Update on Recent Ice Extent

I started the blog off talking about the record low sea-ice extents seen in the Arctic in recent decades, showing a graph of this years data against 'record low' years. It was clear that 2011 experienced the second lowest ice extent in the satellite record, just beaten by the record-breaking 2007 year with it's unusual weather patterns. As discussed, 2011 did not experience 'unusual' weather as in 2007 around the Arctic, making the almost record concerning. I know you haven't been able to sleep since because of it, so I thought I'd give an update as has been recently published.

http://nsidc.org/images/arcticseaicenews/20111102_Figure2.png

The good news is that the ice extent rapidly increased during the end of October, meaning it hasn't yet been lower than 2007. Despite this, it's still far lower than the 1979-2000 average, including 2 standard deviations. 'Record low' years for each decade are also shown, 1984 and 1999, which were lower than the average but nothing compared to the last few years. Just to illustrate the difference, the UK has an area of 243,610 Km squared, meaning the difference between 2011 and 1999 ice extent at the end of October is about 5-6 times the size of the UK. It's also about the same size as 1 Mongolia, 75 Wales(s), 9,375 Liechtensteins and 3,000,000 Vatican Citys (don't say I don't help you out).

To keep up to date and save you those sleepless nights you can keep checking for updates on sea-ice extent here.

Arctic Lakes and Zoological Indicators

As we saw in the last post, it is highly likely that climate is indirectly altering Diatom communities in high Arctic lakes through changing levels and patterns of ice cover. Quinlan et al. (2005) used the same cores as the (previously reviewed) Douglas et al. (1994) study and counted the fossil chironomid (non-biting midge) larvae remains down the cores to investigate whether invertebrate communities have also 'shifted', and if they have, how likely it is that the changes are linked to the results from the previous diatom investigations. It's important to note, however, that these results are only taken from three archives (ie lakes and ponds) from Ellesmere island so further study is required to confirm that these findings are widespread.

Chironomidae are a family of flies which are aquatic organisms until their adult stages (see above) and

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

Thresholds and tipping points? - Arctic lake 'regime shifts'

For the next post I'm going to be reviewing an article by Smol et al (2005) entitled "Climate-driven regime shifts in the biological communities of Arctic lakes". So before I launch into that, I thought it would be best to have a review of the ecological theory surrounding what they are calling 'regime shifts' by looking at the article they reference. Ecological shifts can occur naturally (such as through fires) or, as is more likely in recent times, due to human activities. Click 'Read more' for a proper explanation...

Conceptual diagram of regime shifts and alternative
stable states. Direct from Scheffer et al (2001)

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.

Frozen Planet Extras

Here's a great site, part of the Open University extras for the Frozen Planet series on BBC narrated by Daivd Attenborough. It's a really interesting Google Earth 'mashup' including current weather and ice maps, and a timeline of Arctic exploration. I particularly liked the interactive 'current weather' map which shows the latest meteorological data from loads of weather stations in the Arctic regions. Can't see much use for it, but it's definitely interesting!

Also, thanks to Laura for linking to this, get a free poster. It's mostly of the Antarctic on the sign-up page but I'm assuming (and hoping!) it will have the Arctic on the back!

The C25 HBI Monoene AKA "IP25" biomarker in marine sediment cores - a valuable contribution?

I know at the end of the last post I promised a move away from palaeoclimate studies to ecosystem change, but there's a couple of subjects I've recently come across that I thought would be interesting to consider before moving on (sorry!). The first one is the use of IP₂₅ from Marine sediment cores to reconstruct a history of ice extent in the Arctic region.

Skeletal formula of the IP₂₅ biomarker

Kaufman et al 2004

Catchy title huh? I've just finished reading a really impressive and interesting article by Kaufman et al (2004) called "Holocene thermal maximum in the western Arctic (0–180 W)". The (many) authors included Holocene records from 140 sites, incorporating ice core, peat bog, marine and lake records distributed around the Western Arctic and considered in four major regions shown below. Unlike many of the palaeo-studies available in this region and in general, the authors sought to investigate the spatial distribution and timing of the 'Holocene Thermal Maximum' (HTM), a period in the early-to-mid Holocene in which averaged Northern Hemisphere temperatures peaked. Just as with the paper we considered in the last 'scientific' post, the authors used multiple proxies, all with varying reaction times and resolutions, giving them a fuller picture. By taking this approach they found some interesting and important results. Follow the jump for a summary...