Quarrying the Antarctic for climate

Wed, 21 Dec 2011 07:39:25 +1100

In 1773, Captain Cook described the great southern continent Terra Australis Incognita as ‘A country doomed by nature never once to feel the warmth of the sun’s rays but to lie forever buried under everlasting snow and ice’. But is it? We used to think of Antarctica being completely insulated from the rest of the world, effectively stuck in an ice age which most of the planet finished with 12,000 years ago. Disturbingly, there are signs that the image we’ve conjured up in our minds of a frozen continent is fast disappearing. Across this vast region, the last few decades has seen trends above and below the ice that are far from encouraging. Warming has been observed across large parts of the continent and it seems most probable its down to our high-energy lifestyles that has seen us flood the atmosphere with carbon.

Unfortunately, Antarctica’s connection to the rest of the world means this special part of the world is not immune to rising greenhouses in the atmosphere. As the planet warms, the atmosphere and ocean are driving large changes across the continent. Some parts have warmed massively compared to the rest of the world. Most prominently, air temperatures over the Antarctic Peninsula have increased by 2.5 °C since the 1950s. This is four times the global average which for a frozen landscape can only mean trouble. Under these conditions, the Larsen B Ice Shelf on the eastern side of the Peninsula impressively fell away into the sea in just 31 days during one heady month in 2002. Warming led to pooling of the meltwater on the surface, which found its way down through cracks and broke up the Shelf. For something the size of Rhode Island that had been stable for 12,000 years, it was something of a wake up call.

In January 2012, Chris Fogwill and I will be undertaking scientific exploration of the Patriot Hills, part of Antarctica’s Ellsworth Mountains. Based at the University of New South Wales (Australia), funded by the Australian Research Council and working with Antarctic Logistics and Expeditions, we’ll be working in an average temperature of -20˚C. This is an even more challenging environment than the one we worked in last year. The high winds at Patriot Hills, which average more than 25km/hr, scour the surface of snow, exposing the blue ice below. Fortunately, however, these high winds can work in our favour. The winds are so fast and dry, the ice at the surface is removed by a process known as sublimation, drawing ancient, compressed snowfall up from down below. The practical upshot is this process exposes a wonderfully accessible, detailed record of past climate change preserved in millennia-old ice that allows you to literally walk back through time. Instead of coring for past climate, we'll be working across the surface (and against the elements!) to collect this precious archive. The idea is this will produce the first climate reconstruction for the region over the last twelve thousand years. By extending ‘historical’ records of the last few decades, we hope we’ll gain a better understanding of how Antarctic ice sheets respond to past and future change. At least that’s the plan...

The timetable for our fieldwork can be found at www.christurney.com. If you fancy following us more closely, we’ll be twittering away on ProfChrisTurney during our Antarctic fieldwork, describing the conditions and progress of work in the traditional 140 characters or less. Hope you can join us.

Review of ‘How to get Expelled from School’ by Ian Plimer

Fri, 9 Dec 2011 18:05:08 +1100

I was in two minds about looking at this book, let alone reviewing it. I had been a real fan of Plimer’s earlier work when he challenged young Earth creationists on their beliefs and showed how they twisted data and used statements out of context to put across a terribly skewed view of our planet. A few years ago I had been sent ‘Heaven and Earth’ to review and had assumed it would do the same with the so-called ‘climate sceptics’. Instead the opposite was the case. ‘How to get expelled from school’ is a follow up, designed to encourage students to question the science of climate change.

Scientists have to explain their work to the public; to inspire, to enthuse; to show the relevance of what they do. In a time of austerity, it is no longer good enough to take the public money, keep busy, out of sight, and hopefully out of mind. Scientists largely communicate with one another through journals few people can afford or understand. As a result, efforts to provide a context for the public and explain the science contained within specialised research articles would normally be applauded. Sadly this is not the case with ‘How to get expelled from school’.

With the declaration on the back of the book that the author is ‘Australia’s best known geologist’, hopes might be considered high that this would be a balanced, well-researched piece of work, showing how the past can inform on how our planet works. Unfortunately, the past is referred to throughout the book but badly. If I were in a less charitable mindset I would suggest the author has learnt lessons from the creationists and applied the same cherry-picking approach to climate change. The best I can write is the author doesn’t seem to understand much of the past at all; it’s almost as if the book has been ghost written. Changes in the past seem to be assumed to have happened globally and that to disprove anthropogenic warming, it is necessary to show how carbon dioxide wasn’t the principle cause. The number of misleading statements are far too numerous to be listed here but consider just one example, made on page 174: ‘Some 12,700 years ago, temperatures fell quickly by 8˚C and a 1,300-year cold period, the Younger Dryas began. After this 1,300 year period of intense cold, global temperatures rose very rapidly by about 12˚C marking the end of the Younger Dryas and the end of the latest glaciation. Did this glaciation end rapidly because we sinful humans suddenly put carbon dioxide into the atmosphere? Of course not, there was no industry and no agriculture than and again the hypothesis is wrong.’ Where to start? The Younger Dryas was a marked climatic downturn but it was centred on the North Atlantic region and perhaps across large parts of the Northern Hemisphere but it was not global. It’s been known since the late-nineties that Antarctica was warming up at exactly the same time it was cold during the Younger Dryas in the north. Research over the last few years has shown that warming in the south extends across most of the mid-latitudes of the southern hemisphere, and could have been used to illustrate how we can gain tremendous insights into the climate system from investigating past change. Plimer instead seems to be using the climate signal preserved in Greenland as a record of our planet’s climate and then misleadingly argues the temperature increase at the end of the Younger Dryas in the high latitudes was global. The cause wasn’t carbon dioxide, true, it was most probably linked to changes in the ocean circulation system, but this doesn’t mean increasing greenhouse gas levels in the atmosphere isn’t a problem for the future.

Research published last year in the prestigious journal Science (and before ‘How to get expelled from school’) has shown that without carbon dioxide, global temperatures would soon fall to an average of -21˚C. Fortunately the atmosphere does contain carbon dioxide and as a result we enjoy a relatively balmy 15˚C today. By flooding the atmosphere with carbon you would expect temperatures to increase. After all, science is built on the premise of Ockham’s razor, namely the simplest explanation is invariably the correct one. Ultimately, we've been here before with the young Earth brigade. To paraphrase Plimer from earlier work, all the 'sceptical' view of climate change science has to do is prove the fundamental principle that increasing greenhouse gases in the atmosphere will increase temperature is wrong. A Nobel Prize and instant fame would be the reward for the first scientist – or politician – who could not only explain away future climate change but at the same time expound thermodynamics, energy transfer, infrared absorption etc in a totally different way to that understood by science and used by civilization for centuries. I wish them the very best of luck.

Sub-Antarctic Exposure

Sat, 5 Mar 2011 10:30:35 +1100

In 2010, I was fortunate to be involved in an exciting piece of research led by Matt McGlone at Landcare Research in New Zealand. Published in Nature Geoscience, we reported a long-term record of vegetation and climate change on a sub-Antarctic island known as Campbell. Located at the far southern end of the Pacific, Campbell Island sits at an impressive 52˚S, entirely surrounded by ocean. By looking back through the ancient peat sediments on the island, we found large changes in the different types of preserved pollen grains over the past 18,000 years. It all pointed to big swings in vegetation across the island. Fortunately, because the vegetation is very sensitive to summer conditions, we were able to get a handle on temperatures in the past. Fascinatingly, the island temperatures didn’t appear to track those recorded by ocean cores from the region.

Previous work on temperature records from this part of the Southern Ocean had consistently shown warming began at the end of the last ice age around 18,000 years ago, peaked at warmer than present day temperatures (up to 3˚C warmer) between 12,000 and 8000 years ago and thereafter cooled. In contrast, the Campbell Island results showed summers remained cooler than now until around 9000 years ago, after which they warmed to present day levels. The most likeliest explanation for this divergence of the ocean and land temperature trends is the changing position and intensity of the westerly winds. Today, the strongest westerly winds in the Southern Ocean lie directly over the island. It looks like the vast north-south interchange of heat caused by these westerly winds was established at their current latitude some 9000 years ago, drawing warm air south over the island in summer (relative to the ocean) but having less of an effect in winter, leading to cooling.

The Campbell Island record of climate points towards large changes in the position and intensity of the westerly winds in the past. The winds appear to be very sensitive to subtle changes in climate across the southern hemisphere which in turn may have had a major influence globally. To test these ideas, a PhD student, Alan Williams, and myself, are visiting South Georgia, an island in the Atlantic sector of the Southern Ocean, as part of funding provided by the Australian Research Council. South Georgia is ideally placed to investigate past vegetation and climate changes. The island is some 170 km long and lies immediately downwind of the Drake Passage, through which the Antarctic Circumpolar Current (sometimes shortened to ACC) is forced while travelling from west to east around Antarctica. Importantly, the ACC is a current driven by the Southern Hemisphere westerlies. As a result, the climate of today’s South Georgia is dominated by frequent low pressure weather systems that cross the island, bringing large amounts of rain (on average, a metre and a half each year). If anywhere should pick up changes in westerly airflow in the southern part of the Atlantic, South Georgia should preserve a record of it.

As part of our fieldwork, Alan and I will be looking at peat and lake sediments that span the last 2000 years, using similar methods to Campbell Island, to try to get a precise record of what the climate did on decadal and centennial timescales. Alongside this work, we’ll be taking samples from moraines, ramparts of rock marking the former extent of glaciers, for Dr Chris Fogwill to date their rate of retreat and compare to the climate reconstructions made from the island and those we collected recently from Antarctica. It should give us some real insights into how these high latitude environments respond to past and future climate change. Unfortunately, the downside is a several day boat trip from Port Stanley on the Falkland Islands (each way). Oh well.

Just as with our Antarctic expedition, you can follow our fieldwork in South Georgia (and the crossing) courtesy of Twitter by subscribing to ProfChrisTurney. It’s going to be a long journey but with any luck the trip should be well worth it.

Delving in Antarctica

Thu, 2 Dec 2010 07:50:51 +1100

‘It is almost a reproach to civilization that we have arrived at the close of the nineteenth century without knowing the whole of the superficial appearance of this planet,’ declared an exasperated John Sutherland, Duke of Argyll and former Governor of Canada, in 1897. In spite of the huge progress made across science, technology, engineering and social reform during the Victorian era, the area surrounding the South Pole was unknown. Yet by 1913, a concerted push by the likes of Shackleton and Scott for Britain, Amundsen for Norway, Mawson for Australasia, Filchner for Germany and Shirase for Japan, had reached the South and flung open the door on Antarctica. A frozen continent shaped by climatic extremes and inhabited by wildlife and vegetation unknown to science was being uncovered.

We now know Antarctica and the surrounding Southern Ocean play a hugely significant role in our planet’s climate. By helping regulate the global exchange of heat and carbon dioxide, subtle changes in the region can have far reaching consequences. Importantly, over ninety-eight percent of the continent is covered by three large ice sheets which have an average thickness of 2,300 metres (around 7,500 feet). This equates to a vast amount of fresh water, estimated to be of the order of 70 per cent of world supplies. Some is of immense age, laid down as snow and turned to ice over 880,000 years ago. In the past, however, large-scale melting of Antarctic ice has taken place during periods of sustained warming, driving global sea-level rise. Importantly, Antarctica continues to experience change, seemingly not all of it natural, with some parts of the continent warming five times faster than the world average.

As part of a research program led by the University of New South Wales (and involving the University of Exeter), Dr Chris Fogwill and myself will be working on the Atlantic-facing part of West Antarctic Ice Sheet during January 2011, thanks to funding from the Australian Research Council and supported by Antarctic Logistics and Expeditions. The WAIS is an example of a marine based ice sheet, with the main bulk of its ice (equivalent to a global rise in sea level of around 3.3 metres) grounded well below mean sea level. As a result, the WAIS may be highly vulnerable to future warming. Studies of previous periods of warming suggest if the grounding line retreats, this can trigger a strong positive feedback where the surrounding ocean water bathing the ice sheet triggers separation from the bedrock. The UN’s Intergovernmental Panel on Climate Change (the IPCC), however, regards the loss of the WAIS as high risk because of the possible rise in sea level, but of low probability because warmer air temperatures may increase snowfall in Antarctica, compensating for any loss from increased coastal melting. To help reduce this future uncertainty, we will be investigating how West Antarctica has responded to temperature changes in the recent geological past.

Our scientific exploration will focus on the Ellsworth Mountains, reaching up to 4,892 metres above sea level. At an average temperature of -30˚C, this is a challenging environment in which to undertake research. Yet frozen within the rock and ice of this spectacular range lie crucial clues to the history and future of this great continent in the south. Our work will be on the mountains that protrude through the ice sheet at a strategic junction between the floating Ronne Ice Shelf and continental ice, using exposed rock as a dipstick to establish the thickness of ice and how it’s been thinning over the last twelve thousand years.

The timetable for our fieldwork can be found at www.christurney.com. If you fancy following us more closely, we’ll be twittering away on ProfChrisTurney during our Antarctic fieldwork, describing the conditions and progress of work in the traditional 140 characters or less. Hope you can join us.

Logging Old Weather

Fri, 19 Nov 2010 07:39:43 +1100

Ever since the first Royal Navy vessels set forth to patrol the high seas, its ships have kept meticulous records of the weather. By the 1670s, the might of the British Empire was religiously keeping detailed observations on the state of the elements on and in the world’s oceans. Even during battle, ship crew members would be sent off to make a remarkable suite of measurements, including air and sea temperature, wind direction and speed, and air pressure. Dodging shrapnel hurtling through the air, these observations were diligently put into log books to help forecast the conditions individual ships might face in the near future. Even in the nineteenth century, however, it was realised there was considerable scientific value to this work beyond the immediate need of prediction. One of the most vocal supporters of their expanded use was the Rear-Admiral and great British scientist, Sir Francis Beaufort. Beaufort is best known today for his development of a scale that allows an estimation of wind strength from the state of the sea’s surface (or the tree in next door’s garden). But in 1809 he remarked “There are at present 1000 King’s vessels employed. From each of them there are from two to eight log books deposited every year in the Navy office; those log books give the wind and weather every hour…what better data could a patient meteorological philosopher desire?". Unfortunately his words went largely unheeded. Other time, the ships returned home and the log books eventually found themselves in the UK National Archives where most have been gathering dust...until now.

It’s only recently that the scientific value of this tremendous archive has been properly recognised. Scientists have increasingly pored over these chronicles to find out the state of the world’s weather through the centuries. Importantly, by their very nature, these records capture conditions at sea, providing a much needed view of 75% of the world’s surface. The problem is there is actually an embarrassment of riches; there is almost too much information. Where inroads have been made, the results have given fascinating insights into our changing planet. For instance, in 2006, a scientific paper by Drs Dennis Wheeler and Jose Suarez-Dominguez at Sunderland University looked at early naval records and found a large increase in the number of British summer storms during the 1680s and 1690s, all against a backdrop of generally cooler temperatures. More recently, Dr Joelle Gergis of the University of Melbourne reported weather observations made by HMS Sirius in 1787 as part of Australia’s First Fleet which show the summer at this time was unusually wet, most probably due to a La Niña in the Pacific Ocean. These and other studies all suggest the long neglected naval logs can help fill a valuable gap in our knowledge of historical climate change.

Although the data is safely archived, there’s a huge amount of effort needed to get it in a form that can be useful to science. The bottom line is the data has to be copied into an electronic format but the amount of labour required would be prohibitively expensive if it were fully costed. Fortunately, the increasing accessibility of the internet is allowing the public to take an active role in science without leaving the comfort of their own homes. And this is where Old Weather comes in. A consortium of research interests (including the Citizen Science Alliance and Atmospheric Circulation Reconstructions over the Earth or ACRE for short), the University of Oxford, the UK Met Office and Naval History.net have got together with the UK National Archives, National Maritime Museum and JISC to enlist the help of volunteers to work up these weighty tomes.

Focussing on ship logs from The First World War, the Old Weather website is a delight to visit. Even if you just want to see best practice in science communication, I can’t recommend the site enough; it’s interesting, intelligently set out and colourful. The opening page is filled with cartoons, sharp, snappy text and short movies that are professionally shot and explain what this citizen science project is all about. Old Weather builds on the superb work done by Zooniverse which aims to bring science to the public (much of it astronomical) online. It’s all very impressive.

If you’re interested in working with Old Weather, it couldn’t be easier. The First World War logbooks have been photographed and digitised where they are ready to be worked on. The pinch point is getting this data copied into a digitally useful form. This is where the public can help: by transcribing the handwritten entries, the measurements can be checked by researchers before being added to the growing body of data. After registering your interest, a few short films take you through the process: how to interpret the flowery writing scrawled nearly a century ago, what numbers to copy down (usually in the middle of the page), how to note any relevant remarks, and how to load all this information into the online data entry box that appears on the screen. The system is very user friendly and quite intuitive. Each page holds somewhere of the order of six weather observations and takes just a few minutes to copy.

When you consider British log books total more than 100,000 in number, while other nations and shipping lines have similar records, its clear this is just the start of a huge international effort to shed new light on old climate. It’s a wonderfully exciting time for marrying history with science.