There is an overwhelming scientific consensus that the earth’s atmosphere is warming up due to the release into the atmosphere of carbon dioxide and other greenhouse gases due to human activity. The atmospheric level of carbon dioxide is now far higher than any time in the last 400 thousand years (the last 4 ice age cycles). So far, the global temperature has risen by about 0.5C against the long run average. Over the next 100 years, global temperature is likely to increase by a further 1.5 to 6C (according to the UN panel the IPCC, although the UK’s Tyndall centre believes their is a potential for even higher rises of 8C, if positive feedback is taken into account).
Such climate changes will have widespread effects across the earth.
- There will be increased frequency of heat waves and droughts in already hot or dry areas. This may precipitate famine and conflict over scarce water supplies.
- Hurricanes and other violent weather will increase in intensity. The 2005 Hurricane season was the most destructive on record with the greatest number of storms ever recorded.
- Large parts of marginal semi-desert will turn into desert. In particular, much of the area directly south of the Sahara will be swallowed by the desert. Much of the Mediterranean (Spain, Italy, Greece) may become desert.
- Sea levels will rise. Whilst this is a fairly slow process, once one of the various polar ice sheets starts to melt, it is difficult to arrest the process, since sea/rock absorbs more solar energy than white ice. The melting of the Greenland or west Antarctic ice sheets would each raise the sea level by 6.5m each (13m in total), drowning many islands and costal towns. If the East Antarctic ice sheet melted, the rise would be 84m. Melting in the ice sheets has recently accelerated.
- The flow of cold melt water from the Arctic may interrupt the ‘gulf stream’ part of the heat conveyor that transports energy from the tropics to temperate areas. This will cause Europe and in particular NorthWest Europe to become locally much colder (perhaps 5C), and maybe to have a climate more similar to Newfoundland, Canada.
- Tropical regions such as West Africa may become even warmer. In the last few months there has been evidence that the flow of the Gulf Stream may be as much as 30% less than previously.
- There will be widespread changes in ecosystems including the collapse of the coral reefs (probably inevitable even with moderate climate change).
- Increased disease frequency as e.g. malaria spreads to other areas.
A complex physical system such as the earth’s climate contains both negative and positive feedbacks. For small perturbations, negative feedback effects may dominate; otherwise the system would not persist at this point. However, such systems may have a ‘tipping point’ past which the positive feedback effects may overwhelm the negative feedback loops.
Various potential positive feedback systems have been identified for the earth. For example:
- The melting of ice leads to a change in the colour of the earth’s surface from a reflective white, to black, which absorbs more heat.
- Global warming may cause the collapse of rainforest ecosystems already ravaged by deforestation, releasing much stored CO2.
- There are huge stores of Methane (a greenhouse gas) Siberia in permafrost. This permafrost may melt. (Recently scientists have seen that this may have started to happen).
- Whilst moderate climate change (e.g. 1C) therefore may be counteracted by various natural systems, large climate change (>2C) may well be dangerous. It is clear that humans need to avoid highly polluting behaviour until and unless it is known with certainty that these effects are safe. If anything, the scientific evidence at present points to the reality of many of the proposed changes.
Human activity takes time to adjust. We need to change our methods of transport and energy production so that we emit far less CO2.
It has been estimated that the sustainable level of energy consumption is about 20% of average UK consumption and about 10% of average US consumption. This can be accomplished using a ‘personal energy quota’. (The centre for alternative technology www.cat.org.uk has further info). In particular, we need to insulate our houses well, avoid low occupancy car use, dress up warmly rather than relying excessively on heating, and particularly avoid unnecessary air travel. (E.g. see www.raileurope.co.uk). In fact, this is merely a reversal to habits of a decade or two ago, where people were not noticeably less content than they are today. The author has adopted such a ‘sustainable Carbon Dioxide quota’ without much trouble. It takes a little time to adapt habits but it is not difficult to do. Those with international jobs courses, or families would have twice the usual quota (to allow for the possibility of one intercontinental flight per person per year).
We need to lobby our governments to produce energy through methods that produce little or any carbon dioxide. For example in the UK, and the other major economies with pre-existing nuclear industries (US, Canada, Europe, Japan, Russia, India and China) the ‘baseload’ energy (75% of total) that is needed 24 hours a day can be produced by nuclear energy, as a ‘stopgap’ until renewable energy or fusion power is available. (Economical, technically advanced, efficient and safe. Arguably it is safer to have a well-funded nuclear industry with new and safe reactors rather than to have many demoralised and unemployed nuclear scientists, with poorly funded and/or derelict nuclear facilities. Nuclear reactors design has improved massively over the last decades). Wind power can be used in UK (but requires some backup for when the wind isn’t blowing such as pumped storage hydro plants). Solar energy can be harnessed in other countries without pre-existing nuclear infrastructure. Once energy production is non-CO2 emitting, cars can be converted to being run from electricity, further cutting emissions.
Finally, we need to lobby our governments (particularly in the US but globally as well) to support treaties that cut carbon dioxide emission. The European Union has pioneered an emissions trading scheme which caps total emissions and then charges for permits to emit carbon dioxide. Since low carbon technologies are immature – they can still be improved, (whereas polluting technologies have little scope for improvement)- it may be that action to change energy and transport systems will pay for itself by increasing the economy’s productive capacity.