare orchid in the rainforest—is a finely tuned machine that functions best within a specific temperature range. In these notes, we will explore how shifting temperatures and extreme weather don't just "change the weather"; they threaten our food security, our medical future, and the complex web of life that keeps our planet running. Don't worry if this seems like a lot to take in; we'll break it down piece by piece!

1. Impact on the Global Food Supply

When we talk about the global food supply, we are looking at how climate change creates environmental stress that makes it harder to produce enough food for everyone. This stress comes in two main forms: increased temperatures and extreme weather events (like droughts and floods).

How Heat Stress Affects Plants (Crops)

Think of a plant as a factory. This factory uses enzymes to turn sunlight and CO2 into food. As you learned in the "Energy and Equilibrium" core idea, enzymes have an optimum temperature.
- Enzyme Denaturation: If it gets too hot, essential enzymes for photosynthesis (like Rubisco) can lose their shape and function.
- Increased Photorespiration: In C3 plants (like rice and wheat), high heat causes Rubisco to grab oxygen instead of carbon dioxide, wasting energy and reducing crop yield.
- Water Loss: High heat increases the rate of transpiration. If the plant loses water faster than it can drink, it wilts and dies.

How Heat Stress Affects Animals (Livestock and Fisheries)

- Metabolic Stress: Livestock like cows and chickens use more energy just to stay cool, meaning they have less energy for growth or producing milk/eggs.
- Migration of Fishes: As oceans warm, many fish species migrate toward the poles to find cooler water. This leaves tropical regions with fewer fish to catch, disrupting the local food supply.

The "Double Whammy" of Extreme Weather

It's not just about the heat. Extreme weather events like floods can drown crops and wash away fertile topsoil, while prolonged droughts can turn productive farmland into dust. This makes the food supply unstable and unsustainable.

Quick Review Box: Food Supply
1. Temperature: Directly reduces crop yield via enzyme efficiency.
2. Water: Stress from drought/flood kills plants and livestock.
3. Sustainability: If we can't predict the weather, we can't reliably grow enough food for the global population.

Key Takeaway: Climate change acts as a "threat multiplier," making it significantly harder to grow crops and raise animals, which leads to food shortages and higher prices.

2. Biodiversity and the Tropical Reservoir

The tropics (where Singapore is!) are biodiversity hotspots. They are like a giant "living library" or "biological bank account." Climate change is currently "burning" this library before we've even read all the books.

Loss of Biomedicines

Did you know? Over 25% of all modern medicines were originally derived from plants, many from tropical rainforests.
- Nature's Pharmacy: Plants produce complex chemical compounds to defend themselves against insects or fungi. Humans use these compounds to create biomedicines (e.g., the anti-cancer drug vincristine comes from the Rosy Periwinkle).
- The Risk: As climate change causes species to go extinct, we lose the chance to discover new cures for diseases like cancer, Alzheimer's, or future pandemics.

Loss of Genetic Diversity for Food

Most of the food we eat comes from just a few species (like corn, rice, and potatoes). However, their wild relatives in the tropics hold a secret weapon: genetic diversity.
- The "Backup Drive" Analogy: Imagine if a new disease wipes out all the rice in the world. Scientists look for "wild rice" that might have a gene for disease resistance.
- Climate Resilience: We need these wild genes to breed new crop varieties that can survive in saltier soil or hotter weather. If climate change destroys these wild habitats, we lose our "backup files" for the world's food system.

Common Mistake to Avoid: Students often think "biodiversity" just means "lots of animals." Remember to mention genetic diversity within species, which is crucial for breeding resilient crops!

Key Takeaway: Tropical biodiversity is a "rich reservoir" for both future medicines and the genetic materials needed to keep our crops healthy in a changing world.

3. Stress on Habitats, Food Chains, and Niches

Climate change doesn't just hurt individuals; it breaks the connections between them. Every organism has a niche—which is like its "job" or "role" in the environment (where it lives, what it eats, when it sleeps).

Disrupting Food Chains

In a healthy food chain, everything is timed perfectly.
- Example: A bird might time its egg-laying so that the chicks hatch exactly when caterpillars (their food) are most abundant.
- Phenological Mismatch: Phenology is the study of the timing of biological events. If a warm spring causes caterpillars to emerge 2 weeks early, but the birds still hatch at the usual time, the chicks will starve. This disrupts the food chain and can lead to population crashes.

Niche Occupation and Competition

As habitats change, organisms are forced to move or change their behavior.
- Habitat Loss: Polar bears lose sea ice for hunting; corals lose their symbiotic algae (bleaching) when water gets too warm.
- Shifting Niches: Species from warmer areas might move into cooler areas, out-competing the local species for space or food. This changes which species "occupy" certain niches in the ecosystem.

Analogy: Musical Chairs
Think of an ecosystem like a game of musical chairs. Climate change is moving the chairs (habitats) and changing the speed of the music (timing). Some players (species) can't keep up and are "out" (extinct).

Key Takeaway: Environmental stress forces species to migrate or change their timing, leading to "mismatches" in food chains and loss of specialized niches.

Summary: Putting it All Together

If you're feeling a bit overwhelmed, just remember these three pillars of impact:
1. Food Supply: Higher temps and crazy weather = less food and more stress for farmers.
2. The "Reservoir": Losing tropical species means losing future biomedicines and the genetic diversity needed to "fix" our crops.
3. Ecological Balance: Disrupted food chains and niche occupation mean ecosystems might stop working the way we need them to.

Final Tip for the Exam: When answering questions, always try to link the environmental change (e.g., increased temperature) to a biological process (e.g., enzyme denaturation, transpiration, or phenological mismatch). This shows the examiners you are thinking like a true H2 Biologist!