Quote:
|
Originally Posted by j10asen
Quote:
|
Originally Posted by kmfarm
I believe global warming is happening, I simply wonder what's really causing it. I understand the issues with greenhouse gases, pollution and all, but here's something to think about: If glaciers formed the landscape and then receded, we must have had some warming for quite some time. So how much of the global warming is man-made and how much is naturally occuring? I ask this as a serious question.
Mark
|
You are not the 1st person to pose this question many have inquired about this but we really do not have an answer. I think like most issues facing us today we need to deal with the knowns 1st and then perhaps the unknown will become more understood. Like any journey we begin on the known path and then venture into the unknown. |
Global warming alarmists like myself will sometimes jump to conclusions to advocate that global temperatures have increased since about A.D. 1860 to the present as the result of the so-called " Industrial Revolution," caused by releases of large amounts of greenhouse gases from manmade sources into the atmosphere causing a runaway "Greenhouse Effect."
Was man really responsible for pulling the Earth out of the Little Ice Age with his industrial pollution? If so, this may be one of the greatest achievements of the Industrial Age!
Unfortunately, we sometimes tend to overestimate our actual impact on the planet. In this case the magnitude of the gas emissions involved, even by the most aggressive estimates of atmospheric warming by greenhouse gases, is inadequate to account for the magnitude of temperature increases. Human additions to total greenhouse gases play a still smaller role, contributing about 0.2% to 0.3% to Earth's greenhouse effect. So what causes the up and down cycles of global climate change?
After digging through my notes from past geology courses here is my finale thoughts on what triggers an Ice Age...
Major Causes of Global Temperature Shifts
--------------------------------------------------------------------------------
(1) Astronomical Causes
:arrow: 11 year and 206 year cycles: Cycles of solar variability ( sunspot activity )
:arrow: 21,000 year cycle: Earth's combined tilt and elliptical orbit around the Sun ( precession of the equinoxes )
:arrow: 41,000 year cycle: Cycle of the +/- 1.5° wobble in Earth's orbit ( tilt )
:arrow: 100,000 year cycle: Variations in the shape of Earth's elliptical orbit ( cycle of eccentricity )
(2) Atmospheric Causes
:arrow: Heat retention: Due to atmospheric gases, mostly gaseous water vapor (not droplets), also carbon dioxide, methane, and a few other miscellaneous gases-- the "greenhouse effect"
Solar reflectivity: Due to white clouds, volcanic dust, polar ice caps
(3) Tectonic Causes
:arrow: Landmass distribution: continental drift causing changes in circulatory patterns of ocean currents. It seems that whenever there is a large land mass at one of the Earth's poles, either the north pole or south pole, there are ice ages.
:arrow: Undersea ridge activity: "Sea floor spreading" (associated with continental drift) causing variations in ocean displacement.
