FREE: Warm/Cold Periods Over North America & Europe Were Driven By The Multidecadal Ocean Cycles

Written by on July 29, 2012 in North and South America, Rest of Europe with 0 Comments

Here’s what a warm PDO looks like with the horseshoe of warm.. The opposite to what we have now! (Image courtesy of Wikipedia)

There is plenty of scientific evidence which shows net temperature fluctuations around the globe correlates perfectly with ocean temperature. While much of the media would have you think that the increase in Co2 is rising our planets temperature, the rise since the start of the 1980s is down to an increase in sun activity which warms the oceans but both Pacific and Atlantic see 20-30 years warm and cold phases and these, greatly influence the climate of the continents. Remember the oceans act like a giant thermostat. Warming oceans eventually heat the air above, when cold, they cool the air. Back in the early 2000s when both Pacific and Atlantic where warm, we saw generally warm winters and warm to hot summers across North America and Europe. This happened back in the 40s, 50s and 60s before the Pacific first cooled, then followed by the Atlantic. When both are cold, so too are the continents and cold air is much easier is build.


Between 2000 and 2006, summers were warmer and drier over the UK and Western Europe, recall the cluster of heatwave summers in 2002, 2003, 2005 and 2006) just like they were over the Western and Central USA, but when the Pacific went from warm to cold with a lag of a couple of years, we have seen summers cooler from Alaska to the Southern California but drier. Interestingly, as the PDO turned cold around 2007, the UK summers turned wetter and the amount of rainfall depends upon what phase the ENSO signal is in I believe along with other factors including the NAO. With the recent strong La Ninas which become more frequent and stronger during cold PDO’s, this can be a fly in the ointment of an overall wetter summer cycle for the UK with drier than normal conditions but with the onset of the El Nino it has been wet, likely enhanced by the warm AMO.

What is helping with the increase in wet gloomy UK summers is the warm North Atlantic which supports lower pressures at the latitude of the UK while stronger pressures are increased further north and south where waters over the Azores and Med as well as up off Greenland are warmer.

The tripole of warm, cold, warm over the North Atlantic supports high pressure up over Greenland, so the likilihood of high latitude blocking is increased, like we’ve seen in recent years and with availability of cold increased by a reduction in sunspot activity and the cold PDO, the intensity of cold sent down within the troughs of the blocked pattern can be greatly increased. We saw this last winter over the heart of Europe despite the UK on the whole being warm and better still, we saw this first hand back in 2009-10 which was a brutal winter throughout the Dec-March period and also for a briefer but much more severe episode back during the Nov to late Dec period in 2010..


I blame the return to cold PDO and the still warm AMO combined with the back and forth of the ENSO for the uptick in wild weather across the world. There’s nothing new under the sun as we saw back in the 1950s at a time of global climatic transition. Keep in mind, in order to have wilder, more extreme weather, there must be an increase in cold somewhere which collides with the warmth in order for stormier weather to be created.

The warm North Atlantic during the time the Pacific too was warm and sun activity high, played a significant role in those very warm winters over much of North America and Europe, remember 2006-2007, 2007-2008 and the hot, dry summers of the early to mid-2000s? Then came STRONG La Nina and the Pacific cooling just after we saw some of the warmest winters and summers in recorded history as well as a the sea ice hitting a seemingly record low level over the pole. Interestingly, just around the time the Pacific last started to cool back in the late 50s, so photos were taken of submarines surfacing at the North Pole, it happened before and is happening now..

The point in this post is that our climate has been worse in the past than in the last 10 years. It’s been hotter with the 1930s and 1950s displaying the worst droughts in North America and all-time state temperature records fell left right and centre back during the dustbowl. Yes, the drought of 2012 is severe and very bad. Yes, there has been a lot of records fall but in my opinion, the worst heat seen in the past 120 years occured back in the 1930s and even, for some, the 1950s. Those stunning records which for the majority still stand today, were before the rise of many great cities of today. Today urband heat island effect can help boost the rate of heat records in city’s but interestingly, many city recoirds, despite having help from much greater coverage of concrete and ashalt, still can’t beat records recorded back in the past.

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