2.2.3 Climate change and the biosphere

News article

‘The worst time for wheat’: US farmers face losses to extreme heat and drought

Temperature swings have left crops across the Plains in terrible conditions, with some farmers opting not to harvest

The Guardian · 8 May 2026

Key terms

• Animal migration
  • The seasonal or periodic movement of animals between regions or habitats, usually in response to changes in temperature, food availability or breeding needs. Changing climatic conditions can shift the timing, distance and geographical range of these movements.

• Biome
  • A biogeographical unit consisting of a biological community that has formed in response to the physical environment in which it is found and a shared regional climate. Biomes may span more than one continent. Biome is a broader term than habitat and can comprise a variety of habitats.

• Biosphere
  • The zone of the Earth occupied by living organisms, comprising the global sum of all ecosystems. It spans the parts of the lithosphere, hydrosphere and atmosphere in which life exists and interacts with each of them.

• Crop yields
  • A measurement of the amount of a crop grown, or product such as wool, meat or milk produced, per unit area of land.

• Ecosystem
  • A community of living organisms (biotic components) interacting with each other and with their physical environment (abiotic components), linked together through nutrient cycles and energy flows.

• Habitat
  • The natural environment in which a particular species lives, providing the resources and the physical and biotic conditions it needs to survive and reproduce.

• Limits of cultivation
  • The geographical boundary beyond which crops cannot be grown productively, determined by environmental conditions such as temperature, water availability, growing season, altitude and latitude.

• Permafrost
  • Soil and rock where temperatures below 0°C persist over at least two consecutive winters and the intervening summer.

• Soil erosion
  • The wearing away of the upper layer of soil (topsoil) by natural forces such as water and wind, often accelerated by human activities such as ploughing, overgrazing and deforestation.

• Tree line
  • The edge of the habitat at which trees are capable of growing. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions (usually cold temperatures, extreme snowpack, or associated lack of available moisture). The tree line is sometimes distinguished from a lower timberline or forest line, which is the line below which trees form a forest with a closed canopy.