Such rapid changes in climate will be too great to allow many ecosystems to adapt, and therefore the rate of species extinction will increase. Human agriculture, forestry, dry lands, water resources and health will also be affected due to variations in precipitation (rainfall and snowfall), sea level and the frequency and intensity of extreme weather events. There are also many indicators that countries currently experiencing social, economic and climatic stresses will be the worst affected and least able to adapt when these climatic changes begin to take hold.
Governments across the world are not ignorant to the effects that global warming threatens and, in 1997, a protocol to implement the United Nations Framework Convention for Climate Change was drawn up in Kyoto, Japan. The main features of the protocol are:
- Participating countries are legally bound to reduce worldwide emissions of six greenhouse gasses by an average of 5.2% below their 1990 levels during the period 2008 – 2012.
- Each participating country is assigned a number of “Carbon Credits”. These credits can then be traded with other countries, which may mean some countries using more greenhouse gases than allocated, on the understanding the trading country uses less.
However for the treaty to become legal, countries accounting for at least 55% of 1990 carbon dioxide emissions must be signed up and, as both the USA and the Russian Federation are both opposed to the agreement, this is not possible. The IPCC also believes that the treaty does not go far enough as gases can remain in the atmosphere for more than a hundred years, and emissions would need to be cut by 60% or more to make a real difference.
Case Study: California, USA
Situated on the western (pacific) coast of the USA, with a population of around 30million, California’s weather is poised to be greatly affected by any changes in the global climate. California is a fragile state, in which the eco-systems are delicately balanced and could be destroyed by change, however it is the Californians themselves who contribute substantially to the devastation of their environment by emitting over 400 million tonnes of CO2 per year.
Most of California's precipitation falls in winter, and in the future more of it is likely to fall as rain, less as snow, and as Californian winters will generally become warmer and wetter, these are changes that are likely to lead to increased winter runoff and decreased summer stream flow. The state's summers are likely to remain hot and dry, and perhaps become even hotter and drier. Similarly, the frequency and/or magnitude of some ecologically important processes such as wildfires, flooding, and disease and pest outbreaks is likely to alter as climate changes occur, for example El Niños, with their dramatic effects on California's weather and economy, may increase in intensity and/or frequency as the climate changes, and an increased frequency of booms within the rodent population, which generally precedes a disease epidemic.
Sea level rises of between 8 and 12 inches due to the melting of polar ice caps and general thermal expansion will impact on coastal wetlands, housing, and agriculture, as well as on roads, levees, and other public works, as well as amplifying any increases in the frequency and/or intensity of major storms.
Many natural and agricultural ecosystems are highly sensitive to the availability of water. Thus changes in the timing or amount of precipitation over the next century are likely to have a greater impact than changes in temperature. For example, decreased summer stream flows would intensify competing demands for water to meet the needs of agriculture, industry, and urban areas, and sustain the health of California's aquatic and streamside ecosystems. Profitability of crops such as alfalfa, cotton and grapes would also decrease as demand for water increases.
Complex changes in the food web will occur as a reduced summer runoff of fresh water would increase summer salinity in San Francisco Bay, leading to changes in water circulation and quality. For example, warming of the California Current in recent decades has been linked to population declines of zooplankton and seabirds known as sooty shearwaters, whilst on the rocky shores of Monterey Bay, southern animal species have increased in the warmer waters while native northern species have declined and in the kelp forests off the Southern California coast, the proportion of northern, cold-water fish species such as the green-spotted rockfish has dropped by half since the 1970s, and the proportion of southern warm-water fish species such as Garibaldi has increased nearly 50%. Toxic algal blooms will also become more common in bays and estuaries as sea temperatures increase.
Another example of habitat migration due to a change in climate is the Edith’s Checkerspot variety of butterfly, which has moved its summer breeding area from southern California to the northern parameters of the state, and from lowland areas to high-elevation sites, in order to remain in a similar climatic location. However, isolation increases the vulnerability of many animal communities in the face of even modest climate changes, because it limits the ability of species to migrate in response to changing conditions, for example isolated patches of unique grassland, marsh, and aquatic habitats, such as the Serpentine outcrops of Northern California and vernal pools in the Central Valley, which often harbour rare or spectacular species, are so poorly connected with other patches that migrations required by climate change may be difficult or impossible without dramatic human intervention.
Agriculture, one of the states major industries (second only to tourism), is also poised for chaos as the traditional varieties of crops such as fruit, nuts and grapes will be unable to cope with the climate change and it would take years for farmers to import more suitable varieties of tree and vine and farm them on a profitable scale. Acid rain, caused by an increase in the number or intensity of now-infrequent thunderstorms, which form over land and pick up more acids and other pollutants than Pacific frontal storms, also poses a threat to farmers.
Sources: www.climatehotmap.org
www.mmu.ac.uk
www.ucsusa.org
www.bbc.co.uk/weather
