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Greenhouse - Problems

It is difficult to predict what is going to happen because the earth is complex. Climate modelling is used but the computing power to model the weather of the entire world is not yet available. Scientists try to simplify things by taking averages or using only a few points on the world's surface but this produces inaccuracies and different models giving different results. This is further complicated because many aspects of climate have dual effects. For instance, clouds can reflect sunlight, which cools the earth, or trap heat, which warms it.

Another complication is the fact that as climates change other things that effect climate also change! Some changes result in positive feedback into the system, while other changes result in negative feedback and it is difficult to predict which of the two will dominate.

Positive feedbacks include: increased release of CO2 as more organic matter decomposes in areas where cold stops the breakdown now, and increased evaporation of water because of higher temperatures and water vapour is also a greenhouse gas! Negative feedbacks include the fact that the more CO2 there is in the air, the quicker plants will grow. And growing plants remove CO2 from the air.

If the positive feedback dominates there may be a continuous increase in global temperatures. An extreme example of this is a runaway greenhouse effect, which would result in a world that just keeps heating up until it can no longer support life. If the negative feedback dominates there may be a reduction in global temperature?

It is also quite possible for some areas of the world to have lower temperatures even when the world's average temperatures are going up! This may occur if, for example, the Gulf Stream were to change direction. This ocean current takes huge volumes of warm water from the Caribbean to the coasts of the British Isles and Europe. This creates much warmer climates than would otherwise be the case in these areas. If its flow lessens or changes direction, the climate could become cooler in these areas while the rest of the world heats up!

The world's climate is extremely variable and subject to a variety of natural cycles. The El Nino and La Nina cycles repeats every few years and influence the Earth's climate. Alterations in the Earth's orbit around the sun called Milanovich cycles are thought to have caused ice ages in the past.

Climate change will cause huge problems for the environment, for people and for global peace and security.

Sea levels rise because as water gets warmer it expands and takes up a greater amount space, and also because of the melting of the polar icecaps. Rising sea levels have the potential to cause mass migration and create millions of refugees, as well as huge damage to coastal environments and human infrastructure. Submerged coastal areas will include many cities and islands. There will be fresh water contamination with salt. Even small increases can cause problems such as storm damage. Storms are expected to become more severe.

Global sea levels have been rising at a rate of 0.4mm per year from 2002 to 2005 due to 36 cubic miles (152 cubic kms) of ice a year melting away from the Antarctic ice sheet. Melting ice from glaciers in Greenland is contributing another 0.5mm per year to increased ocean levels. Sea levels rose 0.2 metres in the last century and are expected to rise up to 1 metre this century and 6 metres in 500 years. Major cities such as London and Miami would be underwater, while most of the Netherlands and Bangladesh would be inundated with sea water and islands such as the Maldives would disappear.

Changing climate and rainfall patterns will have an effect on food production. This may be good in some areas where rainfall increases. In other places, less rain and unexpected weather will cause crop losses, increasing the likelihood of famines. Crops unable to adapt to the changes will have to be replaced with another variety. Climate change will disrupt the world's economies and cause serious social problems.

Extreme climatic events such as, droughts, floods and cyclones may become more common. This seems to be the case now as insurance companies are beginning to refuse to insure certain areas against this type of damage.

As climate changes so will the areas suitable for particular plants and animals. Scientific models of possible future climates show that the shifts in suitable climates, out paces the ability of many species to move. Species living in mountainous areas will have the best chance of survival because they will be able to move uphill to get cooler but those living on flat areas will be less able to adapt. Birds will be able to fly to a more suitable climate but the habitat they needed for survival may not be able to keep pace and so they will all die. Even when wild species are able to keep up with the changes, there may not be areas of land available that are not being used by humans. Climate change will create huge ecological upheaval and cause the extinction of many species of plants and animals.

It is only very recently that we have been able to say that the climate really is warmer! Most years for the last two decades have consistently been the hottest years ever on record.

The worst case scenario is the runaway greenhouse, where positive feedback predominates and temperature increases beyond the ability of life to survive. This situation exists on Venus where surface temperatures are over 400 deg C.

One prediction estimates global warming of around 0.3 deg C per decade. This will mean a rise of 1 deg C by 2025 and 3 deg C by the end of the next century. Scientists from the UN’s Intergovernmental Panel on Climate Change predict that global temperatures will rise by at least 6 deg C by the year 2100.

Humans are putting more CO2 into the atmosphere than is staying there because some of it is absorbed by the ocean and soil or taken up by plants. However, the more CO2 we put into the atmosphere the more stays there, and by the middle of this century, it is estimated that all the CO2 we put into the atmosphere will stay there. This will make it very much harder to control climate change.

Types of Emissions (Australia)
Definition	Quantity as a percentage
1. Stationary energy includes emissions from electricity generation, fuels consumed in the manufacturing, construction and commercial sectors and domestic heating.	Stationary energy contributed about half of national greenhouse gas emissions. Electricity generation accounted for most of the stationary energy emissions. This was 37.5% of national emissions. The amount of emissions in carbon dioxide equivalent [co2e] increased by 35% from 1990 to 2004 and most of this increase is due to coal-related emissions.
2. Transport includes cars and commercial vehicles, river and sea-going ships and boats and domestic aviation.	Transport was the second largest contributor to emission from the energy sector with about 13% of national emissions. Road transport is the largest contributor to transport emissions, with cars contributing about 8% of national emissions and domestic aviation 1%. Emissions of CO2e from cars went up 25% from 1990.
3. Fugitive emissions are leakages from coal seams and oil and natural gas production.	Fugitive emissions contributed 5% of national emissions in 2004 (7.6% in 1990).
4. Industrial processes include emissions from industries such as cement manufacture and aluminium smelting.	Industrial processes contributed 5% of national emissions. In 1990 they accounted 22% of national emissions due to the high inefficiency of the aluminium industry at the time.
5. Agriculture includes methane emissions from livestock, nitrous oxide from fertilising soil and CO2 emissions from the burning of savannas.	Agriculture contributed 16% of national emissions (23% in 1990). Livestock accounts for most of the agricultural sector’s emissions (68%).
6. Forestry including commercial forestry and non-commercial State forests are both a source of CO2 and a sink for CO2. In Australia the total effect of forestry was an increase of CO2.	In 2004, removal of CO2 through forest growth were 15 million tonnes. Harvesting of forests gave rise to 50 million tonnes of emissions, resulting in a net increase of 35 million tonnes or 6% of total national emissions.
7. Waste includes methane emissions from the breakdown of solid waste at landfill sites and from the decomposition of organic matter in sewage during disposal of domestic, commercial and industrial wastewater.	The Waste sector contributed 3% of total national emissions in 2004. Most emissions are as methane from solid waste disposal. Since 1993, methane recovery has grown significantly, and in 2003, about one quarter of methane generated from municipal solid waste disposal was recovered. Methane released from the decomposition of sewage during amounted to 0.3% of total national emissions.
8. Land clearing includes burning cleared vegetation, decay of unburned vegetation and emissions from soil disturbed in the process of clearing.	There is a high level of uncertainty about the exact quantity of greenhouse gases produced by land clearing. But in Australia it is estimated that 71.7 million tonnes of CO2-e was produced during 1999. This is the carbon dioxide equivalent of global warming potential from carbon dioxide, methane, nitrous oxide, solvents and other volatile organic compounds.

Although the Kyoto Protocol is an international effort to reduce CO2 emissions, and the fact that it is being seriously discussed at an international level shows how seriously the issue is being taken; it does not seek to stabilise the climate! In fact it only seeks to reduce CO2 emissions to about 6% of the 1990 levels. This is despite the fact that the original reduction in CO2 emissions was 20% and that stabilising climate requires emission cuts of 50 - 90%! Unfortunately countries such as Australia and the USA where the emissions of CO2 are well above the global average are also the most resistant to doing anything about it.

We know enough about global warming and we should seriously consider applying the precautionary principle to this problem.

Greenhouse Gas Percent Reduction in emissions required to stabilise climate.
Carbon Dioxide (CO2)	50 - 90 %
Methane (CH4)	75 - 100 %
Nitrous Oxide (N2O)	80 - 85 %
Carbon Monoxide (CO)	Freeze at current levels
Chlorofluorocarbons* (CFC)	100 %
Halons

* Also responsible for ozone destruction over the Antarctic and Arctic regions

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By Rowland Benjamin

Information for Action

Greenhouse - Problems