"A warmer Arctic could ... affect the pattern of the high-altitude polar jet stream, resulting in longer and colder winters over North America and northern Europe...
The jet stream, a ribbon of high altitude, high-speed wind in northern latitudes that blows from west to east, is formed when the cold Arctic air clashes with warmer air from further south.
The greater the difference in temperature, the faster the jet stream moves.
...the Arctic air has warmed in recent years as a result of melting polar ice caps, meaning there is now less of a difference in temperatures when it hits air from lower latitudes.
...over the past two decades the jet stream has weakened.
...instead of circling the earth in the far north, the jet stream has begun to meander, like a river heading off course.
This has brought chilly Arctic weather further south than normal, and warmer temperatures up north.
...far northern regions like Alaska are going through an unusually warm winter this year.
...Temperatures in the Arctic have been rising "two to three times faster than the rest of the planet,"...
...rising Arctic temperatures are directly linked to melting ice caps.
"The sea ice cover acts as a lid which separates the ocean from a colder atmosphere," ...But if the lid is removed, then warmth contained in the water rises into the atmosphere.
This warming trend and the shifting jet stream [may] have a dire impact on agriculture, especially in the farm-rich middle-latitudes in the United States.
..."Look around the world -- we produce the bulk of our crops around this mid-latitude area,"...
Droughts and freezes are already having "a major impact on animal productivity, it influences meat production, milk and eggs production,"...