
This headline may come as a bit of a surprise, so too might that fact that the  warmest year recorded globally was not in 2008 or 2007, but in 1998.
But  it is true. For the last 11 years we have not observed any increase in global  temperatures. 
And our climate models did not forecast it, even though  man-made carbon dioxide, the gas thought to be responsible for warming our  planet, has continued to rise. 
So what on Earth is going  on? 
Climate change sceptics, who passionately and consistently argue  that man's influence on our climate is overstated, say they saw it  coming. 
They argue that there are natural cycles, over which we have no  control, that dictate how warm the planet is. But what is the evidence for  this? 
During the last few decades of the 20th Century, our planet did  warm quickly. 
Sceptics argue that the warming we observed was down to  the energy from the Sun increasing. After all 98% of the Earth's warmth comes  from the Sun. 
But research conducted two years ago, and published by the  Royal Society, seemed to rule out solar influences. 
The scientists' main  approach was simple: to look at solar output and cosmic ray intensity over the  last 30-40 years, and compare those trends with the graph for global average  surface temperature. 
And the results were clear. "Warming in the last 20  to 40 years can't have been caused by solar activity," said Dr Piers Forster  from Leeds University, a leading contributor to this year's Intergovernmental  Panel on Climate Change (IPCC). 
But one solar scientist Piers Corbyn  from Weatheraction, a company specialising in long range weather forecasting,  disagrees. 
He claims that solar charged particles impact us far more  than is currently accepted, so much so he says that they are almost entirely  responsible for what happens to global temperatures. 
He is so excited by  what he has discovered that he plans to tell the international scientific  community at a conference in London at the end of the month. 
If proved  correct, this could revolutionise the whole subject. 
Ocean  cycles
What is really interesting at the moment is what is happening to  our oceans. They are the Earth's great heat stores.
In the last few years  [the Pacific Ocean] has been losing its warmth and has recently started to cool  down 
According to research conducted by Professor Don Easterbrook from  Western Washington University last November, the oceans and global temperatures  are correlated. 
The oceans, he says, have a cycle in which they warm and  cool cyclically. The most important one is the Pacific decadal oscillation  (PDO). 
For much of the 1980s and 1990s, it was in a positive cycle, that  means warmer than average. And observations have revealed that global  temperatures were warm too. 
But in the last few years it has been losing  its warmth and has recently started to cool down. 
These cycles in the  past have lasted for nearly 30 years. 
So could global temperatures  follow? The global cooling from 1945 to 1977 coincided with one of these cold  Pacific cycles. 
Professor Easterbrook says: "The PDO cool mode has  replaced the warm mode in the Pacific Ocean, virtually assuring us of about 30  years of global cooling." 
So what does it all mean? Climate change  sceptics argue that this is evidence that they have been right all  along. 
They say there are so many other natural causes for warming and  cooling, that even if man is warming the planet, it is a small part compared  with nature. 
But those scientists who are equally passionate about man's  influence on global warming argue that their science is solid. 
The UK  Met Office's Hadley Centre, responsible for future climate predictions, says it  incorporates solar variation and ocean cycles into its climate models, and that  they are nothing new. 
In fact, the centre says they are just two of the  whole host of known factors that influence global temperatures - all of which  are accounted for by its models. 
In addition, say Met Office scientists,  temperatures have never increased in a straight line, and there will always be  periods of slower warming, or even temporary cooling. 
What is crucial,  they say, is the long-term trend in global temperatures. And that, according to  the Met office data, is clearly up. 
To confuse the issue even further,  last month Mojib Latif, a member of the IPCC (Intergovernmental Panel on Climate  Change) says that we may indeed be in a period of cooling worldwide temperatures  that could last another 10-20 years.
Professor Latif is based at the  Leibniz Institute of Marine Sciences at Kiel University in Germany and is one of  the world's top climate modellers. 
But he makes it clear that he has not  become a sceptic; he believes that this cooling will be temporary, before the  overwhelming force of man-made global warming reasserts itself. 
So what  can we expect in the next few years? 
Both sides have very different  forecasts. The Met Office says that warming is set to resume quickly and  strongly. 
It predicts that from 2010 to 2015 at least half the years  will be hotter than the current hottest year on record (1998). 
Sceptics  disagree. They insist it is unlikely that temperatures will reach the dizzy  heights of 1998 until 2030 at the earliest. It is possible, they say, that  because of ocean and solar cycles a period of global cooling is more  likely. 
One thing is for sure. It seems the debate about what is causing  global warming is far from over. Indeed some would say it is hotting up.