Why has global warming happened now?

Answer 1

The current warming cycle is the fifth that we know of. This is the coolest of the five we have the ability to see evidence from. We know these cycles occur due to variances in earth orbit.

The current warming cycle started over 10,000 years ago. It has warmed over 11 degrees C during this period. Since man began using fossil ful we have seen warming of over 0.5 degrees C. All but 0.2 of that warming happened before 1938.

There is some evidence that man has contributed to the current warming of the planet. This is in addition to the natural warming that has occurred. The dominating issue though is a natural cycle that started 10,000 years ago and seems to dovetail with planet alignment.

Answer 2

Unfortunately, all of us share some degree of responsibility for global climate change. Since the Industrial Revolution began, humans have burned gargantuan amounts of coal, oil, gasoline and other carbon-based fuels -- even whale blubber -- to heat our homes, operate our vehicles, and power our factories.

All of these activities create gases like carbon dioxide that absorb heat from sunlight and trap that heat in the atmosphere, much like a greenhouse traps heat -- thus the term "greenhouse gases." Billions of people burning carbon-based fuels for over 200 years have had an impact on Earth's thin atmosphere far in excess of any other source of atmospheric heating (volcanoes, solar activity, etc.).

For more information on global warming and climate change, visit the following website:

http://greenliving.about.com/od/greenlivingbasics/a/climate_change_global_warming.htm

A:1) It is not certain that global warming has come about - though there seems to be a popular belief among scientists that it has, though to what extent is uncertain.

2) If it has, there are a number of possible reasons: some say 'man made' atmoshpheric changes - i.e. higher levels of C02. Others say it may be the result of solar activity (or inactivity.) There are other theories. Some say this; some say that. It's a matter of opinon.

Answer 3

This has happened before. Many theorize that co2 emissions are causing temps to rise, but this is an unproven theory, in spite of what is popular to believe. The earth has been warmer in the distant past than now, and has returned to a cooling pattern, which in fact, may be taking place as we speak.

Here is a link to severe cold weather.

http://newsbusters.org/blogs/tom-blumer/2012/02/04/read-brian-williams-and-nbc-deadly-record-breaking-cold-winter-eastern-e

Answer:

All metrologists and atmospheric scientists agree that life on Earth would not be possible without a natural greenhouse effect. Without it the Earth would be about 33°C cooler reducing the average temperature to -18°C instead of 15°C. The most important natural greenhouse gases are water vapour and carbon dioxide Water vapour makes up about 60% of the natural greenhouse effect, and carbon dioxide about 20%. The present concern about greenhouse gases and climate change generally refers to the excess carbon dioxide, methane and a few other gases that are increased by human activites. These gases in their new amounts are forcing the global climate to reach a new equilibrium.

It is useful to understand the factors involved in the balance of the solar heat reaching the Earth and the planets temperature.

The Sun is the source of all of the energy reaching the Earth. This sunlight falls on all of the Earth's surface which absorbs the greater part of it. Some of it is reflected directly back into space by light coloured surfaces (e.g. ice and snow) and the top of clouds. Gases and particles in the air absorb a part of the incoming solar energy.

Now it gets a bit more complicated. The energy absorbed by the surface of the Earth is re-emitted as heat (long wave infrared radiation), warming the Earth.

and making water evaporate. While a small amount of the infrared radiation goes directly back into space, the clouds mentioned above as reflecting sunlight, absorb the heat radiation from the Earth. A cloudier sky keeps the Earth warm, like a blanket. This same effect (keeping the Earth warmer) is also caused by greenhouse gases.

Even more complication follows as the warmer air releases methane (a potent greenhouse gas from permafrost) in the arctic regions, reduces the Earth's reflective ability by reducing the ice cover (allowing more heat to be adsorbed by the sea), warmer sea water changes sea currents and their impact on climate. The increased atmospheric water vapor also creates a heavier cloud deck which traps more heat from the light which still reaches the ground.