World’s Physical Geography

Model Answer

Permafrost refers to ground that remains frozen at or below 32°F (0°C) for at least two consecutive years. These regions are primarily found in colder climates, and the main areas include:

1. Arctic Region: The majority of permafrost is found here, covering large parts of Siberia, Alaska, Greenland, and Canada. Around 85% of Alaska’s territory sits on permafrost. Undersea permafrost is also present on the Arctic Ocean floor.
2. High-Altitude Regions: Areas like the Tibetan Plateau, the Himalayas, and the Rocky Mountains have permafrost due to their high altitudes, which maintain frozen ground.
3. Southern Hemisphere: Permafrost exists in the Andes Mountains of South America, New Zealand’s Southern Alps, and in Antarctica’s vast expanse.

Impact of Thawing Permafrost on Global Climate and Ecosystems

Thawing permafrost has emerged as a significant threat due to several reasons:

1. Greenhouse Gas Emissions: Permafrost contains large amounts of carbon and methane trapped in the soil. As the ground thaws, these gases are released into the atmosphere, exacerbating global warming. A study in Nature Climate Change suggests that a 1°C increase in global temperature could lead to the loss of permafrost the size of India, while a 2°C rise could result in a 40% global loss. This creates a feedback loop, accelerating the warming process.
2. Release of Ancient Pathogens: Thawing permafrost has also released long-frozen microbes, including viruses and bacteria. In 2016, an anthrax outbreak in Siberia was linked to thawing permafrost, underscoring the potential health risks.
3. Ecosystem Disruption: As permafrost melts, it transforms landscapes, causing the tundra to turn into muddy terrain. This affects local vegetation and wildlife. Additionally, thawing beneath bodies of water can lead to the disappearance of lakes, worsening droughts and destabilizing ecosystems.
4. Geological Instability: The melting of permafrost leads to landslides and the destabilization of terrain. For example, the Batagaika crater in Russia has been widening due to thawing permafrost, causing significant land subsidence.

Thawing permafrost poses a critical challenge to the global climate and ecosystems, requiring urgent global attention to mitigate its effects.

Model Answer

The equatorial region, spanning 0° to 10° latitude, includes areas such as the Amazon lowlands, the Congo Basin, and parts of Southeast Asia. The climate in this region has the following key features:

1. High Temperature: Temperatures range from 25°C to 27°C year-round with minimal variation between day and night. There is no winter in this region.
2. High Humidity: Humidity levels consistently exceed 80%, contributing to a hot, sticky environment.
3. Heavy Rainfall: Annual precipitation ranges from 60 to 100 inches, with rain distributed throughout the year. The peak rainfall occurs around the equinoxes, with a slight decrease around the solstices.
4. Diurnal Conditions: The mornings are generally sunny, but intense evaporation and convection currents lead to rainfall in the afternoons.

Vegetation Characteristics

The vegetation of the equatorial region is dominated by tropical rainforests, which thrive due to the ideal climate:

1. Variety: The region is home to a vast array of species, including hardwood trees such as mahogany and ebony, climbing plants like lianas, and various epiphytes.
2. Layered Structure: The rainforest features multiple layers, with tall trees (150+ feet) in the upper canopy, smaller trees and shrubs below, and ferns in the lower layers.
3. Species Density: Equatorial rainforests boast high species diversity, often hosting hundreds of species in a small area.

Impact on Development

1. Health: The high humidity and warmth provide an ideal breeding ground for disease vectors like mosquitoes, contributing to diseases such as malaria, dengue, and yellow fever.
2. Agriculture: The nutrient-poor soil makes traditional farming difficult, though cash crops such as tea, cassava, coffee, and rubber thrive. Cattle ranching is also practiced in some areas, notably in Brazil.
3. Logging: The complexity of the rainforest ecosystem, with its varied tree species, makes commercial logging difficult. Additionally, tropical hardwoods do not float on water, increasing transportation costs. Southeast Asia, however, remains a key producer of valuable timber.

In summary, while the equatorial region’s climate and vegetation are rich in biodiversity, they also present challenges for agriculture and economic activities, such as logging and health management. However, the region’s resources, like tropical hardwoods and cash crops, contribute significantly to global markets.