Background Information: Predictions of Climate Change
There are no accurate predictions of what will happen to earth's climate with an increase in greenhouse gases. The climate system is very complex, so that scientists have been using a combination of mathematical models, the geological record of past climates, meteorological records and theories on the global atmosphere and oceanic circulation to provide an estimate. The value of such estimates is that they can be used to assess which of our activities is most likely to be affected by changes over the next several decades. This will help us plan sensibly for change.
If our present understanding is correct, the following changes, relative to 1990, may take place by about 2100.
- Global temperature may increase by approximately 2 degrees Celsius [inland would feel the change more than the coast]. This represents the best estimate value of climate sensitivity and is based upon computer models of climate. This is about 1 degree Celsius less than previously estimated.
- Winter may be warmer and nights may be warmer.
It has been estimated that the original area covered by forests was about 6 billion hectares. According to a report published by the Intergovernmental Panel on Climate Change (IPCC), the total area presently covered by forests amounts to some four billion hectares. Half of this is accounted for by the tropical forests. One-third is covered by northern forests and about one sixth represents temperate forests. The total amount of carbon stored in these forests is equal to that presently contained in the atmosphere i.e., about 700 billion tons.
Clearing and burning of forests can cause irreparable damage to the soil, environment and can affect the climate. Deforestation increases the atmospheric carbon dioxide by removing the source Of carbon dioxide uptake.
Commercial logging, establishment of new agricultural plantations, shifting agriculture, cyclones, fire, land and road developments, all contribute to deforestation of Pacific islands. Forests are important not only for their role in maintaining biological diversity, but also because of their role in global climate. The forests absorb carbon dioxide generated by human activities. The present massive destruction of tropical forests at a rate of 17 million hectares per year (11.3 million in 1980) could lead to a greater buildup of carbon dioxide in the atmosphere. This would contribute to the global warming effect.
Deforestation also affects the soil and local climate. It reduces the evaporative cooling that takes place both from soil and from plant life. This can result in increased soil erosion and run off of rainfall, flooding and sedimentation of rivers, lagoons and reefs. In fact the total ambient near surface humidity is drastically modified. Rainfall is no longer intercepted by the forest foliage to be recirculated to the atmosphere, but falls immediately to the ground, to be transported, perhaps directly to the ocean in run-off, or else rapidly made inaccessible in the short term by it being contributed to the underground water-table. Moreover there are no longer the deep roots of the former forest trees to return it by transpiration to the atmosphere. Again the landscape is changed, and usually permanently. The albedo, or reflective capacity of the surface is greatly increased with all that such a change can be inferred for the local climate. Uncontrolled and poorly-managed clearing of forests can have dev
More Predictions of Climate Change
There are no accurate predictions of what will happen to earth's climate with an increase in greenhouse gases. The climate system is very complex, so that scientists have been using a combination of mathematical models, the geological record of past climates, meteorological records and theories on the global atmosphere and oceanic circulation to provide an estimate. The value of such estimates is that they can be used to assess which of our activities is most likely to be affected by changes over the next several decades. This will help us plan sensibly for change.
If our present understanding is correct, the following changes, relative to 1990, may take place by about 2100.
- Global temperature may increase by approximately 2 degrees Celsius (inland would feel the change more than the coast). This represents the best estimate value of climate sensitivity and is based upon computer models of climate. This is about 1 degree Celsius less than previously estimated.
- Winter may be warmer and nights may be warmer.
- The tropical climate belt may extend south in the Pacific bringing more summer rain.
- Cyclones might sometimes move further polewards.
- If the air is warmer it will hold more moisture making heavy rain and storms more likely.
- Frequency of El Niño may also increase.
Even though the global mean temperature varies significantly from year to year and decade to decade, over the Past 125 years, a warming trend is obvious with an overall temperature rise of about 0.5 degrees Celsius. For convenience, scientists take as their reference point for predictions the time when the increases in all the greenhouse gases will have an effect similar to that due to a doubling of carbon dioxide. This is expected by about 2030.
When Climate Changes Significantly
When temperatures drop much below 18 degrees Celsius, we put on warm clothing. When temperatures are too high, we jump into the ocean or turn on fans and air conditioning. In, short, human beings adjust to the natural range of temperatures that occur from day to night and from season to season. Other animals make similar adjustments. Furry animals grow thicker coats to keep warm in the winter. Many animals seek the comparative coolness or warmth of caves, cracks, or crevices. Birds and fish leave home altogether in search of warmer or cooler zones.
Among many causes, the well known phenomenon, El Niño is a temporary climate change which rarely lasts more than two years. Climate change from the greenhouse effect would last much longer. What will happen to the fish off South America? What will penguins do if climate warms so much that the ice on which they live melts? What might happen to a tropical bird if the rainforest dips below freezing?
Would these animals be able to tolerate the stress? Would they move away? Would they die? Such extreme changes are not likely to take place soon. If global greenhouse warming occurs, however, local communities will almost certainly experience shifts in climate. Changes in temperature, humidity, or rainfall might restrict the availability of areas in which a particular animal can survive. Temperature changes affect most animals indirectly as well. For example, the abundance of an animal's food source could be altered by temperature changes. Changing conditions might also favor or hamper predators whose role it is to keep animal populations from increasing unbounded.
In response to changes in their environment, some animals will be able to migrate to new areas, but other animals will be prevented from moving by barriers [examples of barriers include rivers, oceans, mountain ranges, and various structures such as roads, fences, and housing developments]. Winds, rain, storms, currents, and wave energy will all change as climate is altered. Where changes occur, they may be gradual, or they may result in abrupt transitions to new circulation patterns. Some scientists have made the following predictions:
- It is predicted that there will be an increase in the intensity of rainfall with relatively more rain failing in large rainfall events. Changes in rainfall patterns may be either positive or negative, but there is a probability that both droughts and floods will increase.
- It is predicted that the geographic range of tropical cyclone storms will expand polewards, and that their frequency and intensity will also increase.
Areas now in or next to zones of tropical storm activity experience increases in storm damage, thereby dramatically affecting those people who live close to coral reefs.
Climate change will alter regional precipitation and evaporation patterns. Climate models indicate that a doubling of atmospheric concentration of carbon dioxide would increase precipitation by about 5 percent. Higher temperature may alter the earth's water cycle. Higher temperature will also cause the water to become warmer. This will result in an increase in humidity over the oceans causing tropical cyclones and changing wave patterns. This could produce more swells and tidal waves in certain regions.
What perhaps is more important at this stage is to consider how rather than why climate change will occur. It is clear that there will be no violent cataclysm after which all the above dreadful disasters will be upon us. If significant climate change is to occur, we are assured by the scientists that it will take place slowly and continuously over a long period of time. A very relevant question to ask then is, how will the natural flora and fauna, then humanity, and even the geographical environment react? Will there be a steady strain applied to species which will eventually become so stressed that they will collapse one after another? Alternatively, will there be a general acclimatization process, since we are all aware that the human body, for example, has the capacity to accommodate, given time, to great changes in climate, so that we have on the one hand the Eskimos of the high northern latitudes, while on the other we find healthy populations settled in the continental equatorial zones. A similar a
It is important therefore, for the people of the South Pacific islands to be sensitive to the changes in weather patterns. One way of doing this is to become involved in the Schools of the Pacific Rainfall Climate Experiment (SPARCE) program which is already in operation in several countries in the South Pacific. This programmed involves the recording of rainfall and other factors such as temperature and wind direction. Many students and teachers in various schools in the Pacific are already involved in this program Data collected by students and teachers are analyzed and hopefully over a long period of time certain changes in weather pattern can be detected.
