If man is causing "global warming", what caused the Ice Age to end?

Answer 1

Ice ages (and inter-glacial periods) are caused by "orbital forcing", changes in Earth's orbit that cause extended periods of longer or shorter winters in the Northern hemisphere. Since Earth's orbit can be computed for centuries into the past and future, orbital forcing can be computed and predicted with decent accuracy. Orbital forcing indicates that in the current interglacial era, Earth's temperature peaked 6000 years ago, and should be slowly cooling since then. (Here's a reference) http://www.sciencemag.org/cgi/content/abstract/207/4434/943

In other words, the natural cycle that causes ice ages has already peaked, and should be taking us in the cooler direction. Meanwhile the earth's temperature is rising rapidly: all fifteen of the fifteen warmest years on record have occurred since 1990. So clearly something other than natural orbital forcing is at work.

Could solar activity be the culprit? Possible, but not likely. There is no convincing evidence that solar activity has been increasing during the past couple of cycles. Here's another reference. http://ieg.or.kr:8080/abstractII/G0102523037.PDF

Meanwhile, the level of CO2 in the air now is higher than at any time in the last 23 million years, and the growth in CO2 shows no sign of slowing down. (Here's a graph).
http://www.grida.no/climate/ipcc_tar/wg1/fig3-2.htm

Answer 2

Here's today's mini-lesson on climate change:

For the most part, average global surface temperature depends on three things: solar energy taken in, energy lost through radiation and redistribution of heat. The amount of solar energy taken in depends on the amount being produced, the amount striking the earth and the amount reflected, all of which can vary, due to earth's orbit, sunspots, size and positioning of continents (which has, indeed changed over the years) and amount of ice pack cover.

These processes have been going on for millennia. Ice ages have come and gone; average surface temperatures have varied during the last 65 million years by 20 c (36 degrees F). The greenhouse gases only come into play in determining the amount of energy lost to radiation. Greenhouses gases act to block the escape of radiation.

Everyone knows this; so what is the problem; why are people concerned?

) Since the start of the industrial age, atmospheric CO2 levels have increased 100 ppm. It's current level is totally unprecedented (30% higher than the highest) over the last 800,000 years for which ice core samples have been determined

2) Over the last 20 years, CO2 levels have been rising at a rate 50 times greater (that's 5000% faster) than at any time during the last 800,000 years

3) There are feedback mechanisms in play with temperature, where rising temperature melts ice caps which reduce reflectivity which causes more heat to be absorbed. Another example of a feedback mechanism is when you put a microphone in front of a speaker.

4) We've already experienced a huge increase in average global temperature as a direct result of increased greenhouse gases. Some people misguidedly believe this 1c (2 degrees F) warming we've already seen is insignificant because temperatures vary by so much more than that in a single day. Nothing could be further from the truth. The difference in AVERAGE GLOBAL temperature between the start of the industrial age and the coldest parts of the ice ages is only 8c (15 degrees F).

So, to answer your question directly rather than obliquely, just because one source of climate change exists (man burning fossil fuels, for instance) says nothing about the existence of other sources of change.

Answer 3

The Earth’s climate for the past 2 million years has been characterized by ice ages lasting about 100,000
years, punctuated by relatively short (10,000- to 20,000-year) warm periods or interglacials. The swing
from glacial to interglacial is caused by changes in the Earth’s orbit around the sun.
The Earth entered the present interglacial about 10,000 years ago. All things being equal (i.e., in
the absence of a large human-produced source of CO2) it is highly likely that the Earth will swing back
into a glacial period or ice age in the next several thousand to 10,000 years.
The link between ice ages, interglacials and the Earth’s orbit was elucidated in the 1970s, most
notably in a paper by Hays and colleagues (Science, 194, 1976, pg. 1121). On the heels of this discovery
there was a good deal of discussion about the likelihood that the Earth would inevitably return to ice age
conditions in the future. However it was always understood that the time frame for a new ice age is
thousands of years, much longer that the decade-to-century time scale of relevance for global warming
from fossil-fuel burning. Hays et al. make this clear

“Future climate. Having presented evidence that major changes in past climate were
associated with variations in the geometry of the Earth's orbit, we should be able to
predict the trend of future climate. Such forecasts must be qualified in two ways. First,
they apply only to the natural component of future climatic trends - and not to
anthropogenic effects such as those due to the burning of fossil fuels. Second, they
describe only the long-term trends, because they are linked to orbital variations with
periods of 20,000 years and longer. Climatic oscillations at higher frequencies are not
predicted.”

While the work of Hays et al. has been misquoted and misinterpreted by some to discredit the science of
global warming, there is in fact no inconsistency. Concern about global warming relates to climate
changes over decades to centuries. Climatic fluctuations between interglacials and ice ages occur over
thousands of years. The globe can warm over the next hundred years due to greenhouse gas pollution
with devastating effects upon society and still have another ice age thousands of years later.

Answer 4

Ice ages are caused by by periodic reduction in the amount of the sun's energy reaching the earth's surface. They are due to "the eccentricity of the orbit around the sun, the tilt of the Earth's axis, and the direction the north pole points". Once the factors that cause the ice age pass enough energy makes it to the earth's surface for the ice to melt.

Answer 5

While I agree with the 2 long answers, that just won't suite the 'chicken Little's". We have a major problem for them to worry about, so let's feed their flame. It has to be from a civilization that is now long dead. They used all of the wood they could find and just filled the air with carbon dioxide, thus melting off the ice. They had nuclear energy as well and blew themselves up with it, and that's why we can't find any traces of them. We are going to do the same, so all the worry wort's start chewing on your finger nails, it's all going to blow any day now.

Answer 6

Possibly a meteor hitting the earth and changing its orbit putting us closer to the sun. Remember we are just this little pebble in the solar system in orbit. I believe that there has been many Meteors bigger than earth in space out of our orbit. Who's to say in the past one didn't smack into or glance off of earth.

Answer 7

it was obviously the vikings. all those campfires and burning villages added up.