okay, 1 thing about the ozone: it is created by electric discharge. This occurs in badly designed 'little motor they put in remote control cars'
(they spark), photo-copiers, and not to forget: LIGHTNING is the biggest ozone creator we know off. But still - this isn't enough to undo the damage that we did. It's a natural balance between green-house gasses and the natural production of ozone by lightning.
Anyway: about the point of no return... we have indeed passed it, not recently, but long, LONG ago. About a century i'd say: we use more fossil fuel now in 1 year, then in the *entire* 19th century. As for OP2Patriots remark: oceans as well as any other living animal, produces carbon dioxide, a green-house gas. Yes .. "A" greenhouse gas. There are several. Any gas that is capable of trapping heat beneath it, is considered a greenhouse gas.
I KNOW we are not only passed the point-of-no-return, but also VERY close to 'the day after tomorrow'. You should of course not take it that literally. I myself believe it'll happen over the course of a couple years, althou the instantly frozen mammoths as well as other animals, including some prehistoric humans, have been instantly frozen during the last Ice Age. And as the movie puts it so well in the end: we managed to survive the last one, we will sure survive the next one. And so will plenty of other species.
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When is this going to happen? .. pretty soon.. i'm expecting a few years from now. We are seeing some pretty amazing weather this year, and i believe this is the start. Warm weather is causing an unusual amount of tropical storms turning into hurricanes. We've had the first time EVER not enough names for 1 storm-season. And that's not just it: after the 22 names were exhausted with Wilma, 2 more tropical storms emerged, and there could still be more, because ocean temperatures are still high enough to create more.
In Europe we're seeing late-autumn highs of over 22 degrees Celcius (70 Farenheit), about 10 more then they should be this time of year. Also, for the very first time, Spain has seen a tropical storm (Vince). This never happened before. Also hurricane Maria hit the coast of Norway. This is no longer a USA-alone issue.
I don't want to alarm anyone, but the Gulf Stream ... it IS slowing. Scientists are constantly monitoring it, and found a 75% drop this year.
In siberia, a HUGE amount of methane gas was released from a perma-frost region this summer. Methane is 20 times as good at holding heat close to the earth as carbon dioxide. It had been trapped there for thousands of years, when the ice covering it melted. History shows a dramtic increase in this gas also happened just before the last Ice Age started. The sudden release of billions of tons of methane throws off all calculations made by climate experts. It greatly increases the global heating process!
In Brazil, extreme drought is threatening to create widespread fires in the Amazon rainforest.
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These are just a few examples about what is happening to our planet. And thats only THIS year. It is my expectation that the European winter will be as cold as -15 to -25 Celcius (close to 0 Farenheit). Not an ice age, just a cold winter. But it will be very unfortunate for the thousands of homeless people. And it will be difficult for the poor, with fuel prices as high as they are now..
"The day after tomorrow" isn't just a fictional movie - it is based on the book "The coming global superstorm" describing what will happen, according to what we now know about the last Ice Age. Whitley Strieber and Art Bell were laughed at when they published it in 1999. Nobody is laughing now.