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IB DP ESS — Topic 6: Atmosphere and Climate Change | SL & HL | Paper 1 & Paper 2A/2B
🎯 Learning Intentions By the end of this note, you will be able to:
- Define climate change, climate feedback, and tipping point using IB-aligned ESS terminology.
- Explain how rising global temperatures drive changes in ocean systems, cryosphere, and terrestrial biomes at local, regional, and global scales.
- Describe the ecological, social, and economic impacts of climate change on human and natural systems, including food security, sea-level rise, and species range shifts.
- Analyse positive and negative feedback loops that amplify or dampen climate change, using named examples such as the ice-albedo feedback and permafrost methane release.
- Evaluate the differential vulnerability of LEDCs and MEDCs to climate change impacts, considering equity, adaptive capacity, and historical emissions responsibility.
- Discuss contrasting worldviews — ecocentric, technocentric, and anthropocentric — in relation to climate change impacts and the urgency of response.
- Predict how continued greenhouse gas emissions will alter ecosystem services, biodiversity, and human well-being under different IPCC emissions scenarios.
Real-World Context & Relevance
In the summer of 2023, global average surface temperatures exceeded the 1.5 °C warming threshold above pre-industrial levels for the first time on record — a milestone the Paris Agreement had set as a critical guardrail. That same year, the Mediterranean experienced its most destructive wildfire season in decades, with over 96,000 hectares burning in Greece alone. Sea surface temperatures in the North Atlantic reached unprecedented highs, and Antarctica recorded its lowest winter sea-ice extent since satellite monitoring began. These were not isolated anomalies; they were the compounding, interconnected signatures of a climate system under sustained anthropogenic pressure.
The impacts of climate change are not uniformly distributed. In Bangladesh — a low-lying delta nation responsible for less than 0.5% of cumulative global CO₂ emissions — an estimated 17% of land area is projected to be submerged under 1 metre of sea-level rise, displacing tens of millions of people. Meanwhile, in the Arctic, Indigenous Inuit communities are losing the sea ice that has structured their livelihoods, food systems, and cultural identity for millennia. The contrast between those who have contributed most to the problem and those who bear its greatest costs defines one of the central justice dimensions of climate change — and one of the most important analytical lenses in ESS.
🌍 Why This Matters Climate change is not a future threat — it is a present-tense disruption of Earth's interconnected systems. Understanding its impacts requires systems thinking: recognising that a warming atmosphere triggers cascading changes in oceans, ice, ecosystems, food systems, and human societies simultaneously. ESS students must be able to trace these cascades, evaluate their differential effects, and assess the adequacy of human responses.
Core Concepts & Definitions
Before examining specific impacts, it is worth establishing what we mean when we say the climate is "changing" in a way that matters to environmental systems. The atmosphere has always varied — glacial and interglacial cycles have shifted global temperatures by 4–7 °C over tens of thousands of years. What distinguishes the current period is the rate of change: the IPCC Sixth Assessment Report (AR6, 2021) concluded that global surface temperature has increased by approximately 1.1 °C since the pre-industrial period (1850–1900), and that this rate of warming is "unprecedented in at least the last 2000 years." It is this rate — not merely the magnitude — that overwhelms the adaptive capacity of ecosystems and human societies.
📖 Key Definition — Climate Change Climate change refers to long-term shifts in global or regional climate patterns, including changes in temperature, precipitation, wind patterns, and extreme weather events. In contemporary usage, it specifically refers to changes attributed primarily to human activities —