Environmental Science Study Notes

Environmental science is a collective group of sciences that aims to:
- Explain how life on Earth is sustained.
- Identify and analyze the causes of environmental problems.
- Propose solutions to these problems.

Sustainability
- What are we working towards?
A Global Perspective
- Many environmental problems require global solutions.
An Urbanizing World
- Large populations live and work in urban environments.
People and Nature
- The intimate relationship between human societies and natural ecosystems.
Science
- Science is integral in providing solutions or informing decisions regarding environmental issues.

Sustainability has two specific scientific meanings:
1. Sustainability of Resources: Refers to the capacity to maintain resource levels, e.g. global fish stocks.
2. Sustainability of an Ecosystem: Refers to the preservation of ecological balance.
Carrying Capacity:
- Definition: The maximum number of individuals of a species that an environment can support indefinitely without reducing that capacity in the future.

Environmental impacts can:
- Transcend national boundaries.
- Achieve global proportions (e.g., greenhouse gas emissions influencing climate change).
Natural processes can also have global consequences, illustrated by historical events such as:
- The accumulation of free oxygen in the atmosphere approximately 2 billion years ago, which led to the "Oxygen Crisis."

Increasing urbanization is evident, with current statistics:
- Urban areas are now home to 4.2 billion people, marking the majority of the global population (Source: IPCC AR6 Ch 6 - Dodman et al., 2022).
- Between 2015 and 2020, global urban populations grew by approximately 397 million people, with over 90% of this growth occurring in less developed countries (Source: UNDESA, 2018).
Urban area statistics:
- In 2008, for the first time, more than half of the global population lived in urban settings.
- It is anticipated that this figure will increase to two-thirds by 2025.
- The number of megacities (urban areas with over 10 million people) rose from 2 in 1950 to 22 in 2005.
- A significant number of cities are located along rivers and coasts, leading to disproportionate environmental impacts in these regions.

The integration between people and the natural environment is crucial in environmental science.
Individuals’ views of the environment (value systems) dictate how they utilize natural resources.
Value Justifications: There are eight justifications for the value of the environment; two primary ones discussed are:
1. Utilitarian Justification:
- Materialistic perspective where an aspect of the environment is valued for its economic benefits or necessity for human survival.
- Example: Conserving wildlife due to potential benefits from tourism.
1. Ecological Justification:
- Focuses on the necessity of ecosystems for the survival of species of interest or for the ecosystem's own benefits.
- Example: Conservation of mangrove ecosystems since they support fish populations that are ecologically important.

Science is identified as a process resulting in:
- Conclusions, generalizations, scientific theories, and scientific laws.
Scientific methodology is rooted in testable observations, typically relying on empirical data gathered through observation using the five senses or instruments.
Types of Data:
- Qualitative Data: Non-numerical data, e.g., an animal species name.
- Quantitative Data: Numerical data, e.g., concentration of a toxin.

Variables in Science:
- Independent Variable: In observational studies, this is the variable believed to influence the outcome (dependent variable).
- Dependent Variable: This variable changes in response to variations in the independent variable.