Why choose a PICO session at EGU 2015?

19 Nov

Some of the sessions scheduled for the upcoming EGU General Assembly are PICO only sessions. This means that, rather than being oral or poster format, they involve Presenting Interactive COntent (PICO). The aim of these presentations is to highlight the essence of a particular research area – just enough to get the audience excited about a topic without overloading them with information.

PICO presentations at EGU 2014. (Credit: EGU/Stephanie McClellan)

PICO presentations at EGU 2014. (Credit: EGU/Stephanie McClellan)

PICO sessions start with a series of 2 minute long presentations – one from each author. They can be a Power Point, a movie, an animation, or simply a PDF showing your research on a display. After the 2 minute talks, the audience can explore each presentation on touch screens, where authors are also available to answer questions and discuss their research in more detail.

This format combines the best of oral and poster presentations, allowing researchers to stand up be recognised for great research by making an oral contribution as well as discuss their work in detail and network with other participants. This year we are also making a few improvements to the layout of the PICO presentation areas in the large halls to minimise noise disruption to presenters.

See the General Assembly website for more information about PICO. You can also check out the short introductory video below:

Imaggeo on Mondays: Gothic Snow Architecture.

17 Nov

Whilst on a family holiday in Norway, Gerrit de Rooij took this incredible photograph of an ice arch. Understandably geoscience is not his top priority whilst taking photographs on holiday, however Gerrit points out that pretty much every picture of a landscape has hydrology in there somewhere”, as he goes on to describe below.

This picture was taken near Balestrand, a village along the Sognefjord in Norway (Norway’s largest fjord and the second largest in the world!). The altitude was approximately 900 m above sea level (asl), and not always does all snow vanish during summer over there (we were there in August 2013). What you can see in the picture are the remnants of a much thicker snow pack that covered the stream that trickles down. On the right hand side you can see a glimpse of the other side of the arch that  must have gradually been carved out by the stream during the snow melt season (as they call spring over there). Once a tunnel was carved out, thaw took over. The black lines of rock dust on the ridges of the snow arch presumably were left behind by water streaming down along them from the top of the melting snow cover. In the top rim the source of this material is still visible.

Gothic Snow Architecture. (Credit: Gerrit de Rooij via imaggeo.egu.eu)

Gothic Snow Architecture. (Credit: Gerrit de Rooij via imaggeo.egu.eu)

Exposed are ancient rocks, heavily eroded by several glaciations and subsequent Holocene freeze-thaw cycles and snow melt flows. The location of the picture is on the west side of Norway’s mountain range. These mountains force western winds from the Atlantic upward, which makes the air cool down and release a lot of its moisture. The very frequent rains (we had 3 rain free days out of 16) create lush vegetation at lower altitudes (the tree line is between 600 and 700 m asl) and sustain extensive moss carpets higher up, as visible in the image. In places where the rock face is too steep to support moss, lichen covers it, which is evidence of very clean air – lichen are highly sensitive to air pollution.

The stream (and many similar streams nearby) feed a small lake that supplies Balestrand with drinking water. The lake can be reached in a day from Balestrand, but hiking further requires an overnight stay, even for most Norwegians, rugged as they may be. There are no huts or any other facilities, so you need to carry your camping gear with you. We camped a little higher without seeing anybody, and from the condition of the trails it was clear that everything beyond the reach of a day trip was used very infrequently. This unperturbed state, the abundant precipitation, and the inertious rocks made the water of the lake crystal clear (several meters of visibility) and very poor in nutrients (hardly any underwater vegetation), making it an excellent source of local drinking water.

In the composition, I liked the two halves of the snow arch mirroring each other, and the fact that the lines and the slope of the large exposed rock face are similar to those in the larger snow arch. The bright green of the moss upslope adds liveliness and draws the eye. I have a relatively simple camera (you want something light when backpacking) and at the time had no software to manipulate my pictures so I had to choose my viewpoint carefully and work with the light that was there. I scooped and stood very close to the snow to create a sense of perspective and have the arch reach over the camera.

By Gerrit de Rooij, Helmholtz Centre for Environmental Research – UFZ, Halle (Saale), Germany

 

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Geosciences Column: Is it possible to quantify the effect of natural emissions on climate?

14 Nov

The air we breathe is full of tiny particles that can have a big impact on our climate. Industrial activities have greatly increased the number of these particles, cooling the climate and potentially offsetting some of the warming due to greenhouse gases. In this post Kirsty Pringle introduces new research that suggests that it might not be possible to quantify the effect of industrial emissions on climate unless we constrain estimates of the natural emissions (Carslaw et al 2013). Kirsty is a member of Ken Carslaw’s research group at the University Of Leeds (UK) which performed the research.

Deserts, oceans, fire and even pine forests emit tiny particles called aerosol into the atmosphere. Human (anthropogenic) activities also play a role; burning fuel, e.g. in cars or power-plants, emits particles and aerosol concentrations have increased substantially since the start of the industrial revolution. One effect of these particles is to change the properties of clouds, causing them to become brighter, producing a net cooling that can offset some of the warming due to greenhouse gases. Treating this effect in climate models is challenging and it remains one of the most poorly quantified areas of climate science.

Schematic of the first aerosol indirect forcing: Human (anthropogenic) emissions add aerosol particles to the atmosphere, these particles can act as condensation sites, which aids cloud droplet formation.  Anthropogenic emissions result in clouds with more, smaller, cloud droplets.  These clouds are brighter and reflect more solar radiation, resulting in a net cooling. The first aerosol indirect forcing (AIE) is the change in the reflected solar radiation between the present day and the pre-industrial scenarios due to this effect. (Credit: Kirsty Pringle)

Schematic of the first aerosol indirect forcing: Human (anthropogenic) emissions add aerosol particles to the atmosphere, these particles can act as condensation sites, which aids cloud droplet formation. Anthropogenic emissions result in clouds with more, smaller, cloud droplets. These clouds are brighter and reflect more solar radiation, resulting in a net cooling. The first aerosol indirect forcing (AIE) is the change in the reflected solar radiation between the present day and the pre-industrial scenarios due to this effect. Click image for a larger version. (Credit: Kirsty Pringle)

This cloud brightening effect is called the first aerosol indirect effect (AIE). It is thought to produce a global average cooling that is sufficient to offset between 25 to 90% of the warming due to long lived greenhouse gases (IPCC). The AIE is challenging to treat in climate models as atmospheric aerosol has a range of sources, the magnitudes of which are quite uncertain. They also undergo a series of processing steps in the atmosphere, which can change their properties; affecting both their lifetime and their ability to interact with clouds. These processing steps are difficult to represent in climate models and this complexity contributes to the large range of estimates.

As the aerosol indirect effect (AIE) is potentially large, but very uncertain, it is important to try to understand where this uncertainty arises. This has been a focus of Ken Carslaw’s research group for the past four years where a new collaboration between aerosol scientists and a statistician has resulted in some very long meetings, a new approach to uncertainty analysis, and the first study that has identified and quantified the factors that contribute to uncertainty in model estimates of the AIE.

I should clarify that Carslaw just considered parametric uncertainty, this is the uncertainty associated with inputs to the model, e.g. the magnitude of the emissions or uncertain values used within parameterisations. There are other types of model uncertainty, e.g. structural uncertainty, that were not considered in this study. Parametric uncertainty is, however, intrinsic to all climate models, so it is an important starting point.

The first step was to choose which parameters to focus on. The team did this by talking with other scientists to identify which input parameters everyone felt were most uncertain; together they estimated the maximum, minimum and median value for each parameter. They identified 28 uncertain parameters in total; these can be grouped into three categories:

  • Natural emissions (e.g. volcanic emissions, marine sea spray emissions), 6 parameters.
  • Anthropogenic (human-caused) emissions (e.g. fossil fuels emissions, biofuel emissions), 8 parameters.
  • Process parameters used within the aerosol microphysics (e.g. the rate of aerosol aging, or the wet deposition parameter), 14 parameters.

The contribution of each parameter to the uncertainty in the AIE calculation can be found using a statistical technique called Monte Carlo analysis, but to perform Monte Carlo sampling on 28 uncertain parameters one would need to run tens of hundreds of model simulations, which isn’t possible with a complex model. To avoid this, Carslaw ran a few hundred simulations and used a statistical emulator to carry out the Monte Carlo sampling much faster. The emulator is a statistical package that “learns” from the output of the computer model, it can be used to interpolate from the hundreds of runs performed to the thousands of runs needed for the statistical analysis.

Schematic showing the methodology used by Carslaw to perform a sensitivity analysis on the first aerosol indirect effect (AIE). (Figure courtesy of Lindsay Lee).

Schematic showing the methodology used by Carslaw to perform a sensitivity analysis on the first aerosol indirect effect (AIE). (Figure courtesy of Lindsay Lee).

Carslaw found that by varying the values of the uncertain parameters, the model produced a range of estimates of the strength of the AIE forcing that was similar to, but slightly smaller than, the range of values estimated by the multi-model estimate from the IPCC. Surprisingly 45% of the uncertainty was found to be due to uncertainty in natural emissions, 34% was due to uncertainty in anthropogenic emissions and the rest due to uncertainty in process parameters.

Caption: Magnitude and sources of uncertainty in the model estimate of the first aerosol indirect forcing. (Credit: Carslaw et al, 2013)

Caption: Magnitude and sources of uncertainty in the model estimate of the first aerosol indirect forcing. (Credit: Carslaw et al, 2013)

Although the forcing is caused by anthropogenic emissions, the amount of natural emissions has a large effect on how sensitive the climate is to these anthropogenic emissions: the natural emissions don’t produce the forcing but they contribute a lot to the uncertainty in the forcing.

This effect arises because the relationship between aerosol emissions and cloud brightness is not linear; instead it is curved with higher sensitivity of cloud brightness to emissions when emissions are low (as they were in the pre-industrial atmosphere). This means that in the clean pre-industrial atmosphere a change in the amount of natural aerosol emissions has a large effect on the cloud brightness: when natural emissions are small, the initial cloud brightness (albedo) is low and any anthropogenic emissions have a big impact on cloud brightness, so the calculated forcing is larger.

Schematic explaining why the calculation of the first aerosol indirect forcing is sensitive to the magnitude of the natural aerosol emissions.  (Credit: Kirsty Pringle).

Schematic explaining why the calculation of the first aerosol indirect forcing is sensitive to the magnitude of the natural aerosol emissions. (Credit: Kirsty Pringle).

This sensitivity to the natural aerosol emissions is important as it is very difficult to constrain estimates of natural aerosol emissions as measurements taken in today’s atmosphere are almost always affected by anthropogenic emissions. This means that some of the uncertainty in the estimates of the first aerosol indirect effect may be irreducible, but it will still need to be considered in future estimates of warming due to greenhouse gases.

By Kirsty Pringle, Research Fellow, School of Earth and Environment, University of Leeds

 References

Carslaw, K.S., et al.: Large contribution of natural aerosolos to uncertainty in indirect forcing, Nature, 503, 67-71, 2013

Lee, L. A., et al.: The magnitude and causes of uncertainty in global model simulations of cloud condensation nuclei, Atmos. Chem. Phys., 13, 8879-8914, 2013

Lee, L. A., et al.: Emulation of a complex global aerosol model to quantify sensitivity to uncertain parameters, Atmos. Chem. Phys., 11, 12253-12273, 2011

 

GeoLog regularly brings readers information about recent research in the geosciences as well as updates on the EGU’s activities. Part of what makes GeoLog a great read is the variety that guest posts add to our regular features, and we welcome contributions from scientists, students and professionals in the Earth, planetary and space sciences. If you want to report on a recent Earth science event, conferences or fieldwork, comment on the latest geoscientific developments or highlight recently published findings in peer-reviewed journals, like Kirsty has done here, then we welcome your contribution. If you’ve got a great idea, why not submit a post?

 

Showcase your film at GeoCinema at the General Assembly!

12 Nov

Every year, we showcase a great selection of geoscience films at the EGU General Assembly and after five successful years we will again be running GeoCinema in 2015. If you’ve shadowed a scientist in the lab, filmed fantastic spectacles in the field, or have produced an educational feature on the Earth, planetary or space sciences, we want to hear from you.

GeoCinema features short clips and longer films related to the geosciences, and from animations to interviews, all films are welcome. If you would like to contribute to this popular event, please fill out the submission form by 31 December 2014.

To get a feel for what we have screened in previous years, take a look at the online archive, with films that explore all facets of geoscience – from ocean depths to outer space.

Suitable films will be screened at the GeoCinema room during the EGU 2015 General Assembly in Vienna (12–17 April 2014). Note that you must be able to provide us with the film on DVD and you must have appropriate permission to show the feature in a public venue. Films must be in English or have subtitles in English, since it is the language of the conference. Multiple submissions from the same person are welcome.

For more information, please send us an email or get in touch with our Communications Officer Laura Roberts.

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