Extreme weather case studies (WJEC Eduqas GCSE Geography B): Revision Note

Specification links

The notes on this page cover part 2.3.4 of the WJEC Eduqas B specification

2.3.4 - What are the causes, impacts and responses to two contrasting extreme weather events?

• A detailed study of two contrasting extreme weather events located outside of the UK.

• One event must relate to a dominant, long-lasting high-pressure system.

• One event must relate to an intense low-pressure system.

• For each event, coverage must include:

  • Causes

  • Impacts on different groups of people

  • Responses

High-pressure weather event: 2021 North America heat dome

• The 2021 Western North America heat dome was a record-breaking heatwave from late June to early July

  • It brought extreme temperatures to the Pacific Northwest of the U.S. and western Canada

• Many locations broke all-time maximum temperature records, with some exceeding previous records by more than 5 °C

• The Canadian national temperature record was broken by a new record of

  49.6° C in Lytton, British Columbia

Causes

• A powerful and persistent area of high pressure, known as a 'heat dome', settled over Western North America (including British Columbia, Canada, and the US Pacific Northwest) in late June 2021

• The high-pressure system blocked the flow of cooler, wetter air from the Pacific Ocean, trapping scorching hot air below

• Within the high-pressure system, air fell, warmed, and dried out, creating stable weather and clear skies, which made the sun's warming effect stronger

• Scientists think that the event was made worse by human-caused climate change, which amplified factors such as meanders in the jet stream

AWAITING IMAGE

Heat dome over North America in June 2021

Impacts on different groups of people

• The heat dome resulted in record-breaking temperatures (e.g., 49.6°C in Lytton, B.C.), leading to severe consequences: 

  • Vulnerable individuals suffered heat-related deaths, particularly the elderly and those with pre-existing health conditions who were less able to cope with the heat, especially if they lacked air conditioning

    • The heatwave caused over 1,400 deaths across the affected regions, including hundreds in Washington and Oregon

    • Over 600 sudden deaths were reported in British Columbia alone

  • Hospitals and emergency services were overwhelmed by heatstroke victims and fire-related emergencies

    • The high temperatures strained infrastructure, with some power systems failing due to increased demand for cooling

    • Some COVID-19 vaccination centres were forced to close or relocate temporarily

  • Infrastructure suffered as the extreme heat caused buckling roads, melting power lines, and cracking windows

    • The intense dry heat also led to devastating wildfires; the most serious one burnt down the town of Lytton, displacing hundreds of residents and destroying property 

  • The intense heat and dryness contributed to widespread wildfires, which caused significant environmental damage

    • Crops failed and livestock died due to the heat and lack of water, causing financial losses and impacting food security 

Responses

• British Columbia's government declared a state of emergency to help coordinate the response

• People were warned about the dangers of heat and given tips on how to stay cool and drink water through large public health campaigns

• People without air conditioning could go to temporary cooling centres set up in public buildings

• To keep rail lines from buckling, transport services like trains had to go slower

  To fight the widespread wildfires, firefighting equipment was shared between the US and Canada

Low-pressure weather event: Cyclone Idai

• Cyclone Idai's formation and intensification were driven by several meteorological factors 

• The storm developed in the Mozambique Channel

  • Sea surface temperatures were above average, providing the substantial energy needed for intensification

• Favourable upper-level atmospheric conditions, including low wind shear, allowed the storm's vertical structure to remain intact and strengthen

• After initially making landfall as a tropical depression, the storm looped back over the warm waters of the Mozambique Channel

  • It rapidly intensified into a powerful Category 3-equivalent cyclone before its devastating second landfall near Beira, Mozambique

AWAITING IMAGE

Path of Cyclone Idai

Impacts on different groups of people

• The impacts of Cyclone Idai were widespread and varied among different populations

• Vulnerable populations (e.g. poor, rural communities) were especially affected due to:

  • Living in poorly constructed housing

  • Having limited access to early warning systems

  • Living in flood-prone areas

    • They suffered the highest rates of casualties and displacement

• Women and children faced increased risks of gender-based violence in crowded displacement camps and disruption of maternal and child health services

  • The destruction of schools also impacted children's education

• Farmers and agricultural workers suffered huge crop losses and livestock deaths due to flooding

  • This caused immediate food insecurity and long-term economic hardship, as agriculture is the primary livelihood in the affected regions

• Urban residents were impacted by wind damage, flooding, and the collapse of essential infrastructure, such as water supply systems and sanitation, leading to outbreaks of diseases like cholera

Responses

• Responses to Cyclone Idai occurred at local, national, and international levels

• International organisations like the UN, Red Cross, and various NGOs responded quickly to provide search and rescue operations, emergency food, shelter materials, and medical support

• The governments of Mozambique, Zimbabwe, and Malawi declared national emergencies, coordinating relief efforts and appealed for international assistance

  • Their resources were quickly overwhelmed by the size of the disaster

• In many cases, local communities and civil society organisations were the first to help their neighbours by giving them shelter, food, and emotional support

• After the immediate crisis, the focus shifted to fixing roads, bridges, schools, hospitals, and other infrastructure, getting people back to work, and putting in place long-term strategies to make the area more resilient to future climate events