P2c(ii) Global Warming

You will learn about:What causes global warming

The differences of opinion about how to deal with global warming

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Increase of Greenhouse GasesThere are many anthropogenic, or manmade, means causing

an increase in greenhouse gases in our atmosphere.

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Anthropogenic means

Burning fossil fuels

Waste incineration

Deforestation

Cement manufacture

Increased energy use

CO2 and CH4 emissions

Natural Occurrence?The greenhouse effect is a natural occurrence caused by our atmosphere trapping the Sun’s infrared radiation. Without it our planet would be about -18°C. Unfortunately, there are natural and anthropogenic ways of increasing our planet’s temperature further.

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The Kyoto protocol was set up to reduce CO2 emissions by 5.2% by 2012. By 2010 nearly all countries had signed up. The map on the right shows in green which countries did sign. USA produces some of the world’s most CO2 emissions but have not signed the Kyoto protocol.Scientists need to monitor the temperature of Earth but it is difficult because the temperature keeps changing all of the time.

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The dust particles produced by power stations reflect radiation from towns and cities back down to the Earth increasing the temperature.

The ash from a volcano reflects radiation from the Sun back up into space causing the temperature on earth to drop.

Don’t believe everything you read!This is the famous photograph published by the Canadian Wildlife Agency. Al Gore, the Vice-President of United States pictured at middle, scientists and many newspapers used this image to convince people that global warming was happening and that the dangers were evident to see.However, polar bears can swim hundreds of miles and were in fact in no threat at this time. The image was taken in the Summer when the ice floes melt naturally.

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What can you do?Lots of scientific data supports the notion that the earth IS getting warmer. Photos of receding glaciers and floods are just a couple of pieces of evidence. The top image shows a glacier receding after a few decades.Dr. Peter Scott, in 2010 bottom image, looked at all the evidence and concluded that the sea ice was melting in the Arctic and that ocean temperatures were warming. He said it was due to man-made emissions.

Other evidence says the opposite. In 1936 some parts of the United States had 49 consecutive days of temperatures above 30°C. In 1992 there were only five and in 2002 only three. Does this mean that the earth is actually cooling down?

So what should we do? Which scientists should we be listening to?Do they have an agenda or not?It is difficult to be exactly sure.

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Data…againGreenhouse Gas % of Greenhouse Effect % Natural % Man-Made

Water Vapour 95.000 94.000 0.001

CO2 3.618 3.502 0.117

CH4 0.360 0.294 0.066

Other 1.022 0.928 0.094

Total 100.000 99.723 0.278

www.PhysicsGCSE.co.uk If we use the statistics for water vapour in our greenhouse effect analysis we see a very different picture.

The carbon dioxide contribution from humans is just over 0.1%.The total human contribution is under 0.3%.

The argument is anyone’s to win.On the one hand these percentages show just how insignificant our percentages are and that these are within normal statistical values.On the other hand it is hard to ignore the physical reality that the ice caps ARE melting faster than ever and that sea levels are rising as a consequence. And all this since the Industrial Revolution…Which side do you stand?

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Global sea level rose about 17 centimeters (6.7 inches) in the last century. The rate in the last decade, however, is nearly double that of the last century.

Read about for yourself at:http://climate.nasa.gov/evidence/

The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's Gravity Recovery and Climate Experiment show Greenland lost 150 to 250 cubic kilometers (36 to 60 cubic miles) of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic kilometers (36 cubic miles) of ice between 2002 and 2005.

Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades.

The number of record high temperature events in the United States has been increasing, while the number of record low temperature events has been decreasing, since 1950. The U.S. has also witnessed increasing numbers of intense rainfall events.

Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased by about 30 percent.This increase is the result of humans emitting more carbon dioxide into the atmosphere and hence more being absorbed into the oceans. The amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by about 2 billion tons per year.What do you think???

Questions

1. Why are so many scientists concerned with reducing greenhouse emissions?

2. Do you think politicians like Al Gore should be using images, like the polar bears, to get their point across?

3. Do you feel that the 0.278% value of man-made greenhouse emissions is anything to worry about?

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Questions1. Why are so many scientists concerned with reducing greenhouse emissions?

It is difficult to ignore the rise in sea levels, erratic weather patterns, higher global temperatures, receding ice caps, migration of fish and flooding around the world. Link this with the extra energy we now use

and it makes scientists think perhaps we should be accountable for it all. If this continues what will the world be like in the future?

2. Do you think politicians like Al Gore should be using images, like the polar bears, to get their point across? You could argue yes and no.

Yes because it highlights the overall issue. And no because it is morally wrong as the image showed nothing of relevance.

3. Do you feel that the 0.278% value of man-made greenhouse emissions is anything to worry about? You could argue this any way. Yes because we can see the effects of this. And no because it is such a small amount.

www.PhysicsGCSE.co.uk You would have noticed that in answering these questions you will be asked to make an argument from both sides. Scientists agree that the greenhouse effect exists but as to what the effect of humans have is very debatable!