Climate Feedback

Why carbon dioxide concentrations over the past 24 million years or so have never dropped below 200 parts per million, despite environmental conditions that have been favourable for CO2 drawdown by rock weathering and sedimentation, has always been a bit of a mystery.

Now scientists suggest an almost provocatively simple mechanism that might have kept the planet from cooling more severely than it actually did during past glacial climates: Changes in terrestrial vegetation stopped the weathering-driven decline in atmospheric CO2 concentrations which else would have turned Earth into a lifeless freezer.

Weathering is known to be largely controlled by vegetation. So the team, led by Mark Pagani of Yale University, describes in a paper in Nature today a negative feedback whereby limited plant growth during cold conditions slows down the rate of weathering and sedimentation, thus preventing carbon dioxide levels from dropping even further. An editor's summary of the paper is here.

This “bold and provocative” hypothesis provides an “elegant twist” on existing ideas about climate-vegetation interactions, Yves Goddéris and Yannick Donnadieu write in an accompanying News and Views article (subscription required).

But the proposed feedback mechanism raises contentious issues as well. For example, Goddéris and Donnadieu argue that in the tropics the role of vegetation cover in the climate system might not be as significant as proposed.

Quirin Schiermeier

Posted by Quirin Schiermeier on July 02, 2009
Categories: Categories, Biosphere feedbacks, Climate Science, GHG emissions, Palaeoclimate, Quirin Schiermeier, Topics | Permalink | Comments (0) | TrackBacks (0)

Jane Qiu has an interesting interview on Nature News with aquatic ecologist Breck Bowden of the University of Vermont, who is heading up new research looking at what happens when thawing ground in the Arctic begins to fall apart. Here's an excerpt:

Last week marked the start of a US$5 million project to study the effects of thawing permafrost on ecosystems in the Arctic. Based at the Toolik Field Station in northern Alaska and sponsored by the US National Science Foundation, the project will look at the impact of thermokarsts — the scars and pits left behind as melt water from permanently frozen ground leaks away, and soil and rock collapses in its wake.

The project was inspired by a serendipitous discovery in 2003, says Bowden:

My colleagues and I were flying over the high Arctic in search of research sites. We noted that the Toolik River was brown and muddy, which was odd as it hadn't rained recently. As we went further upstream, we came to a tiny stream that was washing tons of thermokarst sediments into the river. We were astounded how this tiny feature was influencing the river 40 kilometres downstream. The volume that had been displaced was enough to smother the bottom of the entire river. The sediments would release a lot of nutrients normally locked up in permafrost into freshwater cycles. That's got to have a significant impact on the ecosystem.

Read the full interview here.

Anna Barnett

Posted by Anna Barnett on July 01, 2009
Categories: Anna Barnett, Cryosphere, Earth science | Permalink | Comments (0) | TrackBacks (0)

It’s Wednesday in Lindau and I’ve spent a chunk of the past 24 hours recording sections of the film about climate change that we’re making here.

Yesterday afternoon, I had the pleasure of talking with Mario Molina and Sherry Rowland about their work on ozone and their views on science informing policy. We were joined by three young, enthusiastic scientists who are working on various aspects of climate research – solar technology, biofuels and ocean health – and are here at Lindau to interact with the laureates.

Molina and Rowland have a lot to say on the issues of ozone and policy, of course. When they called for a worldwide ban on CFCs, following their discovery that CFCs were destroying the ozone layer, they were, in many respects, pioneers. But though their efforts ultimately led to the phasing out of CFCs, their results – and outspoken views – were initially greeted with caution from the scientific community. I asked them what the young scientists working on climate change can learn from their experience.

Rowland was adamant that young scientists should not be afraid to speak up on the implications of their research. I queried them on how far researchers should go in speaking up. Would they, for example, now call for a worldwide ban on the use of coal, given that coal is such a significant contributor to the problem of climate change? They both responded that a worldwide ban would be appropriate, if carbon capture and storage (CCS) was available. Molina added that we should be cautious of building new power plants that will tie us into using coal for the next 30-50 years, unless we have developed CCS technology.

I met the young researchers – Brandy and Brian from the US, and Faroha from Pakistan – again this morning at 730am to catch up on their experiences at Lindau so far. They all got a lot out the session with Rowland and Molina, who were both thoroughly engaging. Of course, I can tell you all of this on the blog, but it will be much more convincing to see the film once it is on nature.com. Out of an hour of filming, I’m guessing that five minutes, at most, of yesterday’s session will make it into the final cut.

After hearing talks on sustainability and energy from Harry Kroto and Walter Kohn, this afternoon, I recorded some of the narrative links for the film. The face-to-camera pieces are by far the trickiest!

The next piece will be recorded Friday as we make our way by boat to Mainau island – home of Countess Bettina Bernadotte – where a panel on climate change is being convened. I’ll be back with an update from that on Friday.

Olive Heffernan

Posted by Olive Heffernan on July 01, 2009
Categories: Lindau Nobel Laureate Meeting, 2009, Olive Heffernan, Politics, Society | Permalink | Comments (0) | TrackBacks (0)

It’s Tuesday in Lindau and a morning session on renewable energy has just finished. The panel, which featured some serious heavyweights, looked at the role of chemistry in developing renewable energies.

Two challenges exist in deploying renewable technologies on a large scale, said the panelists. Namely, these are storage and transport of energy. “ We cannot create energy. We can only transform the energy coming to earth from the sun. So it’s just a question of how we can transform and store this energy”, said Gerhard Ertl, who won the 2007 Nobel Prize in Chemistry.

Robert Grubbs of Caltech, the only organic chemist cum-laureate on the panel, said that materials scientists could play a critical role in solving these problems, such as by designing lightweight, large blades for wind turbines.

There is a huge amount of solar energy available and a smaller amount of wind energy available, said theoretical physicist Walter Kohn, who received the 1998 Prize for his contributions to the understandings of the electronic properties of materials. Kohn said that the challenge is turning this vast amount of energy into something usable.

But that something will also have to be safe, suggested Kohn, who expressed particular concern about replacing fossil fuels with nuclear power. “I’m old enough to have witnessed the affect of nuclear bombs, and I’m a young enough that I can still read the newspapers”, he said, referring to the threat of nuclear proliferation in Iran and North Korea. “If this became a major source of replacing fossil fuel, the number of power plants needed would create…a huge probability of leading to a catastrophe”, said Kohn, who worries that “there will a tremendous pressure to go for nuclear” none-the-less.

Laureate Harold Kroto agreed that the pressure to use nuclear energy will be “irresistible” and raised the issue of whether scientists need a new Manhattan project to develop new technologies. Kroto argued that blues skies research will be perhaps more valuable than applied research here, because often the accidental leads to new discoveries.

“Do we need some kind of new chemistry”?, asked Kroto. In developing new technologies “we have a responsibility to society that our discoveries should not be misused”, he added. “This is a worry that many of us have”.

Olive Heffernan

Posted by Olive Heffernan on June 30, 2009
Categories: Energy, Lindau Nobel Laureate Meeting, 2009, Olive Heffernan, Society | Permalink | Comments (1) | TrackBacks (0)

Nature Geoscience’s latest issue highlights the challenges of understanding fluctuating sea level – from 70 million years ago to the future (sea level content free to registered users). A collection of commentaries and research papers look at how sea level has changed in the past and try to project its future evolution. In addition, the issue provides insights into some of the societal impacts of sea level change, and how some countries are planning for the future.

Continue reading "Focussing on sea level" »

Posted by Alicia Newton on June 30, 2009
Categories: Adaptation, Alicia Newton, Climate prediction | Permalink | Comments (0) | TrackBacks (0)

More than 600 delegates arrived yesterday in the quaint German town of Lindau on Lake Constance for this year’s meeting of Nobel Laureates.

Most of the delegates are students who have been selected by a panel to participate in the event, where they will have a unique opportunity to interact with some of the greatest scientific minds on the planet.

I’m here with a team from Nature, and a film crew, who are making a series of short films on this year’s meeting, which is dedicated to chemistry. A sizeable proportion of the programme is on climate change and sustainability (which is just as well given that I left chemistry behind as a second year undergraduate to pursue earth sciences), so one of our films will focus on those issues, specifically on the role of scientists in informing policy.

After arriving on Saturday we had the tough job of selecting the young researchers who will participate in the films this year. For the film on climate change, that meant choosing just 3 finalists out of the several dozen applicants. It slightly felt like being an 'X factor' judge, but luckily we were all in agreement on the final call.

As well as discussing science itself, many of the young researchers see the Lindau meeting as an opportunity to learn about what it takes to be a great scientist and to discuss the broader role of scientists in society.

In the opening ceremony on Sunday afternoon, Kapil Sibal, Indian Minister for Human Resource Development, who has just been admitted to the Honorary Senate of the Lindau Foundation, said that scientists must stay above politics and not be constrained by history. Science and technology are “value neutral”, but “can used for good or bad”, said Sibal. He urged the next generation of scientists to think carefully about the applications of their work and to whether it can be used for the good of society.

Continue reading "Lindau09: Scientists in society" »

Posted by Olive Heffernan on June 29, 2009
Categories: Lindau Nobel Laureate Meeting, 2009, Olive Heffernan, Society | Permalink | Comments (0) | TrackBacks (0)