The Guardian Unlimited has an interesting article about how scientists have determined that the speed of the Gulf Stream has slowed. This likely means that England and Europe will have less benefit of the warming effect from the Gulf Stream, leading to colder and more dramatic weather. The Stream has slowed due to the increase in fresh water melting occuring from the polar areas which affects the dynamic of the water circulating in the Stream.
If you're into data and details, check out this site showing temperatures around the world for extended periods. Here's another source with a huge amount of diverse historical weather information. And here is a story about Ben Franklin's involvement in identifying the Gulf Stream. Andrew Daley describes the Little Ice Age in the 1500's here.