Human Impact on the Earth’s Ecosystems: Pollution and Climate Change
Land as an Ecosystem
Except for energy from the sun, Earth is a closed system with unchanging components. These components continuously readjust in their situation and location, leading to global biogeochemical cycles. Living organisms play a vital role in these cycles, interacting with chemical and geological elements, thereby altering planetary conditions.
Environmental Impact of the Human Population (Anthropocene)
The large human population and the disproportionate growth in resource demand and waste production modify our environment. This includes biogeochemical cycles and biodiversity loss, which energize and make life possible. This is what we call “human impact,” encompassing all human activities that influence the environment. This influence is now global, affecting all Earth System processes.
Global Change Impact: System Variables and Relationships
- Pollution: Introduction of a new element or an existing element in excessive quantities, overwhelming the system’s absorption capacity.
- Impaired Cycles: Alteration of the status and location of certain elements.
- Stage Modification: Desertification, soil erosion, land-use changes, etc.
- Overfishing: Depletion of renewable, long-term renewable, or non-renewable resources.
- Impact: Consequences for ecosystem services (poverty, reduced quality of life, etc.).
The Greenhouse Effect
The greenhouse effect is the natural warming of Earth. Greenhouse gases in the atmosphere retain some of the sun’s heat, maintaining a temperature suitable for life. Solar energy passes through the atmosphere; some is absorbed, and some is reflected. Greenhouse gases retain a portion of this reflected energy, while the rest returns to space.
Global Warming
Global warming is the long-term increase in Earth’s average atmospheric temperature. It is caused by greenhouse gas emissions from human activities like burning fossil fuels and deforestation. These gases trap more heat, disrupting Earth’s balance.
Global Change
Changes in system variables and relationships produce a new system, leading to consequences like global warming and melting ice caps. This causes sea-level rise, loss of life, changes in thermohaline circulation, and ocean acidification, impacting species and cycles.
Climate Change
Climate has always changed due to natural causes like solar evolution (sunspot cycles), Earth’s movement in space, axial shifts, and events like volcanism. However, current changes are much faster and cannot be explained without considering human activities. These activities produce human-induced changes that the Earth cannot absorb or recover from, resulting in a changing environment. Greenhouse gas emissions play a significant role.
Environmental Impact and Pollution
Pollution is the increase or emergence of harmful substances, detrimental effects, or certain forms of energy in the environment, exceeding its capacity to support and neutralize them. Pollution can be local, regional, or global, depending on its scope. Pollutants can be classified by source:
- Chemical: Harmful and toxic substances like industrial, hospital, or urban solid waste.
- Physical: Magnetic fields, noise, light pollution, microwaves, or ionizing radiation.
- Biological: Pathogens, pests, invasive species.
- Natural: Can be recovered, although in the long term.
- Anthropogenic: Sometimes causes irreversible changes.
Air Pollution
Air pollution is caused by pollutants like toxic substances (gases, liquids, or solids), suspended particulates (small, solid, and chemically inert particles), or forms of energy like ionizing radiation (UV radioactivity) or non-ionizing radiation (radio waves or heat). There are two types of air pollutants:
- Primary: Emitted directly into the atmosphere.
- Secondary: Formed from chemical reactions between primary pollutants or with the environment (e.g., positive synergism, where two individually non-toxic pollutants become highly toxic when combined).
Urban Air Pollution
Urban heat islands concentrate pollutants. Winter smog (dense, polluted air—a mixture of fog, smoke particles, soot, and sulfur) is caused by carbon combustion, reducing visibility. Photochemical smog is a dark orange haze produced by primary air pollutants like nitrogen oxides (NOx) and volatile organic compounds reacting with oxygen to create ozone and other pollutants. Normally, hot air carries these gases to the upper atmosphere, but temperature inversions can trap them with fog and soot near the surface.
Causes of Urban Air Pollution: Fuel combustion, industrial activities, vehicle heaters and air conditioners, and littering.