If Global Warming is happening how long has it been going on?

Question

Global Warming is really important to our Earth and atmosphere.
I want to know even if it's just a simple guess:
If Global Warming is happening how long has it been going on?

Answer 1

There is a trend of temperature increase, this is measured reality. But the relation between temperature increase and greenhouse gasses is not well established. There is no science to support a hypothesis that greenhouse gasses are the primary cause of global warming. There is no validated data to support the prediction that future temperatures will increase drastically.

The fear of global warming comes from predictions that future temperatures will increase drastically. This prediction is bases upon computer models. The models have three problems:

1 - There is no long term temperature data from the past two millenia. Accurate global temperature is available only for the past 140 years or so. Temperatures before that, used for input into computer models, are estimates based upon geographic measurements. There are no methods to validat these estimates. In other words, there is no way to know if the temperatures put into models are correct.

2 - Global climate models use mathematical formulas to predict what future temperatures might be. This is where the real fear of global warming comes from. Users of the Global Climat Models predict that, in the future, very drastic global warming will occur. The trouble with this prediction is, that even if *RANDOM* data are input for past history (see the description in 1. above), then the models predict drastic future warming. More simply, the models predict drastic future warming because the equations force it to make that prediction.

3 - *NO ONE* has any data...at all...to determine what part of current warming is caused by either greenhouse gasses, or by natural fluctuation of the sun.

From the site below: "The majority of climatologists agree that important climate processes are imperfectly accounted for by the climate models."

http://en.wikipedia.org/wiki/Global_climate_model

Answer 2

"Global Warming" has been going on since the end of the "LIttle Ice Age". The Little Ice Age began in the 1200 AD and some scientists say it ended about 150 year ago. Our climate has been in a warming cycle since.

Many great accomplishments happened during the Little Ice Age.
The industrial revolution, modern farming techniques, The Age of Exploration, The establisment of the Western Hemisphere countries, etc.

The Little Ice Age also wiped out the Anazasi civilization of Arizona and New Mexico.

Answer 3

The climate was unusually cold in the little ice age in the late middle ages and was warmer before that and now. But I suspect you are talking about man made carbon dioxide in the air, which started with the industrial revolution, but didn't really become big enough to be of concern until the last 50 or 100 years.

Answer 4

There has always been global warming going on, as long as there are infrared-absorbing species in the atmosphere. If it weren't for this phenomenon, the average temperature of the Earth would be about -60 Celsius.