Pause for Thought

Since I started this blog three months ago, I have covered a wide range of topics. Given this and the enormity of this subject, I thought that this post should summarise the main findings so far.

Here is a summary of the key points and conclusions:

• Different parts of Antarctica are being affected differently. It is easy to consider Antarctica as one unified system which is affected the same when things happen because the whole continent looks homogeneous. For example, “Larsen B has collapsed, quick! We have to find a way to stop the whole continent from melting!” In reality, ice sheets in Antarctica are complex to understand because they are affected by climate change, ocean circulations…etc. The Bipolar Sea-saw Pattern can help explain one part of the observed sea ice changes, however it is only a contributing factor out of many.
• Tourism is a recent phenomenon and as tourist numbers continue to increase, and they will do in the future, animals are being affected in different ways. But the extent that they are affected differs between species. Tourism also has indirect impacts which are just as damaging to the environment, for example oil spills.
• International organisations such as the UN try to create treaties to regulate Antarctica. I have analysed regulation in terms of tourism and found that there are flaws in them. In my view tougher restrictions are required if the environment is to remain unaltered by human actions. Furthermore, regulation can have negative and positive impacts on animals in Antarctica, for example, whaling bans, krill and penguins. It is unlikely that international organisations foresee these indirect food chain effects and this reduces the impact of regulation.
• Krill are immensely important in the Antarctic food chain but fishing activities may be jeopardising them. However, it is difficult to understand whether krill populations are reacting to fishing or natural changes in sea ice extent caused by La Niña. Because of this, separating natural impacts and human impacts is more complex than it seems. 
• Fishing is harmful for fur seals and other mammals because debris lost in the ocean creates entanglement.
• Regulation seems to be the only way that humans are trying to make amends. It seems that banning happens less often.

My Thoughts

Furthermore, I would like to use this as an opportunity to evaluate what I have posted so far, giving my thoughts on what I think I have done well and not so well.

• Diversity: I have tried to include a range of case studies throughout the blog to make it more interesting, drawing on different animals and explaining the different effects where ever I can. For instance, my discussions have drawn on fur seals, Adélie penguins, Gentoo penguins, krill, South Polar Skua…etc. I also want to point out that it has been an enjoyable experience learning about these wonderful animals!
• Geographical dispersion: I have tried to include case studies from different parts of Antarctica to illustrate what’s happening everywhere. This has been supplemented with maps (see below). Antarctica is a large continent and different regions are affected by different activities. Having said this, I believe I have focussed on west side of Antarctica more than the east side. While writing and researching, I have discovered that there is little literature on the east side of Antarctica which is the main reason why. Perhaps this is because eastern Antarctica is less accessible than the west side so research tends to be focussed here.
• Maps: I understand that naming Antarctic islands, ice sheets and seas could be confusing and hold little meaning if no one knows where they are. So where I can, I have places maps throughout the blog and highlighted where my case study locations are. Hopefully I haven’t created an overload, but I feel they are necessary!
• Balance: I have given a balanced view of the impacts throughout the blog, presenting arguments for natural causes as well as human impacts.

Is it S.O.S Antarctica?

The name of my blog suggests that, because of the human impacts, Antarctica is sending a distress signal, asking humans to leave it alone! So far, I have been counting the negative and postive/ natural impacts and they currently stand at 5-3 to negative impacts. Perhaps the continent is in trouble... In my last post I will attempt to answer the above question based on my previous posts and the total score.

Finally I wish to explain what the next few topics are. In this final month or so, I aim to discuss:

• The impact of research stations on Antarctica. Yes research has discovered ways to correct human impacts, but are there any negative impacts?

• The Ozone layer. So far I have focussed on terrestrial and marine impacts, but what about the atmospheric impact?

Thank you for reading, until next week, I’ll end with this cartoon to prepare for the next post. 

 Figure 1. The impact of research

License to Krill II

Last week, I looked at the impact of a whaling ban on krill population and penguin populations. This post will discuss natural causes of changes in krill population that humans have no (direct or indirect) impact on. Like last week I will continue my focus on the West Antarctic Peninsula (WAP).

Figure 1 shows the change in winter sea ice extent from 1980 and 2010 and it is evident that there has been a reduction in winter sea ice extent during the period.

Figure 1. Winter sea ice extent in 1980 and 2010. Adapted from: Lenfest Ocean Program, (2011)

What is causing reduced sea ice extent?

Trivelpiece et al. (2011) and Vaughan et al. (2003) argue that this region has experienced a 5-6^oC increase in mean winter air temperatures in the past 50 years and this is resulting in decreased winter sea ice extent. Figure 2 shows a gradual increase in mean winter temperatures from 1950 to 2000. The grey region is of particular interest because it shows a warming trend from 1980 to 2001.

Figure 2. Mean winter temperatures at the Faraday Station. Adapted from: Lenfest Ocean Program, (2011)

By comparing figure 2 with figure 1, it is possible to correlate an increase in mean temperatures with reduced sea ice extent. However there are also other factors affecting sea ice extent.

Atmospheric and oceanic temperatures are changing in the WAP region due to changes in the El Niño Southern Oscillation (ENSO). This is reducing sea ice extent. El Niño is a weather event that occurs in the Pacific when there are weaker trade winds and this alters the climate in the surrounding regions, notably South America and Australia. During El Niño, warm water that would normally be in the West Pacific flows to the East Pacific and atmospheric pressure falls. South America experiences unusually wetter climate while regions near Australia experience more drought-like conditions. La Niña, on the other hand, is the opposite effect where atmospheric pressure increases, trade winds blow more intensely and cold water flows to the west Pacific.

Shevenell et al. (2011) explain that during La Niña events, there are higher sea surface temperatures in the WAP and this reduces sea ice extent. The reason for this is that there is high pressure in the Bellingshausen Sea (see figure 3) which brings warm air towards Antarctica, causing reduced sea ice extent. Furthermore, north easterly winds dominate which Harangozo (2006) and Quetin et al. (2007) find is negatively correlated with sea ice extent (strong north easterly winds lead to reduced sea ice extent) because it does not provide good conditions for ice formation. Furthermore, Shevenell et al. (2011) mention that there are positive feedbacks that enhance this effect, which can explain how winter sea ice extent falls even when there is no La Niña event. 

Figure 3: Bellingshausen Sea in West Antarctica. Adapted from The Encyclopedia of Earth

Sea Ice Extent and Krill Population

You must be wondering how sea ice extent is related to krill population. One way sea ice helps the krill population is through providing a habitat for microbial communities that young krill use as a source of food (Quetin et al. 2007). This improves their chance of survival and helps increase the krill population in the summer (ibid). Additionally, high sea ice extent and duration is positively correlated with reproductive success of krill (Loeb et al. 1997). The fact that winter sea ice extent is reducing means that there will be a smaller krill population surviving to the summer without the microbial communities to feed on. Hence, krill population will decline in the long term if La Niña events are frequent. Even under normal conditions when there is no La Niña event, there could be lagged responses in the system as it gets used to the normal climatic conditions. This can result in long term variability in krill populations. 

Hopefully in this post I have shown that krill populations are not solely affected by human actions. Natural climate variability is often under-stated in the media and in literature about wildlife. Today, I have highlighted how complex it is to try and understand how humans and natural variability affect Antarctica. 

This post has helped level the playing field, so the updated scores are now negative impacts 4, positive/ natural impacts, 3. Next week, I will move on to the effects of plastics on Antarctic seals. There are no surprises as to which way the scores will lean next week...