Human Impact on Natural Systems: Climate Change and Biodiversity
**Human Intervention in Natural Systems**
_Homo sapiens_ underwent a type of development and evolution based on science and technology that allows us to use nature and science to meet our needs. We can transform nature beyond what corresponds to the biological scale. The adaptive success of our species has replaced cultural evolution with biological evolution. Civilization:
- Consumes increasing amounts of energy
- Exploits natural resources
- Degrades exhaustible natural resources with their wastes, impacting air quality, water, and soil
Systems Theory
Systems theory is a method of thought that studies and introduces us to the understanding of complex phenomena, such as the operation of the climate, with the support of new technologies and software simulation with supercomputers. Systems theory and methods of analysis are a macroscopic lens allowing us to get closer to complex and far-reaching relationships, for example, the complex system of the environment. We understand how natural systems work and know the relationships between natural systems and the social system.
Gaia Hypothesis
Some consider it a scientific metaphor, formulated in 1969 by environmentalist engineer James Lovelock. It interprets that globally, complex relationships are established between the biosphere and other systems so that living beings take part in processes regulating planetary conditions.
The Atmosphere and the Thermal Balance of the Earth
The atmosphere is a thermal machine. The incident light radiation benefits plants for their food. The energy reflected from the surface returns to the atmosphere as infrared radiation (IR) of lower energy. Not all areas of land emit the same amount of radiation, nor is it in the air for the same time. This causes the movement of air masses to regulate the temperature between different areas of the Earth.
Greenhouse Effect
Overheating is experienced in the atmosphere due to the presence of gases in the air, called greenhouse gases. The main greenhouse gases are H2O, CO2, CH4, and N2O. This phenomenon has allowed the Earth to be habitable, but the continued accumulation and emission of these gases from burning fossil fuels are leading to overheating.
Climate
Weather is the pattern (temperature, humidity, precipitation, etc.) over a period of time in large areas, but humidity is forcing or accelerating trends in climate change.
Causes of Climate Change
-
Natural:
- Sudden (eruption)
- Short term (sunspots)
- Medium term (terrestrial oscillation axis)
- Long term (Ma)
-
Anthropic:
- Addition of gases to the atmosphere (greenhouse)
- Landscape destruction (deforestation, urbanization, destruction of soil)
Indicators of Anthropic Influence on Climate: CO2 Concentrations
- The atmosphere has increased 30% since the industrial revolution, from 270 ppm.
- This increase has accelerated in the last 100 years, coinciding with industrialization (fossil fuels) and increased population.
We must worry about the cumulative effect of human actions that flow CO2 into the atmosphere. This is an experiment, the effects of which are not yet known, and climatologists work with simulators that have not taken into account global dimming.
Global Warming
Global warming does not mean an increase in temperature everywhere, but it is a statistical tendency of the atmosphere to increase its average temperature. This figure results from adding temperature records of the year everywhere in the world. Warming is a symptom that causes a series of changes that scientists still cannot interpret accurately. It is not known for sure how it would affect the climate, nor what the true magnitude of the changes would be.
Urban Atmospheres
Cities are surrounded by a layer of denser and hotter air. There is a presence of solids/liquids (aerosols) in suspension, and it is hotter due to the radiation of asphalt and buildings that absorb the radiation and heat slowly. Today, industry has mostly moved out of cities, and the main cause of pollution is traffic. Exhaust (organic compounds) + N2, O2 (air) = nitrogen oxides (heat energy) = O3 (tropospheric ozone).
Hydrosphere
The hydrosphere is all the water on the planet and occupies 3/4 of it. It is in the oceans, ice caps, glaciers, groundwater, rivers, atmosphere, and living beings.
- Residence time: Average time that a certain amount of water remains in a compartment of the hydrosphere (e.g., aquifer – hundreds of years, river – 10-20 days).
- Turnover rate: The number of times a particular compartment is renewed in a year.
Interactions Hydrosphere-Atmosphere – Hydrological Cycle
This is the set of transport processes by which approximately 40,000 km3 of water are mobilized annually from the oceans to the continents and from the continents to the oceans. The water balance is 0, and the water molecules are not lost. For water to circulate, it must pass through the atmosphere, so ocean circulation (marine currents) and atmospheric circulation are coupled and are part of a global convective system that transports heat from the intertropical zone to the poles. Tropical forests’ transpiration loads the atmosphere with water vapor and slows down the warming of the ocean. If rainforest trees are cut down, rainwater is lost from the soil, dragging material to rivers and oceans, which are then altered, changing the global atmospheric-hydrospheric circulation model.
Biosphere
The biosphere includes the part of the planet organized by living beings and ecosystems.
Biodiversity
Biodiversity is the number of species living in a particular place in relation to the total number of individuals in the community. It reflects the quantity and variability of living organisms. The number of individuals is determined by factors such as food availability, absence of predators, etc. The number of species is determined by the degree of maturity and evolution of the ecosystem. Human civilization has been built at the cost of the continued occupation of new territories and access to new resources, threatening biodiversity. As civilization advances, nature and biodiversity are lost and become more vulnerable.
Edge Effect
The forest perimeter protects against external impacts. If the perimeter increases, this forest will be more vulnerable to external impacts, and biodiversity will be lost.
Biodiversity Legislation
- UNEP (United Nations Environment Programme) manages the CITES treaty (Convention on International Trade in Endangered Species of Wild Fauna and Flora), which regulates species trade between different countries. It prohibits the trade and circulation of more than 35,000 species (flora and fauna).
- IUCN (International Union for Conservation of Nature) maintains a red list of all threatened species.