Wrapping up (1)

Unfortunately, it's almost time for this blog to come to an end, so for the last couple of posts I'll try and sum up what I've learned over the course of the past couple of months. At the beginning I posted a few questions that I wanted to answer, so I think these are a good place to start, so I'll use these as a structure for the next couple of posts.

How do we know the sea ice retreat in the past few years is unusual?

The blog started off by looking at this question, firstly by using satellite data. Since satellite data began in 1979, sea ice extent and thickness have been decreasing at an alarming rate. Sea-ice extent during the summer of 2011 (sept) was almost on par with the previous record low during 2007, even without the unusual weather patterns thought responsible for the 2007 low. This strongly suggests that even though sea ice doesn't decrease every winter, overall conditions are worsening for continued survival of permanent sea ice.

A number of proxy records show a sea-ice history going further back than any contemporary records. As part of the blog, I looked at two relatively new methods of constructing these histories; the IP25 biomarker and Quartz records. These, as well as other methods, including documentary and ice-diatom records, show that extent of sea ice has been strongly variable, but also strongly correlated with climate. Sea ice extent is therefore extremely sensitive to temperature changes, meaning if we were experiencing global warming today, we could expect a significant loss of sea ice. Is that what we've been seeing?

Well, the sea-ice is disappearing at a faster rate than any model used by the IPCC has forecast, even the pessimistic 'business as usual' scenarios shown on the graph below. The graph doesn't show the past 5 years, but if it did the trend would be continuing, with 2007 being the minimum.

Sea ice extent output values from 13 IPCC Global climate models with an ensemble mean in thick black.
Actual observations are shown as a thick red line. Direct from Stroeve et al 2007.

Of course, this means a few things could be happening. Firstly, there could be some unknown natural variability that

Melting Permafrost - should I be worried?

Just before getting started, I found the video I really wanted to share with you guys before, but ended up using a replacement. It's from the fantastic series 'Earth: The Power of the Planet', presented by the brilliant Prof Iain Stewart, a Geologist at the University of Plymouth. He's like Geology's answer to Brian Cox! If you missed the series, I'd encourage you to have a catch-up. Interestingly, this video also features the same Dr Walter as the previous video..

Although it's the easiest and most spectacular way of showing the processes which are happening, it's not the lakes that are causing the most concern. Phrases like 'ticking time bomb' and 'unstoppable warming' are used

Arctic Lakes and Diatom Change - A Brief Summary

As promised, I'm going to cover the Smol et al (2005) article this time, as well as some associated references which will form part of the discussion. This post will focus on the Diatom changes seen in a wide range of Arctic lakes and their inferred causation. It's generally accepted that the Arctic regions will experience the effects of climate change disproportionately to other regions. This, coupled with the sensitivity of Arctic lakes, (potentially) makes this form of study an early indicator of the speed and severity of climate change in the future on a global scale. (Oops, I may have partly answered the final question). Oh well, on with the post...

A subarctic lake from Northern Quebec

Arctic Lake ecology is nice summarised by Smol and Douglas (2007) and shows that

Using Quartz as an Ice Rafted Debris (IRD) record

In addition to IP25, Axford et al 2011 (as mentioned in the previous post) also tested the presence of Quartz in marine cores as a proxy for ice rafting in the North Atlantic. Both of these proxies allow a reconstruction of ice abundance in the Northern Atlantic regions. Unlike IP25, however, Quartz is not a biological proxy, rather it is sometimes present as a 'foreign' material assumed to have been transported by floating ice (icebergs). Click 'Read more...' for a short summary of the method and a couple of examples.

Out of sight, out of mind?

Last month (Sept 2011) marked the end of the summer maximum in the northern hemisphere, and the total sea ice extent change data is beginning to emerge. This year’s summer extent was on a par with the record low of 2007 (since satellite records began in 1979) despite weather conditions being less favourable to sea ice loss than in that year. The National Snow and Ice Data Centre (NSIDC) remote sensing records on sea ice extent for the past few years are shown below:

http://nsidc.org/images/arcticseaicenews/20111004_Figure2.png

It is clear from this that recent summer, and to a lesser extent, winter ice extent is far below the average of the past 30 years plus two standard deviations. It could be said then, that the ‘climate’ of sea ice in the region is changing.

Overall, the far north is changing faster than almost anywhere else on earth. For this reason, it is likely that the arctic region is going to give the best warning signs as to the rate and severity of global climatic change. I will try in this blog over the coming months to engage with (and hopefully come to some conclusions about) important questions surrounding the change in the arctic regions, namely:

How do we know the sea ice retreat registered by satellite data in the past c.30 years is unusual?

Are any changes apparent in terrestrial and aquatic arctic ecosystems?
Is anything else apart from rising temperatures causing change?

What is the likely impact of future human activity on marine and terrestrial arctic ecosystems?

Will changes in the Arctic have an effect on the global climate? 
What has this got to do with me? Should I be worried?

Even if you have no interest in the environment (but if you’re reading this I’d expect, and indeed hope that you are) the changes facing the arctic regions are likely to have severe economic, cultural and (geo)political impacts. Although a ‘cold’ war is unlikely (despite scare stories in the media), human activities such as patterns of transport and resource use are likely to be affected. Indeed, geopolitical wrangling has been going on for some time (eg Russian flag planting mission).

The aim of this blog is not to discuss solutions to rising CO₂ emissions and climate change, but rather to see how arctic ecosystems have been and continue to be changed by climate changes and occasionally give examples of how this is likely to affect human activities. This will be done by discussing studies on past change, current measurements and future predictions.

Please feel free to disagree, argue with or debate anything I’ve written (as long as they’re at least mildly constructive!) by commenting.