Components of Global Climate Change

Question 1

Spatial Distribution - Rainfall

Answer 1

• The highest concentration of rainfall takes place at low altitudes near the equator
• Annual rainfall in the tropics can exceed 2500mm (compared to a global average of 1000mm)
• Coastal areas tend to experience higher rainfalls than inland areas
• Areas 60-90 degrees north and south of the equator have low levels of rainfall due to a lack of evaporation

Question 2

Spatial Distribution - Temperatures

Answer 2

• The average global surface temperature is 15 degrees C
• Areas that are closer to the equator are warmer than regions nearer the poles due to the equatorial regions receiving more direct insolation (these areas have an average surface temperature of 25 degrees or higher)
• Despite receiving the most energy from the sun, equatorial regions do not experience the highest temperatures as warm rising air can create daily thunderstorms that drop temperatures
• Areas with low albedo absorb more insolation and therefore tend to have higher temperatures (making forests hotter than alpine regions)
• Areas of low temperatures include regions beyond 37 degrees north and south of the equator, nearer the poles. This is because less insolation reaches the Earth, due to the lower angle of incidence of the sun’s incoming rays

Question 3

Natural Systems - Heat Budget, Including the Greenhouse Effect

Answer 3

• The Heat Budget is the balance between the continuous intake and release of energy from the planet. Incoming short-wave solar radiation (insolation) from the sun enters the Earth’s atmosphere
• Approximately 30% of the incoming solar energy is immediately reflected space by clouds, atmospheric particles or bright surfaces such as ice or snow
• About 20% is absorbed in the atmosphere by water vapour, dust and ozone, while the remaining 50% is absorbed by the land and oceans
• Once the insolation has been absorbed, it is then eventually re-radiated back into the atmosphere in the form of long-wave terrestrial radiation (heat), before exiting the atmosphere back into space. Approximately 23% of the original energy is carried into the atmosphere via water vapour, with the rest releasing through latent heat and conduction
• The natural greenhouse effect is the process where greenhouse gasses absorb some of the terrestrial long-wave radiation exiting the Earth, then re-radiate it in all directions, including back to the ground. This slows the passage of heat exiting and is an essential process. Without it, the surface of the planet would be more than 30 degrees cooler than it is now

Question 4

Natural Systems - Carbon Cycle

Answer 4

• There are two key processes to the carbon cycle; those that remove carbon dioxide from the atmosphere and store it elsewhere, and those that release it back to the atmosphere
• While CO2 is only a small part of the atmosphere (0.04), it plays a key role in the energy balance of the planet
• The atmosphere exchanges CO2 continuously with the oceans where it is stored in shells and sediments. Plants also continuously exchange CO2 with the atmosphere through respiration (the gas is taken in during photosynthesis, and released both when plants respire and when they decay or are burnt)
• Carbon is cycled among Earth’s oceans, atmosphere, ecosystems and geospheres in two cycles; the fast carbon cycle (which takes place over a human lifetime and involves the cycling of carbon between living organisms, the atmospheres and oceans), and the slow carbon cycle (which takes place over millions of years, and involves the movement of carbon between the Earth’s crust, the ocean and atmosphere, through weathering and erosion, volcanic eruptions and subduction)
• Human activities, like burning fossil fuels, disrupt the carbon cycle by releasing large amounts of CO2 into the atmosphere out of the slow carbon cycle, leading to an increased greenhouse effect and global warming

Question 5

Natural Systems - Hydrological Cycle

Answer 5

• The hydrological cycle, a continuous process of water circulation, plays a vital role in Earth’s climate by redistributing heat, shaping weather patterns, and maintaining the planet’s energy balance
• Evaporation from oceans, transpiration from plants, and condensation into clouds regulate global temperature through latent heat exchange, while precipitation and runoff contribute to the distribution of moisture and the formation of weather systems
• Additionally, water vapor acts as a potent greenhouse gas, amplifying the warming effect on our climate
• Approximately 10% of the water vapour in the atmosphere comes from plants transpiring