Scientists have issued a stark warning about greenhouse gas emissions, saying they are rising at an "unsustainable" rate.
Scientists warn that greenhouse gases are having dire effects on the environment
Their report also warns that climate change could cause the Greenland ice sheet to melt, leading sea levels to rise by seven metres over 1,000 years.
The BBC news website's environment correspondent Richard Black has answered some of your questions about climate change.
Is climate change a normal part of a planet's existence? Sure I don't think greenhouse gasses are helping, but I don't think we can stop it. The best thing we can do, as a race, is to prepare and adapt. Do you agree with this?
Riordan Tomlinson, Blackburn, UK
Climate does change naturally; of that there is plenty of evidence in the record of ice-cores, fossils and so on. Humans have adapted in the past and surely will have to adapt again.
As a humble journalist it is not really for me to say what societies should do, but I do think there is another way of looking at the current situation.
If present-day warming is caused predominantly by human activities, then we do have the option of trying to curb it by changing the way our societies are run; whereas with an episode of primarily natural change, presumably we would not have that option.
As levels of CO2 rise, the heating effect should intensify but what I read in the reports is that Russia is witnessing one of the worst winters or New Delhi records a minimum temperature of 0.2C this winter. I just wonder are we drawing conclusions from insufficient data?
Gulab Singh, New Delhi, India
Scientists would always want more data; and many climate researchers do bemoan the relatively short period for which records of direct temperature measurements are available.
Where does Russia's bitter winter fit in to the global warming debate?
The danger implicit in the question though is a different one; the danger of trying to draw a conclusion from what happens in an individual year.
The key issue is the trend over many years - and that does indicate a gradual rise in temperatures, even though there is significant variation from one year to the next and from one part of the world to the next.
Across Eastern Europe people are freezing as temperatures drop below minus 30C. Is this only 'global warming' in summer and "climate change" the rest of the year?
John Smith, Leicester, UK
Getting language right should perhaps be the second concern of journalists, the first being to get our facts right. But it is not quite as simple as it seems.
This new report, for example, suggests we should not use the term "global warming" any more, as the impacts of what we are now seeing stem from many factors - some, such as increased ocean acidification, which are not directly related even to climate. Yet the term 'climate change' can mean a natural phenomenon as well as a human-induced one; this also applies to "greenhouse effect".
Perhaps the best phrase we have is "anthropogenic climate change"; but try using that too many times in a single report and the perils become obvious! We reporters have to try harder, I think.
Can you put me straight on the carbon-neutral (or otherwise) status of trees? If, at the end of a tree's natural life, it is cut down and say made into furniture, then surely the carbon is locked in that wood furniture?
As long as that wood is not burned, then the effect is to reduce the CO2 in the atmosphere.
Leigh Harries, UK
The question is, what happens to the furniture at the end of its life? If the wood is burned, CO2 is released: if it is left to decay, methane could be created which is also a greenhouse gas. On the other hand, some of the carbon could remain locked up in the long term.
This is precisely the kind of question which is leading some researchers to focus on the total life cycle of goods, measuring and calculating the total greenhouse gas "burden", as they call it.
Not long ago, a technical author within the IPCC resigned because his bosses were trying to force him to attribute the recent hurricanes to "man-made global warming", despite a complete lack of evidence.
Are these scares invented so that EU governments can justify ever-higher "green" taxes?
Andrew Howlett, Manchester, UK
The science of climate change has been politicised for several years, and is, if anything, becoming more politicised. Yes, a technical author resigned citing pressure to "conform" to an over-arching IPCC theology, but within the last few days a prominent US researcher, Jim Hansen, has complained of being muzzled by the Bush administration. Same story, opposite direction.
I have tried to sum up the current state of knowledge on hurricanes - which is more mixed than the question implies in this article.
Do EU governments really want to impose "ever-higher green taxes"? What would be their motivation for so doing? Do European governments have a mandate to reduce the competitiveness of European industry in relation to the rest of the world?
I get really confused over the issues of climate change. The report goes on about the reduction of the ice around Greenland and the effect it will have on raising sea levels.
What about the other camp who believe the warming of the ice flow will dilute the sea salt levels thus stopping the "conveyor belt", thus causing an ice age. I am confused. Can someone help me here?
Simon Wilkinson, UK
It is confusing, partly because scientists are not always very good at synthesising the overall picture - and sometimes journalists forget to ask the really obvious questions.
This new report suggests that for Europe, a cooling effect from a collapse of the north Atlantic conveyor would be stronger than the regional heating effect of a more generalised global warming. But there are many uncertainties hidden away there, and I don't think any researcher is going to give an answer which is not full of caveats.
An additional possibility is that the "end of the conveyor" could move southwards, which could mean, for example, Scotland getting colder but Spain getting warmer.
We all wish it was not so, but uncertainties are a major factor in the current picture
Isn't this just another weather cycle that lasts several thousand of years? The world does go through hot and cold spells lasting several decades. Are we in the hot section at the moment?
The best evidence on how current climate fits into the long-term picture comes from Antarctic ice cores; and the longest dataset comes from the EPICA project. These cores suggests we are in the middle of a "hot section" at the moment. This story explains in more detail.
Climate change is the second biggest problem facing the planet. The first is population pressure. Population pressure actually leads to climate change. People don't want to talk about population pressure - why not?
Geoff Landsbury, Cambridge
Population has been called the environment issue that no-one wants to raise - and for understandable reasons, as it is fraught with difficulties. You will be glad to see, I hope, that on the BBC News website we have seen fit to break purdah and open things up in our new series of environmental viewpoint articles, The Green Room