The Impact of Climate Change on The Antarctic Region

Climate change is the alteration in the average weather conditions of an area over a period of time. It can occur naturally through processes such as variable energy from the sun and variation in the Earth’s orbit or through human influences such as the burning of fossil fuels and the clear cutting of forests. This process can have devastating impacts in all areas of the world, including the Antarctic region. Changes such as melting ice and ocean warming can have negative effects on both specific species and food chains, whether it be through breeding, population, foraging for food, or the Antarctic food web itself.

One species that has been negatively impacted by climate change through the process of sea ice reduction or breakage are emperor penguins. The melting or breaking up of various types of ice creates less habitat for Antarctic species. Fast ice, which is attached to the coastline but is still able to move thereby allowing for cracks in the ice, is important for many Antarctic mammals. Emperor penguins depend on fast ice during breeding seasons and it is also important to the success rate of penguin chick populations. If the ice forms late, breaks apart early, or fails to form altogether,­­ the success of a breeding colony may be jeopardized. Emperor penguin colonies are sometimes forced to move about the ice. Warming on Emperor Island most likely necessitated a colony to move due to a reduction in fast ice. But this action of moving about the fast ice does not always solve the problem of finding an ideal breeding area. Penguins breeding habitats need to be a certain distance to predictable and profitable foraging locations. Stable fast ice that is relatively close to a reliable food source is vital for emperor penguin chick survival. As fast ice extends further out, the success of emperor penguin colonies is threatened. Failure to meet the criteria of stable fast ice and a tolerable distance to food resources can affect more than just the success of penguin breeding in a particular season. If ideal breeding locations are not met each year, the size of the penguin colonies present will be affected.

The presence of fast ice also plays a role in the success rate of penguin chicks reaching maturity. The stability of the ice that chicks live on is critical. Mortality rates can be high if the ice breaks up too quickly. Early fast ice breakup has been documented in Antarctica. Considerable chick loss was observed in 2018, when premature break up of fast ice between Ross Island and the Ross Ice Shelf occurred. Another result of chick loss can occur as a result of other weather patterns, or naturally occurring processes. During March 2001, a piece of a mega iceberg settled at Cape Crozier, negatively impacting where emperor penguins could breed. The colony’s chick population went from 1201 in 2000 to 0 in 200. While this loss resulted from a naturally occurring process, climate change will continue to escalate the likelihood of increased ice breaks.

Warming oceans have had a destructive impact on foraging patterns of southern ocean mammals. One type of seal that has been particularly affected by the change in ocean temperature is the crabeater seal. Crabeater seals live on the pack ice. Warming waters are decreasing the habitat in which these seals can live, which in turn leads to their ability to forage for food. Models developed show that along the Westen Antarctic Peninsula, crabeater seals will need to travel further away from the continental shelf break and south boundaries to search for food … the foraging areas around the South Shetland Island, and between the Bransfield Strait and Anvers Islands will also be reduced. The reduction of areas in which these seals can forage will likely result in increased competition for food sources. While most seals have a wide diet, including species such as krill, fish and squid, the crabeater seals’ diet consists primarily of krill. Therefore, increased competition for food sources will have a more swiping effect on the crabeater seals than would be placed on other seal species.

The crabeater seals patterns of foraging do benefit them with the changing locations of their prey. These seals do not live strictly in colonies and instead are flexible to move in order to follow clusters of prey amongst the pack ice … while simultaneously limiting their exposure to predators, and being relatively close to a secure haulout location. But with further warming ocean waters leading to later forming sea ice, these behavioural patterns by crabeater seals may not be enough. By 2100, a delay in sea ice formation, and a forecast of sea ice being land-locked or potentially restricted to southern waters will lead to a larger distance between haulout locations and foraging sites (Hückstädt et al., 2020). This delay in sea ice formation may likely happen as a result of the warming waters that are occuring in our environment. Nevertheless, considering the distance crabeater seals will need to travel between haulouts and foraging areas, this will increase their exposure to predators as well as a greater expense of their energy. The delay in sea ice formation will not only affect crabeater seals, but all southern ocean organisms that depend upon the sea ice and their foraging sites will also be impacted.

Climate change does not only affect mammals near the top of the food chain, it also affects the Antarctic food web at its source. Changes in the amount of sea ice affect the production of phytoplankton growth and leads to a flow-on effect to other species. In the past few decades, ice reduction in the West Antarctic Peninsula has led to deeper mixed layers resulting in less irradiance thereby reducing phytoplankton biomass, size and productivity. A decrease in phytoplankton availability plays a critical role in the reduction of krill populations, as phytoplankton is their source of food. There are other detrimental consequences that the krill population are experiencing in this new and changing environment. Ocean acidification, increasing sea temperatures and diminishing sea ice can add to the negative effects on the population as well. As krill populations decline, it is foreseeable that species feeding off of krill will be adversely impacted. There was a reduction in Chinstrap and Adélie penguin populations observed in the Antarctic Peninsula region which coincided with the decrease in Antarctic krill populations at that time (Barbosa, Benzal, León, & Moreno, 2012). It was also clearly seen how the decrease in krill population affected the population of crabeater seals, as it is their primary source of diet. Based on how phytoplankton and krill affect the success rate of other species such as penguins and seals, we can see how climate change is impacting the entire food web. As phytoplankton and krill populations diminish, food sources for penguins and seals will deteriorate. This deterioration, along with diminishing habitats as a result of warming waters and melting ice will cause a reduction in the populations of these secondary consumers. As you move further up the food chain, it can be hypothesized that a flow-on effect will occur with a decrease in the population of tertiary consumers, such as leopard seals, and from there a decrease in quaternary consumers, such as killer whales to begin to decrease

The changing climate is having noticeable impacts on Antarctic species, whether it be through melting ice or warming oceans. Melting sea ice is leading to declines in penguin populations, by impacting breeding and the survival rate of chicks. Warming oceans diminish the foraging ability of seals by decreasing the availability of their food sources. Penguins and seals are not the only species affected by climate change. Less ice and higher oceans temperatures affects the entire Antarctic food webs by impacting the growth and population of the primary producers, such as phytoplankton. This decline can lead to devastating consequences to the life of every other species in the food web. By looking at both specific mammals and the entire food web it can clearly be seen that if something is not done to help mitigate climate change we will lose our ocean ecosystems.