UN meteorologists say global temperatures should be slightly lower this year as a result of the La Nina phenomenon.
However, climate change deniers shouldn't necessarily rejoice.
The World Meteorological Organisation's secretary-general, Michel Jarraud, told the BBC it was likely that La Nina would continue into the summer.
This would mean global temperatures have not risen since 1998, prompting some to question climate change theory.
But experts have also forecast a record high temperature within five years.
'Variability'
La Nina and El Nino are two great natural Pacific currents whose effects are so huge they resonate round the world.
El Nino warms the planet when it happens, La Nina cools it. This year, the Pacific is in the grip of a powerful La Nina.
It has contributed to torrential rains in Australia and to some of the coldest temperatures in memory in snow-bound parts of China.
Mr Jarraud told the BBC that the effect was likely to continue into the summer, depressing temperatures globally by a fraction of a degree.
This would mean that temperatures have not risen globally since 1998 when El Nino warmed the world.
A minority of scientists question whether this means global warming has peaked and the earth has proved more resilient to greenhouse gases than predicted.
But Mr Jarraud insisted this was not the case and noted that 1998 temperatures would still be well above average for the century.
"When you look at climate change you should not look at any particular year," he said. "You should look at trends over a pretty long period and the trend of temperature globally is still very much indicative of warming."
"La Nina is part of what we call 'variability'. There has always been and there will always be cooler and warmer years, but what is important for climate change is that the trend is up."
The UK's Met Office Hadley Centre issued the following on March 5:
A significant drop in global average temperature in January 2008 has led to speculation that the Earth is experiencing a period of sustained cooling.
A brief look at the graph depicting January global average temperatures reveals large variability in our climate year-on-year, but with an underlying rise over the longer term almost certainly caused by man-made emissions of greenhouse gases.
There are a number of natural factors contributing to so-called interannual variability, the single most important being the El Niño Southern Oscillation or ENSO. The global climate is currently being influenced by the cold phase of this oscillation, known as La Niña (see Met Office: Expert speaks on La Niña).
The current La Niña began to develop in early 2007, having a significant cooling effect on the global average temperature. Despite this, 2007 was one of the ten warmest years since global records began in 1850 with a temperature some 0.4 °C above average.
The NYT had the following on March 2: Skeptics on human climate impact seize on cold spell
According to a host of climate experts, including some who question the extent and risks of global warming, it is mostly good old-fashioned weather, along with a cold kick from the tropical Pacific Ocean, which is in its La Niña phase for a few more months, a year after it was in the opposite warm El Niño pattern.
If anything else is afoot — like some cooling related to sunspot cycles or slow shifts in ocean and atmospheric patterns that can influence temperatures — an array of scientists who have staked out differing positions on the overall threat from global warming agree that there is no way to pinpoint whether such a new force is at work.
Many scientists also say that the cool spell in no way undermines the enormous body of evidence pointing to a warming world with disrupted weather patterns, less ice and rising seas should heat-trapping greenhouse gases from burning fossil fuels and forests continue to accumulate in the air.
“The current downturn is not very unusual,” said Carl Mears, a scientist at Remote Sensing Systems, a private research group in Santa Rosa, Calif., that has been using satellite data to track global temperature and whose findings have been held out as reliable by a variety of climate experts. He pointed to similar drops in 1988, 1991-92, and 1998, but with a long-term warming trend clear nonetheless.
“Temperatures are very likely to recover after the La Niña event is over,” he said. ...
Some scientists who strongly disagree with each other on the extent of warming coming in this century, and on what to do about it, agreed that it was important not to be tempted to overinterpret short-term swings in climate, either hot or cold.
Patrick J. Michaels, a climatologist and commentator with the libertarian Cato Institute in Washington, has long chided environmentalists and the media for overstating connections between extreme weather and human-caused warming. (He is on the program at the skeptics’ conference.)
But Dr. Michaels said that those now trumpeting global cooling should beware of doing the same thing, saying that the “predictable distortion” of extreme weather “goes in both directions.”
Gavin A. Schmidt, a climatologist at NASA’s Goddard Institute for Space Studies in Manhattan who has spoken out about the need to reduce greenhouse gases, disagrees with Dr. Michaels on many issues, but concurred on this point.
“When I get called by CNN to comment on a big summer storm or a drought or something, I give the same answer I give a guy who asks about a blizzard,” Dr. Schmidt said. “It’s all in the long-term trends. Weather isn’t going to go away because of climate change. There is this desire to explain everything that we see in terms of something you think you understand, whether that’s the next ice age coming or global warming.”