Climate Change, Acidification, & the Oceans

Rivers and streams on the Greenland ice sheet a major contributing factor to global sea level rise

Meltwater runoff from the Greenland ice sheet, which covers 80% of the country, is a major contributing factor to global sea level rise.  The processes by which melting water reaches the ocean is still a subject of research, with most studies focusing on large chunks of ice that break off the ice sheet forming icebergs, or on large lakes which can abruptly drain.  Recently, a study lead by Dr Laurence Smith, Professor and Chair of Geography, and Professor of Earth, Planetary, and Space Sciences at University of California revealed that the network of 523 rivers and streams flowing on top of the Greenland ice sheet may be draining as much – if not more meltwater through sinkholes, than the other two processes combined.

The research team utilised remote sensing, remotely controlled boats equipped with specially designed instruments, and helicopter flyovers to map the network of rivers and streams, and collect data on water flow.  Alongside the importance of rivers and networks, the study also indicated that discharge from the Isortoq River, one of the largest rivers on the ice sheet, is lower than expected given the amount of water flowing down it.  Where and how this ‘missing’ water is being captured under the surface is not yet understood, but is contrary to models used by the Intergovernmental Panel on Climate Change, which assumes all meltwater goes into the ocean.  The study will help researchers refine climate models, ultimately developing better global sea level rise projections.

The paper which was published in PNAS is open access.

Image:  Supraglacial river networks represent an important high-capacity mechanism for conveying large volumes of meltwater across the Greenland Icesheet surface.  Taken direct from the paper.

Climate Change, Acidification, & the Oceans, Marine Conservation & Sustainable Management, Marine Life

News from the life aquatic

There are three great open access papers out this week that I want to share. Three! But which to share? Well why not all three. Here’s a quick round-up of some of the latest research in ocean science. Best served with a nice slice of your favourite treat.

Can you tell what (species) it is yet?
Every time we explore life in the deep sea we find more and more creatures that bioluminensce. Around 80% of all eukaryotic life in waters below 200 meters are thought to have this ability. In this study by Matthew Davis of The University of Kansas (USA) and fellow researchers, it emerges that diversity of species (species richness) in deep sea fish groups may be influenced by photophores – light emitting cells on the body of fish. The researchers work found that some lineages of the lanternfishes (Myctophidae) – which are made up of over 250 species – have photophores with species-specific patterns. This means species can clearly be identified from one another. This diversification seems to have happened after the evolution of the lanternfishes photophores some 73 – 104 million years ago. As diversification of photophores occurred, so too did speciation.  http://dx.doi/10.1007/s00227-014-2406-x

 

Where the young turtles swim
We watch baby turtles hatch and make their way into the open ocean. We watch them when they show up in coastal waters years later as ‘teenagers;. But where do they go when they are growing up? That is what Kate Mansfield of the University of Central Florida and fellow researchers set about to discover for loggerhead turtles (Caretta caretta) . 17 young turtles – all between 3.5 and 9 months old and reaching a maximum length of just 18 cm were tagged with small solar-powered satellite transmitters. And what an adventure these guys had. Staying mostly at the surface, these critters were found enjoying a wide area of the ocean past the continental shelf, – with one turtle travelling up to 2,672 miles! What was particularly surprising for the researchers was that they didn’t just hang out in gyre-associated currents – sometimes they went off exploring
http://dx.doi10.1098/rspb.2013.3039

 

I’m sure there used to be people living there
With changing climate comes changing sea levels. And for many areas that means a sea level rise. In this study by Ben Marzeion from the University of Innsbruck (Austria) and Anders Levermann from Potsdam University (Germany), looked at all 720 UNESCO World Heritage Sites to see what increasing sea levels would mean for them. The researchers decided to take a not-too unrealistic prediction of 3 degrees Celsius above pre-industrial levels in the next 2000 years. Under this scenario, their models indicated that 136 sites (19%) would be impacted by sea level rise. Doesn’t sound too bad, on the grand scheme of things but those sites do include key heritage areas like the Sydney Opera House, the Tower of London, and Independence Hall. Check out some visualisations from The Weather Channel, created using ‘Drown your Town’. But the researchers didn’t stop there. They also looked at how much of the current human population would be impacted by sea level rise. The same scenario indicated that 7% of the world’s population is living on land that will be undersea within 2000 years. Around 60% of those affected live in just 5 countries – China, India, Bangladesh, Vietnam, and Indonesia. Sobering thoughts for the future.  http://dx.doi:10.1088/1748-9326/9/3/034001

 

Image: ‘Drown your Town’ used on Cape Town, South Africa (50m rise – possibly a little extreme!). Credit: Drown your Town

Climate Change, Acidification, & the Oceans

Pacific Islanders to face climate change challenges

Ahh the Pacific Islands…white sand, warm water, sun shining down….it sounds wonderful (especially for me – I’m having a ‘year of winter’ with my moving about).

But things are changing, and perhaps nothing is quite changing on a global scale quite like the climate.  If your a Pacific Islander, climate change is likely to be a huge problem.  It all comes down to reliance on local resources, and in many cases these resources come from local marine waters.  From a food perspective, Dr Johann Bell of the Secretariat of the Pacific Community and colleagues from around the globe predict things are going to change a fair bit….here’s some highlights from the paper: Continue reading “Pacific Islanders to face climate change challenges”