What is the formal definition of desertification?

Desertification is the degradation of land in arid, semi-arid and dry sub-humid areas resulting from climatic variations and human activities.

How do reduced precipitation totals contribute to desertification?

Lower overall rainfall reduces soil moisture and water availability, limiting vegetation growth and making land more vulnerable to degradation.

Why does increased rainfall variability promote desertification?

Unpredictable rainfall patterns prevent vegetation from establishing reliably, and intense sporadic rainfall can cause erosion on exposed soils.

How do rising temperatures contribute to desertification?

Higher temperatures increase evaporation rates, reduce soil moisture and stress vegetation, accelerating land degradation.

Explain how higher evapotranspiration rates lead to desertification.

Increased evapotranspiration removes water from soils and plants faster than it can be replenished, causing vegetation dieback and soil desiccation.

AQA A-Level Geography 7037

Water and Carbon Cycles

Topic overview Systems, Stores and Flows Mass Balance in Water and Carbon Stores Fieldwork and the Rainforest Case Study Measures of Central Tendency and Dispersion Spearman's Rank, Chi-Square and Data Analysis Scatter Graphs, Triangular Graphs and Logarithmic Scales Atlas, Thematic and Flow-Line Maps OS Maps, Sketch Maps and Field Sketches Remote Sensing, GIS and Big Data Qualitative Data, Questionnaires and Interviews Sampling, Accuracy and Measurement Error Data Misuse and Research Ethics The Global Water Stores Evaporation, Condensation and Cloud Formation Precipitation and Cryospheric Processes The Drainage Basin as an Open System Infiltration and Overland Flow The Water Balance Equation Flood Hydrographs Human Impacts on the Water Cycle The Global Carbon Stores Photosynthesis, Respiration and Carbon Transfer Farming, Land Use and Carbon Sinks Greenhouse Gases and Links between the Cycles Feedback Loops and Climate Change Carbon Sequestration and Mitigation Mass Balance in a Drainage Basin Unit Conversion and Flux Calculations Line Graphs, Bar Graphs and Pie Charts Water and Carbon Cycles in the Tropical Rainforest The Amazon rainforest case study Stores within a River Catchment Transfers and the Controls on Catchment Hydrology The River Eden catchment case study

Hot Desert Systems and LandscapesLandscape

Topic overview Deserts as Systems: Inputs, Stores, Flows and Feedback Desert Climate, Soils and Vegetation The Aridity Index Energy, Sediment and Geomorphic Processes in Deserts Thermal Fracture and Rock Breakdown Deflation, Abrasion and Aeolian Transport Desert Water Sources and Ephemeral Streams Deflation Hollows, Yardangs and Zeugen Barchan and Seif Dunes Wadis, Bahadas and Pediments Playas, Inselbergs and Landscape Development Observation, Measurement and Mapping in Deserts Death Valley hot desert case study The Causes and Definition of Desertification Environmental Impacts of Desertification Human Impacts and Responses to Desertification Desertification on the Yatenga plateau, Burkina Faso

Coastal Systems and LandscapesLandscape

Topic overview Energy Inputs to the Coastal System Coastal Flows and Feedback Waves, Tides and Sediment Cells Marine Erosion and Transport Processes Cliffs, Notches and Wave-Cut Platforms Beaches, Spits and Bars Sand Dune Formation and Succession Estuaries, Mudflats and Saltmarsh Sea Level Change and Coastlines of Submergence Emergent Coastlines and Present Sea Level Rise Hard Engineering at the Coast Soft Engineering and Managed Retreat The Holderness coast case study The Sundarbans and the Ganges–Brahmaputra delta

Glacial Systems and LandscapesLandscape

Topic overview Glaciers as Systems: Inputs, Stores and Flows Ice-Albedo and Negative Feedback Dynamic Equilibrium, Landforms and Landscapes The Glacial Mass Budget and Ice Movement The Distribution of Cold Environments Climate, Soils and Vegetation in Cold Environments Corrie Formation Glacial Troughs and Hanging Valleys Roches Moutonnées, Drumlins and Erratics Moraines, Till and Fluvioglacial Landforms Periglacial Landforms and Processes Thermokarst and Landform Distribution The Fragility of Cold Environments Impacts and Management of Cold Environments Fieldwork Skills in Glaciated Environments Glacial Case Study Requirements Cwm Idwal and the Ogwen valley case study Alaska as a contrasting glaciated landscape

HazardsHazards or ecosystems

Topic overview Natural Hazards: Types, Perception and Responses The Park Model The Hazard Management Cycle The Internal Structure of the Earth Plate Tectonic Theory and Plate Movement Plate Margins and Seismicity Where Vulcanicity Occurs Volcanic Hazards and Eruption Magnitude Volcanic Prediction, Impacts and Responses A Recent Volcanic Event How Earthquakes Happen Seismic Hazards, Distribution and Magnitude Earthquake Prediction, Impacts and Responses Focus, Epicentre and Seismic Vulnerability The 2011 Tōhoku earthquake and tsunami Tropical Storm Formation and Intensification Tropical Storm Hazards, Distribution and Magnitude The Impacts of Tropical Storms Managing Storm Risk in Contrasting Places Typhoon Haiyan and Hurricane Maria compared Wildfires and Vegetation Type Weather Conditions and Wildfire Risk Causes of Ignition Primary, Secondary and Environmental Impacts of Wildfires Social, Economic and Political Impacts of Wildfires Short- and Long-Term Responses to Wildfires Wildfire Preparedness, Prevention and Adaptation The 2018 Camp Fire The Philippines as a multi-hazard environment Living with Vesuvius in the Naples area

Ecosystems Under StressHazards or ecosystems

Topic overview Biodiversity Levels and Causes of Decline Biodiversity Loss and Ecosystem Services Ecosystem Structure, Trophic Levels and Food Webs Ecosystem Inputs, Outputs, Stores and Transfers Biomass, Net Primary Production and Succession Nutrient Cycling, Climate and Soil Environmental Controls and Ecosystem Feedback Biomes and the Tropical Rainforest Environment Rainforest Stratification and Adaptations Savanna Climate, Soils and Adaptations Human Impacts on the Tropical Rainforest Human Impacts on the Savanna Succession and Climatic Climax Temperate Deciduous Woodland Plagioclimax and Heather Moorland Coral Reef Conditions, Services and Stresses Human Pressures and Coral Reef Management The Great Barrier Reef: Extent and Bleaching Crown-of-Thorns Starfish and Reef Tourism Local Ecosystems: Heathland, Parkland, Ponds and Dunes Adaptations to Dry Environments Agriculture, Urbanisation and Invasive Species Ecological Change and Conservation Strategies Sustainability and Stakeholder Conflict Studying Local Ecosystems and Ecological Change The Sefton Coast sand dunes case study Ecological change in Borneo

Global Systems and Global Governance

Changing Places

Topic overview What Place Means Endogenous Factors: Location, Physical and Built Setting Endogenous Factors: Demographic and Economic Exogenous Factors, Relationships and Connections Continuity and Change in Places Local and Contrasting Place Studies Detroit as a contrasting place study Migration, Investment and Cultural Change in Places Policy as an External Force on Place The Legacy of Past Connections Global Networks and Changing Place Characteristics Inequality and Access between Places Lived Experience and Shaping Place Meanings Representing Place and Contested Meanings The Requirements of a Place Study Sources for Place Studies

Contemporary Urban EnvironmentsHuman option

Topic overview Urbanisation and Its Related Processes The Drivers of Urbanisation Deindustrialisation, Decentralisation and Regeneration Policy Megacities and World Cities What Shapes Urban Form Cultural Diversity and Urban Segregation New Urban Landscapes and the Post-Modern City Economic Inequality within Cities Managing Urban Inequality and Diversity Employment Programmes and Top-Down Strategies The Urban Heat Island and Urban Precipitation Urban Winds and Air Quality Impermeable Surfaces and Urban Catchments Urban Hydrographs Sustainable Urban Drainage Systems River Restoration and the Benefits of SUDS Who Delivers River Restoration Cheonggyecheon river restoration in Seoul Sources and Composition of Urban Waste Recycling, Recovery and Waste Disposal Landfill and Incineration Compared Urban Air and Water Pollutants Dereliction and Pollution in Contrasting Cities Managing Urban Pollution and Dereliction The Local Environmental Impact of Cities Dimensions of Urban Sustainability Compact Form, Mixed Use and Liveability Contrasting Urban Case Studies

Population and the EnvironmentHuman option

Topic overview The Physical Environment and Population Global Food Production and Agricultural Systems Tropical Wet and Semi-Arid Climates Zonal Soils: Chernozems and Latosols Soil Erosion and Its Management Waterlogging, Salinisation and Soil Structure The Dimensions of Food Security Studying Climatic Types and Zonal Soils Glasgow: place and health case study Health, Morbidity and the Epidemiological Transition Physical Environment and Disease Malaria: Distribution, Impacts and Management Coronary Heart Disease and Non-Communicable Diseases Global Health Initiatives and Disease Studies The Demographic Transition Model Fertility, Population Structure and the Demographic Dividend Migrant Types and Causes of Migration Push and Pull Factors in Migration The Components of Population Change Optimum Population and Resource Demand Ecological Footprint and Population–Resource Theories Ozone Depletion and Human Health Climate Change, Heatwaves and Vector-Borne Disease Climate Change, Food Supply and Nutrition Global Population Projections Japan's population decline

Resource SecurityHuman option

Topic overview Stock and Flow Resources and Reserves Resource Certainty and Development Stages Resource Frontiers, Peaks and Sustainable Development Environmental Impact Assessment Global Production and Consumption of Energy and Minerals The Geopolitics of Energy, Minerals and Water Water Sources and Demand Water Supply Strategies The Colorado River water supply scheme The Costs of Supply and Managing Demand Water Conflict and Major Supply Schemes Energy Types, Mix and Physical Controls on Supply TNCs, National Interests and Energy Impacts Increasing Energy Supply: Unconventional, Nuclear and Renewable Reducing Energy Demand Environmental Impacts and Sustainability of Energy The Alberta oil sands development Choosing a Mineral Ore Case Study Demand for and Occurrence of Mineral Ores The Environmental Cost of Mineral Extraction The Bingham Canyon copper mine Sustainability in Mineral Supply Alternative Energy Futures Alternative Water Futures Mineral Ore Futures Drivers of Resource Transitions Resource Security and Human Welfare

Hot Desert Systems and Landscapes

The Causes and Definition of Desertification

3 things to know
Component 1

Overview

Recall questions on how desert extent has shifted over 10,000 years, the formal definition, and the rainfall changes that drive it.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

How has the extent and distribution of hot deserts changed over the last 10,000 years?

Key term

What role do prolonged droughts play in causing desertification?

Key term

Name the major global regions at risk of desertification.

Questions from this subtopic

Each one with the model answer underneath.

1
How has the extent and distribution of hot deserts changed over the last 10,000 years?
Model answer
Hot deserts have experienced periods of both expansion and contraction, linked to climatic shifts since the early Holocene.
2
What is the formal definition of desertification?
Model answer
Desertification is the degradation of land in arid, semi-arid and dry sub-humid areas resulting from climatic variations and human activities.
3
How do reduced precipitation totals contribute to desertification?
Model answer
Lower overall rainfall reduces soil moisture and water availability, limiting vegetation growth and making land more vulnerable to degradation.
4
Why does increased rainfall variability promote desertification?
Model answer
Unpredictable rainfall patterns prevent vegetation from establishing reliably, and intense sporadic rainfall can cause erosion on exposed soils.
5
How do rising temperatures contribute to desertification?
Model answer
Higher temperatures increase evaporation rates, reduce soil moisture and stress vegetation, accelerating land degradation.
6
Explain how higher evapotranspiration rates lead to desertification.
Model answer
Increased evapotranspiration removes water from soils and plants faster than it can be replenished, causing vegetation dieback and soil desiccation.

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AThe horns have less sand volume, so they move more quickly.

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