Climate change – Geography
Climate change is causing severe problems for plant and animal species around the globe. It is largely caused by the emission of greenhouse gases, which cause the atmosphere to retain more heat. Scientists are concerned about climate change because its effects are far-reaching.
Animals are threatened by shifting climates, melting ice caps, rising sea levels, and many other issues resulting from climate change.
Causes of Climate Change
Astronomical causes are the changes in solar output associated with sunspot activities. These high-energy particles can penetrate into the earth’s magnetic field and influence its rotation. They may also affect the intensity of cosmic rays that indirectly affect cloud cover on earth.
An another astronomical theory is Milankovitch oscillations, which infer cycles in the variations in the earth’s orbital characteristics around the sun, the wobbling of the earth and the changes in the earth’s axial tilt.
All these alter the amount of insolation received from the sun, which in turn, might have a bearing on the climate.
Volcanism is considered as another cause for climate change. Volcanic eruption throws up lots of aerosols into the atmosphere.
The most important anthropogenic effect on the climate is the increasing trend in the concentration of greenhouse gases in the atmosphere which is likely to cause global warming.
Global Warming
Greenhouse gases are gasses that keep the heat from escaping from Earth to outer space. Greenhouse gases have been a focal point within the field of global warming.
The atmosphere also transmits the incoming solar radiation but absorbs the vast majority of long wave radiation emitted upwards by the earth’s surface.
The gases that absorb long wave radiation are called greenhouse gases. The processes that warm the atmosphere are often collectively referred to as the greenhouse effect.
Greenhouse Gases (GHGs)
Greenhouse gases (GHGs) are gases in Earth’s atmosphere that absorb and emit radiation at specific wavelengths within the spectrum of infrared radiation emitted by the Earth, thus creating an overall “greenhouse effect.”
The primary GHGs of concern today are carbon dioxide (CO2), Chlorofluorocarbons (CFCs), methane (CH4), nitrous oxide (N2O) and ozone (03).
Some other gases such as nitric oxide (NO) and carbon monoxide (CO) easily react with GHGs and affect their concentration in the atmosphere.
The effectiveness of any given GHG molecule will depend on the magnitude of the increase in its concentration, its life time in the atmosphere and the wavelength of radiation that it absorbs.
The chlorofluorocarbons (CFCs) are highly effective. Ozone which absorbs ultra violet radiation in the stratosphere is very effective in absorbing terrestrial radiation when it is present in the lower troposphere.
The largest concentration of GHGs in the atmosphere is carbon dioxide.
The emission of CO2 comes mainly from fossil fuel combustion (oil, gas and coal). Forests and oceans are the sinks for the carbon dioxide.
Forests use CO2 in their growth. So, deforestation due to changes in land use, also increases the concentration of Co2.