The evidence

• There has been a marked increase in the incidence and severity of storms over recent decades. Over the past 50 years high pressure systems have increased by an average of three millibars whilst low pressure troughs have deepened by the same amount, thereby intensifying the dynamics of weather systems. Greater extremes of the hydrological cycle are leading, on the one hand, to increased area of desert, and, on the other, greater intensity of rain storms which increase run-off and erosion of fertile land. In both cases there is a loss of carbon fixing greenery and food producing land.

• In the first months of 2000 Mozambique experienced catastrophic floods which were repeated in 2001. In 2002 devastating floods occurred across Europe inundating historic cities like Prague and Dresden creating 'one of the worst flood catastrophes since the Middle Ages' (Philippe Busquin, European Union Research Commissioner). The following year saw a similar occurrence with the rivers Elbe and Rhone bursting their banks.

• In July 2004 Southeast Asia experienced catastrophic floods due to exceptional rainfall, rendering 30 million homeless in Bangladesh and the Indian state of Bihar. At the same time central China also suffered devastating floods whilst Delhi experienced a major draught. The people of Ethiopia are facing starvation in their millions because of the year-by-year failure of the rains.

• Insurance companies are good barometers of change. One of the largest, Munich Re, states that claims due to storms have doubled in every decade since 1960. In that decade there were 16 disasters costing £30 billion. In the last decade of the century there were 70 disasters costing £250 billion. In the first years of this century the pace has quickened. Munich Re has reported that the 700 natural disasters in 2003 claimed 50 000 lives and cost the insurers £33 billion. The Loss Prevention Council has stated that, by the middle of this century, losses will be 'unimaginable'. Yet, these extreme climatic events are only part of the scenario of global warming.

• Besides the effect of increasingly steep pressure gradients another factor contributing to the intensification of storms is the contraction of snow fields. These have in the past created high pressure zones of cold stable air which have kept at bay the Atlantic lows with their attendant storms. This barrier has weakened and shifted further east allowing the storms to reach western Europe. The increased frequency of storms and floods in this area during the last decade of the twentieth century adds weight to this conclusion.

• El Niño has produced unprecedentedly severe effects due to the warming of the Pacific. There is even talk that the El Niño reversal may become a fixture which would have dire consequences for Australia and Southeast Asia.

• Receding polar ice is resulting in the rapid expansion of flora; Antarctic summers have lengthened by up to 50 per cent since the 1970s and new species of plants have appeared as glaciers have retreated. In Iceland Europe's largest glacier is breaking up and is likely to slide into the north Atlantic within the next few years, highlighting the threat to sea levels from land-based ice (The Observer, 22 October 2000). The Arctic ice sheet has thinned by 40 per cent due to global warming (report by an international panel of climate scientists, January 2001).

• Sea level has risen 250 mm (10 inches) since 1860. Up to now much of the sea level rise has been due to thermal expansion.

• Sea temperatures in Antarctica are rising at five times the global average, at present a 2.5°C increase since the 1940s. The major threat lies with the potential break-up of land-based ice. The recent breakaway of the 12 000 sq. km of the Larson B ice shelf has serious implications. In itself it will not contribute to rising sea levels. The danger lies in the fact that the ice shelves act as a bulwark supporting the land-based ice. In the May 2003 edition of Scientific American it was reported that, following the collapse of the Larson ice shelf 'inland [land based] glaciers have surged dramatically towards the coast in recent years'. Satellite measurements have shown that the two main glaciers have advanced 1.25 and 1.65 km respectively. That represents a rate of 1.8 and 2.4 metres per day. When the West Antarctic ice sheet totally collapses, as it will, this will raise sea level by 5 m (Scientific American, op. cit., p. 22). In April 1999 The Guardian reported that this ice shelf was breaking up 15 times faster than predicted. Even more disconcerting is the fact that the largest glacier in Antarctica, the Pine Island glacier, is rapidly thinning - 10 metres in eight years - and accelerating towards the sea at a rate of 8 metres a day. This is another indication of the instability of the West Antarctic ice sheet.

• At the same time there has been massive melting of glacier ice on mountains. The Alps have lost 50 per cent of their ice in the past century. The International Commission on Snow and Ice has reported that glaciers in the Himalayas are receding faster than anywhere else on Earth.

• In Alaska there is general thinning and retreating of sea ice, drying tundra, increasing storm intensity, reducing summer rainfall, warmer winters and changes in the distribution, migration patterns and numbers of some wildlife species. Together these pose serious threats to the survival of the subsistence-indigenous Eskimos (New Scientist, 14 November 1998).

• From Alaska to Siberia, serious infrastructure problems are occurring due to the melting of the permafrost. Roads are splitting apart, trees keeling over, houses subsiding and world famous ski resorts becoming non-viable. In Alaska and much of the Arctic temperatures are rising ten times faster than the global average - 4.4°C in 30 years. This may, in part, be due to the melting of the snow fields exposing tundra. Whilst snow reflects much of the solar radiation back into space, the bare tundra absorbs heat, at the same time releasing huge amounts of carbon dioxide into the atmosphere - a classic positive feedback situation. The village of Shishmaref on an island on the edge of the Arctic Circle is said to be 'the most extreme example of global warming on the planet' and 'is literally being swallowed by the sea'. Some houses have already fallen into the sea; others are crumbling due to the melting of the permafrost supporting their foundations. The sea is moving inland at the rate of 3 m a year (BBC News, 23 July 2004).

• Global mean surface air temperature has increased between 0.3 and 0.6°C since the later nineteenth century. The average global surface temperature in 1998 set a new record surpassing the previous record in 1995 by 0.2°C - the largest jump ever recorded (Worldwatch Institute in Scientific American, March 1999). The warmest year on record was 1999. Global warming is increasing at a faster rate than predicted by the UN IPCC scientists in 1995. They anticipated that temperatures would rise between 1 and 3.5°C in the twenty-first century. According to the Director of the US National Climate Data Center, in only a short time the rate of warming is already equivalent to a 3°C rise per century. This makes it probable that the end of century temperature level will be significantly higher than the IPCC top estimate (Geophysical Research Letters, vol. 27, p. 719).

• NASA scientists report satellite evidence of the Greenland land-based ice sheet thinning by 1 m per year. Altogether it has lost 5 m in southwest and east coasts. On the one hand, this threatens the Gulf Stream or deep ocean pump and on the other, it leads directly to a rise in sea level, threatening coastal regions (Nature, 5 March 1999). Over the past 20 years the polar ice cap has thinned by 40 per cent.

• Concentrations of CO2 in the atmosphere are increasing at a steep rate. The pre-industrial level was 590 billion tonnes or 270 parts per million by volume (ppmv); now it is 760 billion tonnes or around 380 ppmv and rising 1.5-2 ppmv per year. Most of the increase has occurred over the last 50 years. According to Sir David King, UK Chief Government Scientist, this is the highest concentration in 55 million years. Then there was no ice on the planet. The previous highest concentration was 300 ppmv 300 000 years ago (New Scientist, 29 January 2000, pp. 42-43). At the present rate of emission, concentrations could reach 800-1000 ppmv by 2100. Even if emissions were to be reduced by 60 per cent against 1990 levels by 2050 this will still raise levels to over 500 ppmv with unpredictable consequences due to the fact that CO2 concentrations survive in the atmosphere for at least 100 years.

• Altogether it would seem that a temperature rise of at least 6°C is very possible with the worst case scenario now rising to 11.5°C. Bearing in mind the observed rate of temperature increase as mentioned above, the aim now should be to prevent the planet crossing the threshold into runaway global warming whereby mutually reinforcing feedback loops become unstoppable.

• Spring in the northern hemisphere is arriving at least one week earlier than 20 years ago; some estimates put it at 11 days. A 40-year survey by Nigel Hepper at the Royal Botanical Gardens at Kew involving 5000 species indicates that spring is arriving 'several weeks earlier'. A study of European gardens found that the growing season has expanded by at least ten days since 1960. Munich scientists studied 70 botanical gardens from Finland to the Balkans (616 spring records and 178 autumn). The conclusion was that spring arrived on average six days earlier and autumn five days later over a 30-year period (Nature, February 1999).

• Extreme heat episodes are becoming a feature of hitherto temperate climate zones. The majority of heat-related deaths are due to a lethal assault on the blood's chemistry. Water is lost through sweating and this leads to higher levels of red blood cells, clotting factors and cholesterol. The process starts within 30 minutes of exposure to sun. The summer of 2003 saw heatwaves across Europe that were exceptional, not only in terms of peak temperatures but also their duration. According to the Earth Policy Institute in Washington DC, 35 000 died in August across Europe and 14 800 in France alone from heat-related causes. Other estimates put the figures at 20 000 and 11 000 respectively. According to scientists in Zurich reporting in 'Nature on-line', this kind of sustained summer temperature could normally be expected every 450 years. Towards the latter part of the century they predict such an event every second year. On 4 February 2004 the temperature in central England reached 12.5°C which was the highest early February temperature since records began in 1772 according to the UK Meteorological Office. That month was also the occasion of a severe heatwave in Brisbane, North Australia, where there were 29 sudden deaths in one night.

• One of the predicted results of global warming is that there will be greater extremes of weather, which not only means higher temperatures but also more extensive swings of atmospheric pressure. Research at the University of Lille has indicated that when the pressure falls below 1006 millibars or rises above 1026 millibars the risk of heart attacks increases by 13 per cent. The study also showed that a drop in temperature of 10°C increases the risk of a heart attack by the same percentage (reported at a meeting of the American Heart Association, Dallas, November 1998). According to the UN Environment Protection Agency director, the cost of premature death due to rising numbers of heatwaves is reckoned to be £14 billion a year in the EU and £11 billion in the US. Worldwide the assessment is £50 billion.

• Oceans are the largest carbon sink. As they warm they are becoming less efficient at absorbing CO2. The latest prediction is that the carbon absorption capacity of oceans will decline by 50 per cent as sea temperatures rise.

• Methane emissions from natural wetlands and rice paddy fields are increasing as temperatures rise. To repeat, methane is a much more potent greenhouse gas than CO2 and levels are rising rapidly.

• The year 2000 saw an unprecedented catalogue of warnings. The warming that is eroding Europe's largest glacier in Iceland also created clear water across the North West Passage at the top of Canada making navigation possible. This has not happened since prehistoric interglacial warming.

Finally, the assumption generally held by policy makers is that a steady rise in CO2 concentrations will produce an equally steady rise in temperature. The evidence from ice cores reveals that the planet has sometimes swung dramatically between extremes of climate in a relatively short time due to powerful feedback that tips the system into a dramatically different steady state. Scientists meeting for a workshop in Berlin in 2003 concluded, on the evidence of climate changes to date, that the planet could be on the verge of 'abrupt, nasty and irreversible' change (Bill Clark, Harvard University, quoted in New Scientist, 22 November 2003).

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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