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Fact or Fiction: How much do you know about Climate Change?

 
 

- Climate change is not happening.

- Climate change and the loss of the ozone layer are not the same thing.

- Climate change is nothing to do with humans.

- Carbon dioxide only makes up a small part of the atmosphere and is responsible for global warming.

- Rises in CO2 occur after global warming, not before.

- The sun getting hotter is changing the temperature.

- The impacts of Climate change are exaggerated.

- Computer models which predict the future climate are unreliable.

 
 

- Climate change is not happening.

False. Climate change is a reality. The IPCC synthesis report 2001, shows that the earth warmed between 1900 and 1940, then subsequently cooled between 1941 and 1965, but surface temperatures have been warming ever since. Data from millions of thermometer measurements taken from all over the world from as far back as 1860, allow calculation of average surface air temperatures. This data is believed to be the most useful when describing the state of the global climate. It can be seen that 1998 is the warmest year on record, with the ten warmest all occurring since 1990.

- Climate change and the loss of the ozone layer are not the same thing.

True. Climate change and the loss of the ozone layer are two different problems that are not very closely connected.
The largest contributor to global warming is carbon dioxide gas released when coal, oil, and natural gas are burned. CFCs, gases which cause stratospheric ozone depletion, play only a minor role in climate change. The depletion of the stratospheric ozone layer, including the ozone hole, is a serious environmental problem because it causes an increase in ultraviolet radiation which can harm people, animals, and plants. This is a different problem from the problem of climate change.

- Climate change is nothing to do with humans.

False. It is true that the world has experienced warmer or colder periods in the past without any interference from humans. The Earth's climate is complex and influenced by many things - particularly changes in the Earth's orbit in relation to the Sun, as well as volcanic eruptions and variations in the energy being emitted from the Sun. But even when we take all these factors into account, we cannot explain the temperature rises that we have seen over the last 100 years.
So what is causing this increase in average global temperature? The natural greenhouse gas effect keeps the Earth around 30°C warmer than it would otherwise be and, without it, the Earth would be extremely cold. It works because greenhouse gases such as carbon dioxide, methane, but mostly water vapour, act like a blanket around the Earth. Any increases in the levels of greenhouse gases in the atmosphere mean that more heat is trapped and global temperatures increase - an effect known as 'global warming'. It has been alleged that the increased level of carbon dioxide in the atmosphere is due to emissions from volcanoes, but these account for less than one per cent of the emissions due to human activities.


- Carbon dioxide only makes up a small part of the atmosphere and is responsible for global warming.

True. Carbon dioxide only makes up a small amount of the atmosphere, but even in tiny concentrations it has a large influence on our climate.
The properties of greenhouse gases such as carbon dioxide mean that they strongly absorb heat a fact that can be easily demonstrated in a simple laboratory experiment. While there are larger concentrations of other gases in the atmosphere, such as nitrogen, because they do not have these heat trapping qualities they have no effect on warming the climate whatsoever.
Water vapour is the most significant greenhouse gas. It occurs naturally, although global warming caused by human activities will indirectly affect how much is in the atmosphere through, for example, increased evaporation from oceans and rivers. Humans have been adding to the effect of water vapour and other naturally occurring greenhouse gases by pumping greenhouse gases such as carbon dioxide into the atmosphere through, for example, the burning of fossil fuels and deforestation. Before industrialization carbon dioxide made up about 0.03 per cent of the atmosphere or 280ppm (parts per million). Today, due to human influence it is about 380ppm. Even these tiny quantities have resulted in an increase in global temperatures of 0.75ºC.


- Rises in CO2 occur after global warming, not before.

False. It is true that the fluctuations in temperatures that caused the ice ages were initiated by changes in the Earth's orbit around the Sun which, in turn, drove changes in levels of carbon dioxide in the atmosphere. The reasons for this are partly because the oceans emit carbon dioxide as they warm up and absorb it when they cool down and also because soil releases greenhouse gases as it warms up. These increased levels of
greenhouse gases in the atmosphere then further enhanced warming,
creating a positive feedback'.
In contrast to this natural process, we know that the recent steep increase in the level of carbon dioxide - some 30 per cent in the last 100 years - is not the result of natural factors. This is because, by chemical analysis, we can tell that the majority of this carbon dioxide has come from the burning of fossil fuels. And, carbon dioxide from human sources is almost certainly responsible for most of the warming over the last 50 years.


-The sun getting hotter is changing the temperature.

False. Changes in the Sun's activity influence the Earth's climate through small but significant variations in its intensity. When it is in a more active' phase as indicated by a greater number of sunspots on its surface it emits more light and heat. While there is evidence of a link between solar activity and some of the warming in the early 20th Century, measurements from satellites show that there has been very little change in underlying solar activity in the last 30 years there is even evidence of a detectable decline and so this cannot account for the recent rises we have seen in global temperatures.
Over the first part of the 20th Century higher levels of solar activity combined with increases in human generated carbon dioxide to raise temperatures. Between 1940 and 1970 the carbon dioxide effect was probably offset by increasing amounts of sulphate aerosols in the atmosphere, and a slight downturn in solar activity, as well as enhanced volcanic activity.
During this period global temperatures dropped. However, in the latter part of the 20th Century temperatures rose well above the levels of the 1940s. Strong measures taken to reduce sulphate pollution in some regions of the world meant that industrial aerosols began to provide less compensation for an increasing warming caused by carbon dioxide. The rising temperature during this period has been partly abated by occasional volcanic eruptions.


- The impacts of Climat Change are exaggerated.

False. Under one of its mid-range estimates(*), the Intergovernmental Panel on Climate Change (IPCC) - the world's leading authority on climate change - has projected a global average temperature increase this century of 2 to 3 ºC. This would mean that the Earth will experience a larger climate change than it has experienced for at least 10,000 years. The impact and pace of this change would be difficult for many people and ecosystems to adapt to.
However the IPCC has pointed out that as climate change progresses it is likely that negative effects would begin to dominate almost everywhere. Increasing temperatures are likely, for example, to increase the frequency and severity of weather events such as heat waves, storms and flooding.
Furthermore there are real concerns that, in the long term, rising levels of greenhouse gases in the atmosphere could set in motion large-scale and potentially abrupt changes in our planet's natural systems and some of these could be irreversible. Increasing temperatures could, for example, lead to the melting of large ice sheets with major consequences for low lying areas throughout the world.
And the impacts of climate change will fall disproportionately upon developing countries and the poor those who can least afford to adapt. Thus a changing climate will exacerbate inequalities in, for example, health and access to adequate food and clean water.


- Computer models which predict the future climate are unreliable.

False. Modern climate models have become increasingly accurate in reproducing how the real climate 'works'. They are based on our understanding of basic scientific principles, observations of the climate and our understanding of how it functions.
By creating computer simulations of how different components of the climate system - clouds, the Sun, oceans, the living world, pollutants in the atmosphere and so on - behave and interact, scientists have been able to reproduce the overall course of the climate in the last century. Using this understanding of the climate system, scientists are then able to project what is likely to happen in the future, based on various assumptions about human activities.
It is important to note that computer models cannot exactly predict the future, since there are so many unknowns concerning what might happen. Scientists model a range of future possible climates using different scenarios of what the world will 'look like'. Each scenario makes different assumptions about important factors such as how the world's population may increase, what policies might be introduced to deal with climate change and how much carbon dioxide and other greenhouse gases humans will pump into the atmosphere. The resulting projection of the future climate for each scenario, gives various possibilities for the temperature but within a defined range.
While climate models are now able to reproduce past and present changes in the global climate rather well, they are not, as yet, sufficiently well-developed to project accurately all the detail of the impacts we might see at regional or local levels. They do, however, give us a reliable guide to the direction of future climate change. The reliability also continues to be improved through the use of new techniques and technologies.

 

 

 

Source:

http://royalsociety.org/page.asp?id=6229

www.gwenet.org

www.worldwatch.org

   
 
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