The last post (a rather abrupt end I would suppose)

So yes, this is going to be the last post for this blog (unfortunately). So refresher's course time!!!!!

The Antarctic is more than 10 times the size of the Arctic Ocean (ice volume).

Both are affected by the recent global warming. There are localised variations in the rates of decrease of ice cover in both poles. Take for example the Antarctic Peninsula, where in some areas glaciers have retreated while there are some that have actually advanced in the same period of time. 

Changes in ice cover are not just directly affected by temperature changes, though temperature changes is one of the main drivers of changes in ice extent. Ocean currents, upwelling of warm water, stationary warm water along coasts have also affected changes in ice cover. And also solar forcings have come into play here. Which shouldn't actually be a huge surprise, since sunspots and solar flares have been scientifically proven to affect our climate, albeit on a rather short-term scale. 

We've seen the Antarctica from the beginning of the Holocene (12,000 years ago) and the Arctic Ocean (1,450 years ago) and we've seen even more evidence that even in a cool climate (Little Ice Age), other influencing factors have made ice extent in certain areas decrease. 

We've also talked about Greenland (though we focussed more on one glacier, which can be used to represent quite a number of glaciers in the region). Greenland's important to our study of the poles since it holds a significant volume of landlocked ice and contributes greatly to the threat of sea level rising. 

There's one mislabelled entry 'IPCC's forecast about the Arctic Sea ice melting completely by 2020'. It's actually Dan Miller's interpretation of it) Check out Jonny's blog post that's related to that video. http://66degreeslatitude.blogspot.com/2012/01/i-think-i-need-to-be-more-careful-with.html#comment-form. It's basically about sensationalism in the context of global warming and falsifying facts for personal motives. 

And then we had the Durban Climate change talks and Frozen Planet by BBC, which tied in nicely with the aim of my blog and also the current popular debate AGW. Do continue reading the progress on the Durban Climate change deal. It'll be quite a significant progress if it truly succeeds. 

And then there's the whole issue of multiyear ice and first year ice, where exposure of multi year ice reflects much about the recovery rates of the glaciers and ice sheets. 

Not to forget, we talked about polar bears and other Arctic animals (like in the previous post) being directly affected by the ice and whether or not we should even try to save them. 'Their future looks bleak no matter what we do, so why waste more money' stand: Adopt or not to adopt this stand? 

I was going to squeeze in one more post about how the changes in the Arctic Ocean is influenced by atmosphere, sea ice, and ocean and recently, anthropogenic activities from this rather long and technical paper by John E. Walsh titled 'Climate of the Arctic Marine Environment' (2008). Since it basically just reiterates the posts I put up from NSIDC and NASA etc, it isn't that big a loss. But since we've mostly been talking about history, let's take a tiny peek into the predicted future of the Arctic Ocean through this diagram (which is basically self-explanatory) from John Walsh. 

Look how small the ice cover is getting from 1980 to the future in 2090!

I hope you gained at least a little bit of knowledge from this blog about the poles. My apologies for not fully covering everything about the poles. If I've somehow managed to spark off your interest in learning about the poles and the environment, NASA and NSIDC websites are a good place to start. They explain diagrams and do not have as much jargon as any scientific article found in a journal, so it's easier to understand. 

So with the little bit of knowledge and facts about the poles and what they signify, please put that knowledge to good use. Critically analyse the articles in the news about global warming as well. Not everything out there is the truth.

I'll leave you with this short video about how scientists take cores from the Antarctic for analysis. Just for general knowledge!

 

Have a great year ahead! Don't miss me too much :)

Wrapping up the blog: a video you TOTALLY MUST WATCH

This is a video of a Google Tech Talk in 2009. It's called 'Dramatic Changes in Polar Ice: Are we waking sleeping giants?' It's about (what else) changes in the ice extent in the Polar regions and what's the projected estimates of that extent in the next 10 to 100 years and what will be the consequences.

The reason why I think this video must be watched by all is that it's a great lecture for everyone about the mechanisms of the changes in the ice extent in the Polar regions. It's simple to understand and yet it covers the basic knowledge about the polar regions and more. He teaches how ice sheet works in the global context and how to read the diagrams and the graphs that he shows. It's an hour long but I can't emphasis just how great this video is for anyone to understand the Poles. 

It's simple, concise and straightforward. None of the political crap that we hear interspersed in a many such scientific debates/conferences. Do, DO, DO, watch this. It does a much better job than I did in explaining ice mechanisms and the instruments used to measure ice extent. 

such depressing news!

Baby Harp seals being drowned, crushed amid melting ice by National Geographic.

Arctic Ocean: fast forwarding the last 1,450 years

To date, the Arctic sea ice extent is more than 2 million sq km smaller than in the late 20th century. It's been observed that the late-summer ice cover, mainly composed of thick multi-year ice, has been shrinking at about 8.6% per decade, which is unprecedented in the last 1,450 years. 

Just to refresh your memory, loss of sea ice in the Arctic Ocean will have disastrous consequences on climate, ocean circulation (which will be expounded in this post), ecology (remember the polar bears) and economics of the Arctic (shipping lines, eskimos etc etc). Sea ice cover responses to temperature changes and is influenced by the atmosphere and the ocean. This study by Kinnard et al. confirms (as expected) that the recent decrease in summer Arctic sea ice is 'consistent with anthropogenically forced warming' (Kinnard et at., 2011) through charting Arctic sea ice changes in the last 1,450 years. 

Methodology

They took raw data from areas around the Arctic basin (circum-Arctic) (Fig. 1). In total, there were 69 proxies used.They were obtained from ice cores, tree-ring chronologies, lake sediments. Two historical series of sea ice observations were used to get an anthropogenic view . 

Ice core proxies were mainly stable isotope ratio of oxygen. It's an air temperature indicator amongst other uses. Data of sea ice openness and sea surface windiness was also obtained through measurements of sea salt ions concentrations amongst others. (Read the paper for more descriptions about the proxies and their uses)

Results

Coverage of the central Arctic is poor because they were unable to get any samples from there. Sea ice variability is the greatest in the marginal ice zone as expected. They found that the proxy-based reconstructed history of the late summer Arctic sea ice extent from AD 561 to 1995 showed that pronounced decline in summer Arctic sea ice cover that began in the late 20th century is 'unprecedented in both magnitude and duration when compared with the range of variability (of sea ice extent) of the previous 1,450 years'. The low ice extent observed since the mid-1990s is well below the range of natural variability when we study the reconstruction. 

The reconstructed history of the summer ice in the Arctic sea was also paralled in the Barents sea: low values at AD 1600 and an increase afterwards and a minimum in the late 20th century. (Figure 3)

While the Barents Sea and Chukchi Sea and Fram Strait show similarity in changes in ice extent with the Arctic Circle, North Iceland diverges slightly with a significantly lesser extent of sea ice before AD 1200 and an overall increase afterwards (Fig. 3e). The reason for sea ice along its coast during winter and spring is partly because of sea drifting out of the Arctic rather than it being formed there. 

Surprisingly, there seems to be a poor correlation between NAO index and the Arctic sea ice cover in the reconstructed history. Only in the 20th century, did the positive NAO index correspond with the pronounced warming in the 20th century. This result only confirms that while the NAO plays an important part influencing ice extent in the Arctic, it is a combination of it with other factors that ultimately causes the changes in ice extent. However, the reconstructed NAO indices are still severely limited in showing us the changes of meridional atmospheric circulation which could confirm the theory of the lesser extent of sea ice during the Little Ice Age compared to the Medieval Warm Optimum was caused solely due to enhanced southerly advection of warm air into the Arctic.

Figure 3h suggests that there was an increase in invasion of warm and saline water from the North Atlantic into the Arctic Ocean causing a decrease in sea ice cover in the Arctic Ocean.  

Conclusion

So basically, what this article is saying is that the Arctic sea ice cover during the pre-industrial period was probably influenced by the intrusion of warm Atlantic water into the Arctic Ocean. The reason for this periodic intrusion is probably just part of the ocean-atmosphere-sea ice dynamics. From figure 3, the clear decrease of Arctic ice extent in recent decades can be linked to increasing warming of the Arctic that hasn't been observed in the last 1,450 years. For now, the most possible reason for that is because the warming it's experiencing recently is anthropogenically forced. 

This study is quite well-rounded in terms of the data that they obtained to reconstruct the Arctic's history. They were able to study cores taken from areas around the Arctic basin that had significant co-relation to the Arctic itself so parallels could be made between them. 

However, we still need to know what's going on in central Arctic. We need to know if the center of the Arctic (which this study was unable to obtain data from) is unstable and vulnerable to melting because that would mean that the multi-year ice may be gone and the Arctic Ocean might be ice free in the summer sooner than expected. 

Reference:

Kinnard, C. et al (2011) 'Reconstructed changes in Arctic sea ice over the past 1,450 years', Nature, 479. 

More graphs of the Arctic and Antarctic ice extent

Well, this blog is heading towards it's final few posts. Hopefully, I'll be able to make the most of the next few days to conclude this blog well. 

Anyway, in quite a few posts back, I mentioned old ice and new ice and the significance of their proportions relative to each other. I found this good online article on (where else) the NSIDC comparing the age of sea ice in the Arctic in the year 1985 and 2011 in March. The image below shows the Arctic basin. The one on the left is in the year 1985 and the right, 2011. The deeper the blue is the older the ice (the thicker the ice is, the older the ice is likely to be right at the bottom, remember?) 

A study by Maslanik et al. was found that in 1987, 57% of the ice was at least 5 years old and a quarter of that was at least 9 years old. In 2007, only 7 of it was at least 5 years old and none of it was 9 years old! That's a huge decrease in just 20 years!

So far, in all the posts I've been talking about ice thickness but I never really found a graph to show the changes (other than videos that don't really quantify the thinning of the ice). Here, below, I found a rather simple one where ice thickness has been plotted out. It is probably the average of ice thickness throughout the entire Arctic Basin. The multi year ice is basically ice that's present for a few years and first-year ice is newly formed ice in the recorded year. There is a slight increase from 2006 to 2007 in both types of ice probably because of newly fallen snow cover. Overall, however, there is a decrease in thickness of both types of ice. If you look at the heat graph, you'll find that there's a lot more areas covered in pink in Feb-Mar '08 than in '06.

The reasons for this have been discussed in previous posts but I want to bring up a point that I haven't managed to discuss properly yet. It's generally accepted that the general cause of the decline in extent and thickness of sea ice is due to the warming. However, temperature works together with the North Arctic Oscillation (NAO). That's a pressure system and changes periodically with the shifts in the position of the mid-latitude jet stream. When the jet stream moves up north, sea ice decline increases in rate (Positive phase) and the reverse is true. So even if the climate isn't warming, the movement of the jet stream is natural and depending on whether it's positive a negative phase, extent of sea ice will be affected in the Arctic Basin. And that strong positive signal in the mid 1990s may have been part of the reason why the older ice was exposed and melted, though it's certainly not the main factor. 

What needs to be focussed on is that in the early 2000s, the Beaufort Gyre (which is a pressure system in the Arctic, think of a water whirl pool but in the air and affects the ocean and ice circulation pattern in the Beaufort sea). It forms a sort of protection for ice that is within the Gyre's circulation, allowing it to remain for years without melting. However, this ice is melting in the southern end of the Gyre due to warming temperatures and more extensive melting in the summer. 

The more pressing matter is that the melting rate is increasing but the recovery rate is slowing down. In the previous post we see that the Arctic sea ice has almost halved in extent and we're not seeing nor expecting any sort of recovery. 

I'm trying to find some sort of positive tone to end of this post (unlike the other 10 posts). So here's a graph that's somewhat optimistic (though misleading). The red line shows that the Antarctic sea ice extent is increasing from 1978 to 2011 (just slightly). Through the opposite can be seen in the Arctic according to the graph below. Looking at the red graph, we see that even if the ice extent is increasing, there seems to be huge variations from year to year, signalling that the ice extent isn't stable and that we shouldn't let down our guard on global warming. The Antarctic's ice needs to be watched carefully since most of the ice is locked on land. If the ice shelves collapse, the glaciers behind it will follow and soon, the ice on the Antarctic might be all lost. That is, if the climate warms even further. 

So much for a positive ending. But well, we shouldn't be depressed. At least we're starting to do something.

IPCC's forecast about the Arctic Sea melting entirely by 2020

Two posts ago, Scientists Jennifer Kay mentioned that it's currently too difficult to pinpoint when all the ice in the Arctic Sea will be completely melted thought they know that it will be if we don't do anything to save it. In this video, Dan Miller shows us a graph from the IPCC and a video animation of the changes happening in the Arctic Sea. They predict that the sea ice will be completely gone by 2020 and that the extent of the Arctic sea ice has halved already.

He mentions feedback, which is basically a concept where even after an event as occurred, the consequences of it carries on, making the effects stronger. In this case, when ice melts, the natural albedo is gone and with the dark water of the sea exposed, more heat is retained making the poles warmer as well.

But his claims about ice disappearing entirely by 2020 isn't backed up by any real scientific proof. He merely extrapolated the thick, black line. But it does seem quite convincing doesn't? With so much scientific uncertainty about the dynamics of the ocean-atmosphere-sea ice, continuing the linear line down to 2020 seems as possible as 2100. Unfortunately for Dan Miller, his method of proving that the ice will be completely gone by 2020 seems dubious especially since he's a businessman with stakes in green technology.

Just another video

Here's another NASA video showing the changes in ice extent in the Antarctic. It starts from May 26 2009 to July 31st 2010. It starts with an over view of Antarctica then zooms to the Antarctic Peninsula, going over the entire continent before zooming out again.

Again, we can see the changing thickness of the sea ice other than the boundaries consistently changing. Note that the Antarctic has 10 times more locked up water in volume than the Arctic Ocean. Think about what it'll be if the entire continent melts (which isn't impossible).