Freshwater lakes and rivers contributing to climate change

Variant I

Control work

Список использованных источников

1. Современные экологические проблемы: Сборник текстов на английском языке / Авт.-сост.: М.Н. Макеева, Л.П. Циленко, А.А. Гвоздева. Тамбов: Изд-во Тамб. гос. техн. ун-та, 2004. 96 с.

2. Don Hinrichsen. Ocean Planet in decline // People and the planet. 2005. 35-44 p.

Amanda Chui. Ocean Planet in decline // People and the planet. 2007. http://www.peopleandplanet.net/?lid=26460&section=45&topic=44

3. http://www.peopleandplanet.net/images/greenhouseeffect.html

4. "Millennium Ecosystem Assessment - Synthesis Report". United Nations. 2005. http://www.millenniumassessment.org/en/Synthesis.aspx.

5. The Moscow News.№38 26 September-2 October 2008 Ocean Debris will likely worsen.

6. The Moscow News.№19 16-22 May 2008 Lake Baikal faces multiple threats.

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Read the text and answer the questions

Methane emissions from lakes and rivers are a significant factor in the greenhouse gas cycle, claims a new study in Science which urges climate scientists

and policy-makers to pay it closer attention.

The 'other' greenhouse gas, as it is sometimes known, is regularly left out of the public discourse on climate change - one usually dominated by discussions of carbon dioxide (CO2). It makes up a small portion of the atmosphere in comparison to CO2 but is 20-30 times more potent in its ability to absorb infrared energy and contribute to the global warming effect.

As well as natural sources like wetlands and lakes, methane is also emitted from industrial sources and agriculture (rice fields and livestock).
Scientists from Sweden, Brazil and the US investigated methane emissions from 474 freshwater systems and explained their 'previously neglected' role in recycling the carbon absorbed by the land. The natural landscape absorbs carbon dioxide but decaying trees, vegetation and plant matter in water systems then produce significant amounts of methane and CO2 emissions.

“Our accounting system is focused solely on land and trees but the landscape is bigger than that and we should be taking account of the role freshwater systems play in the greenhouse gas cycle,” said lead study author David Bastviken from Lopatking University, Sweden.

The study estimated total emissions of methane from freshwater systems to be 103 million tones per year - the equivalent to 25 per cent of all the carbon dioxide absorbed by the world's land areas.

However, Bastviken dismissed suggestions that climate engineering solutions could be used to negate methane emissions from lakes and rivers. “It seems much better to focus our efforts on reducing fossil fuel emissions which are the main problem. Large scale ecosystem engineering would be shifting the attention away from the real problem and is dangerous and not very cost-effective in this case,” he said.

1. What is the role of freshwater system in greenhouse gas cycle?

2. Where is methane emitted from? Describe the process.

3. What are the most dangerous emissions which contribute to global warming?

Are the statements true or false?

1. Fossil fuels emissions are more dangerous than methane.

2. Decaying vegetation does not produce any harmful emissions.

3. The absorbed by land carbon dioxide is completely recycled.

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