Since the 1960s, scientists have observed a gradual increase in the global temperature. This is believed to be caused by the mass release of a greenhouse gas, carbon dioxide, produced by burning fossil fuels (coal, oil, natural gas). If strategies for slowing global warming are not found, some scientists believe that it could accelerate at a runaway pace, melting the ice sheets in Antarctica and Greenland, causing the world's sea levels to rise 18 to 59 cm (7.08 to 23.22 in) by 2100. Other negative effects, including more intense hurricanes, is thought to be resulting from human-caused global warming.
Numerous strategies have been offered for slowing global warming. These include quotas on fossil fuel production, energy efficiency and conservation, alternative energy sources, using fossil fuels that produce the least greenhouse gases (natural gas), carbon capture-and-storage (from the exhaust pipes of power plants), carbon sequestration (from the atmosphere itself), solar shades, societal controls, international treaties, legal action, and personal choice.
The most popular strategies for slowing global warming seems to be a combination of energy efficiency/conservation, or "going green," and the development of alternative energy sources, such nuclear, wind, hydro, and solar power. Billions of dollars have been invested in alternative energy expressly for the purpose of slowing global warming. However, fossil fuels still remain the primary power source for generating electricity worldwide.
There are more exotic methods that have been proposed for slowing global warming. Paul J. Crutzen, a Dutch Nobel Prize-winning atmospheric chemist, has proposed releasing sulfur aerosols into the upper atmosphere to decrease the incident solar flux on Earth by a small percentage, reversing the effects of greenhouse gases. In this same vein, plans have been proposed to increase the density of the low-level cloud layer, creating a Saturn-like ring of small particles around the Earth, and putting a thin wire mesh between the Earth and the Sun. Most of these proposed strategies would cost in the range of $10 - $100 billion US Dollars. This is quite a price tag, but it might be worth paying if the most dire predictions of climate scientists prove true.
