Human Impact on the Environment and Climate Change
Human Evolution and Environmental Impact
Our species, Homo sapiens, has evolved through the development of mind and culture, creating the science and technology needed to adapt nature to our needs. Thanks to tools and machines, we have acquired a tremendous capacity to transform nature, far exceeding the scale of biological evolution. Humans have replaced biological evolution with culture.
Environmental Problems in History
Environmental problems may seem new, but archaeological remains of ancient civilizations document several environmental crises. Many had natural causes, but some were caused by the same groups of people. Generally, especially in Europe, there are alternating periods of stability, where food is plentiful and the population grows rapidly, and periods of crisis.
Understanding the Ecological Footprint
The ecological footprint, a term defined by Rees and Wackernagel in 1996, is an indicator that measures the area of land needed to produce the resources consumed by a citizen or town, and also the area needed to absorb and detoxify the waste it generates, regardless of where these areas are located.
The Gaia Hypothesis
- It was formulated by James Lovelock in 1969.
- Lovelock considers the planet a superorganism, a life of its own, with the ability to regulate itself and maintain conditions suitable for life, using energy from the Sun for its self-maintenance and auto-structuring.
- Example: The ocean receives salts dissolved from the continent, but its salinity does not increase indefinitely because there are living beings that regulate it.
The Greenhouse Effect
The overheating of the atmosphere is due to the presence of various gases, called greenhouse gases, which scatter radiation as heat and increase the temperature.
Greenhouse gases include water vapor, carbon dioxide (CO2), methane (CH4), dinitrogen oxide (N2O), and oxygen (O2).
Climate Change
Increased levels of carbon dioxide in the atmosphere, due to fossil fuel consumption, coincide with increasing population and energy consumption. Increased levels of methane in the atmosphere are also a concern, as it is a natural gas.
The Hydrosphere
The hydrosphere is the water that forms the surface of the Earth. It is composed of water in the oceans (3/4 of the total), ice caps and glaciers, lakes, rivers, the atmosphere, and groundwater contained within living beings. Only fresh water is readily available, from rivers, lakes, and groundwater (0.7%). Desalination of ocean water is possible but expensive and energy-intensive. The polar ice caps regulate the climate and cannot be used. Drought is a significant problem for humanity.
The Water Cycle
The water cycle is the movement of water between oceans and continents.
It includes:
- Evaporation: Solar energy moves water into the atmosphere.
- Condensation: Water vapor concentrates in clouds.
- Precipitation: Clouds discharge water (rain, hail, or snow) over oceans and continents. Water returns to the oceans through infiltration, underground runoff, and surface runoff.
Biodiversity
Our world contains a variety of organisms and landscapes. Biodiversity reflects the number and variability of living organisms. It measures the number of species living in a particular place relative to the total number of individuals in the community. In general, more mature or older ecosystems have greater diversity. An example is the Amazon rainforest.