5.S: Unit 5 - Summary

Unit 5.2

Biodiversity exists at multiple levels of organization and is measured in different ways depending on the goals of those taking the measurements. These measurements include numbers of species, genetic diversity, and ecosystem diversity. Ecosystems provide ecosystem services that support human agriculture: pollination, nutrient cycling, pest control, and soil development and maintenance. Loss of biodiversity threatens these ecosystem services. Estimates of contemporary extinction rates vary, but some rates are as high as 1000 times the background rate, as determined from the fossil record, and are predicted to rise. Loss of biodiversity will impact the number of pharmaceuticals available to humans, loss of crop diversity and ecosystem services, as well as psychological benefits to humans. Additionally, there are moral arguments for the maintenance of biodiversity.

The core threats to biodiversity are human population growth and unsustainable resource use. To date, the most significant causes of extinctions are habitat loss, invasive species, pollution, population (human), predator losses, overharvesting, and climate change (HIPPPOC). New technological methods such as DNA barcoding and information processing and accessibility are facilitating the cataloging of the planet’s biodiversity. There is also a legislative framework for biodiversity protection, including international treaties. Conservation preserves are a major tool in biodiversity protection. Presently, 11 percent of Earth’s land surface is protected in some way, however, preserves have limitations imposed by political and economic forces. In addition, climate change will limit the effectiveness of preserves in the future. Habitat restoration has the potential to restore ecosystems to previous biodiversity levels before species become extinct. Zoos have attempted to take a more active role in conservation and can have a limited role in captive breeding programs.

Unit 5.3

Natural drivers of climate change include Milankovitch cycles, changes in solar activity, and volcanic eruptions. None of these factors, however, leads to rapid increases in global temperature or sustained increases in carbon dioxide. The burning of fossil fuels is an important source of greenhouse gases, which plays a major role in the greenhouse effect. Long ago, climate change resulted in the Permian extinction: a large-scale extinction event that is documented in the fossil record. Currently, modern-day climate change is associated with the increased melting of glaciers and polar ice sheets, resulting in a gradual increase in sea level. Plants and animals can also be affected by global climate change when the timing of seasonal events, such as flowering or pollination, is affected by global warming and other associated factors.

Unit 5.4

Sustainability refers to three simple concerns: the need to arrest environmental degradation and ecological imbalance, the need not to impoverish future generations, and the need for quality of life and equity between current generations. Added up, these core concerns are an unmistakable call for transformation. Many problems face indigenous people, including lack of human rights, exploitation of their traditional lands and themselves, and degradation of their culture. Despite the lofty U.N. goals, the rights and feelings of indigenous people are often ignored or minimized, even by supposedly culturally-sensitive, developed countries. Business-as-usual is no longer an option.

The concept of ethics involves standards of conduct. These standards help to distinguish between behavior that is considered right and that which is considered wrong. The ways in which humans interact with the land and its natural resources are determined by ethical attitudes and behaviors. Environmental justice is achieved when everyone enjoys the same degree of protection from environmental and health hazards and equal access to the decision-making process to have a healthy environment.