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

Natural Climate Variability and The Arctic Oscillation

Last week, I posted about the Larsen B ice shelf, proposing that its break up may have been human induced. There is a lot of uncertainty about climate change at the moment. In my very first post, I highlighted this issue explaining that it can leave you feeling confused about what is actually happening! Some researchers believe that the Larsen B ice shelf collapsed because of greenhouse gases, while other researchers, primarily climate change sceptics, believe that natural climate variability is actually contributing to the climate in Antarctica. This post is going to present their arguments. 

The Arctic Oscillation

Antarctica experiences changes in climate due to natural climate variability. One example of this is the Arctic Oscillation. The Arctic Oscillation fluctuates between a positive and a negative state, as shown in Figure 1. When in a positive state, the Arctic experiences unusually low atmospheric pressure and a warmer climate (Bjornaes and Pal, 2012, 'The State of the Poles', p.19). Furthermore, the jet stream blows strongly from west to east. When in a negative state, the Arctic experiences high pressure and the jet stream is weaker. 

Figure 1. Arctic Oscillation. Adapted from Bjornaes and Pal (2012, 'The State Of The Poles': p.19). 

The Arctic Oscillation affects the climate in Antarctica. A study by Chylek et al. (2010) investigated the effect of the Arctic Oscillation on the Antarctic climate and found that when the Arctic warms, Antarctica cools and vice versa. Additionally, Brunier and Brook (2001) observed this “bipolar see-saw pattern” from ice core records dating back to the last glacial period, demonstrating that this phenomenon is independent of human impacts. Figure 2 is a graph that illustrates the bipolar see-saw pattern, plotting temperatures against time. It is evident that as temperatures in the Arctic fall, in Antarctica they rise, despite emissions and other anthropogenic interferences with climate change.

Figure 2. Bipolar Seasaw Pattern. Source: Chylek et al. (2010).

Arctic (blue) and Antarctic (red) temperature time series smoothed by a 11 year running average (thin lines) or 17 year running average (thick lines)

Larsen B 

The bottom right of figure 1 shows a time series of the patterns of negative and positive oscillation indexes. The circled year represents the year 2002, the same year that the Larsen B ice shelf collapsed. The figure shows that the Arctic Oscillation Index (a measure of the magnitude of the Arctic Oscillation phenomenon) was negative that year, demonstrating that when the Arctic cooled, Antarctica warmed. It can be argued that this warming accelerated the melting of ice during the summer months which led to the break-down of the Larsen B ice shelf. In fact, Domack et al. (2005) conducted a study to determine the stability of the Larsen B ice shelf during the Holocene and found that the ice shelf had been thinning throughout the Holocene, i.e. throughout the past 11,500 years! This is evidence against human induced warming affecting the Antarctic right? 

How does the Arctic Oscillation work? 

In this description, I will explain how the oscillation leads to a warmer Arctic. A similar mechanism operates in the opposite direction to explain Antarctic warming as well. Described by Chylek et al.(2010), winds over the Southern Ocean are drawn to the surface by wind stress. This water is heated by the sun and the Atlantic surface current transports it away from Antarctica. As the water warms more, it travels towards the Arctic leaving Antarctica deficient in heat. The more efficient this transport, the greater the warming. This demonstrates the importance of the role of ocean currents in natural climate variability.

Conclusions

Arctic Oscillation and the work done by the researchers mentioned above are just one of many scientific models and explanations for the Larsen B ice shelf collapse and for climate in Antarctica. If studying Economics and geography at UCL has taught me anything, its that the world is full of uncertainties. Researchers aiming to devise what is human induced and what isn't in our planet will always end up with different explanations because Earth is complex. 

My personal view regarding this matter is that natural causes are not strong enough to determine what caused the Larsen B ice shelf to disintegrate. Although evidence presented suggests that Arctic Oscillation impacts the climate in Antarctica, uncertainty lies in the magnitude of the positive feedback systems between Antarctic waters and heating from the sun. There is also uncertainty in the strength of the transportation of these waters. To me, it seems unlikely that early humans at the start of the Holocene caused enough warming to contribute to the thinning of the Larsen B ice shelf, as illustrated by figure 3 in my post last week. 

That's all today! The score so far is 1-1. Next time, I will explore how tourism has affected Antarctica, thank you for reading!

Melting Ice - Larsen B

In my last post, I introduced melting sea ice as one of the major changes occurring to our planet, and one that is certainly affecting Antarctica at the moment. Today I’m going to discuss the melting ice in more depth.

Over the past 200 years or so, the human footprint on the world has become so apparent and so profound that we humans now ‘rival the great forces of Nature and are pushing Earth to a new planetary terra incognita’ (Steffan et al. 2007: 614). This has created to need for a new epoch away from the Holocene to one that is more reflective of human actions. “The Anthropocene” was termed to capture this. Although there is much debate about the precise time that this epoch started, e.g. at the start of the Industrial Revolution, or a few hundred years earlier (Zalasiewics, et al. 2011; Crutzen and Stoermer, 2000; Gale and Hoare, 2012), this epoch signifies that because of humans, Earth is becoming warmer, less biologically diverse, less forested, wetter and stormier (Steffan et al. 2007). The emission of greenhouse gases, like carbon dioxide and methane, into the atmosphere is creating a warming effect, i.e. the greenhouse effect, whereby the Earth will warm by 1.4 to 5.8^oC by the end of the century (Crutzen, 2002). I came across a very insightful TEDx talk in which Steffan Will goes into more depth explaining the origins of the Anthropocene which can be view here if my readers wish to learn more. 

Unsurprisingly, a warmer planet is troublesome for ice. Below is a graphic representation of Antarctica, displaying the continent's ice shelves and glaciers.

Figure 1. Source: Adapted from Rignot and Stanley (2002)

According to Pritchard et al. (2009), some glaciers are thinning at alarming rates. For example, Pine Island glacier is thinning by up to 18 feet per year, while the Smith glacier is thinning by 27 feet per year. This highlights the severity of warming occurring today. Glaciers in Antarctica are at risk of becoming less stable as the planet warms.

The circled ice shelf in Figure 1 is the Larsen B ice shelf. In 2002, it collapsed and fell apart. Cited by Schmidt (2011), this was predicted by Mercer (1968), who wrote that global warming caused by industrial pollution would lead to a collapse West Antarctica’s ice shelves. Figure 1 shows the levels of carbon dioxide emissions from 1850 onwards. The figure agrees with Mercer, showing that emissions have risen due to industrialisation. I have also included a diagrammatic representation of the change in global temperatures, shown in figure 3. Figures 2 and 3 are complementary in that they demonstrate the correlation between carbon dioxide emissions and global temperature rises

Figure 2: Total global carbon dioxide emissions from fossil fuel combustion initiated by industrialisation.
Source: Hardy (2003) 'Climate Change: Causes, Effects and Solutions', p. 13.

Figure 3: Variations in Earth's temperature for (a) the past 1,000 years and (b) the past 140 years, gathered from proxy measurements based on tree rings, corals, ice cores and historical records. Source: Hardy (2003) 'Climate Change: Causes, Effects and Solutions', p. 41.

A recent study by Rebesco et al. (2014) showed that the Larsen B ice shelf collapsed because of warmer air, partly by human activities and our effects on warming the planet. Their results show that the Larsen B ice shelf shattered in the following way:

• Warmer temperatures warmed up the air
• Warmer air melted ice during the summer months
• This water flowed into cracks inside the ice shelf
• As winter approached, all the water froze again and expanded in the cracks
• This caused the ice shelf to shatter from the increased pressure in the cracks

Below is a very short video capturing the Larsen B ice shelf collapse from satellite images in 2002, illustrating what happened visually. Unfortunately I can't post the actual video on the blog. 

https://www.youtube.com/watch?v=N61EP5zB8uU#t=28

To summarise this post, I’ve presented the view that the Larsen B ice shelf collapse was partly caused by humans because of human induced warmer air in Antarctica. The score for negative human impacts verses positive/ natural impacts is 1-0. In my next post, I will present some of the criticisms of the views presented in this post.