CLIMATE CHANGE

TYPES OF CLIMATE CHANGE

Health - Climate changes affect ecological systems, and changes in ecological systems influence the processes of disease transmission. Changes in temperature and precipitation, as well as extreme climate events such as floods or droughts, are capable of changing ecological systems. For example, research links increases in diarrheal disease to flooding, and cholera outbreaks to warmer sea surface temperatures. Different weather conditions are known to affect vector-borne diseases such as malaria and dengue.
Coastal Area’s - Impacts to oceans from climate change are expected to include increases in sea surface temperature and global sea level. As a result of rising sea levels, many coastal areas will experience increased flooding, accelerated erosion, intrusion of seawater into freshwater areas, and the loss of wetlands. Other anticipated changes include changes in wave conditions, ocean circulation patterns, and decreases in sea-ice cover.
Forest - Different climate models project how the range of forest species will change as global warming continues into the future. Researchers anticipate that many species of deciduous trees such as beech trees will move northward and to higher elevations where conditions are cooler. In the process, coniferous tree species such as pine may be displaced. Changes in the distribution of tree species will, in turn, have an impact on biological diversity.
Agriculture - It is obvious that climate change will affect agriculture, but the complexity of the climate system makes it hard to make exact predictions. Increases in temperature can have both positive and negative effects. Some locations may experience higher crop yields while others will experience declines.
Water Resources - Water is a critical resource for humans as well as other ecosystems. The water cycle is likely to be altered by climate change. Because of the complexity of the hydrosphere in the Earth system, it is difficult to predict how precipitation patterns might change. Changes expected include the timing, amount, and location of precipitation and runoff. Such changes will alter patterns of water availability and quality.
Species and Natural Areas - Climate is the most important factor controlling the distribution of vegetation and animal species. Anticipated increases in mean global temperatures will cause significant changes in species distribution.

MILESTONES

• 1827: French polymath Jean-Baptiste Fourier predicts an atmospheric effect keeping the Earth warmer than it would otherwise be. He is the first to use a greenhouse analogy.
• 1863: Irish scientist John Tyndall publishes a paper describing how water vapour can be a greenhouse gas.
• 1890s: Swedish scientist Svante Arrhenius and an American, P C Chamberlain, independently consider the problems that might be caused by CO2 building up in the atmosphere. Both scientists realise that the burning of fossil fuels could lead to global warming, but neither suspects the process might already have begun.
• 1890s to 1940: Average surface air temperatures increase by about 0.25 °C. Some scientists see the American Dust Bowl as a sign of the greenhouse effect at work.
• 1940 to 1970: Worldwide cooling of 0.2°C. Scientific interest in greenhouse effect wanes. Some climatologists predict a new ice age.
• 1957: US oceanographer Roger Revelle warns that humanity is conducting a "large-scale geophysical experiment" on the planet by releasing greenhouse gases. Colleague David Keeling sets up first continuous monitoring of CO2 levels in the atmosphere. Keeling soon finds a regular year-on-year rise.
• 1970s: Series of studies by the US Department of Energy increases concerns about future global warming.
• 1979: First World Climate Conference adopts climate change as major issue and calls on governments "to foresee and prevent potential man-made changes in climate."
• 1985: First major international conference on the greenhouse effect at Villach, Austria, warns that greenhouse gases will "in the first half of the next century, cause a rise of global mean temperature which is greater than any in man's history." This could cause sea levels to rise by up to one metre, researchers say. The conference also reports that gases other than CO2, such as methane, ozone, CFCs and nitrous oxide, also contribute to warming.
• 1987: Warmest year since records began. The 1980s turn out to be the hottest decade on record, with seven of the eight warmest years recorded up to 1990. Even the coldest years in the 1980s were warmer than the warmest years of the 1880s.
• 1988: Global warming attracts worldwide headlines after scientists at Congressional hearings in Washington DC blame major US drought on its influence. Meeting of climate scientists in Toronto subsequently calls for 20% cuts in global CO2 emissions by the year 2005. UN sets up the Intergovernmental Panel on Climate Change (IPCC) to analyse and report on scientific findings.
• 1990: The first report of the IPCC finds that the planet has warmed by 0.5°C in the past century. IPCC warns that only strong measures to halt rising greenhouse gas emissions will prevent serious global warming. This provides scientific clout for UN negotiations for a climate convention. Negotiations begin after the UN General Assembly in December.
• 1991: Mount Pinatubo erupts in the Philippines, throwing debris into the stratosphere that shields the Earth from solar energy, which helps interrupt the warming trend. Average temperatures drop for two years before rising again. Scientists point out that this event shows how sensitive global temperatures are to disruption.
• 1992: Climate Change Convention, signed by 154 nations in Rio, agrees to prevent "dangerous" warming from greenhouse gases and sets initial target of reducing emissions from industrialised countries to 1990 levels by the year 2000.

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