The Arctic is a beautiful, sensitive and complex ecosystem with relationships with the Atmosphere, Ocean, and with a wide range of Biodiversity, makes it even more sensitive. This ecosystem is in great jeopardy because of human-induced Climate Change. There are many things that will be and are affected by these warming trends like the animals that live on the land as well as in the sea, and the ocean and atmosphere circulations. This very complex and sensitive system can be altered by anomalies in temperature which will then go on to influence other systems that are interconnected. We have seen a 1.08 ± 0.13 (F°) temperature change in the past decade, as well as depletion in Arctic Sea ice. Alaska is also feeling the effects with a 1.5 (F°) change temperature in the past 30 years. (NCA4) and the trend shows no signs of slowing down.
So, what is it that makes the Arctic is so important and vulnerable? We discussed in the last blog Albedo, which is the measurement how much solar radiation is reflected off of a surface. Because water has such a low albedo it means that more energy is absorbed than reflected. The Arctic sea ice and snow cover have a very high albedo (75%-95%) so it helps from allowing solar radiation to be absorbed in the Arctic ocean. We have seen a decrease in the amount of Arctic Sea ice since 1979, and an acute acceleration around the early 2000s. This is very alarming because the sea ice effects and can fluctuate ECVs such as air temperature, ocean temperature, ocean salinity and even have catastrophic consequences for the ecosystem. It has been observed that a 3.5% – 4.1% loss in sea ice per decade has occurred since around 1979.
This is partly because of the increasing temperature in the ocean. Since water warms up slower thus cools down slower, we see a reduced freezing time and an increased melting season. With the increasing temperatures in the ocean, new problems for the ecosystem are now in play.
When we think of animals that are in danger the most common picture that comes to mind is a polar bear floating on a small sheet of sea ice, However, there are many more plants and animals that are being affected by the increase of Arctic ocean temperatures. The Grey whale is part of one of the largest mammal migrations on Earth and has been migrating the waters for thousands of years. Off the coast of Mexico mothers nurse and feed their young as they prepare for a long 6,000 mile trip to feeding grounds in the Arctic, but we have a problem. In the Arctic, an abundance of plankton, crustacean and other fish used to thrive off the edges of the sea ice floating in the shallow waters. Since the water temperatures are rising the sea ice is melting and breaking away into deeper water. The plankton and other organisms are now out of reach for larger predators and then themselves fail to reproduce and reduce their own numbers. This is the case for the amphipod, a crustacean that is full of vitamins and fat that the grey whale needs in order to make the trip back to the Mexican coast from the Bering Sea. The decrease in the amphipod forces the whales to eat other crustaceans that are not as nutritious and puts the whales in a dangerous position. In 1990 – 2000 stretching from Alaska to Mexico the beaches were scattered with over 200 grey whales. The whales were malnourished and one in every ten looked close to death.
As temperatures continue to increase the rate of glacial depletion increase as well. Alaska is an example of some of the fastest melting glaciers. The fast rate of the melting glaciers puts a strain on the environment in several ways. The melting glaciers add a lot more water to the oceans and causes even faster sea level rise than thermal expansion. In Greenland glacial melting estimated 269 Gt of water and mass release into the ocean (< 0.26 inches per decade sea level rise) between April 2002 and April 2016. This positive feedback will continue as time moves on.
With the melting of Arctic Sea ice, a positive feedback forms. As the air temperature increases the rate of glacial and sea ice melting increases. As the ice melts the surface albedo decreases because there is more water to absorb radiation than ice to reflect it. The ocean temperatures will then begin to rise amplifying the rate of ice melt. Thus the cycle will continue.
The increase of temperatures in the Arctic Ocean may also be linked to a more global problem in the Atlantic Meridional Overturning Circulation (AMOC). Our planet does incredible things, one of which is its ability to carry warm equatorial water poleward and bring cold water from the poles towards the equator.
This happens because of the differences in water density. Warm water is less dense than cold, and water with a higher salinity is denser than water with lower amounts of salinity. It is because of the AMOC Europe has milder weather even though it is located at a higher latitude and should have really cold temperatures. So then how is it that there is a possibility that the AMOC could be affected? Like I stated a moment ago the AMOC is driven by differences in water density. With stronger differences in temperature and salinity, stronger gradients are present. This ensures that the cold water moving to equatorial regions and warm waters moving poleward are correctly and efficiently balanced to allow a circulation of ocean currents. However, because of the increasing water temperatures and increased amounts of fresh water melt from glaciers and sea ice in the North the densities may reach an unbalanced state and not allow the colder water to sink as deep as before. This weakened density gradient may slow down the AMOC by creating a blocking or pile up of ocean waters. If this happens then the Gulf stream will not be able to efficiently move waters with a higher salinity concentration North and with lower salinity levels in the Gulf the water will be lighter than usual and prohibit waters to sink and mix. This deep water formation is the key driver to an active Gulf stream current and without it, scenarios from model runs show that abrupt cooling may take place within the Atlantic. European data records show an increase in cooling days throughout the year. Although Europe seems to be caught in the middle of a squabble between Climate change and a possible AMOC slowdown, the overall average temperature still continues to increase despite a lower number of heating days and an increasing number of cooling days.
As if it seems the situation in the Arctic couldn’t get worse, it can. Because of the cold environment when plants and animals die they do not decompose but remain frozen in the permafrost. This means that the organic matter from the organisms is still present. The problem is when temperatures increase and the permafrost begins to melt, the organic matter begins to decompose. Several models show possible projections of the amount of CO2 that may be released into the atmosphere because of a melting permafrost.
This will release large amounts of CO2 and CH4 that will can lead to a positive feedback that will then accelerate the amount of CO2 and CH4 being released due to decaying matter even further. It is estimated that there is about 1,300 – 1,600 GtC (gigatonnes of carbon) in the permafrost. It is estimated that a possible release of 5% – 15% of this carbon within this century may take place increasing the greenhouse effect. The estimated time for maximum permafrost melt and CO2 release is 2100. We can only hope that we never actually reach this point in permafrost loss or that the models are wrong. in the situation we do, we will be way beyond the tipping point.
As we can see the environment is extremely sensitive to change, some more sensitive than others. The fact is human-induced climate change is not a one-way street. It affects everything around us and we are not the only ones feeling its effects. Increasing temperatures result in less snowfall and more snow melt which allows more of the sun’s energy to be absorbed in our oceans and land masses. Our geography is altered which can destroy beautiful landscapes and release dangerous amounts of CO2 that lie deep within the permafrost. Increasing SSTs can change the oceans global circulation and chemistry, and lead to a reduction of animals such as the amphipods that thrive off sea ice that can result in hundreds of whales laying dead on the western shores. It’s amazing that one geological spot can be so important and have such strong connections with the rest of the world. As we bring this blog to a close I hope this sheds some light and gets your mind wondering about other interactions that occur and tie together in our world and how they to may be in jeopardy. As we look to the horizon of uncertainty one thing is certain, A storm is coming but are we ready for it?