GeoLog

This year it is once again possible to upload your oral presentations and posters from EGU 2013  for online publication alongside your abstract, giving all participants a chance to revisit your contribution – hurrah for open science!

Files can be in either PowerPoint or PDF format. Note that presentations will be distributed under the Creative Commons Attribution 3.0 Licence. Uploading your presentation is free of charge and is not followed by a review process. The upload form for your presentation, together with further information on the licence it will be distributed under, is available here. You will need to log in using your Copernicus Office User ID (using the ID of the Corresponding Author) to upload your presentation.

Presentations and posters will be linked to from their corresponding abstracts. If your presentation didn’t have an abstract (this is the case for Short Courses, Educational & Outreach Symposia and others), you can upload your presentation to slideshare or figshare as a PDF to share it with the wider community. Add a link to it in the comments section below and we’ll compile those that aren’t on the EGU 2013 website!

Share your presentation with the world by uploading it to the 2013 General Assembly website.

With the mammoth task of Storifying #EGU2013 this week, I’m wondering just how useful social media, particularly Twitter, has become at conferences.

While having a hashtag for a conference with 4,684 oral, 8,207 poster, and 452 PICO presentations (#EGU2013) won’t give you an insight into what’s going on in all the sessions – there’s simply too much science – it provides a guide to what’s happening next (as speakers share their sessions) and is an indicator of the “hot topics” as multiple media-savvy participants share their experience of particular sessions. More importantly though, it gives people attending the conference an opportunity to interact and extend their discussion online.

When there’s over 3,800 tweets on the #EGU2013 hashtag during the General Assembly, curating a scintillating story that also falls into the category of ‘short and sweet’ no longer seems achievable. But do we need it? Perhaps it’s better to preserve the discussion that surrounds topical sessions such as the Great Debate on fracking and shale gas (Storify to come – watch this space!) and short courses, which can then be used as a resource for hints and tips later.

Just a sample from #EGU2013 (click for larger).

While making something public via Twitter can bring up the subject of potentially being “scooped” on science before it’s published. At a conference you are already communicating your work externally, so this is not an issue. Instead, it presents an opportunity to communicate your research with the wider public and scientific community. Here are some of the benefits:

Enriched discussions

Twitter provides opportunities for a much richer discussion during a conference – not only are you listening to the speaker’s insights on a topic, but you can tune in to the knowledge and experience of others in the audience. The knowledge gathered in a scientific conference is phenomenal and in the case of the EGU General Assembly, having over 11,000 brilliant scientific minds at your fingertips, why wouldn’t you ask a question?! Okay, so they aren’t all on Twitter, but the chance of a well-informed reply is high, so it’s still worth asking!

Remote participation

To add to the already enriched discussion, when something is being broadcast on Twitter, anyone can follow the goings on – be it the colleagues you left back in the lab, the geologist whose fieldwork clashed with the event, or the interested twitterer, who happens upon the hashtag! If a talk is being live tweeted (someone is tweeting updates about the speaker’s presentation) then it’s even easier for others to participate in the conference online and ask their own questions of the audience and the speaker.

Leaving a legacy

So we have a rich discussion, that involves members of the audience and connects with the wider public, potentially sharing the science with individuals across the globe – is there more to gain from a conference Twitter feed? Yes. The online discussion can be condensed and curated using Storify, which leaves a legacy of the discussion that people can return to later. Take the #EGUjobs session for example, Sarah Blackford and Helen Goulding gave an excellent talk on how to apply for jobs both in and out of academia last week and you can return to their recommendations here.

What did you gain from the conference Twitter feed? Fancy more of the same next year? Less? Or an even bigger online presence in 2014? Leave a comment below, or include it in the conference feedback form and we’ll do our best to make it a reality. 

For those with a keen eye, you may have spotted a red balloon soaring high above the EGU Centre this week. The little white box attached underneath is the Light Optical Aerosol Counter (LOAC), a device that has been measuring the aerosols it the air around the conference.

LOAC hangs from the red balloon outside the EGU. Picture Courtesy: Eric Hamonou.

Aerosols are air borne particles that can be liquid or solid, natural or manmade. Salt, fog, sand, plaster and carbon are common aerosols found in the air.

Studies have shown particles less than 2.5 micrometres (mm) and 10 mm can be detrimental to human health as they are small enough to get into your lungs and enter your cells. An average human hair for example is about 200 mm. Regulations set thresholds for the amount of a particular particle size that should be in the air we breathe.

LOAC is an optical instrument that sends a beam of light through particles and the way the light scatters determines the size and shape. From this, the scientists can work out if the aerosol is carbon, mineral or liquid.

EGU GeoLog reporters managed to catch up with Jean-Baptiste Renard to explain his experiment this week…

So what did you find in the air around the EGU?

Indoor air pollution was worse than outside. On Wednesday as it was too windy outside to fly; we flew the balloon in the exhibition hall. Particle levels sized10 mm (the dangerous kind) were at least five times more inside, almost reaching the threshold of alert levels.

Results from the indoor flight – minerals are reaching threshold levels. Graphs: Jean-Baptiste Renard.

These particles come from our clothes, in our hair, the dirt we scuff on the floor, is all lifted back up into the air. We are full of dust!

Outside, the concentration changed a lot during the day. In the morning there was a lot of carbon measured, possibly from the traffic that you would expect in a big city or the direction of the wind.

Measurements in the afternoon showed more mineral particles. This may be because of all of the building work going on in the towers on the right of the conference centre entrance. Every time someone uses a saw or hammer, tiny particles are produced and we can measure them in the air.

In the morning there is more carbon, and in the afternoon more minerals. Graphs: Jean-Baptiste Renard.

But won’t they measure the same – on the ground or in the sky?

No – the ground level concentration of aerosols can be completely different to 100 meters in the air. The higher you are, the greater more mixture of aerosols you find because up there, the particles that have been transported from elsewhere. At ground level, it is much more localised and the aerosols present are specific to what is close by.

Is that what’s so great about LOAC, you can put it on a balloon?

The key to LOAC is that it is airborne. As it is so small and lightweight, it can be attached to any kind of balloon. Before, the instruments had to be attached to planes or much larger balloons. Now, we can accurately trace if particles are locally produced or if the conditions in a small area, say on a specific street, are reaching an unhealthy threshold.

Being able to measure particles less than 1 mm is also totally new. We can distinguish between aerosols too. Before LOAC, instruments had to be set to detect a certain particle in the air, say salt. You would need to calibrate to look for salt. If there were no particles in the air, there would be no results, but now we can use one piece of equipment for multiple measurements, we can always collect data!

 by Becky Summers, City University, London

video by Sue Voice, University of Otago

Congratulations to Philipp Stadler, Yiming Wang and Eva van Gorsel, winners of this year’s Imaggeo photo competition!

Winning image: Frost by Philipp Stadler

Second place: Icebear Rising by Yiming Wang

Third place: Regrowth after fires by Eva van Gorsel.

Imageo photos are distributed by EGU under a Creative Commons licence and are available in Imaggeo, the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their images to this repository and since it is open access, these photos can be used by scientists for their presentations or publications as well as by the press. 

This week at the EGU General Assembly, we’ve heard how the global environment is changing before our very eyes. As the Earth warms, sea levels rise, and weather patterns shift, the food security, health, and economic prosperity of societies around the world has come under threat. In the Anthropocene, an era dominated by human impact on the natural world, it seems that environmental and development goals are fast becoming one and the same. We have to find solutions that will allow us to live and grow sustainably, a task that falls largely to the hands and minds of the scientific community.

To shepherd Global Environmental Change (GEC) research into a new era of collaboration, communication and innovation needed to meet these challenges, the Future Earth initiative was conceived at the Rio+20 UN Summit on Sustainable Development last year. EGU’s GeoLog sat down with Anne-Sophie Stevance of the International Council for Science and Owen Gaffney, the Director of Communications for the International Geosphere-Biosphere Project, two of the driving forces behind this new project. Here, they explain what Future Earth means for geoscientists.

Future Earth hosted a Townhall Meeting at the EGU Assembly on Tuesday night to introduce their initiative and solicit feedback from the scientific community. Credit: Sue Voice.

First of all, what is Future Earth?

AS: Future Earth is a new international research program focused on producing the knowledge we need to address global environmental changes and the transition towards sustainability. The idea is to unite people who are not used to working together, building a community around Future Earth with stakeholders from academia but also other from sectors like policy and business. We are still very much in the early stages of development and we are eager to work with scientists on defining our research agenda and structure.

What sets Future Earth apart from previous Global Change initiatives?

OG: For the past 20-30 years, Global Environmental Change (GEC) research has focused on understanding human impacts on the planet and how the planet works. For Future Earth, that research agenda is changing to one centered on global sustainability. Also, the world has become far more interconnected in recent decades. Future Earth now has dual roles: to continue coordinating research but also to promote international collaboration and outreach.

How will Future Earth actually work from an operational point of view?

AS: Our goal is to have scientists come together with common research interests and populate the research framework from the bottom up. We don’t want to impose things from the top. Next week, for example, we will host a networking conference for young scientists to discuss food futures. It’s done within the framework of Future Earth and will be all about discussing the research agenda, identifying research themes and priorities, and developing collaborations.

You gave the example of food futures, but what are the other topics that fall under the purview of Future Earth?

OG: The starting point is our three broad research themes: dynamic planet, global development, and transformations toward sustainability. Within these, we’ve already had a call for proposals in two research action groups on freshwater and coastal vulnerability, and we are working on food security and infrastructure. But we want to be very open and create a platform that any scientist feels they can approach.

Owen, your expertise is in communication. Will communication be a big part of Future Earth?

OG: The old model of communication was to make more knowledge accessible to people. I think we need a new model that starts with this idea of co-design. This involves engaging the stakeholders from the beginning so that the users of this knowledge have a larger vested interest in the research and feel that it is addressing their needs.

AS: We highlight co-design as a big opportunity that can bring a lot of value to Future Earth but we also identify it as a challenge. We need to define research questions that appeal to policy and business and that requires building a common language.

Is that where data visualisation comes in? You spent a big part of the Townhall Meeting on Tuesday night talking about this.

OG: Data visualisation is rapidly evolving, and it is such a powerful way of communicating science. It can change how you think about the world by displaying scientific evidence in an understandable way and impressing issues of scale. One of the added values of Future Earth is that we can create partnerships with organisations like Google or Mozilla or Microsoft who are investing heavily in data visualisation. We also plan to offer summer schools on data visualisation and communication for young scientists. Bringing up a community who’s thinking like that is very important, and we need to given them the skills to interact with the public, the media, and policymakers in new ways.

You expressed interest in engaging funding agencies in the goals of Future Earth. Can you explain how that might work?

AS: We are already working with the Belmont Forum, a coalition of groups that fund environmental research, as well as NSF, NERC, national funding agencies and others. They have been involved from the start in setting up Future Earth and establishing the research agenda. Now, they can help further the goals of Future Earth by setting common criteria for funding – for example, that we want to see natural and social sciences together, we want to see elements of co-design and outreach to stakeholders. That incentivises the core elements of Future Earth.

OG: In a similar way, the International Polar Year (IPY) was an extremely positive model of how international endorsement can help with funding. It built a very large community very quickly and that community held together for a long time after the IPY was over. We can adapt some of their ideas for endorsing projects, which can then be taken to funding agencies with a stamp saying “these have been endorsed by Future Earth, will you fund it?”.

At the end of this 10-year initiative, what is an example of an outcome of Future Earth that you would consider a success?

AS: For me, it would be a young scientist trained in holistic, trans-disciplinary research and working on developing pathways to sustainability or researching the link between GEC and how we can transition to sustainability.

OG: The new UN sustainable development goals are going to start in 2015 and run to 2030, but it will be important for the research community to play a role in measuring, monitoring and evaluation the targets underneath the goals. To me, that would be a significant policy outcome from the Future Earth initiative.

You can learn more and get involved at http://www.icsu.org/future-earth.

Here is a powerful data visualisation by Owen Gaffney to inspire you more!

By Julia Rosen, Freelance science writer and PhD student in Earth, Ocean, and Atmospheric Sciences at Oregon State University

Scientists are building walls of willow trees in the Southern French Alps gullies to trap dirt that blocks hydroelectric dams downstream.

Sediment in rainwater washes off the steep valley slopes in the Francon marly basin into gullies. These smaller waterways then feed larger rivers. When the water reaches the slower-moving reservoirs above dams, the sediment drops out and settles behind the barrage.

This can cause big problems as dams are only engineered to withstand a set about of force pressing against them. If this is not removed periodically, the dam can eventually burst or overflow. So the muddier the river, the faster the build up. Every 15 years, energy companies in must pay millions of euros to scoop out the mounds of dirt.

Freddy Rey and colleagues are adapting ancient bioengineering systems, high up in the mountains, to prevent the amount of sediment reaching the dam. Willow cuttings are buried 30cm within wooden walls that stretch across the channels. These are placed roughly every three meters up the gully like a staircase.

The stepping willow walls placed in the gully. Picture courtesy: Freddy Rey.

Similar to a sieve, the willows allow water to flow through but trap the sediment back. Within a year, these structures can trap up to 10cm of sediment. Over time, this increases as the willows become more established and more sediment can be kept back. After 20 to 30 years, the vegetation will have complete cover and sediment erosion is almost completely stopped.

In with the new

Rey and his colleagues figured that instead of trying to prevent erosion on the banks of the gorges, it was cheaper to plant the walls actually in the gully base. “The sediment is eroded off the slopes but is instead trapped in the gully floor,” says Rey. In the long run, the bioengineering works out more cost effective.“It costs 15 Euros per m³ of sediment to scoop dirt out of the dam and this has to happen every 15 years,” says Rey. “The willow walls however have a one off cost of four Euros per m³. Once they are in – they don’t need to be replaced.”

Bioengineering is a cheaper alternative. Picture courtesy: Freddy Rey

Looking back in time

The work presented at the EGU only started in 2002 and so in early days. The team needed to see how reliable these structures were and if they hold out in the long term and especially during intense rainfall. They looked for evidence in similar structures, using Austrian black pine plantations, that were used 136 years ago to stop soil erosion caused by agriculture.

“If you dig down into the sediment of these old walls – you can see the original gully shape and the result of 150 years of action,” says Rey. “We know there has been heavy rainfall during this time and so know the structure have stayed in place.”

Location, location, location

The walls in this research were placed in gullies in the Francon catchment, spanning an area of around 50,000ha. However, the structures must be strategically placed. If conditions are too dry, for example, the cuttings cannot get established into saplings and sediment trapping is ineffective.

‘‘It is really important to find the right places,” says Rey. “Even in France, if the aspect is to the south we can have problems.”

Other experiments are using cuttings from different species such as Popular (Populus nigra) and rooted plants such as Seabuckthorn (Hippophac spp.) to see if the amount of dirt trapping can be increased.

The scientists are experimenting with the best time of species for the walls. Picture courtesy: Freddy Rey

 by Becky Summers, City University, London

Today is the last full day to visit the Exhibition at the European Geosciences Union General Assembly 2013!

Exhibition booths for companies, publishers, research facilities, scientific societies, among others, are scattered throughout the blue (basement), yellow (ground floor), and green (first floor) levels of the Austria Center Vienna. Make sure you don’t miss the EGU Booth in the Blue Level.

New results presented this week at the EGU General Assembly have scientists adjusting the assumptions that have longed acted as bookends on the way we understand the evolution of planetary atmospheres. On one side, researchers have identified a previously unrecognised greenhouse effect that could have warmed the early Earth. On the other, the Curiosity rover has uncovered evidence that Mars has lost up to 95% of its original atmosphere, resolving a lost-standing discrepancy between previous estimates and confirming that conditions in the past could have been much more hospitable to life than they are today. Together, these new insights show how humble gases like hydrogen, nitrogen and argon hold the key to some of the great mysteries of the universe.

Source: Wikimedia Commons.

The early Earth continues to fascinate our imaginations, evoking images of seething volcanoes and fiery meteorites raining down on barren landscapes. It also continues to confound efforts by scientists to understand a seemingly straightforward question: how come the entire planet was not swaddled in ice? In 1972, the famous cosmologist, Carl Sagan and his colleague, George Mullen, posed what came to be known as the Faint Young Sun Paradox: if our sun is like other stars, it should have been about 30% weaker 4 billion years ago than it is today. Such a dimming of our solar furnace should have plunged our planet into global glaciation. But among the few pieces of geologic evidence to survive from the early Earth are unequivocal signs of liquid water. How can this be?

Researchers have proposed numerous mechanisms to warm the Earth, including insulating it with high levels of greenhouse gases or reducing the amount of solar radiation reflected back to space by small, young continents. Both hypotheses have merit, but they have also been plagued by complications. New work by Robin Wordsworth and Raymond Pierrehumbert at the University of Chicago presented at EGU on Tuesday raises yet another possibility: the very different composition of the early atmosphere may have allowed inert gases like H₂ and N₂ to act like powerful greenhouse gases.

The modern atmosphere lacks hydrogen because these light molecules easily defy Earth’s gravitational pull and escape into space. However, this loss takes time, and Wordsworth believes that the atmosphere could have been rich in hydrogen 3.8 billion years ago, the era of the Faint Young Sun. At this time, the atmosphere also contained two to three times more nitrogen than today — an inference deduced by the abundance of nitrogen now stored in the Earth’s mantle that does not appear to have originated there. Full of H₂ and N₂, the atmosphere could have experienced some unexpected phenomena.

The atmosphere allows most incoming solar radiation to reach the surface, but traps outgoing radiation in the bands of shaded grey. Most of the long wave radiation that cools the Earth escapes through the “water vapor window” centered around 10 um. Source: Wikimedia Commons.

H₂ and N₂ do not absorb radiation on their own, but at high concentrations they can act like greenhouse gases when they interact. “There are two basic processes,” explains Wordsworth, “first, H­-N₂ dimers can have additional vibrational and rotational modes, and allow for absorption in new regions of the spectrum. You can also have intense collisions between molecules that can allow previously forbidden transitions to occur.” The end result is that H₂-N₂ interactions can allow absorption at frequencies inside the so-called water vapor window, a region of the spectrum where outgoing radiation can escape to space and cool the Earth without being trapped by water vapor, the most abundant greenhouse gas of all. For this reason, says Wordsworth, “a little bit of absorption can have a big effect.”

In the conditions likely to have prevailed on the early Earth, their new study suggests the H₂-N₂ effect could account for 10-15°C of warming. And while this is not enough to explain the Faint Young Sun Paradox by itself, it can help if several mechanisms are allowed to work in tandem. As is often the case in nature, there may be no single “smoking gun”. In fact, Wordsworth thinks it may be time to shift how we think about the Faint Young Sun Paradox altogether. “The Faint Young Sun problem is important as a motivation for studying the early Earth”, he says, “but there is also the broader, more long-term aim of just understanding what the climate was like”.

The habitable zone is defined as the range of distances from a host star that planets could be warm enough to host life. Source: Wikimedia Commons.

With this expansive mindset, Wordsworth has also started extending the H₂-N₂ mechanism beyond our own planet to understand what conditions might be like on exoplanets and whether or not they could host life. “The habitable zone is defined as a runaway water vapor greenhouse on the inner edge and the maximum possible greenhouse you can have from CO₂ alone on the outer edge,” says Wordsworth of the traditional conception of planets where life might thrive. In light of this new greenhouse effect, the definition of the outer edge has grown blurry; planets that once seemed frigid could now be balmy. Now, he says, “You can have a greenhouse that is very efficient at warming very far away from the host star”.

But you don’t have to look all the way to exoplanets to find a place where the H₂-N₂ effect might have significant implications; Mars presents a great opportunity closer to home. While Wordsworth was unable to comment on the details of this situation, he confirmed that such a mechanism could indeed be important. “Thinking of additional greenhouse effects that we’ve ignored is very important for early Mars because the Faint Young Sun problem is much harder to explain there. There’s a lot of thinking going on at the moment about how we can get to situations where we increase surface temperatures so you get transient periods of liquid water or episodic melting.”

Surish Atreya of the University of Michigan, on the other hand, was eager to share new results about the modern Martian atmosphere at an EGU press conference showcasing updates from the Curiosity rover on Monday. Curiosity carries a suite of instruments onboard collectively known as SAM, for Sample Analysis at Mars. One of these instruments is a mass spectrometer that recently measured the ratio of heavy and light isotopes of argon in the Martian atmosphere (isotopes are molecules which differ in the numbers of neutrons and their atomic weight). Their new results, which achieve unprecedented precision for an argon measurement on Mars, help clear up a long-standing question: how much of its atmosphere has Mars lost over time?

New results from the Curiosity rover show argon ratios that indicate that Mars has lost most of its original atmosphere. Source: NASA/JPL-Caltech

“Argon isotopes are the clearest indication of atmospheric loss”, explained Dr. Atreya. This is because Argon does not participate in any reactions – it is an inert noble gas – so any deviation from the expected ratio must be due to preferentially losing the light isotope to space. Previous measurements from the early Viking rover and from Martian meteorites gave conflicting results, suggesting Mars could have lost all or none of its atmosphere. The new results from SAM show that Mars has probably lost 85-95% of its original atmosphere, a conclusion supported by similarly disproportionate abundances of the heavy isotopes of carbon and oxygen. While these results are not proof of life on Mars, they at least suggest that conditions could have been much friendlier early in the planet’s history when its atmosphere was thicker.

Together, these studies show how simple gases like hydrogen and nitrogen may have shaped the evolution of our planet, and how argon may contain the secrets of another. They reveal how much a planet can change over its history, and how we might need to rethink the way we understand planets far from home. All in all, it seems as though the universe has been, and might be, growing more hospitable by the day.

By Julia Rosen, Freelance science writer and PhD student in Earth, Ocean, and Atmospheric Sciences at Oregon State University

Biofuels are set to replace 10 per cent of EU transportation fuel by 2020. Yet, the long-term sustainability of first generation biofuels, made from grains and vegetable oils, has raised concerns as production starts to compete with food supplies.

Attention has now turned to second generation biofuels, produced from non-edible sources such as wood or waste plant residual like straw. In the next decade, these biofuels are expected to replace three to five per cent of transport fuel.

At the moment however second generation biofuel production is not commercially viable, says the most recent 2010 International Energy Agency report. Sylvain LeDuc, from the International Institute for Applied Systems Analysis has been looking at the consequences of scaling up biofuel production and the conflicting policy implications this may have in Europe.

What does your research involve?

My work looks at the production of second-generation biofuels from woody biomass, such as managed forests of willow or popular plants. This involved identifying the most cost effective locations for the biomass plants. For example moving the feedstock, the woody biomass, over long distances (from where it is grown to where it is processed) will increase costs. Since biomass is a limited resource, the best use of wood was also looked at as there are several industries competing for the feedstock. The pulp and paper industry, sawmills and Combined Heat and Power (CHP) plants are the three main candidates.

How did you do this?

So we asked what is the best use of the forest right now? We looked at the total amount of woody biomass available in Europe today. The demand for existing industries, paper and saw mills, was taken out. Using the feedstock left over, we calculated the best use of this resource in terms of cost, efficiency and carbon emissions.

And what was the best use?

CHP plants are preferred over biofuel production plants, unless financial support for biofuels is high.  We assumed that the biofuel plants were already up and running commercially and found for one tonne of wood, it will cost less and produce more energy if the wood is convert into heat and power instead of biofuels. This could have big policy implications for the future. In addition, carbon emissions were greater from the biofuel production so CHP plants in have a  greater mitigation potential.

How will this alter the EU plans for biofuels?

What policy the EU should put into place to meet the 2020 target will change depending on what the objectives are and if it is to meet the transportation fuel quota then high financial support will be needed. If it were to meet carbon emissions, then CHP would be a better option. So conflicting policies would need to be chosen between. For example, a large policy instrument and high financial support would be needed if the EU wants to push forward second generation biofuels into the market.

So then electric cars make more sense?

Yes, that is what our work shows us. It is more efficient to use the wood to produce heat and electricity and charge our cars than to convert it into biofuels to use as a fuel.

But aren’t the two activities aiming at different markets? CHP produces electricity whereas biofuels are liquid fuel we can put in our cars?

That is the big problem. With biofuels, people can carry on happily driving their normal cars. If we decide to use biomass for CHP instead, a big transportation system change would be needed. You’d need to buy a completely new electric car.

Do you think EU will reach its 10% target by 2020?

Yes this can be achieved overall but maybe not domestically produced. Biofuel can be imported from other countries outside the EU such as Brazil.

 by Becky Summers, City University, London

You’ve probably heard of supermodels like Heidi Klum and Kate Moss, but have you heard of SUMO? It’s an abbreviation for a project called Super Modeling by Combining Imperfect Models, and although it doesn’t sound nearly as glamorous, it may mean big things for climate modeling. This innovative approach, pioneered by an interdisciplinary group of scientists from around the world, seeks to build on the success achieved by using the mean of an ensemble of different climate models to predict future climate change. Instead of running the models independently and averaging them after the fact, SUMO has developed a framework to couple models interactively during a simulation. This might not seem like a big change, but it represents a tremendous technical challenge, one that might prove well worth the effort if the project achieves its ambitious aims. So far, the results look promising.

This figure from the Intergovernmental Panel on Climate Change 4th Assessment Report released in 2007 shows predicted changes in regional precipitation patterns associated with climate change using the mean of an ensemble of state of the art climate models. Source: IPCC.

To estimate the effects of anthropogenic climate change, researchers use complex mathematical models to simulate the behavior of the Earth’s climate system. These models are based on a handful of fundamental physics equations – like conservation of momentum, energy, and mass – and they overwhelmingly agree on the general direction of changes we can expect to see (for example, they unanimously project that global average temperature will rise). However, individual models produce markedly different estimates of the amplitude of future warming, the regional pattern of precipitation changes, and the sensitivity of global temperature to atmospheric CO₂ concentrations. These discrepancies arise from differences in model architecture and most importantly, from the ways each model accounts for processes that cannot be simulated organically in the model because they operate on scales too small to be captured, or because they require additional physics.

State of the art models disagree about the magnitude of future warming. The colored lines represent different emissions scenarios while the grey error bars on the right show the spread between models. Source: IPCC.

Researchers have long noted that the best way to synthesise these disparate results is to take the average of a group of climate models. This approach generally provides the best match to empirical observations, and the spread between models provides a useful measure of model uncertainty. While the success of averaging might seem lucky, or even coincidental, many scientists say it isn’t all that surprising. After all, people don’t pick values for important model coefficients out of thin air; they spend a great deal of time trying to choose optimal numbers by “training” the models on observational data and by using outside constraints for the most likely value of a parameter. “It’s like one of those games at the fair where you have to guess the number of balls in a jar,” says Dr. Win Wiegerinck, a machine learning specialist at Radboud University Nijmegen in Holland who presented early results of the SUMO project at the EGU General Assembly on Monday. “If you take the average of many people’s guesses, you often get the right answer.”

Based on this idea, Wiegerinck and his colleagues at the SUMO project are taking averaging to the next level. At every time step of a multi-model simulation, they require the models to agree on an intermediate result, essentially binding every model to the instantaneous mean. “If conventional model-mean studies use a coupling of zero,” says Wiegerinck to put things in sufficiently quantitative parlance for the EGU crowd, “SUMO represents setting the coupling between models to infinity.” He notes that it is possible to use any degree of coupling between these two extremes and in their initial experiments, the SUMO group has experimented with partially and fully coupled model ensembles. The benefit of this new approach is that it might prevent models from diverging dramatically due to cumulative errors that would grow during independent model runs. Their hope is that it will also provide the best way of simulating reality.

The Lorenz Attractor is a set of differential equations that illustrates the so-called “butterfly effect” in which the occurrence of a significant event (like a hurricane) might depend on whether or not something seemingly inconsequential happened before (like a buttefly flapping its wings). The solution of the Lorenz Attractor depends strongly on the initial values and, coincidentally, looks a bit like a butterfly itself. Source: Wikimedia Commons.

SUMO brings together experts in climate science, nonlinear dynamical systems, and machine learning, like Wiegerinck, to tackle the considerable challenge of coupling many complex models. As a preliminary test, they modeled a simple chaotic system like the famous Lorenz attractor. It seemed like a good prologue to climate modeling, because like the global climate system, the Lorenz equations depend strongly on small differences in initial conditions that can lead to drastically different solutions. After passing this test, SUMO embarked on an experiment with a simplified atmospheric circulation model.

In this first attempt, the coupled and ensemble-mean models performed better than any individual model at simulating northern hemisphere circulation, as expected. In addition, SUMO performed as well as the traditional model-mean approach in simulating the average climate state, a sign that the researchers are on the right track. The coupled models also did a bit better than the ensemble mean at simulating the correct degree of variability, an achievement just as important as getting the absolute value correct in a climate model. These results are encouraging, although the scientists stress that it is too early to know whether or not SUMO will be up to the long-term goal of predicting climate using complex models like the ones employed by the Intergovernmental Panel of Climate Change Assessment Reports to advise policymakers around the world on the expected impacts of climate change.

The researchers are nonetheless optimistic about short-range predictions. Dr. Frank Selten of the Royal Netherlands Meteorological Institute who oversees the climate science branch of SUMO thinks coupled models could be very useful for sub-annual forecasts. He says they have the potential “to reduce the contribution of model error to the prediction error [and] to estimate the reliability of the forecast.” In any case, SUMO represents a novel approach to climate modeling, and one to keep an eye on as it progresses towards integrating increasingly complex models. Based on the solid first results shown here at EGU, it looks like SUMO may indeed have something in common with those other supermodels: it might just be onto the next big trend.

Source: Wikimedia Commons

By Julia Rosen, Freelance science writer and PhD student in Earth, Ocean, and Atmospheric Sciences at Oregon State University