Science / Mass Extinction And Climate Change
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Autor: anton 01 December 2010
Words: 1958 | Pages: 8
Mass extinction underway due to climate change and habitat loss
The greenhouse theory of climate change postulates that Earth's average temperature will rise over time due to the increased concentrations of certain gases within the atmosphere. Earth derives its energy from the sun, but much of the sun's radiation bounces back after reaching Earth. Some of this "bounced" radiation strikes molecules of carbon dioxide, water vapor, and other gases within the atmosphere, which results in the retention of some of this energy within the atmosphere. Without this effect, life on Earth would not be possible, since the planet would be too cold to support life.
Fossil records indicate that variances in temperature correspond significantly with the presence of greenhouse gases. Although the cause and effect cycle of the past is not completely understood, there is some indication that the gases act as a feedback mechanism, exacerbating other climatic changes.
Atmospheric concentrations of green house gases have risen significantly since the pre-industrial period, primarily due to the use of fossil fuels, destruction of forests, and agricultural practices. Climate scientists have prepared models predicting temperature change based upon different levels of fossil fuel consumption.
The model for the "high" scenario presented in this graph assumes that consumption of fossil fuels continues until cheap new technologies are developed to replace these energy sources. Under this scenario, atmospheric carbon dioxide concentrations would peak at about 1200 ppm, more than four times the pre-industrial levels. The global average temperature would rise 10 degrees.
In the medium scenario, no significant action is taken to replace fossil fuels until 2100. Carbon dioxide concentrations would rise to 850 ppm, and average temperatures could reach six degrees above the current mean.
The low scenario assumes significant action immediately. Even under this scenario, carbon dioxide concentrations will rise slightly, and temperature will increase about three degrees. This lingering effect is due to the fact that greenhouse gases have long life cycles within the atmosphere, enduring for decades or centuries until they pass into sinks in the ocean or forests.
These increases are in addition to the 0.6-1.2 degree increase that has already occurred since 1860, when good temperature records began. There is now a virtual consensus that this increase is due to the rise in greenhouse gas concentrations in the lower atmosphere. Since 1860, carbon dioxide concentrations have increased 30%, methane concentrations have increased 15%, and nitrous oxide levels have doubled. The result of these changes has been a rise in sea level of 4-10 inches, and an increase in annual rainfall. Many scientists believe that the greater number of severe weather events (El Nino/La Nina, Class 4 & 5 hurricanes, and typhoons) experienced during the 1990s are a direct result of the decade's high temperatures occurring due to green house gases.
These projected temperature levels do not correspond to conditions in Earth's recent past. The only era that appears to resemble the levels of global warming currently occurring is the cusp of the Cretaceous and Eocene era, also known as the Late Paleocene Thermal Maximum. This period was characterized by a global warming trend that began approximately 60 million years ago, when temperatures increased so substantially that the oceans ceased to turnover the deep, cold water efficiently, which is essential to marine ecosystems, and to the atmospheric cycle. This breakdown caused a huge mass extinction in sea life, and may have resulted in a large input of methane from the oceans to the atmosphere, which caused the terrestrial warming. Terrestrial conditions were substantially different during that time period. Sea levels were very high, because the poles retained very little of their ice caps. Antartica may have been covered with forest.
These were the conditions that eventually gave rise to the Age of Mammals, causing an increase in evolution, as well as large extinctions. Although humans could certainly survive in these temperatures, life would be much less pleasant. Looking at the current estimates for global warming, scientists predict a great increase in tropic diseases throughout the world, with outbreaks of malaria, hanta virus, encephalitis, and even dengue fever occurring frequently in the United States.
Responses to the Threats of Climate Change
The international community began to recognize the potential impacts of climate change more than two decades ago, and established the World Meteorological Organization (WMO), which convened an international climate conference and established a monitoring and study organization. In 1988, the Intergovernmental Panel on Climate Change was established.
The IPCC three separate working groups. One group focuses on scientific issues related to the climate system. The second looks at the impacts of climate change on the planet and its ecosystems. The third considers the economic and social dimensions. The three working groups have prepared two comprehensive assessment reports on climate change, in 1990 and in 1995. The IPCC has agreed to publish new assessments approximately every five years; therefore, the Third Assessment Report in scheduled for publication in late 2000/early 2001.
The 1995 report - the Second Assessment - provided more up-to-date information on the increase in greenhouse gases and their impacts. Some important observations in the report are 1) if carbon emissions remain relatively stable, atmospheric carbon dioxide concentrations will approach twice that of pre-industrial levels by 2100; 2) stabilization of carbon dioxide concentrations (at a much higher level than current amounts) can be achieved only in carbon dioxide emissions drop to 1990 levels; 3) cumulative levels depend heavily upon early emissions, so greater reductions will be required in future years if smaller efforts are made now; 4) stabilization at current levels would require an 8% reduction in emissions from the 1990 levels; 5) thermal inertia of oceans will cause temperatures to continue to increase after 2100, even if gas concentrations are stabilized.
The report attempts to describe the impacts on general types of biospheres, and to project impacts on agriculture, human settlements, and health. The scientific models, as well as the potential impacts, provided important guidance to the industrialized nations as they began to negotiate agreements to address the climate change issues.
For business and industry, one of the most important pieces of the report is the analysis of energy use, summarized as follows:
The Second Assessment asserts that 10-30% energy efficiency gains can be achieved, with little impact, through "technical conservation measures and improved management practices." The report acknowledges that these gains are dependent on cost reductions, financing availability, technology transfer, and overcoming "non-technical barriers," i.e., public and industrial opposition.
The IPCC provides some general recommendations for reducing greenhouse gas emissions from each of the three sectors. For industry, ideas include greater process efficiency, co-generation, use of more efficient motors, recycling, and use of materials that emit lower amounts of greenhouse gases. Regarding transportation, the report states that projected energy use could be reduced by about one-third by using very efficient drive-trains, lightweight materials, and more aerodynamic design. Additional reductions in transportation related uses could come from smaller vehicles, changes in land-use patterns and lifestyles, and greater use of "less energy-intensive transport modes." Alternative fuels might also play an important role, if industry develops efficient technologies, particularly for automobiles.
The Kyoto Protocol, which was negotiated on December 10, 1997, established legally-binding limits on emissions for developed countries for the first time. The thirty-nine developed nations (Annex I countries in the agreement parlance) agreed to specific targets using 1990 emissions as a baseline. Overall, the goal is to reduce emissions to 5% below the 1990 baseline. The agreement provides for different goals for the individual countries based both upon current emissions and ability to convert to cleaners fuels. The U.S., as the largest consumer of fossil fuels, consented to the greatest reduction in consumption. This agreement is consistent with domestic air quality standards.
Reductions must be accomplished within the commitment period, 2008-2012. Countries may exceed the limits during a given year within the commitment period, but the average emissions must adhere to the agreed-upon levels.
The Protocol provides four different mechanisms for Annex I countries to meet their commitments:
a) take any domestic action to reduce emissions from their industrial sectors, such as replacing fossil fuel use with renewable energy sources;
b) take domestic action through a limited set of forest-sector activities -- afforestation and reforestation that count as reductions, and deforestation that counts as an emission;
c) use two market-based mechanisms (emissions trading and project-based credit trading) that allow them to buy, sell, or trade greenhouse gas reductions and emission allowances from other Annex I countries; and
d) use a third market mechanism that allows buying or trading of project-based credits from non-Annex I countries -- e.g., the Clean Development Mechanism.
The hope is that market-based mechanisms will allow the flexibility to develop innovative solutions, and that developing countries will be able to forward their economies without incurring the same natural resource losses that first world nations caused.
Impacts on California
Agreements such as the Kyoto Protocol are important steps toward combating climate change, but this is a very long-term solution which will probably not prevent some increase in temperature from occurring. Even a small increase can have substantial impact on fragile ecosystems, especially in areas that are threatened on other fronts. In our own backyard, unique plant and animal habitats have been destroyed or are threatened by the ongoing development of human communities. While environmental scientists must continue to push for change in resource consumption and fuel use on the global level, Californians need to make difficult decisions today in order to preserve rare habitat (such as coastal sage scrub) and species (such as the gnatcatcher or one of the other 358 endangered species in the state).
Growth limits can have positive impacts on both the natural environmental and human communities. Development moratoriums allow the preservation of natural landscapes, as well as higher quality of life of urban and suburban residents. Excessive growth tends to strain government and community resources as they do natural resources. In enacting growth limits, however, Californians must ensure that they do not end up with "ring cities," like those seen around Portland and Boulder, which defeat the purpose of growth limitations.
Redevelopment within urban areas also has the potential to assist in habitat preservation. The state expects California's population to reach 58 million by 2040. Redeveloping urban cores, in the dense patterns seen in Eastern and European cities, can help minimize the land use impact of population growth.
Reform of risk management policies can also help to preserve fragile habitat. Coast sage scrub, a unique type of habitat in southern California, is threatened by development more immediately than climate change. These habitats are generally located along beach areas, which are vulnerable to natural phenomenon. The floods and fires experienced in Malibu during recent years will continue to be a common occurrence if Californians persist in developing these dry coastal zones. Currently, the bailouts that have been offered through FEMA and the state provide incentive to build in these sensitive areas. Reform of these policies, with cooperation from the insurance industry, could provide a deterrent to growth. The risk management industry might also take a lead role in warning of the potential for property damage from climate change. However, flood insurance in the U.S. is provided by the federal government, which eliminates that market incentive that insurance companies might have to try to prevent rising waters in coastal areas.
Other actions important to California's ecosystems are establishing more reserves, funding restoration projects, and controlling non-native species invasions. Each of these actions, however, may prove useless, if climate change trends are not stopped.
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