Understanding the Greenhouse Effect, Climate Change, and Carbon Cycle

The greenhouse effect is a natural process that warms the Earth's surface. Here's a breakdown:

1. Solar radiation received: 100%.
2. 30% is reflected by the atmosphere and the Earth's surface.
3. 19% is absorbed by clouds and other atmospheric components.
4. 51% is absorbed by the land surface, which then heats up.
5. The heated surface emits infrared radiation.
6. Some of this infrared radiation is absorbed by greenhouse gases and re-emitted back to the surface.
7. The remaining infrared radiation passes through the atmosphere and dissipates into outer space.

Reconstructing Past Climates

Ice core records help reconstruct past climates:

1. Air bubbles trapped in ice: Ice accumulated in layers, particularly in Antarctica, contains small air bubbles. These bubbles reveal the composition of the atmosphere at the time the snow fell. Scientists can analyze these bubbles to verify changes in the proportion of oxygen or carbon dioxide.
2. Fossil Remains: Each organism lives in a particular habitat, and their remains can indicate past climate conditions.

Causes of Climate Change

Climate change can be caused by both external and internal factors:

1. External Causes:
   • Astronomical: Changes in solar radiation received.
   • Changes in solar activity: Affecting the source of energy reaching the Earth.
   • Changes in the Earth's orbit: The Earth's orbit gradually changes from almost circular to more elliptical, modifying the solar radiation reaching the Earth.
   • Meteor impacts: A large impact can cause a cloud of dust that prevents solar radiation from reaching the Earth's surface.
2. Internal Causes:
   • Albedo changes: Changes in the Earth's surface coverage affect global temperature.
   • Changes in atmospheric composition: Human activities increase or decrease the concentration of greenhouse gases like CO₂.
   • Changes in ocean currents: Thermohaline circulation is an ocean current driven by differences in temperature and density.

An increase in greenhouse gases is caused by:

• Burning of fossil fuels (oil, gas, coal).
• Deforestation: Removing vegetation reduces the amount of CO2 absorbed from the atmosphere.
• Farming activities: Domestic livestock emit methane, and certain crops generate other gases.
• Other gases: Ozone, nitrous oxide, chlorofluorocarbons, and water vapor.

CO2 per capita = Total CO2 emissions in a country / Number of inhabitants.

The Carbon Cycle

The carbon cycle describes the exchange of carbon among four natural reservoirs: the atmosphere, hydrosphere, biosphere, and lithosphere.

1. Plants remove atmospheric CO2 and produce organic matter.
2. Organic matter, and the carbon it contains, is transferred to other living organisms.
3. Organisms breathe and expel CO2; decomposition of organic debris releases CO2.
4. CO2 is released into the air.
5. CO2 dissolves in water, and water can move to the air.
6. CO2 is linked to calcium in the limestone shells of organisms and deposited on the seabed.
7. Remains of organisms form oil and coal deposits.
8. Burning fossil fuels emits CO2 into the atmosphere.
9. Volcanic eruptions and forest fires also emit CO2.

Climate Predictions

Climate models predict the following:

1. The global average temperature of the Earth will increase between 1.4 and 6°C.
2. Sea levels will rise between 20 and 80 cm. Many coastal areas will be flooded.
3. Extreme weather events will become more frequent and intense.
4. Environmental effects: Loss of biodiversity, disruption of seasonal variations of species, disappearance of wetlands and other ecosystems.
5. Health effects: Tropical diseases could spread to areas with temperate climates.

Kyoto Protocol

The Kyoto Protocol is an agreement signed by industrialized countries to reduce their emissions of greenhouse gases. The European Union is undertaking the following measures:

1. Increasing the use of renewable energy sources.
2. Improving energy efficiency in automobiles.
3. Improving energy efficiency in appliances.
4. Promoting energy efficiency in buildings.
5. Promoting energy efficiency in scientific research and technological development.
6. Protecting and enhancing natural sinks and experiencing technologies.
7. Investigating artificial technologies that act as CO2 sinks.