HOW DOES CLIMATE CHANGES
Monday, March 16, 2009
Climate is defined as an areas long-term weather patterns.
The simplest way to describe climate is to look at average weather temperature and precipitation over time. Other useful elements for describing climate include the type and timing of precipitation, amount of sunshine, average wind speeds and directions, number of days above freezing, weather extremes and local geography.
While it is fairly easy to describe a locations climate by examining weather data, a greater challenge is figuring out why the climate of one place differs from that of another. To do so ,you must consider all the factors that work together to determine climate.
Climate change is any long term significant change in the average weather of a region or of earth as a whole. Average weather may include average temperature, precipitation and wind patterns. It involves changes in the variability or average state of the atmosphere over durations ranging from decades to millions of years. These changes may be cause by dynamic processes on earth external forces including variations in sunlight intensity and more recently by human activities. Human influences on climate change. Anthropogenic factors are human activities that change the environment and influence climate. In some cases the chain of causality is direct and unambiguous.
While in others it is less clear various hypothesis for human induced climate change have been debated for many years though it is important to note that the scientific debate has move on from skepticism, as there is scientific consensus on climate change that human activity is beyond reasonable doubt as the main explanation for the current rapid changes in the worlds climate, consequently in politics the debate has largely shifted on to ways to reduce human impact and adapt to change that is already in the system.
The biggest factor of present concern is the increase in the carbon dioxide levels due to emission from fossil fuels conbutions, followed by aerosols which exert a cooling effect and cement manufacture. Other factors, including land use ozone depletion, animal agriculture and deforestation also affect climate
Moreover glaciations is another factor, Glaciers are recognized as being among the most sensitive indicators of climate change, advancing substantially during climate cooling and retreating during climate warming on moderate time scales. Glaciers grow and collapse both contributing to natural variability and greatly amplifying externally forced changes. For the last century however glaciers have been unable to regenerate enough ice during the winters to make up for the ice lost during the summer months.
The most significant climate processes of the last several millions years are the glacial and interglacial cycles of the present ice age. Shaped by orbital variations earth based responses such as the rise and fall of continental ice sheets are significant sea level changes helped create the climate. Ocean variability also changes climate. On a time scale often measured in decades or more climate changes can also result from the interaction between the atmosphere and the oceans. Many climate fluctuations including the El Niño southern oscillation ,the pacific decadal oscillation, the north Atlantic oscillation, and the arctic oscillation owe their existence at least in part of different ways ,that heat may be stored in the oceans and the way it moves between various reservoirs.On longer time scales ,ocean processes such as thermohaline circulation also play a key role in redistributing heat by carrying out a very slow and extremely deep movement of water and the long term redistribution of heat in the oceans.
Finally the memory of climate generally forms internal variability system can be recognized as a form of hysteresis, meaning that the current state of climate reflects not only the inputs but also the history of how it got there for example ,a decade of dry conditions may cause lakes to shrink or plains to dry up and deserts to expand In turn these conditions may lead to less rainfall in the following years. In short climate change can be a self perpetuating process because different aspects of the environment respond at different rates and in different ways to the fluctuations that inevitably occur.
Author: By Yahya Sanyang, The Gambian Civil Engineering student at the national Taipei university of technology