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中文Global warming generates changes in the climate which will affect and have multiple implications both to the natural environments and human livelihoods. Policymakers need objective sources of information about the causes of climate change, its potential environmental, social and economic consequences and the adaptation and mitigation options to respond to it.
Global warming – the greenhouse gas effect
Life on earth is made possible by the energy received from the sun. Almost thirty per cent of the sunlight is reflected back by the outer atmosphere. The rest of it reaches the earth’s surface, as infrared radiation and is then carried out by air currents. The radiations’ escape into space is delayed by greenhouse gases such as water vapour, carbon dioxide, ozone, and methane.
Greenhouse gases are about one per cent of the atmosphere. Still they act like a cover around the earth, like the glass roof of a greenhouse, trapping heat. This keeps the planet thirty Celsius degrees warmer than it would be otherwise .
Human activities are increasing the natural levels of those gases, by emitting carbon dioxide from the burning of fossil fuels such coal, oil, and natural gas; methane and nitrous oxide produced by agricultural activities and changes in the use land use; and by some industrial gases that do not occur naturally but are long lived in the atmosphere.
These changes are happening rapidly. If emissions continue to grow at the present levels, the concentration of carbon dioxide will double those from pre-industrial levels during this century. The result, known as the “enhanced greenhouse effect,” is a warming of the earth’s surface and lower atmosphere. The rise in temperature will generate changes in the climate, which include rainfall, winds and changing in seasons.
Studying the impacts
The key scientific aspects of Climate Change are analysed by the Intergovernmental Panel on Climate Change (IPCC). This is a United Nations body which was established by the World Meteorological Organisation (WMO) and United Nations Environment Program (UNEP) in 1988. The IPCC is a scientific body which provides reports based on scientific evidence and reflects existing viewpoints within the scientific community. Because of its intergovernmental nature, the IPCC is able to provide scientific technical and socio-economic information in a policy-relevant but policy neutral way to decision makers.
The IPCC provides periodical reports on the state of climate, know as Assessment Reports. The latest one was published in 2007 and the main issues that were highlighted in this report were that the warming of the climate system is unequivocal, which is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level; and that there is very high confidence that the net effect of human activities since 1750 has been one of warming.
In that Fourth Assessment Report, the IPCC projects that heat waves and heavy precipitation events are very likely to increase in frequency in the twenty first century. In a world that is and under stress, millions of people depend on weather patterns, such as monsoon rains, to continue as they have in the past.
Effects of global warming and measures to address them
The main aspects that may be affected by changes in the weather include:
- 5 food production which is affected by both changes in rain patterns and extreme weather conditions, such as droughts and floods;
- 6 life on low coastal areas which may suffer from flooding;
- 7 loss of natural biodiversity and irreversible environmental damage;
- 8 increase cases of diseases as a consequence of higher temperatures;
- 9 changes in water supply; and
- 10 human economic activities based on the taking actions to reduce the emissions of greenhouse gases
The changes in the climate have been dealt with internationally by the United Nations. Based on the outcome of the IPCC reports, a special body was created to tackle Climate Change issues. The UN Framework Convention for Climate Change (UNFCCC) then decided to take actions, using “the Precautionary Approach”. This means that it would take measures to anticipate, prevent and minimize the causes of climate change and mitigate its negative effects. The UNFCCC stated that when there are threats of serious or irreversible damage, lack of full scientific certainty should not be used as reasons for postponing taking measures.
The UNFCCC has classified the types of actions required in actions for mitigation, which prevent the emission of greenhouse gases, and measures for adaptation which will help different countries to take preventive measures to avoid major incidents.
Taking measure for mitigation will have effect on many human activities which generate emissions. For example, energy generation, industrial activities and transportation are amongst the most emitting economic sectors. Hence, by addressing mitigation the whole of the economy will face changes that will require increased investment and development of new technologies.
Energy is a particular difficult issue because it is considered the main source of economic development. Many countries have significant energy reserves which are high emitting, but would be essential to guarantee their energy supply. This is the case of the use of coal in China. To access these energy resources new breakthrough technologies are being developed in other coal rich countries like the UK, US and Australia.
Domestic consumption in the developed world is also an issue o debate. The citizens of developed countries have a stronger input in carbon emission, or carbon footprint, in average than the emissions from citizens in the developing world. They have also been emitting greenhouse gases for longer periods of time. This is the reason for which the UNFCCC has created mandatory and distinguished requirements for the countries in the developed world. The UNFCCC Kyoto Protocol creates commitments that aim to reduce the risky effects of global warming whilst ensuring that economic and human development is still achieved.
Adaptation will aim to create the necessary infrastructure to deal with extreme weather incidents, such as natural disasters like Hurricane Katrina in the US. Many small state islands and developing nations, such as Bangladesh, would have a quarter of its surface covered by water with a rise in the sea level of only one metre, which scientists predict could happen by 2100. It would displace thirty to forty million people. Whether measures will involve relocating people or building complex protective systems, such as the flood control device in the Thames Barrier in the UK, is still being debated.
The case of the UK
In the case of the UK, the issue of taking actions towards addressing climate change has been thoroughly studied. The outcome of that analysis was the Stern Report, which evaluated the economic impacts of precautionary measures and mentioned that, although there are no absolute predictions on the consequence of climate change, there is sufficient knowledge base to understand the risks of possible consequences. It stated that mitigation should be seen as an investment to prevent those risks, rather than costs. The reviews conclude that the benefits of strong, early action considerably outweigh the costs.
Global warming is a “cross-cutting issue” which affects the environment, societies and economies. To conclude, global warming has the potential to generate disruptive changes in human lifestyles in the centuries to come. Thus, it should be considered the biggest challenge for humanity of our times. Actions to reduce the risks and adapt to the changes are being taken globally but more efforts are required. Measures promoted by international, multi-government organisations will allow the global society to take concerted actions to address this pressing issue.
