The Children's Theatre Ed Pack (2007)
Science - Page Two
Science in the News
Using the following two articles entitled:
- Global Warming: We’re all to blame for the scourge
Warming by 2°C ‘risks damage’: Cause of drought
- Global Warming
and the Science in the News table look for the science words and ideas used in the article, the procedures, attitudes and values, and the effects on our lives and how we live. Here are some examples:
Science words and ideas: carbon dioxide, greenhouse effect, etc
Science procedures: scientists collect ice cores
Attitudes and values: (can be implicit or explicit) global warming concerns people
Effects on our lives and how we live: flooding, storms, loss of islands, etc.
Use the table to note these things down and think about some questions that would need to be asked as well as how you could find the answers out.
Global Warming: We’re all to blame for the scourge
Warming by 2°C ‘risks damage’: Cause of drought
Sunday Times (Perth)
Dr. Neville Nicholls
Copyright 2007 News Ltd. All rights reserved.
All nations must accept responsibility for the heating of the planet – and the consequences. Dr. Neville Nicholls explains the facts behind the crisis.
What is global warming?
Global warming is the heating of the atmosphere near the surface of the Earth by increases in greenhouse gases due to human activities, such as burning fossil fuels (oil, coal, gas).
The Earth’s temperature has risen about 0.74°C in the past 100 years, mainly because of these gas increases.
What is the “greenhouse effect” and what are greenhouse gases?
Greenhouse gases include carbon dioxide, methane, and water vapour. They keep the surface of the Earth warmer than if they were not present in the atmosphere.
This is the “natural” greenhouse effect. Without this effect, life on Earth would be very different.
Are global warming and the greenhouse effect linked?
Yes, global warming is the result of strengthening of the greenhouse effect by increases in the amount of greenhouse gases.
Is global warming a man-made phenomenon or simply the natural evolution of our planet?
Warming in the past 100 years is mainly due to increases in greenhouse gases from human activity, especially the use of fossil fuels.
The climate and Earth’s temperature varies naturally also, but the increases in greenhouse gases are a strong influence on the climate.
Why are there such divergent opinions in the scientific community about global warming?
Most atmospheric scientists agree about the reality of the greenhouse effect and that increases in greenhouse gases lead to warming.
There is still uncertainty about how much warming will result from continuing greenhouse gas emmissions.
This uncertainty leads to quite broad ranges of predictions about how much warming there might be by the end of the century. These range from about 1°C to 4°C.
How has global warming caused a hole in the ozone layer?
The hole is caused by chemical processes linked to human activities and the release of gases used for refrigeration and in aerosol cans.
These gases contribute a little to the increased greenhouse effect, but the destruction of the ozone layer is mainly a separate question to global warming.
Why is the hole above Antarctica and why does it continually contract and expand?
The answer to this is complex, but it is due to very low atmospheric temperatures above Antarctica in winter and the unique chemical processes related to this chilling.
Will coastal South Australia be submerged this century by rising sea levels, as some global warming experts predict?
The ocean expands when it warms. The melting of glaciers caused by warmer temperatures also increases sea levels.
The rise in sea levels expected by the end of the century is between about a quarter and a half a metre. This would lead to flooding in some low-lying coastal areas.
What are the Kyoto Protocols and how are they meant to fight global warming?
The protocols were contained in a diplomatically negotiated agreement by many nations to cut future greenhouse gas emissions. The cuts agreed to were modest, but they would slow the rate of global warming.
Why didn’t China and India sign at Kyoto?
The reductions in greenhouse gas emissions agreed to in Kyoto were to be binding for developed countries, which have produced most of the extra greenhouse gases in the atmosphere so far.
Once the developed countries had “done their bit” to reduce global warming, the developing countries, such as China and India, were expected to also start cutting emissions or greenhouse gases as their economies grew.
Why has Prime Minister John Howard been so slow to embrace the concept of global warming?
Mr. Howard and his Government do, clearly, accept the reality and science of global warming – and that human influences are causing the Earth to warm.
If all the world’s gas-generating power stations were turned off tomorrow, how long would it take before it affected global warming?
Carbon dioxide remains in the atmosphere for a long time, so warming would continue for several decades, even if we stopped all activities creating greenhouse gases. But the rate of warming would definitely slow.
Has global warming increased temperatures on Earth in the past 50 years? If so, by how much?
The Earth has warmed about 0.65°C in the past 50 years. Most, perhaps all, of this warming is due to increases in greenhouse gases from human activity.
How much do temperatures have to increase before it becomes a significant issue?
Some scientists believe a warming of about 2°C would cause substantial damage to the planet. There is a great deal of evidence that warming has already affected the flowering plants and animal breeding times.
How much have sea levels risen due to global warming?
Sea levels, averaged across the Earth, have increased by about 8cm in the past 40 years.
Can global warming really melt icebergs and flood cities as depicted in disaster movies?
If warming continues, the ice sheet on Greenland would melt. This would raise sea levels about 6m, causing widespread coastal flooding.
However, this is not expected soon. Sea levels were about 5m higher now than 125,000 years ago when the Earth was about 4°C warmer.
What effect will global warming have on plant and animal life?
If warming is not too fast, much plant and animal life would adapt to changes in climate. But some species would be vulnerable, even to small temperature increases, including animals used to cold mountain temperatures. Large increases in sea levels would have a devastating effect on coastal life.
How accurate is computer modelling of global warming?
Computer models of the climate are much better than computer models of the economy and have improved in the past decade.
This is one reason why projections of warming have such a large range. But the general understanding of the greenhouse effect was worked out in laboratory experiments many years ago.
Computer models confirm this understanding and provide more detail, such as where rainfall might change, though rainfall projections are more uncertain than temperature predictions.
Our understanding of the greenhouse effect and global warming does not depend on models, but getting details right depends on improving the models.
Is Australia’s drought linked to global warming?
Many climate models predict that increasing greenhouse gases should lead to drying along the south coast of Australia.
However, the main cause of the intense droughts Australia suffers, including the drought this year, is the El Nino phenomenon.
We don’t know if El Nino will get worse with global warming.
How will global warming, as it is accepted today, affect the way we live in, say, 50 years?
The world would be warmer and some coastal areas would be flooded. There would likely be more hot days and heatwaves each year and fewer colder days.
There should be more heavy rainfall. Changes in rainfall will cause changes in farming practices.
The competitiveness of our farming may change as the cold areas of Russia and Canada warm up and become more productive.
Isn’t warming caused by cities getting bigger and measurement being made in urban areas?
We also have temperature measurements from rural sites well away from cities, from small islands in the middle of oceans, and sea-surface temperatures.
All these show warming. As well, sea ice is retreating, glaciers are melting almost everywhere and the amount of snow is decreasing.
This indicates that warming is widespread, pervasive, and not just restricted to the cities.
Could the warming be happening because the sun is getting more intense?
We now have several decades of observations of the energy being received from the sun. There is no evidence that the radiation we receive from the sun has increased, but the world has warmed during this period. So the warming is not caused by the sun becoming more intense.
Do volcanoes affect global temperature?
When Mt. Pinatubo erupted in the Philippines, the global temperature cooled about half of a degree and stayed low for a few years.
So if we had a series of severe volcanic eruptions this would offset the warming caused by the greenhouse gases.
Together, volcanoes and solar variations have probably caused cooling in the past 50 years, reducing the warming that has been caused by the increase in greenhouse gases.
Do other human activities affect the climate?
Changing land use, such as clearing forests for agriculture, does affect local climate, but there is no agreement on whether it affects global climate.
Industrial pollution and aerosol gases cool the Earth, offsetting some of the warming caused by increases in greenhouse gases. They probably caused the cooling seen between 1950 and the 1970s.
**Dr. Neville Nicholls is a the School of Geography and Environmental Science at Monash University, Victoria. He spent 35 years in the Bureau of Meteorology Research Centre where he conducted research on El Ninos, climate prediction and climate change. He led the Bureau’s research group on climate prediction for two decades and has published about 150 scientific papers.
Global Warming
Whalley, K., Neville, C., Roberson, P., & Rickard, G. (2005). Science Focus 4. Melbourne: Pearson Education Australia.
Scientists have investigated climate change for several decades. It is only recently that they have looked at its likely impact on specific locations.
THE GREENHOUSE EFFECT
The greenhouse effect is caused by the gas carbon dioxide together with other trace gases in the atmosphere. These gases, commonly called greenhouse gases, provide a ‘blanket’ that keeps the Earth warm. Too little carbon dioxide and the planet would be too cold to sustain life. Too much, and the resulting high temperatures would also be unsuitable for life. The greenhouse effect is natural and is required for the continued survival of all Earth’s species.
A car left in the sun on a fine day can become very unpleasant inside. The temperature can easily reach 50°C even when the temperature outside is only between 20°C and 30°C. Heat enters the car easily, but much of the heat cannot escape. For this reason, animals and young children should not be left in cars: these high temperatures can kill. The greenhouse effect could well have been called the ‘hot car effect’, but it is named after greenhouses that trap heat from the sun to help plants grow more quickly.
How does it work?
Carbon dioxide and other gases in the atmosphere behave like the glass in a greenhouse or car windows. Energy from the Sun reaches the Earth as electromagnetic waves with a short wavelength. These waves are able to pass through the atmosphere (and glass). The energy is absorbed by the Earth and re-emitted into the atmosphere as long-wavelength radiation. Carbon dioxide (and glass) effectively blocks the transmission of long-wavelength radiation, stopping it from reaching space. Much of this energy is therefore trapped in the atmosphere, warming the Earth to a temperature suitable for life. If not for the greenhouse effect, the Earth would be about 30°C colder on average!
THE ENHANCED GREENHOUSE EFFECT
Over the past century the levels of greenhouse gases in the atmosphere, particularly carbon dioxide, have increased. The blanket of greenhouse gases in the Earth’s atmosphere has effectively become thicker. This results in the enhanced greenhouse effect, where the same amount of heat energy is coming from the Sun, but less is escaping back into space. The enhanced greenhouse effect is leading to global warming, increasing the average temperature of the Earth.
Hanging around
Greenhouse gases remain in the atmosphere for many years. Carbon dioxide persists for more than 100 years.
EVIDENCE IN THE ICE
Scientists collect ice cores from Antarctica by drilling into the ice. The deeper you go into the ice, the older the ice is, as new snow falls on top each year. When the snow falls, air bubbles are trapped in the ice. Analysis of these trapped gases reveals the amount of carbon dioxide present in the atmosphere in the past. So far scientists have drilled down 3.27km, which means we have data about carbon dioxide levels going back roughly 900,000 years.
It is normal for the levels of carbon dioxide to go up and down, but the amount of carbon dioxide in the atmosphere is now at its highest level ever. The Earth’s temperature changes when the amount of carbon dioxide in the air changes.
THE FUTURE
Over the past 100 years or so, the Earth’s average surface temperature has increased by about 0.5°C and a further increase between 1°C and 4°C is expected by the end of this century. Such a rise, though seemingly small, is enough to raise sea levels by an estimated half a metre – possibly up to a metre – and cause flooding of low-lying coastlines due to the increase of water in the oceans and melting of land ice. Many of the island nations in the Pacific and Indian Oceans would virtually disappear.
Predicting local effects
We do not fully understand the implications of global warming for society and the environment. Some regions will be drier, some wetter, some cooler and most will be hotter. We can also expect more storms, droughts, floods, hurricanes and temperature extremes.
Australian Scientists predict that some of the following changes may occur:
 | The melting of much of the polar ice caps will raise sea levels, flooding coasts, cities and some entire island countries. |
| Liquid water expands slightly when warmed and so the oceans will expand, also raising sea levels, causing further flooding. |
| Increases in the numbers of wild storms and cyclones. Cyclones could move further south. |
| More droughts and heat waves. |
| More bushfires. |
| Less rain and snow. Managing and saving water will become important. |
| Habitats will change, causing the extinction of some plants and animals. |
| Increased temperatures may cause bacteria to grow faster, causing more diseases in humans and other organisms. |
| Some plants may grow faster with higher temperatures. This would be good for farmers, but less rain may mean fewer plants grow and fewer varieties can survive. |
| Increased heat may cause more heat stroke and illness. |
(Whalley, K., Neville, C., Roberson, P. & Rickard, G. (2005). Science Focus 4. Melbourne: Pearson Education Australia.
Aim
To simulate conditions required for the greenhouse effect.
Small cardboard box (eg. shoe box)
2 thermometers
sheet of glass or polythene plastic
lamp
1. Assemble the apparatus as shown in figure.
2. Turn on the lamp and measure the temperature at regular intervals (eg. every minute) for 10 minutes.
3. Turn off the lamp, but continue to measure the temperature for another 10 minutes.
4. If time permits, investigate the effect of an additional layer of glass or plastic.
1. Construct a graph showing temperature versus time for each section of the box.
2. Summarise any differences in the temperature patterns in each section.
3. Describe what takes the place of the glass or plastic sheet in the global greenhouse effect.
Identify what adding another layer of glass or plastic represents if modelling the Earth.