Climate Types (HL) (DP IB Environmental Systems & Societies (ESS)): Revision Note

Climate Types

Tropical, temperate and polar climate types

• There are three general patterns of climate types that relate to specific biome types

• These general climate types are:

  • Tropical

  • Temperate

  • Polar

• Each type has distinct characteristics based on temperature and rainfall

Tropical climate types

• Tropical climates:

  • Closer to the equator

  • Between the Tropics of Cancer and Capricorn

  • High temperatures and rainfall

  • Most regions have two seasons (wet and dry)

• Tropical climates can be further divided into two subtypes:

  • Seasonal

  • Equatorial

• Seasonal tropical climates:

  • Distinct wet and dry seasons

  • During the wet season, rainfall is abundant (averaging more than 1000 mm per year)

  • Support savannas, which are grasslands scattered with trees

  • Examples:

    • Forests of the Congo in Africa

    • Central American tropical forests in Panama and Nicaragua

    • Seasonal forests on the Indian subcontinent, Indochina, and in northern Australia (Queensland)

• Equatorial tropical climates:

  • High temperatures and high humidity year-round

  • Consistent rainfall (monthly precipitation greater than 60 mm, annual precipitation greater than 2000 mm)

  • Support tropical rainforests, which are rich in biodiversity and contain dense vegetation

  • Examples:

    • Amazon rainforest

    • Southeast Asian rainforest

• The main biomes found in tropical climates include tropical rainforests and savannas, each adapted to their specific seasonal patterns

Temperate climate types

• Temperate climates:

  • Moderate mean annual temperatures (average temperature greater than 10° C in warmest months and greater than -3° C in coldest months)

  • Most regions have four seasons

• Temperate climates can be further divided into two subtypes:

  • Maritime

  • Continental

• Maritime temperate climates:

  • Influenced by large bodies of water, leading to mild, wet winters and cool, dry summers

    • Often linked to weather patterns caused by prevailing winds

    • Oceans store heat energy, which moderates temperate regions near the sea (giving more consistent temperatures)

  • Often found on the western coast of continents (the prevailing winds bring in wetter weather at certain times of the year)

  • Receive consistent rainfall throughout the year

  • Support temperate forests with diverse tree species

  • Examples:

    • Western Europe: countries like the UK, Ireland, and the coastal areas of France, Spain, and Portugal experience a maritime climate due to the Atlantic Ocean's influence

    • Pacific Northwest (North America): The Pacific Ocean has an impact on Canada's coastal regions of Washington, Oregon, and British Columbia, resulting in mild, wet winters and cool summers

• Continental temperate climates:

  • Have greater temperature extremes than maritime temperate climates, with hot summers and cold winters

  • Mostly found in the interior of continents away from the influence of oceans

  • Support grasslands or deciduous forests, which have trees that lose their leaves in winter

  • Examples:

    • Eurasia (mainly Russia)

    • North America (mainly Canada, some areas in northern USA)

• The main biomes found in temperate climates include temperate forests, grasslands, and scrublands

Polar climate types

• Polar climates are characterised by:

  • Very low temperatures (average temperature less than 10° C in all months)

  • Limited precipitation, primarily as snow

  • Often windy

  • Examples:

    • Arctic and Antarctic regions (average temperature less than 0° C in all months)

    • Areas of northern Canada, Russia and Greenland

• These climates support tundra biomes, which have short growing seasons and vegetation that includes mosses, lichens, and low shrubs

• Polar regions often have ice caps and glaciers, with very few organisms able to survive the extreme conditions

Influences on biomes

• The biome predicted by any given temperature and rainfall pattern may not develop in an area due to:

  • Secondary influences

  • Human interventions

• Secondary influences are factors that affect the development of a biome beyond just temperature and rainfall

• These can include:

  • Soil quality: Poor soil may limit plant growth, even in areas with suitable climate

  • Topography: Mountains, valleys, or slopes can alter water drainage, sunlight exposure, and temperature, impacting local ecosystems

  • Fire and natural disturbances: Frequent fires or storms can change the types of vegetation and animals in an area

• Human activities such as urban development, agriculture, and deforestation can prevent natural biomes from forming. For example:

  • A region that would naturally develop into a temperate forest may instead become a city or agricultural land

  • Agricultural practices can change the natural vegetation and soil quality, further impacting the local biome

  • Urban development alters local climate conditions, leading to a phenomenon known as the urban heat island effect, with:

    • increased temperatures

    • changes in rainfall patterns

• All these influences can prevent the expected biome from developing in a given climate zone