• Climate is shaped by 7 factors: latitude, altitude, continentality, ocean currents, aspect, prevailing winds, and pressure systems.
• The equatorial climate is hot and wet all year round — no seasons — because it sits under permanent low pressure.
• The hot desert climate is hot and dry with huge temperature swings, because it sits under permanent high pressure at 15°–30° N/S.
• The tropical rainforest (TRF) ecosystem has the highest biodiversity on Earth, a rapid nutrient cycle, and infertile soil — because nutrients live in the plants, not the ground.
• The hot desert ecosystem has low biodiversity, a slow nutrient cycle, and nutrients stored mostly in the soil (not the plants).
• Plants and animals in both biomes show clear adaptations to survive extreme heat, extreme dryness, or intense competition for light.
• Deforestation has environmental, social, and economic causes and effects — you need real case study detail (Malaysia) to score top marks.
• Hot desert ecosystems face their own human threats — tourism, mining, agriculture, poaching (Namib Desert case study).

Before you can explain any single climate, you need the toolbox of 7 reasons climate differs from place to place. Think of these as dials — turn each one and you change the temperature or rainfall of a location.

The 7 Climate Controls

The equatorial climate sits in a narrow belt hugging the equator itself — think the Amazon Basin, the Congo (Zaire) Basin, and parts of South-East Asia and New Guinea. It's defined by one thing above all: it's permanently under low pressure, so it's always hot, always wet, with no real seasons.

Key Statistics to Memorise

Notice the pattern is diurnal (daily), not seasonal — that's the exam-favourite distinction. A hot desert has big annual temperature swings; the equatorial climate barely has any annual swing at all, but a noticeable daily one.

Hot deserts form in a belt roughly 15°–30° N and S of the equator — the Sahara, the Kalahari, the Namib, the Arabian Desert, and parts of Australia. The defining feature here is the opposite of the equatorial climate: permanent high pressure, meaning air is constantly sinking, warming, and staying dry.

Key Statistics to Memorise

Why Hot Deserts Form: The Pressure Cell Explanation (this is a favourite exam diagram)

1. Air rises at the equator (it's hot and full of moisture — that's the equatorial low pressure belt).
2. As it rises, it cools, loses its moisture as rain over the equatorial zone, and moves outward in the upper atmosphere towards 30° N and S.
3. By the time it reaches 30°, it has become cool and dry. It then sinks.
4. This sinking creates a permanent zone of high pressure at about 30° N and S.
5. Sinking air warms as it descends and — crucially — sinking air cannot condense or form clouds. Result: very low rainfall, high aridity.

The tropical rainforest biome grows wherever the equatorial climate provides the constant heat and moisture it needs — mainly a band between 15°N and 15°S. It covers just 6% of Earth's land surface, but contains the richest concentration of life on the planet.

Where TRFs Are Found

Biodiversity

TRFs hold the highest biodiversity on Earth — estimates range from 50–80% of the world's plant and animal species. A single 10 km² patch can contain up to 1,500 flowering plants, 750 tree species, 400 bird species, and 150 butterfly species.

The Nutrient Cycle — This Is Where Students Lose Marks

Here's the part that trips people up: tropical rainforest soil is actually not fertile, even though the vegetation growing on it is unbelievably lush. Why? Because the nutrient cycle is rapid — nutrients move through the system so fast that almost none of them sit around in the soil.

Structure: 5 Layers

Picture it like a very crowded apartment building where every "floor" is a different micro-habitat with its own light levels, temperature, and animal residents — that's exactly why different species live at different heights (see the worked example below).

Adaptations — Plants

Adaptations — Animals

Now flip everything you just learned. If the rainforest is a nutrient cycle running on fast-forward, the hot desert ecosystem runs in slow motion — because there simply isn't enough water or warmth-consistency to fuel fast growth or fast decomposition.

Where Hot Deserts Are Found

Roughly 20% of the Earth's land surface is desert.

Biodiversity — The Opposite of the TRF

Hot deserts have one of the lowest biodiversity levels on Earth. Around 5,000–6,000 plant species survive here in total (compare that to a single 10 km² TRF patch having 1,500 flowering plants alone), many invertebrates, and up to only about 20 bird species.

Nutrient Cycle

Adaptations — Plants

Adaptations — Animals

Deforestation is the felling and clearance of trees. Malaysia, Brazil, India, and Indonesia experience the world's highest levels of it. Malaysia is estimated to have the fastest rate of deforestation in the world — since 2000, an average of over 140,000 hectares of forest has been felled and cleared every year.

Location & Context

Malaysia is in South-East Asia; almost 70% of its land is covered by tropical rainforest, with a typical equatorial climate of high rainfall and high temperatures all year round. Its rainforest is exceptionally biodiverse — over 15,000 plant species (including 5,500 flowering plants and 2,600 tree species), 750 bird species, and 250 mammal species.

6 Human Causes of Deforestation (general)

Wildfires are the main natural cause — and their frequency/severity has increased due to human-induced climate change, so even "natural" causes are becoming tangled up with human ones.

Malaysia-Specific Causes (case study detail)

Environmental Impacts

• Loss of biodiversity: monoculture plantations replace diverse forest; oil palm plantations cause a 35% reduction in species. Orangutans, pygmy elephants, Sumatran rhinos, and Malayan tigers are all endangered.
• Soil erosion: without roots to bind it, soil is more easily eroded; exposed soil is more vulnerable to nutrient leaching and becomes less fertile.
• Sedimentation: reduced interception/infiltration → increased overland flow → soil erosion → sediment builds up on riverbeds → increased flood risk.
• Local climate change: less transpiration/evaporation → less precipitation and higher temperatures; rainfall becomes less reliable and more extreme.
• Global climate change: fewer trees absorb less CO₂; burning for clearance adds even more CO₂ — both add to the enhanced greenhouse effect.
• Increased landslide risk due to lack of roots holding soil together.

Social Impacts

• Indigenous communities (e.g. the Orang Asli and Temiar) have less land to sustain their traditional way of life and may be forced off land, leading to loss of culture and traditions.
• Reduced pollination (fewer insects/bats) means less available food.
• In Kuala Koh village (2019), at least 15 Indigenous Batek people died from a disease outbreak possibly transmitted by loggers working near the village.
• Increased flood risk for settlements; loss of potential medicines that might have come from undiscovered forest species.
• Some positive impacts too: improved quality of life for some people through increased income and jobs.

Economic Impacts

• More jobs in mining, forestry, agriculture, and HEP.
• Increased national income through exports (minerals, timber, crops).
• Almost a quarter of Brazil's GDP comes from activities in deforested areas of the Amazon — a useful comparative statistic even in a Malaysia answer.

The Namib Desert stretches over 2,000 km along Namibia's west coast (from Angola to South Africa), and is about 160 km wide. Its cool coastal position makes it a fascinating exception among hot deserts.

Climate

• Daytime highs over 45°C; night-time lows can hit 0°C
• Coastal areas are cooler due to the cold Benguela ocean current
• This cooling effect also produces fog, which affects coastal areas more than half the year — and, crucially, becomes a vital water source for specially adapted species
• Annual precipitation varies between just 2–200mm a year

Biodiversity — Higher Than You'd Expect

Because of its unique fog-based ecosystem, the Namib actually has higher biodiversity than most other hot deserts, and many species found here are endemic (found nowhere else on Earth): roughly 3,500 plant species (over 50% endemic), 200 mammal species, 268 reptile species, and over 6,000 insect species.

Standout Adaptations

Human Threats to the Namib Ecosystem

• I can list and explain all 7 factors that cause climate to vary across the world (latitude, altitude, continentality, ocean currents, aspect, prevailing winds, pressure systems)
• I can state the key statistics of the equatorial climate (rainfall, temperature range, humidity, diurnal range)
• I can explain why the equatorial climate has daily rainfall but no seasons
• I can state the key statistics of the hot desert climate (rainfall, temperature range, diurnal/annual range, humidity)
• I can explain the pressure-cell process that creates hot deserts at 15–30° N/S
• I can explain why tropical rainforest soil is infertile despite abundant vegetation
• I can name and order the 5 layers of a tropical rainforest with approximate heights
• I can give at least 3 plant and 3 animal adaptations for the tropical rainforest, with reasons
• I can give at least 3 plant and 3 animal adaptations for the hot desert, with reasons
• I can compare biodiversity and nutrient cycles between TRF and hot desert ecosystems
• I know the 6 human causes of deforestation and can explain (not just state) each one
• I can give environmental, social, and economic impacts of deforestation in Malaysia with specific facts/figures
• I can describe specific threats to the Namib Desert ecosystem (tourism, mining, agriculture, poaching) with examples
• I can name at least 3 specially adapted Namib species and explain their adaptations