If we don't change at all in the way and the amount we pollute the Earth right NOW? I've seen people say from a few decades, to 2800, lol.

A long time. Basic physics tells us that doubling CO2 concentration would warm the planet by about 1.2C. With negative feedbacks, this 1.2C would shrink to a much smaller number.

It takes maybe 50 years to reach the first doubling. After that another doubling would take at least 100 years, probably more.

Honest calculations are not necessarily right, because there is too much uncertainty in how climate works. this is why, not only "skeptics" but also "warmers" question computer models. The difference is that the "warmer" does not jump to the conclusion, that computer models are needed to prove that carbon dioxide is a greenhouse gas. To see how it was discovered that carbon dioxide is a greenhouse gas, follow this link

http://en.wikipedia.org/wiki/File:Tyndal...

As far as how long we can go before the environment becomes a catastrophe, all we can do is switch to clean energy sources, such as solar, wind and nuclear power, as fast as possible, and hope for the best.

Kano

Don't worry about the next ice age. If it happens on schedule, it will only cool at a rate of about 0.01 degrees C per century. In fact, as of the mid 1800s, Earth was 6,000 years into the cooling which was happening right on schedule.

http://upload.wikimedia.org/wikipedia/co...

The thing is, we don't know enough to be sure of any calculations we give.

Though we know about what climate sensitivity to CO2 itself is, we're not sure what feedbacks our warming will trip. How much methane is frozen in the Arctic tundra? How much methane is in clathrates below the ocean? How fast will the world's glaciers melt, exposing bare rock? What exactly are clouds doing? What feedbacks exist that we know absolutely nothing about?

We also don't know what human behavior will be. Solar energy is getting cheaper than ever--will we all switch to solar instead of coal for purely economic reasons within the next decade or so? Will thorium reactors overcome Certain Parties' absolute panic about nuclear power? Will we develop cold fusion within the next few years? There are a lot of technological advancements that could happen in the next decade or 2 that could, in essence, render the question moot. Or, we could simply burn more gas and more coal until we run out or choke on our own fumes.

And, at what point do you declare the situation a catastrophe? How many extinctions have to occur? How many people dead? How many climate refugees? How much erosion of our quality of life? How bad, exactly, does it have to get to go from "not good" to "catastrophe"?

My vague ballpark is that if we don't start taking at least some serious action within about 2 or 3 decades, we'll reach a point where we'll either have to take truly drastic action (think power rationing, banning cars, and so on) or start suffering truly dire consequences. But, frankly, it's all crystal ball stuff at this point. We don't have enough information to do more than make informed guesses.

Current warming is 0.61C. This is the current Global average temperature above the established normal temperature. In January 2007 the Global average temperature was 0.94C above the established normal, but by the following January (2008) the Global average temperature dropped to 0.24C. If the temperature varies this much over time, then it is hard to understand that humans have any effect on these natural climate variations.

February 1994 -'95 is another example where Global average temperatures varied by 0.77C in one year only this time it increased from 0.01C (below the established normal temperature) to 0.76C. CO2 had nothing to do with that increase.

http://data.giss.nasa.gov/gistemp/tabled... - Extreme increases/decreases in global average temperatures are very prevalent in our instrumental records over the past 133 years. CO2 has no bearing on these fluctuations.

Extremely hard to know. It depends how much time lag there is in the climate system, which is difficult to identify at present. There may be an awful lot (bad news) or there may be very little (we can do something about it).

I am seriously worried, the last ice age was 12,000yrs ago usually the gap between ice-ages is 10,000yrs so we are overdue.

If another ice-age starts all the CO2 we can make, will not make the slightest difference, remember we had an ice-age in the Ordovician period when CO2 was ten times higher than now, and that ice age retreated at a time when CO2 was declining, shows how much notice climate takes of CO2.

Just look in the Bible. Ecclesiastes 1:4 says the earth will be here forever. God's promise is the most honest calculation there ever was.

I know, you can buy GW survival kits. Though I don't think they are really hot sellers. I'd be more worried about how to start a fire with a solar panel on a cloudy day.

If you are waiting for man-made Global Warming to kill us, you are going to be waiting a long time.

Top climate scientists say there is no man-made Global Warming.

The Great Global Warming Swindle