climate change

Topics: Climate change, Climate, Ocean Pages: 6 (1552 words) Published: October 19, 2013

Submitted by:
Ayesha Amjad

Climate change:
Climate change is simply define as change in global weather condition such as temperature, pressure etc. Climate change is a change in statistical distribution of weather pattern over time ranging from decades to millions of years. It may be change in weather conditions or distribution of weather around the average condition. Climate change is caused by factors such as oceanic process (e.g. oceanic circulation) , biotic processes , variation in solar radiation , volcanic eruption , plate tectonic and human activities. Scientists actively work to understand past and future climate by using observation models and theoretical models. Floral and faunal record, glacial and periglacial process, stable isotope and other sediment analyses and sea level record serve to provide climate records that span the geologic award. Causes On the broadest scale, the rate at which energy is received by the sun and energy release to space determines the equilibrium temperature and climate of the Earth. Factors that can change the climate are called climate forcing or forcing mechanism. These include the process such as variation solar radiation, variation in mountain building and continental drift & change in concentration of green house gases. Forcing mechanisms can be either internal or external. Internal forcing mechanisms are natural processes within the climate system itself. External forcing mechanisms can be either natural (e.g. changes in solar output) or anthropogenic (e.g. increased emissions of greenhouse gases). Whether the initial forcing mechanism is internal or external, the response of the climate system might be fast, slow or a combination. Therefore, the climate system can respond abruptly, but the full response to forcing mechanisms might not be fully developed for centuries or even longer. Ocean variability:

Ocean is central part of climate system, some changes occurs on lager timescales than in atmosphere, massing hundreds of times and having high thermal inertia. Short term fluctuation (from years to decades) represents climate variability instead of climate change such as Arctic oscillation and pacific oscillation. On large time period scales alternation to ocean processes such as thermohaline circulation play an important role in redistributing heat by carrying out extremely deep or slow movement of water. Life:

Life affects climate through its role in the water and carbon cycle and such mechanisms as cloud formation, weathering and evapotranspiration. Examples of how life may have affected past climate include: glaciations 2.3 billion years ago triggered by the evolution of oxygenic photosynthesis & global cooling over the past 40 million years cause by expansion of grass-grazer ecosystems. Solar output:

The sun is central source of energy to the life on earth. Long & short term variation in solar intensity affects the global climate. Three to four billion years ago the sun emitted only 70% power as it does today. If the composition of atmosphere had been the same as today, liquid water should not have existed on Earth at that time in past. However, there is evidence for the presence of water on the early Earth, in the hadean & archean eons, leading to what is known as faint young Sun paradox. Hypothesized solutions to this paradox include a vastly different atmosphere, with much higher concentrations of greenhouse gases than currently exist at this time. Interestingly, a study in 2010 suggests, that the effects of solar variability on temperature throughout the atmosphere may be adverse to current expectations. Human activities:

The scientific...
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