Unit 9 APES
Explain the causes and effects of ocean acidification.
- Ocean acidification is the decrease in pH of the oceans, primarily due to increased CO2 concentrations in the atmosphere, and can be expressed as chemical equations. - As more CO2 is released into the atmosphere, the oceans, which absorb a large part of that CO2, become more acidic. - Anthropogenic activities that contribute to ocean acidification are those that lead to increased CO2 concentrations in the atmosphere: burning of fossil fuels, vehicle emissions, and deforestation. - Ocean acidification damages coral because acidification makes it difficult for them to form shells, due to the loss of calcium carbonate.
Explain the causes and effects of ocean warming.
- Ocean warming is caused by the increase in greenhouse gases in the atmosphere. - Ocean warming can affect marine species in a variety of ways, including loss of habitat, and metabolic and reproductive changes. - Ocean warming is causing coral bleaching, which occurs when the loss of algae within corals cause the corals to bleach white. Some corals recover and some die.
Explain how changes in climate, both short- and long- term, impact ecosystems.
- The Earth has undergone climate change throughout geologic time, with major shifts in global temperatures causing periods of warming and cooling as recorded with CO2 data and ice cores. - Effects of climate change include rising temperatures, melting permafrost and sea ice, rising sea levels, and displacement of coastal populations. - Marine ecosystems are affected by changes in sea level, some positively, such as in newly created habitats on now-flooded continental shelves, and some negatively, such as deeper communities that may no longer be in the photic zone of seawater. - Winds generated by atmospheric circulation help transport heat throughout the Earth. Climate change may change circulation patterns, as temperature changes may impact Hadley cells and the jet stream.- Oceanic currents, or the ocean conveyor belt, carry heat throughout the world. When these currents change, it can have a big impact on global climate, especially in coastal regions. - Climate change can affect soil through changes in temperature and rainfall, which can impact soil's viability and potentially increase erosion. - Earth's polar regions are showing faster response times to global climate change because ice and snow in these regions reflect the most energy back out to space, leading to a positive feedback loop. - As the Earth warms, this ice and snow melts, meaning less solar energy is radiated back into space and instead is absorbed by the Earth's surface. This in turn causes more warming of the polar regions. - Global climate change response time in the Arctic is due to positive feedback loops involving melting sea ice and thawing tundra, and the subsequent release of greenhouse gases like methane. - One consequence of the loss of ice and snow in polar regions is the effect on species that depend on the ice for habitat and food.
Identify the greenhouse gases.
- The principal greenhouse gases are carbon dioxide, methane, water vapor, nitrous oxide, and chlorofluorocarbons (CFCs). - While water vapor is a greenhouse gas, it doesn't contribute significantly to global climate change because it has a short residence time in the atmosphere. - The greenhouse effect results in the surface temperature necessary for life on Earth to exist.
Explain the importance of stratospheric ozone to life on Earth.
- The stratospheric ozone layer is important to the evolution of life on Earth and the continued health and survival of life on Earth. - Stratospheric ozone depletion is caused by anthropogenic factors, such as chlorofluorocarbons (CFCs), and natural factors, such as the melting of ice crystals in the atmosphere at the beginning of the Antarctic spring. - A decrease in stratospheric ozone increases the UV rays that reach the Earth's surface. Exposure to UV rays can lead to skin cancer and cataracts in humans.
Identify the sources and potency of the greenhouse gases.
Carbon dioxide, which has a global warming potential (GWP) of 1, is used as a reference point for the comparison of different greenhouse gases and their impacts on global climate change. Chlorofluorocarbons (CFCs) have the highest GWP, followed by nitrous oxide, then methane.
Identify the threats to human health and the environment posed by an increase in greenhouse gases.
Global climate change, caused by excess greenhouse gases in the atmosphere, can lead to a variety of environmental problems including rising sea levels resulting from melting ice sheets and ocean water expansion, and disease vectors spreading from the tropics toward the poles. These problems can lead to changes in population dynamics and population movements in response.
Describe chemicals used to substitute for chlorofluorocarbons (CFCs).
Ozone depletion can be mitigated by replacing ozone-depleting chemicals with substitutes that do not deplete the ozone layer. Hydrofluorocarbons (HFCs) are one such replacement, but some are strong greenhouse gases.
