How long before Earth gets caught into a runaway greenhouse effect?

Never

Read old magazines.

This is a bunch of hype.

There is always some disaster prediction like this.

In general, the climate has a driver: this can be changes in orbit (Milankovitch cycles), changes in the solar forcing (sun getting hotter over time, or Maunder minimum), or human CO2 emissions. The climate also has feedbacks: the big one is water vapor: as the climate warms, more water evaporates, leading to more water vapor, leading to more warming. The CO2 feedback occurs because warmer oceans can hold less CO2, and this feedback is thought to have contributed to the warming started by the Milankovitch driver in glacial/interglacial cycles. Ditto ice sheet retreat. (note all these feedbacks operate both ways: as the climate cools, water condenses, oceans hold more CO2, ice sheets grow). Of course, as the earth warms, it radiates more heat (Stefan-Boltzmann law). In order to have runaway warming, the feedbacks need to outweigh the Stefan-Boltzmann effect. Making this more complicated is that systems have multiple equilibrium points, where certain feedbacks can occur only over limited ranges. For example, the ice sheet retreat feedback can only keep going until there are no more ice sheets. Even the most famous case of runaway warming, Venus, eventually reached a point where it reached a new equilibrium (albeit, a really really hot and nasty one). Generally, climate scientists today do not worry about "runaway warming". They think the positive feedbacks are there, but, like a geometric series (1 + 1/2 + 1/4 + 1/8 + ...) a given impulse of a driver will lead to an ever diminishing cycle of feedbacks, with a finite total temperature change. This is what the term "climate sensitivity" is used to define: a doubling of CO2 leads to about 1 degree C direct warming, but because of feedbacks the systems new temperature will be larger. Best estimates of climate sensitivity range from 2 to 4.5 or so.

Don't know. We can only guess at what that might be, and what might cause it to happen. We have no recorded data of this event happening. We can theorize it happened millions of years ago, but no one was there with high tech equipment tracking the changes and the causes.

Did you ever consider that the Earth is heating up due to natural cycles of hot and cold? 65 mil years ago, it was really hot. 1 mil years ago it was really cold. Now it is in the middle. With that information alone, is it not possible that the Earth is heating up again and going towards a time when it will be very hot and humid like it was 65 million years ago?

Unlikely. Al Gore and company are fearmongers. There are natural cycles of warming and cooling, which have gone on since the beginning. Check out "State of Fear" by Michael Crichton. It's FICTION (I want to say that first), but it is well researched and heavily footnoted. Makes it a lot easier to understand. Also, 30 years ago, they were forecasting an ice age...

i actually read an article on yahoo news that was about experiments conducted by some smart scientific types that said the ozone hole was actually shrinking....so i'd say we'll never experience a runaway greenhouse effect....

Never as the global warming / greenhouse affect is a mith. Made up by tree huggers to sway us into driving little crappy cars with no power.

The greenhouse effect began at the dawn of the industrial age in the early 1800's.

How long is "never"? In nature, runaway effects are usually self-modifying. For instance, before there was a "global warming" phase in history, there was the "ice age" phase. Mother Nature does what she has to in order to perpetuate herself. Even the warming/freezing cycle is for purposes of (Mom's) preservation.

Two generations after the current one around a 100 years time.

The earth has been doing this for millions of years.

It heats up and then sometimes enters an ice age.

There is nothing you or I can do to stop it.