Managing Climate Change

• In the UK, electricity from renewable sources often reaches 40–50% daily, with wind power accounting for about 40% of this total.
• Nuclear power provides a reliable "base load" of electricity and emits zero $CO_2$ during production, but carries radiation risks and high decommissioning costs.
• The transition to alternative energy is currently dominated by High-Income Countries (HICs). Many Newly Emerging Economies (NEEs), such as India (79% coal) and China (69% coal), still rely heavily on fossil fuels for rapid industrialisation.

Evaluating Alternative Energy:

• Pros: Switching to solar, wind, or nuclear eliminates greenhouse gas emissions during energy generation, directly addressing the root cause of global warming.
• Cons: Renewable sources like solar and wind are geographically constrained and intermittent (weather-dependent). Without massive battery storage, they cannot independently provide 100% of energy demand.
• Overall Judgement: While alternative energy is the most effective long-term global solution to address the root cause of climate change, high costs and intermittent supply mean a complete transition requires significant advancements in battery storage and international cooperation.

Mitigation: Carbon Capture and Storage (CCS)

Can we continue using fossil fuels without releasing greenhouse gases? Carbon Capture and Storage (CCS) is a technological strategy that involves catching carbon dioxide emissions from point sources like power plants before they reach the atmosphere.

• Capture: Up to 90% of $CO_2$ emissions are separated from waste gases.
• Transport & Storage: The $CO_2$ is compressed into a dense liquid and piped underground into geological formations, such as depleted oil fields or saline aquifers.
• The UK's Captain Sandstone formation has the capacity to store all $CO_2$ from UK gas plants for the next 100 years.
• Carbon Sequestration is the broader term for capturing and storing atmospheric $CO_2$, whether artificial (like CCS) or natural.

Evaluating CCS:

• Pros: Allows for the continued use of reliable fossil fuels during the transition to renewables and reduces emissions from "hard-to-abate" industries like cement works.
• Cons: CCS machinery has a massive "energy penalty", requiring 10% to 40% of a power station's total energy just to run. It is also extremely expensive, and there is a risk of underground $CO_2$ leaks contaminating groundwater.
• Overall Judgement: CCS is technologically feasible and crucial for maintaining base-load power during the green transition, but its extreme economic cost and massive energy penalty currently limit its widespread global viability.

Mitigation: Planting Trees (Afforestation)

A growing forest absorbs carbon rapidly, but an old, mature forest eventually reaches a steady state where it stops being a net carbon sink. Afforestation is the process of planting trees in an area with no previous forest cover to create a Carbon Sink (a natural reservoir that stores carbon).

• Trees remove $CO_2$ from the atmosphere through photosynthesis, converting it into biomass.
• The UK aims to plant 30,000 hectares of new woodland annually until 2050 to help offset emissions.

Evaluating Afforestation:

• Pros: It is relatively cheap compared to CCS and provides vital secondary environmental benefits, such as increasing biodiversity and reducing soil erosion.
• Cons: It faces high competition for land use against agriculture and housing. Furthermore, the stored carbon is released back into the atmosphere if the trees are destroyed by wildfires or disease.
• Overall Judgement: Afforestation is a highly cost-effective strategy with excellent secondary environmental benefits, but its overall global impact is ultimately restricted by intense competition for land use and the slow growth rate of trees.

Mitigation: International Agreements

You can reduce your own carbon footprint, but tackling a global issue requires every country to pull in the same direction. Global treaties aim to reach Net Zero, a state in which the greenhouse gases going into the atmosphere are balanced by removal out of the atmosphere.

$$Total\ Emissions - Total\ Sequestration = 0$$

• The Paris Agreement (2015): Signed by 195 parties, this legally binding treaty aims to limit global warming to well below 2°C (preferably 1.5°C). Countries submit updated emissions targets every 5 years.
• Developed nations pledged US$100 billion a year to support climate mitigation in developing countries.
• COP26 (2021): Focused heavily on reaching Net Zero by 2050, requiring global emissions to fall by 45% from 2010 levels by 2030.

To calculate a country's percentage reduction in emissions, use this formula:

$$\frac{Change}{Original} \times 100 = Percentage\ Reduction$$

(Example: If the UK reduced emissions from 600m tonnes to 450m tonnes, the change is 150m. $150 / 600 \times 100 = 25\%$ reduction.)

Evaluating International Agreements:

• Pros: They are the only viable way to tackle a transboundary problem, facilitating wealth and technology transfers to poorer nations.
• Cons: Pledges are often voluntary and lack strict enforcement mechanisms. National economic priorities frequently override environmental commitments (e.g., the USA temporarily withdrawing in 2020).
• Overall Judgement: Global treaties are fundamentally essential to tackling the transboundary nature of climate change, but their overall success is severely undermined by a lack of strict enforcement and the tendency of nations to prioritize short-term economic growth over environmental targets.

Adaptation: Changing Agricultural Systems

Imagine trying to grow crops when your fields are flooded for weeks at a time. As weather patterns shift, farmers must change their methods to maintain food security.

• Crop Relocation: Warming temperatures allow new crops like grapes to be grown in southern England, though traditional crops face failure in hotter regions like southern Europe.
• Biotechnology: This involves using biological processes to genetically modify crops. Examples include Siri M82 (drought-tolerant wheat) and Scuba Rice (survives being submerged in floods for two weeks).
• Irrigation & Agroforestry: Drip irrigation reduces water wastage in drought-prone areas like Kenya. Agroforestry (combining crops with trees) provides vital shade and soil stability.

Evaluating Agricultural Adaptation:

• Pros: HICs can invest in advanced tech like vertical farming (e.g., Almeria, Spain) to completely decouple food production from the local climate, greatly increasing resilience.
• Cons: Biotechnology creates economic barriers; GM seeds are heavily patented and often too expensive for small-scale farmers in Low-Income Countries (LICs).
• Overall Judgement: While highly successful in HICs capable of funding advanced technologies, the high economic barriers of biotechnology leave vulnerable populations in LICs exposed, highlighting severe global inequalities in climate adaptation.

Adaptation: Managing Water Supply

Understanding how to manage water is critical because water stress occurs the moment a person has less than 1700m³ of clean water a year. Water Security means having a reliable, clean, and affordable source of water for an entire population.

• Reducing Demand: London aims to retrofit homes with free water-efficient appliances (dual-flush toilets) by 2030 and encourages greywater recycling.
• Increasing Supply: Desalination is the process of removing salt from seawater to make it drinkable. The Beckton Desalination Plant in London produces 140 million litres of water a day.
• In Ladakh, India, communities build small-scale "artificial glaciers" to store winter meltwater for spring irrigation.

Evaluating Water Supply Strategies:

• Large-scale (Desalination): Provides immense, reliable water security independent of drought. However, it requires huge amounts of energy, generating a massive carbon footprint, and produces toxic brine waste.
• Small-scale (Artificial Glaciers): Cheap, sustainable, and easily managed by locals, but limited in capacity and vulnerable to long-term glacial retreat.
• Overall Judgement: Large-scale infrastructure provides immediate water security but at a high environmental cost, whereas small-scale solutions are sustainable but struggle to meet growing urban demands. A truly effective approach requires a combination of both strategies tailored to regional needs.

Adaptation: Coping with Rising Sea Levels

How do you protect a country where 80% of the land is less than one metre above the sea? Global sea levels have risen 20 cm since 1900 and are projected to rise up to 82 cm by 2100 due to thermal expansion and melting ice caps.

• Hard Engineering (Maldives & UK): The Maldives built a 3m high sea wall around its capital, Malé. London relies on the Thames Barrier, though the TE2100 plan prepares for future upgrades as breach risks increase.
• Soft Engineering: Building homes on stilts and restoring mangrove forests to trap sediment and absorb wave energy.
• Managed Retreat: This strategy abandons existing coastal defences, allowing the sea to flood low-lying land to create natural buffer zones. At Medmerry, West Sussex, £28 million was spent to create 180 hectares of protective salt marsh.

Evaluating Sea Level Strategies:

• Sea Walls: Highly effective at protecting valuable infrastructure, but extremely expensive (up to £5,000 per metre) and can worsen erosion further along the coast.
• Managed Retreat: Cheaper than hard engineering and creates biodiverse wetland habitats. However, it results in the traumatic loss of homes and productive farmland, often causing significant social distress.
• Overall Judgement: Hard engineering provides essential short-term protection for high-value coastal infrastructure, but its exorbitant costs mean sustainable long-term management must increasingly incorporate managed retreat, despite the severe social disruption it causes.