2004

"Global warming could plunge North America and Western Europe into a deep freeze, possibly within only a few decades.

That's the paradoxical scenario gaining credibility among many climate scientists. The thawing of sea ice covering the Arctic could disturb or even halt large currents in the Atlantic Ocean. Without the vast heat that these ocean currents deliver--comparable to the power generation of a million nuclear power plants--Europe's average temperature would likely drop 5 to 10°C (9 to 18°F), and parts of eastern North America would be chilled somewhat less. Such a dip in temperature would be similar to global average temperatures toward the end of the last ice age roughly 20,000 years ago.
...
Some scientists believe this shift in ocean currents could come surprisingly soon--within as little as 20 years,"

[link to science.nasa.gov]