Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions, or in the distribution of weather around the average conditions (i.e., more or fewer extreme weather events). Climate change is caused by factors such as biotic processes, variations insolar radiation received by Earth, plate tectonics, and volcanic eruptions. Certain human activities have also been identified as significant causes of recent climate change, often referred to as "global warming". Scientists actively work to understand past and future climate by using observations and theoretical models. A climate record — extending deep into the Earth's past — has been assembled, and continues to be built up, based on geological evidence fromborehole temperature profiles, cores removed from deep accumulations of ice, floral and faunal records, glacial and periglacialprocesses, stable-isotope and other analyses of sediment layers, and records of past sea levels. More recent data are provided by the instrumental record. General circulation models, based on the physical sciences, are often used in theoretical approaches to match past climate data, make future projections, and link causes and effects in climate change. Causes
On the broadest scale, the rate at which energy is received from the sun and the rate at which it is lost to space determine the equilibrium temperature and climate of Earth. This energy is distributed around the globe by winds, ocean currents, and other mechanisms to affect the climates of different regions. Factors that can shape climate are called climate forcings or "forcing mechanisms". These include processes such as variations in solar radiation, variations in the Earth's orbit,mountain-building and continental drift and changes in greenhouse gas concentrations. There are a variety of climate change feedbacks that can either amplify or diminish the initial forcing. Some parts of the climate system, such as the oceans and ice caps, respond slowly in reaction to climate forcings, while others respond more quickly. Forcing mechanisms can be either "internal" or "external". Internal forcing mechanisms are natural processes within the climate system itself (e.g., the thermohaline circulation). 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 (e.g., a sudden cooling due to airborne volcanic ash reflecting sunlight), slow (e.g. thermal expansion of warming ocean water), or a combination (e.g., sudden loss of albedo in the arctic ocean as sea ice melts, followed by more gradual thermal expansion of the water). Therefore, the climate system can respond abruptly, but the full response to forcing mechanisms might not be fully developed for centuries or even longer. What causes climate change?
Earth is a very special planet – its orbits close enough to the sun to receive a lot of energy, but far enough away not to be scorched. It is in what you might call the "goldilocks zone", where the conditions are just right for life as we know it. To help keep these conditions constant, our planet is wrapped in a layer of greenhouse gases. This layer acts like a blanket, keeping the earth warm and shielding it from the cold of universe. This is commonly referred to as the greenhouse effect. Carbon dioxide (CO2), which, while not the most potent greenhouse gas, is nevertheless the main driver of the greenhouse effect. When fossil fuels - coal, oil and natural gas - are burnt they release CO2 into the atmosphere. Because of this the layer of greenhouse gas is getting thicker, which is in turn making the Earth warmer. Thus the ongoing unlimited burning of fossil fuels is the cause of climate...
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