Environmental Concepts: Sustainability, Desertification, Erosion, and Ecological Footprint

What is Sustainability?

The term "sustainable" refers to the ability to endure. Thus, sustainable development has been defined as one that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Conditions for Sustainable Development

For sustainable development, at least two conditions must be fulfilled:

1. Resource Exploitation Rate: The rate at which resources are consumed cannot exceed their renewal rate.
2. Waste Emission Rate: The waste emission rate must be less than the assimilative capacity of the ecosystem to which it is discharged. For example, until the Industrial Revolution, CO2 emissions from human activities were below the system's assimilative capacity, so that the concentration of this gas remained stable. Thereafter, the volume of emissions exceeded the assimilative capacity, resulting in an increased concentration of CO2 in the atmosphere.

Understanding Desertification

Desertification is a process of land degradation in arid and semi-arid regions, produced by climate variations or human activities. It usually starts with soil degradation, or a deterioration in quality and fertility, which reduces vegetation and ends with soil erosion.

Conditions Contributing to Desertification

Two conditions influence desertification processes:

1. Climatic Risk: Considered in arid and semi-arid climates, whose annual rainfall is less than 200 mm and between 200 and 600 mm, respectively, and with strong seasonality.
2. Land Misuse or Inappropriate Land Use: This includes activities such as:
   • Deforestation: Excessive cutting of forests to use their wood or replace them with agricultural crops.
   • Overgrazing: Excessive consumption by livestock grazing that leaves the ground without protection.

Factors Influencing Soil Erosion

The risk of land erosion depends on factors such as:

1. Climate: Determines rainfall patterns. Mediterranean climates, with periods of drought punctuated by torrential rains, lead to significant soil erosion.
2. Land Slope: The erosive capacity of a stream of water increases with its volume and speed, which depend on the slope. Any slope greater than 15% carries a high risk of erosion.
3. Vegetation: Plants hold the soil with their roots, slowing runoff and increasing infiltration of subsurface waters. This protects the soil from erosion.
4. Soil Vulnerability: Not all soils have the same characteristics. The texture of the mineral fraction and humus content make some soils less susceptible to erosion than others.

Calculating the Ecological Footprint

To calculate a person's ecological footprint, the following are mainly considered:

1. Agricultural land and pasture
2. Maritime space
3. Forest land (for timber and products)
4. Carbon absorption land (or "Forest area for CO2 absorption")
5. Built-up land (or "Surface used for housing")