ClimateandFuel

Global Warming

How the build up of Carbon Dioxide leads to global warming and the climate changes to expect

Delicate balance, suns rays and cooling

The effect of the sun warming the earth and the earths various cooling mechanisms are normally in balance retaining the earths temperature at a value which nicely sustains life on earth as we know it. Variations in the suns effect, as described below, and other variations happen and these can force a semi permanent change in world climate.

Fuel use now increasing CO2.

The extraction and burning of coal, oil and gas for electrical power generation, industry, domestic use and travel in the last 200 years is a man made effect. Oxygen in the air is consumed and in the process combines with carbon in these fuels to release CO2. Today the CO2 content has risen to 380 ppm in the atmosphere, and is increasing at a rate of 2 ppm every year. This is upsetting the balance and may, if not checked, force a semi permanent change warming the earth, the effect which will last for many hundreds of years.

CO2 traps heat from sun and heats up earth.

The Suns energy in the form of light reaches earth and is absorbed, warming the earth. The warmed earth radiates energy, this time as heat (infra red) back to space. Heat radiation is absorbed by cloud, CO2 and other gases and reflects some heat energy back to earth. A greenhouse tends to trap heat also so these gases such as CO2 are referred to as greenhouse gases. Greenhouse gases are CO2, methane, nitrous oxide, ozone, CFCs and water (cloud.)

As greenhouse gases build up the delicate balance is upset and the earth warms up. The earth is now warming; glaciers, the ice cap on Greenland, the Arctic and parts of the Antarctic ice cap are melting. However once the CO2 blanket is increased, the effect of the extra thickness of today could continue the warming process for 100 years.

CO2 level of 500 ppm could cause run away temperature.

The prediction is that the earths temperature will rise by between 6 deg. C by year 2100 if the emissions of CO2 are not limited and reduced (ref 147). The best estimates are that we need to contain the CO2 level to within 450 ppm in the atmosphere to retain the earths temperature within a further 2 deg C rise. If the level reaches 500 ppm, warming will continue to increase and due to the earths feedback processes it will accelerate or run away (ref 2.)

CO2 level, Earth's temp. rise and consequences. Deserts spread, hunger increase, water shortages, tropical forests shrink, infertile seas (ref156)

The following table shows the effect of a range of CO2 levels on world temperature and resulting range of effect on planet and life sustaining systems.

The above table shows that :-

At a sustained CO2 level of 450 ppm (parts per million) the eventual temperature rise compared to pre industrial level will be between 1 and 3.75 deg C.

Between 1.5 and 3.75 deg C rise, deserts will spread, crops fail, there will be a 25% to 80% increase in people affected by hunger in 2080s.

Between 1.5 and 3 deg C rise melting of greenland ice sheet will be irreversible.

Between 2 and 4 deg C rise glaciers disappear, one billion people suffer water shortages, increase in hurricane damage to US doubles.

At a sustained level of 550 ppm the eventual temperature rise above pre industrialized levels will be between 1.5 and 4.4 deg C.

Between 3 and 6 deg C rise the west Antarctic ice sheet melts, ecosystems collapse.

At 1 to 5 deg C rise the onset of collapse of Amazon rain forest will happen. The tropical forest areas will shrink or be lost due to higher temperature and less water retention. With a rise of sea temperature the area of infertile sea will increase; fertile areas will recede further towards the poles, with more storms, droughts & forest fires and possible natural methane releases.

Between 4 and 6 deg C rise sea level threatens world cities, Shanghi, Hong Kong, Calcutta, Tokyo, New York, London, Tokyo.

At a sustained level of 650ppm the eventual temperature rise above pre industrialized levels will be between 2 and 6 deg C.

At a temp rise of 4 deg C entire regions will experience crop failures.

Sea rise of 62 metres would flood capital cities.

If the Greenland ice melts, the sea will rise by 7 metres. If the west Antarctic ice shelf melts the sea will rise by 5 metres and if the East Antarctic ice eventually melts (probably a long way off now) the sea will rise by another 56 metres. (See country maps for worst cases.)

Populations also increasing with pressure on land, food and fuel.

In spite of disease and war the world population of 1.7 billion in year 1900 reached 6.7 billion in year 2000. At this rate the population would be 28 billion by year 2100 and although some predict lower figures, one must also consider the effect of the success of medicine, elimination of disease, prolongation of life, lower child deaths. With less productive land, more desert regions, greater infertile seas, worlds population rapidly increasing, more people are likely to face starvation. There are likely to be much bigger problems in Africa and the East than we have seen in the last century.

Limit on fuel that can be burnt in the future - danger levels in red below.

The atmosphere holds 800 billion tonnes of Carbon today (held as 3000 billion tonnes of CO2). There is a balance between the CO2 generated by animal life/surface oceans and that absorbed by land vegetation/surface oceans slightly in favor of absorption, at present; so that half of the CO2 generated by man made by fuel burning and deforestation (itself 10%) is absorbed, the rest remains in the atmosphere.

To limit the CO2 level to within 450 ppm, probably a maximum to prevent catastrophe we should limit the amount of extra carbon generated from fuel to 400 billion tonnes. The world currently burns 7 billion tonnes of carbon a year. In other words we should stabilize the emissions now at the current level and then drop to zero after 60 years.

A limit of 450 ppm will be very difficult to achieve and a limit of 550 ppm seems more likely but will result in population migrations, resource wars (ref 155 & 156).

The director of Nasa's Goddard space science labs, Dr Jim Henson, warns that we should be aiming to reduce carbon in the air from 380 ppm to between 300 - 350 ppm, more toward the pre-industrial level in order to avoid a catastrophe. To do this coal burning must be phased out quickly (ST news review 10 2 08.)

Other greenhouse gases

Gases with a less simple molecule structure than Hydrogen (H2) Oxygen (O2) and Nitrogen (N2) are greenhouse gases. More potent than CO2 are Methane, Nitrous oxide and Sulphur hexafluoride (SF6) but they exist in smaller quantities. Methane could be released in quantities as a result of warming (see feedback on page of past warming). SF6 is used in electrical transmission products (ref168).

Peat bogs hold probably 800 billion tonnes of carbon and destruction of them can cause release of CO2 and Methane. They absorb 0.7 tonnes per hectare .

Particles and Aircraft emissions

Mark K Jackobson suggests that diesel cars emit 25 to 400 times more particulate black carbon particles and organic matter than gas/petrol cars which more than offset the 25 -30% saving of CO2 in diesel cars (ref100).

Prof. Schuldt suggests that aircraft emissions at high level are particularly harmful as, in contrast to low level emissions (cars homes industry etc), these emissions cannot disperse and thus overall this contributes to warming via gaseous layers towards outer space coating the globe (ref 153).

Aircraft condensation trails form cirrus cloud which traps heat at night (but reflects light by day) Nitrous dioxide from aircraft forms ozone, a greenhouse gas. Reducing the altitude of aircraft by 2000 m could reduce trails by 45%.

In the shorter term existing oil reserves could run out in 30 years.

Shell estimates that demand will overtake supply in 2015 (ref 247)

Increase in disease due to global warming

Climate change will contribute to the spread of diseases due to changing patterns, rainfall, storms and higher temperature: Cholera, Ebola, Avian Influenza, parasites - internal and external, Plague, Yellow Fever, Tubercolosis, Sleeping Sickness, Rift Valley Fever, Babesiosis, Lyme Disease.

Look to the past for indications of the future.

The link between the amount of CO2 in the air and resulting temperature rise is complex. Large releases of greenhouse gases in the past, of the order that could happen in a short time in this century, have resulted in global warming, melt of ice, and rise in sea level. Recovery from this condition has taken a period of 200,000 years when CO2 has been drawn down again due to spread of forests and absorption by the sea. At one time in the past, the antarctic has supported mammals and been free of ice.

There are several other mechanisms that affect the earths climate, some every 100,000 years and others more frequent. The ' past page' looks at past changes of warming and cooling and these can give an indication as to how the planet can 'flip' over and stabilize at a much higher temperature.

 

 

 

 

 

The IPCC (International Panel for Climate Change) have stated that it is 90% certain that man made emissions are causing climate change today.

27 Oct 07 Prof David J Dunstan Department of Physics Queen Mary, University of London, wrote in the Times p22 :-

"........we now know without question that over half we emit (ie anthropogenic carbon dioxide emissions) remains in the atmosphere.... and there performs the simple physics called the greenhouse effect....... the question is not by how much temperatures will rise but when....".