Analysis- Global Warming

NEW YORK TIMES
http://topics.nytimes.com/top/news/science/topics/globalwarming/index.html#

Claim: Global warming, whether humans have more to do with its cause, is affecting the planet and changes will continue to happen- temperatures will continue to rise- for years to come.

Data/ Evidence: -United Nations claimed that human activity has much to do with global warming.
-Intergovernmental Panel on Climate change found that humanity had likely played a role in the build up of global warming.
- Carbon Dioxide and other heat-trapping gases played a role in rising the surface temperature by more than one degree F, since 1990.
-“Supreme court made its first global warming decision- Environmental Protection Agency had not justified its position that it was not authorized to regulate Carbon Dioxide.”
- “Gases like carbon dioxide and methane allow sunlight to reach the earth, but prevent some of the resulting heat from radiating back out into space.”
- “But as ever larger amounts of carbon dioxide have been released along with the development of industrial economies, the atmosphere has grown warmer at an accelerating rate: Since 1970, temperatures have gone up at nearly three times the average for the 20th century.”
-“The climate panel predicted that the global climate is likely to rise between 3.5 and 8 degrees Fahrenheit if the carbon dioxide concentration in the atmosphere reaches twice the level of 1750. By 2100, sea levels are likely to rise between 7 to 23 inches.”

Assumptions that Warrant the evidence:
- The author of the source believes that the organizations/influential groups cited for their opinions and predictions about global are credible and reliable. Also with the evident data that the author of the source itself includes, the assumption for this data being important in supporting the claim is that the statistics of rising numbers in temperature and sea levels are factual and logical to the reader.


Science Daily:
http://www.sciencedaily.com/releases/2008/03/080325141202.htm

Claim: Climate change will irreversibly alter water circulation in Lake Tahoe in the next ten years; drastically changing the conditions for plants and fish in the lake.

Data/Evidence:
- At the Tahoe scientific conference the new findings of global warming’s affects on the lake and the life within it were announced by three lake experts from the Tahoe Environmental Research Center at UC Davis.
- One of the experts stated that he expected “deep mixing of Lake Tahoe's water layers will become less frequent, even non-existent, depleting the bottom waters of oxygen. This will result in major, permanent disruption to the entire lake food web, leading to Anoxia (oxygen depletion).”
- Another expert believed that “lowered global greenhouse-gas emissions would significantly slow the lake's decline, or even prevent it”.

-December 2004, the experts reported that the lake was showing a new influence. The waters were getting warmer. The experts deduced that it was because of a global climate change. Its water was warming up, probably because of global climate change. Their assumption is backed by 40 years of weather data in the basin and logical/mathematical models of global climate.
- The scientists who have studied the lake closely released a new study that if global greenhouse-gas emissions continue at current levels, mixing could become less frequent and less deep -- even stop altogether as soon as 2019. The mixing of the lake “has profound ecological and water-quality impacts. Deep mixing moves nutrients from the lake bottom to the water surface, where they promote the growth of algae. And it takes oxygen from the surface and distributes it throughout the lake, which supports aquatic life.”
- If the mixing stops new oxygen will not be able to get to the bottom of the lake and creatures will die. As well as the phosphorous at the bottom of the lake that would rise and cause and algae bloom, this has many ecological problems in itself.
- The problems in this specific lake are happening all around the world.

Assumptions that Warrant Evidence:
- The source includes direct evidence and data found by the actual scientists who have been deeply affiliated with Lake Tahoe itself. The source must believe that the source, in which the evidence is found, is credible. With the credibility/reliability of the scientists, the sources own data and evidence is taken to be credible as well. Overall the evidence and data is pertinent to the argument that global warming is affecting our lakes.



Global Warming - an Overview BBC
http://www.bbc.co.uk/weather/features/global_warming1.shtml

Claim: “…man is adding to and changing the levels of the gases responsible for the greenhouse effect and is therefore enhancing this warming.”
Data:
- 'Greenhouse effect' is a natural and essential feature of our atmosphere without which our planet would be unable to live on. The greenhouse effect works by atmospheric gases that permit short wave radiation from the sun to pass through them, not being absorbed. However, at the same time absorbing some of the long wave radiation reflected back to space. Thus more heat is received from the sun than is lost, which keeps the earth's surface 30 to 35C warmer than it would be.
- “Globally 1998 was the warmest year ever recorded and eight of the ten warmest years fell in the last decade.”
- “Global ice sheets have decreased, so has global snow cover.”
- However the time now is the most rapid change in temperature since the Ice Age.
- CO2 is the gas most responsible for the causing global warming.
- “The combustion of fossil fuel (oil, natural gas and coal) by heavy industry and other human activities, such as transport and deforestation, are the primary reasons for increased emissions of these gases.”
- Scientist’s simulations determine that global temperature will rise approximately 3 degrees in the next generation. However, the difference between average global warming temperatures now and the last ice age is only 6 to 8C.
- The Simulations also predict changes in rainfall and continued rise in sea level. Sea level rises will be due to thermal growth of the ocean as well as with the melting glaciers and mountain snow/ice. (estimate is 50cm by 2100)
Assumptions that Warrant Evidence:
- The evidence given as whole was relevant to global warming and how humans have contributed to the rise in temperatures. The data proved what global warming is and what gas emissions specifically cause the earth’s surface temperature to increase. The source itself is a credible Broadcast Meteorologist, as stated prior to the actual article. So the evidence given by the source must also be reliable.