How can global warming cause an ice age

The blob could impede the flow of the Gulf Stream, which carries warm water north. And if that happens, the temperature in Europe may drop steeply, hurricanes may become more intense, and sea levels on the East Coast of the United States may rise even more rapidly than they are already.

The possibility that climate change could flip and, in just a matter of years, plunge part of the world into a new ice age is something that has occasionally made its way into the media. Yet the world has done very little about it. Massive amounts of greenhouse gases are still being pumped into the atmosphere. The climate is getting warmer and weirder. Calvin , a theoretical neurophysiologist based at the University of Washington in Seattle.

The match was chilling, so to speak. Of course, those previous warm spells were not accelerated by human activity. Calvin also suggested that the flip-flop would not be gradual; once under way, it could wreak its havoc in just a few years.

As for what would happen in the aftermath, Calvin foresaw starvation, a population crash, and powerful countries invading poorer ones in order to commandeer their food supplies. Recovery would be very slow. He was hardly alone, of course. Read on to learn what scientists have to say. According to one school of thought, a warming planet is one that's less likely to wind up in an ice age.

Because the Earth is always going through warming and cooling cycles, and we've been in one of the warming cycles for about 12, years now, scientists say it's inevitable that we'll hit another big chill sometime in the next 10, to , years. If that happens, much of the world -- including Europe and North America -- would be covered in a thick sheet of ice. According to some researchers, the heat trapped in the Earth's atmosphere from the greenhouse effect will offset this cooling -- essentially preventing the Earth from entering another ice age [sources: Science Daily , Cosmos ].

Though averting an ice age sounds like good news, the researchers caution that global warming isn't any picnic, either. It could lead to other drastic and unpleasant effects on the planet think rising sea levels and dwindling global food supplies. Another school of thought makes the opposite prediction: Global warming might actually lead to another ice age.

According to this theory, warming temperatures disrupt ocean currents -- particularly the Gulf Stream, the flow that redistributes warm water from the Gulf of Mexico to northern Europe. As the Gulf Stream makes its deposits of warm water along the coasts of Great Britain and northwestern Europe, it keeps the temperatures there warmer than they would be otherwise. The worry is that, when Arctic ice melts as a result of global warming, huge amounts of fresh water will pour into the North Atlantic and slow down the Gulf Stream.

A study of circulation in the North Atlantic has discovered that there already has been a 30 percent reduction in currents flowing north from the Gulf Stream [source: Pearce ]. A slowed Gulf Stream could potentially lead to dramatic cooling in Europe.

Will either of these scenarios really happen? It's hard to say for sure. Climate experts haven't even come to a consensus about the cause and effects of global warming, let alone whether it might prevent or trigger the next ice age. The question of whether reversing global warming might lead to an ice age could be irrelevant if it never happens.

According to a study by the National Oceanic and Atmospheric Administration NOAA , the changes in ocean surface temperature, rainfall, and sea level that have already occurred are irreversible for a thousand years after carbon dioxide emissions are completely stopped [source: NOAA ]. That means no matter how much we curb our emissions today, we may not be able to undo the damage that has already been done anytime soon. By the late s, the scientific consensus was that it had stopped in the past and could do so again , possibly with disastrous consequences — albeit not overnight.

Gulf Stream anxiety reached its apogee in when scientists at the University of Southampton, UK, discovered that the North Atlantic current had weakened by a third. But follow-up measurements by the same team showed no clear trend. But science is never settled and the fate of the North Atlantic current is back on the agenda. There is nowhere near enough data to suggest another U-turn is on the cards.