The earth is warming and this is supported by numerous observations and studies by climate scientists, and even verified by some studies financed by global warming skeptics, such as the BEST study.
This past century average global temperatures have risen 0.8 C (1.4 F) and 0.6 C (1.1 F) in just the last 30 years! The source of this increase in global temperatures is very likely the increased concentration of carbon dioxide (CO2) put into the atmosphere from the combustion of fossil fuels. For the last 400,000 years the concentration of CO2 has fluctuated from around 180 parts-per-million (ppm) to 300 ppm, varying with the waxing and waning of the ice ages.
Now all of a sudden we have an unnatural curve due to the activities of man; a CO2 concentration of 280 ppm at the dawn of the Industrial Revolution has now increased to 390 ppm today with no let up in sight. The increase is approximately 2 ppm per year (or 2%). Studies have shown that there is a sensitivity of +3 C with each doubling of CO2 concentration.
"Forcing" is a term used in global warming science to describe what causes something, such as the climate forcing which is leading to the global warming. The main forcing agents in place today is around 3 watts per meter squared (W/m2) for greenhouse gases countered by -2 W/m2 for atmospheric aerosol effects, from pollution. Droplets due to these aerosols can lead to more scattering and reflecting of incoming solar radiation back to space (and hence less for warming of the atmosphere).
The net result of this forcing is +0.5 W/m2, which means the earth on average is taking in more energy than it is emitting and we are out of balance half a watt. It doesn't sound like much, it is just a Christmas tree light (typically 2 W) for each 4 square meters (approximately 4 square yards). But this seemingly small forcing, when summed over the entire globe, has large global warming effects.
This out-of-balance forcing of 0.5 W/m2 has lead to an increase of 0.6 C over the last 30 years, as mentioned earlier. (the earth's average temperature is 15 C or 59 F) Keep in mind that during the height of the last major ice age, 20,000 years ago, the average global temperature was only 5 C lower than today, yet parts of New York City was under at least a mile of ice! Sensitivity of the climate to small changes can also be understood when one considers the fact that if we reach approximately 450 ppm of CO2 concentration, the earth will probably be free of ice. Sea levels would be approximately 75 m (250 feet) higher than today, a major impact of global warming.
While on the subject of sea level...as a result of the warming, sea levels have been rising at a rate of 3 cm (1.5 in)/decade. According to global warming science the rate is expected to increase over the coming decades. After the last ice age, the breaking up of glacial ice led to rapid increases of up to a meter (yard) in 20-25 years! By the way, at the height of the last ice age, the sea level was around 105 meters (350 feet) lower than today.
There is a chance of runaway global warming if we reach a tipping point and enter a positive feedback loop, if we continue "business as usual". The main consequences of global warming are sea level rise (a billion people around the world live within a few meters of the ocean) and extinction of species, with rapidly shifting climate zones. (the current extinction rate is 100 times the natural rate)
With all this info on future doom and gloom, you might ask what can we do to prevent global warming. According to global warming science - first and foremost, we need to phase out the use of fossil fuels, not just spread usage around (i.e., cap and trade). Fossils fuels need to stay in the ground. A fossil fuel fee can be part of the phasing out process.
This past century average global temperatures have risen 0.8 C (1.4 F) and 0.6 C (1.1 F) in just the last 30 years! The source of this increase in global temperatures is very likely the increased concentration of carbon dioxide (CO2) put into the atmosphere from the combustion of fossil fuels. For the last 400,000 years the concentration of CO2 has fluctuated from around 180 parts-per-million (ppm) to 300 ppm, varying with the waxing and waning of the ice ages.
Now all of a sudden we have an unnatural curve due to the activities of man; a CO2 concentration of 280 ppm at the dawn of the Industrial Revolution has now increased to 390 ppm today with no let up in sight. The increase is approximately 2 ppm per year (or 2%). Studies have shown that there is a sensitivity of +3 C with each doubling of CO2 concentration.
"Forcing" is a term used in global warming science to describe what causes something, such as the climate forcing which is leading to the global warming. The main forcing agents in place today is around 3 watts per meter squared (W/m2) for greenhouse gases countered by -2 W/m2 for atmospheric aerosol effects, from pollution. Droplets due to these aerosols can lead to more scattering and reflecting of incoming solar radiation back to space (and hence less for warming of the atmosphere).
The net result of this forcing is +0.5 W/m2, which means the earth on average is taking in more energy than it is emitting and we are out of balance half a watt. It doesn't sound like much, it is just a Christmas tree light (typically 2 W) for each 4 square meters (approximately 4 square yards). But this seemingly small forcing, when summed over the entire globe, has large global warming effects.
This out-of-balance forcing of 0.5 W/m2 has lead to an increase of 0.6 C over the last 30 years, as mentioned earlier. (the earth's average temperature is 15 C or 59 F) Keep in mind that during the height of the last major ice age, 20,000 years ago, the average global temperature was only 5 C lower than today, yet parts of New York City was under at least a mile of ice! Sensitivity of the climate to small changes can also be understood when one considers the fact that if we reach approximately 450 ppm of CO2 concentration, the earth will probably be free of ice. Sea levels would be approximately 75 m (250 feet) higher than today, a major impact of global warming.
While on the subject of sea level...as a result of the warming, sea levels have been rising at a rate of 3 cm (1.5 in)/decade. According to global warming science the rate is expected to increase over the coming decades. After the last ice age, the breaking up of glacial ice led to rapid increases of up to a meter (yard) in 20-25 years! By the way, at the height of the last ice age, the sea level was around 105 meters (350 feet) lower than today.
There is a chance of runaway global warming if we reach a tipping point and enter a positive feedback loop, if we continue "business as usual". The main consequences of global warming are sea level rise (a billion people around the world live within a few meters of the ocean) and extinction of species, with rapidly shifting climate zones. (the current extinction rate is 100 times the natural rate)
With all this info on future doom and gloom, you might ask what can we do to prevent global warming. According to global warming science - first and foremost, we need to phase out the use of fossil fuels, not just spread usage around (i.e., cap and trade). Fossils fuels need to stay in the ground. A fossil fuel fee can be part of the phasing out process.