Scientists from 113 countries issued a landmark report Friday saying they have little doubt global warming is caused by man, and predicting that hotter temperatures and rises in sea level will "continue for centuries" no matter how much humans control their pollution.

A top U.S. government scientist, Susan Solomon, said "there can be no question that the increase in greenhouse gases are dominated by human activities." Environmental campaigners urged the United States and other industrial nations to significantly cut their emissions of greenhouse gases in response to the long-awaited report by Intergovernmental Panel on Climate Change.

"It is critical that we look at this report ... as a moment where the focus of attention will shift from whether climate change is linked to human activity, whether the science is sufficient, to what on earth are we going to do about it," said Achim Steiner, the executive director of the U.N. Environment Program. READ MORE.

What do YOU think — Is global warming a threat, and if so, what should the world's nations do about it?

Write to us at speakout@foxnews.com and tell us your opinion. Check back later to see if your comment was posted!

Here's what some FOX Fans are saying:

"The only thing man-made about global warming is the name." — Mike (North Carolina)

"Global warming is extremely risky. Although scientists are unable to predict exactly what will happen do to increased greenhouse gases in the atmosphere, what will likely happen as a result will be devastating to our economy and to those around the world. There is much that can be done, but people and governments can't wait any longer to make changes! It has been demonstrated in many countries that reducing harmful emissions does not have to be detrimental to our economy. The longer we wait, the harder it is going to be, and the consequences we risk facing will become more severe." — T.S.

"There is much debate around global warming, and it all centers around what is happening today. A true scientist cannot ignore past history when studying climate. There is proof that the planet has warmed and cooled several times and that was not caused by human intervention. To say this is caused completely by man is irresponsible science." — Jerry (Dale, IN)

"You have 113 countries supporting scientists with political agendas. If man actually caused global warming, then we can fix it. But they say we can't. Global warming is a natural cycle, and mankind will adapt as we always have!" — Chris

"I am tired of hearing words like global warming and greenhouse gases. I am tired of college professors beating it into the heads of students. Global warming is an opinion! How do scientists know that it is not a natural occurrence? I think this is a major hoax by scientists to bring home a paycheck!" — Jason (Diamond Bar, CA)

"Perhaps I'm being just stubborn and hard-headed, but there is not a whole lot that any scientist can tell me that will make me think that humans are the cause of global warming. Over the entire history of the earth there have been times when it has warmed itself and times when it has cooled itself. The earth takes care of itself. I am not denying the chance that perhaps this time humans have been a cause of global warming, but I do NOT believe that humans are THE cause!" — Greg (Alabama)

"Climate change has been occurring since the beginning of the Earth, however it is a news flash to many, if not most, that the climate changes. The climate, like the rest of the Earth's systems, is a dynamic system, nothing stays the same for long. Periods of glaciations and periods of intense heat are both found in the geologic record. I marvel that many scientists are willing to come down so conclusively that climate change is our fault, yet at the same time admit the Earth's weather is so complex as to make it impossible to truly make accurate forecasts for more than three days out." — John

"This is the fastest the U.N. has ever acted on anything in its history. I am not convinced that global warming and climate change is something we mere humans can have much of an impact on, but when science is able to plug volcanoes and stop natural forest fires, then I agree that humans will be able to do more than we are doing. Also, when weather forecasters can be accurate on next week's weather, I'll listen to what they have to say about the climate change 80 years out." — Susan (Malvern, PA)

"Global warming started when the industrial revolution started, and we are just now beginning to see the consequences and adverse affects of decades of pollution and neglect to our mother Earth. There is a solution, but at what price are we as a human race willing to pay?" — Dane

"This report is another in a long line of many reports since the '60s that reconfirm what we already know: that man's practices contribute to air and water pollution if it is not managed properly. To have another report to tell us this is meaningless. To dictate through more restrictions and laws that we stop doing certain practices is as useful as passing a law to hold our breath so we can save the oxygen in the air." — David (Seattle, WA)

"How did ice ages and warming of the Earth occur before man even existed? Furthermore, if it is happening and we can't stop it, then why cut greenhouse gases at all?" — Peter

"I am absolutely not concerned about global warming, any more than the global cooling which is causing abnormally frigid conditions in geographical areas where these cold temps generally do not occur." — Arlen

"Global warming may definitely cause us some consternation, such as high water and other problems, but the idea that man is the cause and some little 'green' thing we do will have a significant effect on it one way or another is ludicrous. Three large volcanoes spouting millions of tons of ash into the atmosphere will have more effect in a week than all of mankind combined from then until now! We would be more effective if we spent the money they are preparing to go for on this on food and fuel to cope with whatever climatic changes are occurring." — Doyle

"The issue of global warming has gone from a scientific question to a political issue. Those who take to position that global warming is because of the advancements, and lifestyle of today's society, and then blame the United States, have a political agenda that has nothing to do with global warming. This country has done more to reduce pollution than any other country, and continues to look for ways to reduce pollution. This is another useless report form a useless organization." — Wince (Clermont, FL)

"I do not believe global warming is anything the human race can control. Anyone who has done any reading at all knows the Earth has gone through changes several times and there were no automobiles, power plants, etc. when those changes occurred. I think this is just another way the Left is trying to change the way we live. If they want to change the way they live, that is their business. I will not change the way I live." — K.L. (Manchester, MD)

"Global warming is the biggest hoax yet on mankind. It is junk science, pure and simple. The earth goes through periodic heating and cooling periods, and this is no exception." — Jay (Ohio)

"I don't believe that it is a threat at this point, but I think as a responsible nation we need to make changes. Because of the global effect of this problem, the government should appoint a watchdog to make sure deadlines are met." — Jan (Wisconsin)