VMBO Year 3 · Sustainable living · Section 7.5

Climate change

Climate and the greenhouse effect

Climate describes the typical weather and its variation in a region over a long period, commonly using at least 30 years of observations. Earth's atmosphere strongly influences it. The atmosphere is mostly nitrogen and oxygen, with smaller amounts of other gases, including carbon dioxide and variable water vapour.

Greenhouse gases, including carbon dioxide, methane and water vapour, absorb and emit infrared radiation. They reduce the rate at which energy escapes to space, keeping Earth's surface warmer than it would otherwise be. This natural greenhouse effect helps make the planet habitable.

The enhanced greenhouse effect

Human activities, particularly fossil-fuel use and changes in agriculture and land use, increase greenhouse-gas concentrations. This strengthens the greenhouse effect and drives global warming. Warming can also increase water vapour in the atmosphere, amplifying the change.

Consequences include:

• Rising global average temperature.
• Melting glaciers and land ice.
• Rising sea levels through melting land ice and the expansion of warming seawater.
• Thawing permafrost, which can release additional greenhouse gases.

Changes in weather patterns

Climate change affects the likelihood and intensity of different extremes, depending on the region.

• Heatwaves become more frequent or intense in many places.
• Some areas experience greater drought and water stress.
• Other areas experience heavier rainfall and increased flood risk.
• Rising sea levels increase coastal flooding risks.

Not every type of storm increases everywhere; effects differ between regions and weather systems.

Effects on organisms and people

Species may shift their ranges or decline where conditions become unsuitable. Seasonal timing also changes: plants may produce leaves or flowers earlier, and animals may alter migration or breeding. Interacting species do not always change at the same rate, creating mismatches. Some disease vectors and pests can expand into new areas, while heatwaves increase health risks and deaths.

Sea level and salinisation

Rising sea levels can push salt water further into coastal groundwater and rivers. This salinisation can reduce the suitability of soils for crops and limit freshwater availability. Drought and water extraction can also contribute.