Complete Notes on Hazardous Earth for Edexcel B Geography GCSE

Global Atmospheric Circulation and Climate Patterns

Think of Earth's atmosphere like a giant conveyor belt system that moves air around the planet. Winds form because air naturally flows from high pressure areas to low pressure areas, creating predictable patterns that drive our weather.

The atmosphere works through three circulation cells in each hemisphere: Hadley, Ferrel, and Polar cells. Here's how it works: the Sun heats air at the equator, making it rise and create low pressure. This warm air cools as it moves away from the equator, then sinks at 30° north and south, forming high pressure belts where you'll find many of the world's deserts.

Trade winds blow from these 30° zones back toward the equator, whilst westerlies blow from 30° toward the poles. Understanding this system helps explain why certain regions have consistent weather patterns and why storms move in predictable directions.

Climate has always changed naturally. During the Quaternary period (the last 2.6 million years), Earth cycled between cold glacial periods lasting 100,000 years and warmer interglacial periods lasting 8,000-12,000 years. However, in just the last 200 years, temperatures have risen 0.8°C - that's incredibly fast in geological terms.

Key Point: The greenhouse effect occurs when greenhouse gases absorb long-wave radiation reflected from Earth's surface and re-radiate it back, trapping heat in our atmosphere.

Evidence for Climate Change and UK's Climate History

Scientists use clever methods to understand past climates. Ice cores act like frozen history books - each annual layer of ice contains gases that reveal ancient temperatures and atmospheric conditions stretching back thousands of years. Tree rings work similarly; thick rings indicate warm, wet growing seasons whilst thin rings show harsh conditions.

The UK has experienced dramatic climate shifts throughout history. During the Medieval Warm Period $950-1100 AD$, temperatures were 1-2°C warmer than in 2000, likely due to increased solar radiation. Conversely, the Little Ice Age $1600-1685 AD$ brought temperatures 1°C cooler, causing harsh winters and cool summers that affected agriculture and daily life.

Natural climate change happens through several mechanisms. Volcanic eruptions blast particles into the atmosphere that reflect sunlight away from Earth, cooling temperatures whilst also releasing CO₂. Earth's orbit changes from circular to elliptical over 96,000-year cycles, affecting how much solar radiation we receive.

Human factors now dominate climate change. Fossil fuels release massive amounts of greenhouse gases when burned for energy and transport. Deforestation removes trees that naturally absorb CO₂. Even agriculture contributes - cows produce methane through digestion, and rice paddies emit methane as organic matter decomposes underwater.

Key Point: Human activities now release greenhouse gases much faster than natural processes can absorb them, causing rapid warming.

Impacts of Global Warming

Climate change is already transforming our planet in measurable ways. Arctic sea ice shrinks by 13% per decade, and global sea levels rose 16-21 cm between 1900 and 2016. These aren't distant future problems - they're happening now.

Environmental impacts include more frequent heatwaves and extreme weather events since 1950. Rising sea surface temperatures cause coral bleaching and fuel stronger, more frequent cyclones. Species distributions are shifting as animals and plants struggle to adapt to rapidly changing conditions, with those unable to evolve quickly enough facing extinction.

Social impacts affect human communities directly. Coastal flooding from sea level rise forces people to migrate, potentially creating overcrowded areas and resource conflicts. Changing precipitation patterns and higher temperatures reduce crop yields in many regions, threatening food security.

Water availability becomes critical as hotter temperatures increase drought frequency. This could spark conflicts between nations competing for clean water resources. More heat-related deaths occur during extreme weather events, which also cause significant financial damage to communities.

The speed of current climate change is the real problem. Whilst species and ecosystems can adapt to gradual changes over thousands of years, the rapid pace of human-caused warming leaves little time for natural adaptation.

Key Point: Climate change impacts are interconnected - environmental changes directly affect human society through food, water, and housing security.