Last week in the article about the Natural Cause of global warming I pointed out that the Atlantic Multidecadal Oscillation (AMO for the rest of the article) correlated to the warming trend that started in the 1970’s. The AMO temperature and the global temperature have gone up together. Since it is known that the AMO is a natural event, the affects of the AMO are also natural. The difficulty in understanding the AMO is that it happens on a much longer time scale than most people are used to dealing with. It is a long term cycle, at least on a human time scale.
In the earlier article I pointed out that such a warming in the Northern Atlantic Ocean would certainly have an impact on the Arctic sea ice. Today I am going to show that by going into the comparison of the AMO temperatures and the Arctic sea ice.
Today will also be the first time I put some of the discussion under the label of Science Content. That section will have some added details of the science of this topic. To keep the article from being a long drawn out technical manual (which is what happens when engineers get going) I will keep that part separate.
Measurements of the Arctic sea ice started at the end of 1978. Unfortunately that was after the AMO had already started trending up in temperature. It had already gone up about 0.2 °C by the time the Arctic ice was being measured. So the ice was already being impacted by the warming Atlantic Ocean.
Once more I will show the graph that compares the AMO and Global temperatures from the 1970’s until the current day.
The impact of the AMO on global temperatures is clearly evident. Now I will show the SST (Sea Surface Temperature) of the Earth and then a more focused section of the Atlantic with the area that is primarily impacted by the AMO.
Here is the AMO impacted portion of the Atlantic.
Since a strong portion of the warm AMO is around Greenland, it makes perfect sense that the AMO would cause the sea ice to be reduced in that area. The warmer the AMO gets, the more it should reduce the ice extent. With that in mind, here is what the sea ice has done in the period of time that the AMO has been transitioning to the warm phase and then been stable in that phase.
Aside from the overall trend that an increasing AMO correlates to an overall trend in decreasing Arctic extent, there are some very interesting specific correlations as well. The surge in warm AMO in 88-91 resulted in a drop in extent from 89-91. Then when the AMO cooled from 92-95, the extent increased in a natural response.
Then in 2003-2006 as the AMO reached a maximum level, the sea ice dropped dramatically. The AMO then dropped for a couple of years and the sea ice then started increasing again. The AMO and the sea ice and the AMO are looking to be comparable for the current year as well. I will put out an update when this year completes.
This shows that the Arctic sea ice extent appears to be greatly impacted by the warm phase of the AMO and also by the strength of the AMO for any group of years. It is really too bad that there is not satellite data of the sea ice extent from the warming AMO of 1913-1940. That would very likely confirm this correlation of the extent to the AMO.
This does show that one of the main dangers that is attached to global warming is really just another indicator of the natural cycle of the Atlantic Multidecadal Oscillation. There are more of these and in the future I will also be putting together more articles on each of the various impacts that the AMO has on the Earth’s climate. Most of these natural impacts are also being used as “proof” of global warming.
The Earth is always changing. That is first thing that everyone must understand.
Warning!!!! Science Content Ahead:
Do not drive or operate a vehicle while reading science content. We are not responsible for naps or other sudden issues of falling asleep while reading the following. 😀
The first step is to understand what is being measured when people discuss the sea ice.
Sea Ice Extent: The sea ice extent is the area that is covered by at least 15% ice.
Sea Ice Area: The amount of area that is completely covered by ice.
There are advantages and disadvantages to each measure, but extent is the one that is used most often and that is the one that I used as well.
Both are measured by daily analysis of satellite pictures taken of the Arctic. The two main problems with the Area measure is that the satellite does not actually take a picture of the very top of the Earth. It is safe to assume that the north pole is always at least 15% sea ice, but that assumption on the area is not a safe assumption.
The other problem with area is its accuracy. It is easy to tell if there is 15% ice in water. It is not always possible to determine if an area is 100% ice. During the summertime, areas that are solid ice get covered with meltwater ponds. Since the ponds are water on top of ice it is difficult to determine from a satellite image if it is water covered ice or just ocean. So even if the ice is solid, it is beneath melted water that can appear to be open water.
Those two factors mean the error for area will always be greater. Extent is not perfect, but it is accurate and sensitive enough for most purposes.
Sea Ice Data Source: I compiled the monthly averages into the annual average. This has the effect of reducing odd monthly results and also makes comparison easier.
AMO Data Source: I used the AMO unsmooth long format. Again made into the annual averages.