In addition to solar cycles, temperature cycles in the planet’s oceans play critical roles in our ever changing climate and also on the extent of global sea ice. Oceanic temperature cycles are often quite long-lasting and a warm or cold phase can persist for two or three decades at a time. In general, the Atlantic Ocean experienced a cold phase from the early 1960’s to the mid 1990’s at which time it flipped to a warm phase and that has continued for the most part ever since.
The current warm phase; however, is now showing signs of a possible long-term shift back to colder-than-normal sea surface temperatures (SST) and this could have significant implications on US climate and sea ice areal extent in the Northern Hemisphere.
[Will the radicals now say global warming has caused global cooling and we must redistribute all our wealth in order to control the weather, even though we can predict nothing accurately? We can’t even predict the weather next week.]
There is supporting evidence from the National Oceanographic Data Center that something significant is indeed occurring in the Atlantic Ocean for the long term.
Since around early 2007, there has been a definitive downward trend in “monthly heat content anomaly” in the top 700 meters of the northern Atlantic Ocean (arrow region). The heat content in this part of the Atlantic Ocean ramped up rather sharply beginning around the middle 1990’s and seemingly peaked during early 2007.
Indications are that this current (warm) phase has peaked during the latter part of last decade and it has generally been descending during the past few years providing support to the notion that a cool-down is indeed occurring in the North Atlantic.
If the Atlantic Ocean is indeed slipping back into a colder-than-normal phase then this would quite likely have a significant impact on Northern Hemisphere (NH) sea ice areal extent.
The NH sea ice areal extent was generally at above-normal levels before the middle 1990’s (arrow in plot below) which is when the Atlantic Ocean temperature phase change took place from cold-to-warm. Once the warm phase of the Atlantic Ocean became established in the late 1990’s, the NH sea ice areal extent trended sharply downward from positive levels into well below-normal territory. In recent years, there has been a jagged, but generally sideways trend in NH sea ice areal extent at those well below-normal levels. However, if these recent signs of a possible long-term Atlantic Ocean temperature phase change from warm-to-cold are real and sustained (sometimes there are false starts), then the NH sea ice areal extent will very likely return to above-normal levels in the not too distant future – just as it was during the last cold phase pre-mid 1990’s.
The largest body of water in the world by far is the Pacific Ocean and it is well understood that its temperature cycles play a critically important role in weather and climate not only in the US, but throughout the world. While the Atlantic Ocean is far smaller than the Pacific Ocean, its temperature cycles can also play an important role in the US for weather and climate.
The cold phase from 1975-1995 featured colder-than-normal winters on average throughout the US whereas in the recent 20-year warm phase period of 1995-2015, the opposite took place with virtually nationwide warmer-than-normal winters. No doubt many other important factors played a role in the weather conditions during the past forty winter seasons (e.g., El Nino/La Nino), but these dramatic differences in US temperatures that took place during different phases of the Atlantic Ocean suggest it is definitely something to monitor closely over the next several years.
Meteorologist Paul Dorian
Source: Vencore Weather and NOAA