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Is UV-B radiation a factor in the decline of frogs and other amphibians?

Last updated 18 January 2002
Originally answered 18 January 2002

Full Question

Is UV-B radiation a factor in the decline of frogs and other amphibians?

Answer

According to the 1998 United Nations Environment Program Assessment: Environmental Effects of Ozone Depletion:



“Possibly. Amphibian populations are in serious decline in many areas of the world, and scientists are seeking explanations for this. Most amphibian population declines are probably due to habitat destruction or habitat alteration. Some declines are probably the result of natural population fluctuations. Other explanations for the population declines, as well as the reductions in range of habitation, include disease, pollution, atmospheric changes and introduced competitors and predators. UV-B radiation is one agent that may act in conjunction with other stresses to adversely affect amphibian populations. Field studies in which embryos of frogs, toads, and salamanders were exposed to natural sunlight or to sunlight with UV-B radiation removed have shown conflicting results. Some studies resulted in increased embryonic mortality after UV-B exposure, whereas others show that current levels of UV-B radiation are not detrimental. Factors such as water depth, water colour, and the dissolved organic content of the water at the sites of egg deposition effectively reduce UV-B penetration through the water and reduce exposure to UV-B radiation at all life history stages. Biotic factors, such as jelly capsules around eggs, melanin pigmentation of eggs, , and colour of larvae and metamorphosed forms, further reduce the effects of UV-B exposure.”


The above entry is posted under the following topic(s): Impacts of Ozone Depletion

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Does water protect aquatic organisms from UV exposure?

Last updated 17 January 2002
Originally answered 17 January 2002

Full Question

Does water protect aquatic organisms from UV exposure?

Answer

Well, according to FAQ # 9 from the “Frequently Asked Questions about Stratospheric Ozone Depletion” published in “Environmental Effects of Ozone Depletion: 1998 (United Nations Environment Program Assessment), (see: http://www.gcrio.org/ozone/toc.html), not necessarily. It depends on how clear the water is, and where in the water column the organism lives.

“No. Pure water is quite transparent to UV radiation; a beam of UV-B radiation must travel over one-half kilometre through pure water in order to be completely absorbed. Natural waters do contain UV-absorbing substances, such as dissolved organic matter, that partly shields aquatic organisms from UV-B, but the degree of shielding varies widely from one water body to another. In clear ocean and lake waters ecologically-significant levels of UV-B can penetrate to several tens of meters; in contrast, in turbid rivers and wetlands UV-B may be completely absorbed within the top few decimetres. Most organisms in aquatic ecosystems, such as phytoplankton, live in the illuminated euphotic zone close to the water surface where exposure to UV-B can occur. In particular, UV-B radiation may damage those organisms that live at the surface of the water during their early life stages.”


The above entry is posted under the following topic(s): Impacts of Ozone Depletion

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Excluding fossil fuel combustion, how else do humans affect the carbon cycle?

Last updated 15 November 2001
Originally answered 15 November 2001

Full Question

Excluding fossil fuel combustion, how else do humans affect the carbon cycle?

Answer

Data on CO2 emissions from all sources, including cement manufacture, can be found in the Environmental Protection Agency (EPA) report “EPA Inventory (2002) of U.S. Greenhouse Gas Emissions & Sinks: 1990-2000” http://www.epa.gov/oppeoee1/globalwarming/publications/emissions/us2002/index.html, especially Chapter 3. Industrial Processes
http://www.epa.gov/oppeoee1/globalwarming/publications/emissions/us2002/industrial_processes.pdf

These other sources also have CO2 emissions data and information:

Carbon Dioxide Information Analysis Center.
http://cdiac.esd.ornl.gov/by_new/bysubjec.html#carbon

International Energy Agency, Greenhouse Gas Research & Development Programme.
A conference report- Emission Reduction of Greenhouse Gases from the Cement Industry
http://www.ieagreen.org.uk/prghgt42.htm

News report on an article in Science, Oct. 2000. “Humans Altered Global Carbon Cycle In Last 200 Years”
http://www.climateark.org/articles/2000/4th/hualglcc.htm


The above entry is posted under the following topic(s): Emissions data and trendsGlobal Carbon CycleHuman Contributions and Responses

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How do human activities affect global climate?

Last updated 25 April 2000
Originally answered 25 April 2000

Full Question

Could you please describe some of the important lines of evidence that support the idea that human activities are affecting global climates? what are some of these human activities?

Answer

For a good introduction to the causes and impacts of global change, take a look at the online publication “Common Questions about Climate Change” that was published in 1997 by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO).

There is a section of this publication covering human activites contributing to climate change, and how we know that the increase in atmospheric levels of greenhouse gases is due to human activity.

The US National Academy of Sciences published “Climate Change Science: An Analysis of Some Key Questions” in the summer of 2001.

Another source you might want to look at is the “Questions and Answers” box on the USGCRP Educational Resources page.

Highlights of recent and planned research on Human Contributions and Responses to global environmental change are addressed in the chapter on Decision-Support Resources Development and Related Research on Human Contributions and Responses of Our Changing Planet: The U.S. Climate Change Science Program for Fiscal Year 2006.

The full report is available online in both HTML and PDF formats. You can also order a copy of the report, free of charge, as either a hardcopy report or CD-ROM from the GCRIO Online Catalog.


The above entry is posted under the following topic(s): Global Change ScienceHuman Contributions and Responses

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How might climate change affect flooding, especially in North Carolina?

Last updated 18 April 2000
Originally answered 18 April 2000

Full Question

How might climate change affect flooding, especially in North Carolina?

Answer

The USGS, Water Resources of North Carolina.
http://nc.water.usgs.gov/
They have historic streamflow data if you’re planning to do your own statistical analysis. A new addition to the site, is Flooding in Eastern NC. This site is still under construction but you may find some useful resources or contacts.

The US EPA Global Warming site has information on the potential impact of climate change on coastal zones, and on each state.
http://www.epa.gov/globalwarming/impacts

Floods As Usual. Academic Press.
http://www.apnet.com/inscight/12091997/grapha.htm
A news report covering a research talk from the 1997 fall AGU (American Geophysical Union) meeting. Researchers from the USGS presented data supporting the view that recent flooding was not an abnormal climate pattern. This should be a good lead for finding some published papers about this research.

The National Climatic Data Center.
http://www.ncdc.noaa.gov/ol/climate/globalwarming.html

Global Warming and Changes in Flood Potential.
http://www.ncdc.noaa.gov/rcsg/wflooding/gwcfp.html


The above entry is posted under the following topic(s): Hydrology & Water ResourcesRegional Impacts

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