Global climate change: There are several potential effects of global climate change.

The idea

Global climate change is the long-term shift in average weather patterns across the Earth, driven mainly by increased greenhouse gases such as carbon dioxide and methane. Its potential effects are varied and interconnected. Rising global temperatures melt ice sheets and glaciers, adding water to oceans, while warmer water expands, so sea levels rise and low-lying coasts flood. Weather may become more extreme: heatwaves, droughts, storms and heavy rainfall occur more often. Habitats shift, so some species move towards the poles or to higher ground, while others cannot and face extinction. Crop yields may fall where drought and heat stress plants, threatening food security. Human health is affected by heat stress and changing ranges of disease-carrying insects. These effects are potential because their size and timing depend on future emissions and on how natural systems respond.

What earns the marks

• Identify that global climate change is a long-term change in average weather patterns, not a single weather event.
• Describe at least two distinct effects, such as sea level rise from melting ice and thermal expansion of seawater.
• Explain how one effect links to a cause, for example higher temperatures melting ice sheets and glaciers.
• Recognise that effects are potential and depend on future greenhouse gas emissions and natural feedbacks.
• Give a consequence for living organisms, such as habitat loss, changed species distribution or reduced crop yield.
• Use correct terms such as greenhouse gas, sea level, habitat and extinction.

Common mistakes and how to put them right

• Confusing weather with climate.

  Put it right: Climate is the long-term average, so judge trends over decades.

• Thinking only polar bears are affected.

  Put it right: Describe wider impacts on habitats, food production and human health.

• Stating that sea level rise is only from melting ice.

  Put it right: Thermal expansion of warmer water also raises sea level.

Exam tips

• Read the command word: 'describe' needs effects, while 'explain' needs a cause-and-effect link.
• Use named examples, such as melting of polar ice or drought reducing crop growth, to make answers concrete.
• Link each effect back to a cause, such as increased greenhouse gases trapping more energy.