Tim Naish: Sea level rise heading toward upper limit of 2 meters by end of century

Polar science diary

by Sue Nelson, BBC News, June 12, 2010

(Science writer and broadcaster Sue Nelson is at the world's largest polar science conference, which is taking place in Oslo, Norway, 8-12 June 2010. Experts have gathered to discuss everything polar -- from penguins and sea ice to permafrost and Inuit communities. She is writing a daily diary for BBC News about her time there.)

 
Friday 11 June: Fever pitch

Across the Arctic, bore holes are drilled into permafrost -- the frozen ground upon which many communities live -- so that sensors can measure the planet's health.

"It's like sticking a thermometer into the Earth," explained Antoni Lewkowicz from the University of Ottawa, "and the patient has a fever."

Prompted by International Polar Year, a project assessed temperature changes in permafrost over thirty years. The results were published for the first time during the polar science conference and show that, in North America and parts of Russia, temperatures have risen by a steady 0.2-0.3 °C each decade.
"In North Alaska it's worse," said Lewkowicz. "The permafrost has warmed by 2.5 degrees since 1985."

Lewkowicz, a member of the International Permafrost Association, is in no doubt about the importance of their findings. "We can see what's happening in the permafrost all the way round the Arctic for the first time and in some places it's actually thawing. Permafrost doesn't lie."

In areas covering northern Sweden, Finland, Norway and north-west Russia, a winter thaw is affecting both small and large communities, from reindeer herders to the forestry industry.

Reindeer eat lichen beneath the snow during winter but thawing causes a crust of ice and stops reindeer reaching their food.

"In Sweden herders have to buy additional feeding pellets or hay," said Carina Keskitalo, a political scientist in the department of social and economic geography at the University of Umea, Sweden. "Some small herders can't afford this and are going out of business."

Even big business is suffering. "In forestry you need hard ground in order to harvest," said Keskitalo, "but you can't drive in the soft ground and in some areas you can't harvest."

The changes in climate are forcing companies to rethink their machinery. Communities are being forced to rethink their livelihoods. If ever any proof was needed of the sheer enormity and range of changes affecting our planet's poles, then this polar science conference has delivered.
 

 
Killer whales are moving in to new territories

Thursday 10 June: Winners and losers
The Arctic is home to all manner of creatures and not all of them are welcome. Over the last few years, killer whales have being spotted in areas where they've never been seen before -- and the consequences are deadly.

The sea ice is melting and, without ice as a natural barrier, killer whales are entering new territories. For one of the world's most natural predators, a veritable feast awaits. For the seals, narwhals, belugas and other whales that make up their diet, it's a bloodbath.

When the balance of an ecosystem shifts, there are always winners and losers. In the Western Arctic diving sea ducks and walruses are definitely losers.

"The type of neighbourhood these creatures live in is changing," said biological oceanographer Jackie Grebmeier, from the University of Maryland Center for Environmental Science. "Their food supply is declining because of the retreating ice."

The life cycles of many Arctic species are synchronised with the seasons. The timing of events along the food chain -- such as the blooming of nutrient rich algae -- has now become out of sync and this is affecting the clams, worms and small crustaceans that walruses feed on.

Walruses and sea ducks also use ice to rest on during feeding. Without ice platforms they use more energy as well as needing to dive deeper to try to find more food. Dr Grebmeier becomes visibly upset when describing lone walrus calves barking from stress.

 
Retreating ice means fewer places for walruses to rest during feeding

In 2008 the United Nations Environment Programme passed a resolution expressing "extreme concern" over the impact of climate change and highlighted potential consequences. These included the disappearance of sea ice, flora, fauna, permafrost peatlands and the decline of certain species.

The Arctic Biodiversity Trends 2010 report, officially launched at the conference this evening, provides evidence that some of these anticipated impacts are already taking place -- and that the repercussions will be global.

Wednesday 9 June: Vuntut Gwitchin
Polar science is not all about penguins and polar bears. The changes in ice cover and permafrost are also affecting the lives and livelihoods of communities within the northern polar region.

Representatives from many of these communities are here -- which explains the reindeer-skin Saami tents outside the conference hall entrance -- and the colourful presence of traditional dress.

It took a second glance, however, to realise that one woman in a frilled skirt, silver tassled belt, embroidered shawl and red pom poms on her pointed leather shoes, was also sporting a modern Puma sports bag and trendy glasses.

I met Samantha Frost-Lindstrom from the Vuntut Gwitchin First Nation community in the northern Yukon, Canada, to try and persuade her to be my guest on Friday's Polar Exchange.

Vuntut Gwitchin means "people of the lakes" and Samantha lives within the Arctic Circle in the Old Crow Flats. Currently working as a field assistant to a permafrost scientist, her community has already noticed considerable changes.

"Spring comes early, there's a lot less snow and the river is lower," she said.

As water is the only form of local transport to different camps in this isolated area, the change is a significant problem.

"There's not as much salmon as there was when I was little either," she added.

Hunting is an important way of life for the Vuntut Gwitchin. "We eat caribou three times a day."

There are now less people in the community and the loss of hunting, due to declining numbers of caribou, also means the young are not being taught traditional skills.

Shel Graupe, director of Natural Resources for the Vuntut Gwitchen Government, quoted one of the community elders. "Hard times are coming."
 
Tuesday 8 June: Polar Eurovision

The Norwegian Crown Prince Haakon joined 2,000 polar scientists this morning for the official conference opening. A choir of white clad youths could be seen singing sweetly on the screens outside.

It reminded me of the recent Eurovision song contest in Oslo. "It was the same presenter," Linda Capper from the British Antarctic Survey laughed.

Fun stuff aside, Russian Prime Minister Vladimir Putin's special adviser on Arctic and Antarctic issues set most tongues wagging. Dr Arthur Chilingharov announced that Russia is proposing an international decade devoted to polar science.

Obviously a two-year-long "International Polar Year" was not enough.

 
The upper limit of sea level rise by the end of the century could be 2 m

The proposal is being warmly received as all agree that much more science needs to be done at the poles - especially when lives and livelihoods are at stake.

Professor Tim Naish, one of my guests in today's Polar Exchange session, couldn't be clearer about the risks ahead.

Director of the Antarctic Research Centre at the Victoria University of Wellington in New Zealand, Professor Naish told me: "The international scientific community assessed all the latest science post Copenhagen and it's converging on agreeing a sea level rise of one meter by the end of the century."

This is double the figure quoted in the IPCC report -- possibly because the dynamic effects of large ice sheets were not included.

Naish wasn't finished. "It's heading towards an upper limit of 2 meters."

The impact would be considerable. "It's huge," he agreed. "One-hundred-and-fifty-million people live within one metre's elevation above sea level."

Understandably, our first polar exchange theme concerns sea levels. There is dismay at the lack of trust surrounding the effects of climate change because these people are at the front line and have seen it for themselves.

And the news isn't good.

Link:  http://news.bbc.co.uk/2/hi/science_and_environment/10273566.stm

Tim Naish: Evidence for anthropogenic climate change is unassailable

Unassailable Evidence

Published by RedLogix on July 8, 2009 at 6:00 am in climate change.100 Comments

Tim Naish

Inaugural Lectures are very traditional university events, held these days to permit outstanding researchers to present an overview of their work to the wider academic community and public. Last night Prof. Tim Naish delivered a clear and decisive verdict about human-induced climate change: the evidence is unassailable.

Held in the very formal surrounds of the Hunter Building Council Chambers, the room was full to what I would guess its capacity of 400-500 people. His presentation wove together threads of the science, his own career, acknowlegements to those who went before him and the numerous mentors and colleagues whom all modern researchers depend on. Modern science is a very complex business; while the rare lone genius occasionally contributes ground-breaking insights, the vast bulk of progress these days is made by teams of people supporting each other, and all standing on the shoulders of those who went before them.

Starting with the Scottish mathemetician James Croll (1870), who was the first to deduce and calculate what are now more popularly known as the Milankovitch (1930s) cycles, Naish gave a brief introduction to the naturally occurring Ice Ages and sea-level changes that accompany them. The next major figure referenced was Sir Nicholas Shackleton (1937-2006), a pioneer in the use of mass spectrometry to determine changes in climate as recorded in the oxygen isotope composition of calcareous microfossils. Using ocean sediment cores, his team convincingly demonstrated that oscillations in climate over the past few million years could be correlated with variations in the orbital and positional relationship between the Earth and the Sun. However, even late in his life, Shackleton realised that the underpinning ideas of his work were only theoretical, that corroborating physical evidence was still required.

Tim Naish’s PhD work (1980s) studying sedimentary sequences in the Wanganui basin provided that evidence. The Wangaui basin is a 5-km-deep depression in the earth’s crust that has been filled over millions of years with erosion material from the continuously uplifting Southern Alps, material that is driven north up the West Coast by part of the Great Oceanic conveyor currents to form layer upon layer of beach material in the basin. Within that record is embedded clear evidence of numerous, dramatic sea-level changes, often in the order of 50-100 m, that exactly correlate with Shackleton’s records. Subsequent work has detailed a precise and robust sequence of almost 100 such oscillations, going back millions of years.

After working for Bob Carter for a number of years, Naish joined GNS (Geologic and Nuclear Sciences CRI based in Seaview Lower Hutt and closely attached to Victoria University), initially as a petroleum geologist. Very quickly he became involved in various Antarctic drilling programs, the first at Cape Roberts. This last summer, he was the Science Team leader for the ANDRILL project, an ambitious and successful core drill sited on the Ross Sea Ice shelf. Essentially, the drill penetrated 80 m of floating ice, 800 m to the sea bed, and then another 1000 m into the sedimetary layers beneath. (This alone was a remarkable technical tour-de-force and currently a world record.)

Most such core drills only recover about 40% of the potential record, but a specialist New Zealand company has pioneered innovative techniques allowing them to recover 98% of the material, greatly enhancing the quality of the data that can be derived from them. In the 2007-2008 season, the team’s sedimentologists identified 60 cycles when ice sheets or glaciers advanced and retreated across McMurdo Sound, dating back at least 5 million years.

Now for the takeaway message.

Over the last 3 million years, the Earth’s climate has undergone at least 60 naturally driven Ice Age cycles, each accompanied by major changes in sea level. As the temperature changes, so does the CO2 level. Over very long time scales, it is apparent that the Earth is gradually cooling, but the amplitude of the cycle changes is of the same order, i.e., the peak warm periods are almost as warm as they were million years ago, before gradually sinking back into the next Ice Age. Critically, it is vital to understand that the warm peaks of this natural glacial cycle always coincide with a peak CO2 level of not more than 300 ppm. [Blogger's note: we are pretty much at 390 ppm, now.]

Normally, these changes take place over many tens of thousands of years. Humans, however, have taken CO2 from about 280 ppm pre-Industrial to almost 400 ppm in around 100 years. In geological/climatic terms, this time scale is less than an eye-blink; it is a massive, virtually instantaneous, shock to the system. The last time the Earth’s climate had this much CO2 in it was about 3 million years ago when the climate was 5-6 °C warmer, there was no ice at either pole, and sea level was about 100 m higher than present. The major reason why this has not already happened is that the oceans represent a monstrous thermal mass, and the time lag for them to respond will be in the order of many hundreds of years, but respond they inevitably will. And it is the warming oceans that melt the Antarctic Ice shelves.

The ANDRILL sediments clearly show that during the warm periods the Antarctic oceans were full of algae blooms and the sea temperature was at least 5 °C. No ice existed in Antarctica during these warm inter-glacial periods. None at all.

There are two Antarctic ice shelves. The Eastern Ice shelf (EAIS) is by far the larger, grounded mostly above sea level and considered relatively stable for the foreseeable future. The West Antarctic Ice Shelf (WAIS) is totally different. Much of it is grounded at depths of 1-2 km below sea level. Therefore, it is peculiarly exposed to the effects of warming oceans in a potentially unstable and difficult to predict fashion.

The current IPCC’s mainstream predictions are of a 0.5 m sea-level rise by 2100, and exclude melting of the Greenland ice sheet and WAIS because at the time of publishing the IPCC considered the science around them too uncertain. The ANDRILL work has greatly reduced one aspect of that uncertainty. Alone, the linearly projected melting of the WAIS will add another 0.5 m of sea-level rise to the IPCC figure. A total of 1-m rise by 2100 is now considered a mainstream prediction in the community.

Worse still, Naish and his colleagues are now faced with clear evidence that the WAIS does not necessarily melt in a linear fashion, rather it is prone to highly unstable events that could lead to massive breakups, potentially adding up to 3.2 m of average sea-level rise in quite short periods of time. And, due to the way the earth’s gravitational field works, that average rise would not be distributed evenly over the earth’s surface; in some places like North America the rise could be up to 4.0 m… within our, or our children’s, lifetimes.

In the longer run, CO2 over 400 ppm commits the climate to a complete loss of the WAIS, the Greenland ice sheet and EAIS, totalling a sea-level rise of about 100 m. The evidence is now unassailable; a firm commitment to Copenhagen later this year is our last chance to act. Failure will bring only our grandchildren’s condemnation.

(And yes I took the train into town.)

Link to article: http://www.thestandard.org.nz/unassailable-evidence/