A community of 30,000 US Transcriptionist serving Medical Transcription Industry
Most climate scientists agree the main cause of the current global warming trend is human expansion of the "greenhouse effect"1 -- warming that results when the atmosphere traps heat radiating from Earth toward space.
Certain gases in the atmosphere block heat from escaping. Long-lived gases, remaining semi-permanently in the atmosphere, which do not respond physically or chemically to changes in temperature are described as "forcing" climate change whereas gases, such as water, which respond physically or chemically to changes in temperature are seen as "feedbacks."
Gases that contribute to the greenhouse effect include:
|
|
|
On Earth, human activities are changing the natural greenhouse. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2. To a lesser extent, the clearing of land for agriculture, industry, and other human activities have increased concentrations of greenhouse gases.
The consequences of changing the natural atmospheric greenhouse are difficult to predict, but certain effects seem likely:
The role of human activity
In its recently released Fourth Assessment Report, the Intergovernmental Panel on Climate Change, a group of 1,300 independent scientific experts from countries all over the world under the auspices of the United Nations, concluded there's a more than 90 percent probability that human activities over the past 250 years have warmed our planet.
The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels from 280 parts per million to 379 parts per million in the last 150 years. The panel also concluded there's a better than 90 percent probability that human-produced greenhouse gases such as carbon dioxide, methane and nitrous oxide have caused much of the observed increase in Earth's temperatures over the past 50 years.
They said the rate of increase in global warming due to these gases is very likely to be unprecedented within the past 10,000 years or more. The panel's full Summary for Policymakers report is online at http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr_spm.pdf.
Solar irradiance
It's reasonable to assume that changes in the sun's energy output would cause the climate to change, since the sun is the fundamental source of energy that drives our climate system.
Indeed, studies show that solar variability has played a role in past climate changes. For example, a decrease in solar activity is thought to have triggered the Little Ice Age between approximately 1650 and 1850, when Greenland was largely cut off by ice from 1410 to the 1720s and glaciers advanced in the Alps.
But several lines of evidence show that current global warming cannot be explained by changes in energy from the sun:
For all the doubters out there. Can you honestly say there are no immediate health hazards to humans across the globe RIGHT NOW behind manmade emissions, or is this your idea of God's handiwork?
http://www.flickr.com/photos/chaspope/8373014234/
The scene this AFTERNOON in Beijing, where the pollution index at the US Embassy reached the astonishing level of 728 755 (including 804 886 parts per million of PM2.5). Even the local Chinese monitoring stations have been reporting indexes of 500 (at which point the scale breaks) across the North China Plain. The high pollution levels are predicted to last up to three days. This image - untouched in Photoshop - should be showing the CCTV and TVCC towers, around 500m away.
The cost of doing business without air quality regulations. Beijing's government's solution? Wear an air mask.
http://ww4report.com/node/11848
Tehran's pollution killed 4,460 in 2012. Evacuation of Isfahan on Jan 2 was urged for its 1.5 million. Tehran (population around 14 million) had a similar evacuation around Thanksviging on account of its annual pollution "buildup."