GeoLog

California

Imaggeo on Mondays: Sunset and moonrise at Yosemite

Imaggeo on Mondays: Sunset and moonrise at Yosemite

This side view of Half Dome at Yosemite National Park (California, USA) was taken from Washburn Point, a less frequented overlook a few hundred meters away from the popular Glacier Point outlook. The sun just on the right side behind the camera, which gave the orange tint to the back side of Half Dome. At the same time a full moon was mere minutes from bursting in the background, which resulted in the warm glow of the horizon. A few stars have already started appearing on the clear sky and a few star trails are visible.

Description by Teamrat Ghezzehei, as it first appeared on imaggeo.egu.eu.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Geosciences Column: Using volcanoes to study carbon emissions’ long-term environmental effect

Geosciences Column: Using volcanoes to study carbon emissions’ long-term environmental effect

In a world where carbon dioxide levels are rapidly rising, how do you study the long-term effect of carbon emissions?

To answer this question, some scientists have turned to Mammoth Mountain, a volcano in California that’s been releasing carbon dioxide for years. Recently, a team of researchers found that this volcanic ecosystem could give clues to how plants respond to elevated levels of carbon dioxide over long periods of time. The scientists suggest that studying carbon-emitting volcanoes could give us a deeper understanding on how climate change will influence terrestrial ecosystems through the decades. The results of their study were published last month in EGU’s open access journal Biogeosciences.

Carbon emissions reached a record high in 2018, as fossil-fuel use contributed roughly 37.1 billion tonnes of carbon dioxide to the atmosphere. Emissions are expected to increase globally if left unabated, and ecologists have been trying to better understand how this trend will impact plant ecology. One popular technique, which involves exposing environments to increased levels of carbon dioxide, has been used since the 1990s to study climate change’s impact.

The method, also known as the Free-Air Carbon dioxide Enrichment (FACE) experiment, has offered valuable insight into this matter, but can only give a short-term perspective. As a result, it’s been more challenging for scientists to study the long-term impact that emissions have on plant communities and ecosystems, according to the new study.

FACE facilities, such as the Nevada Desert FACE Facility, creates 21st century atmospheric conditions in an otherwise natural environment. Credit: National Nuclear Security Administration / Nevada Site Office via Wikimedia Commons

Carbon-emitting volcanoes, on the other hand, are often well-studied systems and have been known to emit carbon dioxide for decades to even centuries. For example, experts have been collecting data on gas emissions from Mammoth Mountain, a lava dome complex in eastern California, for almost twenty years. The volcano releases carbon dioxide at high concentrations through faults and fissures on the mountainside, subsequently leaving its forest environment exposed to the emissions. In short, the volcanic ecosystem essentially acts like a natural FACE experiment site.

“This is where long-term localized emissions from volcanic [carbon dioxide] can play a game-changing role in how to assess the long-term [carbon dioxide] effect on ecosystems,” wrote the authors in their published study. Research with longer study periods would also allow scientists to assess climate change’s effect on long-term ecosystem dynamics, including plant acclimation and species dominance shifts.

Through this exploratory study, the researchers involved sought to better understand whether the long-term ecological response to carbon-emitting volcanoes is actually representative to the ecological impact of increased atmospheric carbon dioxide.

Remotely sensed imagery acquired over Mammoth Mountain, showing (a) maps of soil CO2 flux simulated based on accumulation chamber measurements, shown overlaid on aerial RGB image, (b) above-ground biomass (c) evapotranspiration, and (d) normalized difference vegetation index (NDVI). Credit: K. Cawse-Nicholson et al.

To do so, the scientists analysed characteristics of the forest ecosystem situated on the Mammoth Mountain volcano. With the help of airborne remote-sensing tools, the team measured several ecological variables, including the forest’s canopy greenness, height and nitrogen concentrations, evapotranspiration, and biomass. Additionally they examined the carbon dioxide fluxes within actively degassing areas on Mammoth Mountain.

They used all this data to model the structure, composition, and function of the volcano’s forest, as well as model how the ecosystem changes when exposed to increased carbon emissions. Their results revealed that the carbon dioxide fluxes from Mammoth Mountain’s soil were correlated to many of the ecological variables analysed. Additionally, the researchers discovered that parts of the observed environmental impact of the volcano’s emissions were consistent with outcomes from past FACE experiments.  

Given the results, the study suggests that these kind of volcanic systems could work as natural test environments for long-term climate research. “This methodology can be applied to any site that is exposed to elevated [carbon dioxide],” the researchers wrote. Given that some plant communities have been exposed to volcanic emissions for hundreds of years, this method could help paint a more comprehensive picture of our future environment as Earth’s climate changes.

By Olivia Trani, EGU Communications Officer

References

Cawse-Nicholson, K., Fisher, J. B., Famiglietti, C. A., Braverman, A., Schwandner, F. M., Lewicki, J. L., Townsend, P. A., Schimel, D. S., Pavlick, R., Bormann, K. J., Ferraz, A., Kang, E. L., Ma, P., Bogue, R. R., Youmans, T., and Pieri, D. C.: Ecosystem responses to elevated CO2 using airborne remote sensing at Mammoth Mountain, California, Biogeosciences, 15, 7403-7418, https://doi.org/10.5194/bg-15-7403-2018, 2018.

Imaggeo on Mondays: Bristlecone pines, some of Earth’s oldest living life forms

Imaggeo on Mondays: Bristlecone pines, some of Earth’s oldest living life forms

About 5,000 years ago, the ancient city Troy was founded, Stonehenge was under construction, and in the rugged Sierra Nevada mountain range, groves of bristlecone pine seedlings began to take root. Many of these pines are still alive today, making them the world’s oldest known living non-clonal life forms. Raphael Knevels, a PhD student from the Friedrich-Schiller-University’s Department of Geography in Jena, Germany explains why these particular species live so long.

On a field trip in the western United States, my colleagues and I traveled to various interesting spots in the beautiful and scenic diverse California. One of the most unforgettable places we visited during our trip was the Inyo National Forest in the eastern Sierra Nevada mountain range. Here, we could experience the oldest known individual living life forms on Earth: the bristlecone pines.

Scientific interest in the bristlecone pine started around 1953 with Edmund Schulman, a dendrochronologist from the University of Arizona who studied tree-rings to better understand the impact of past climate change. Schulman and his scientific team discovered many ancient trees, some older than 4,000 years. But why do bristlecone pines persist so long?

Bristlecone pines are located in the upper-mountain ranges of the Great Basin of the western United States in altitudes of 2,700 to 3,700 m. The environment is relatively arid with an annual rainfall of around 315 mm. They grow typically on limestone outcroppings that provide sparse ground cover and scarce litter, making the trees relatively safe from wildfires. Especially at high-elevation sites, the population is isolated, stands are open and productivity is low. Scientists believe that past fires in the region have been infrequent, usually small, and of low-severity, with an expected likelihood of an outbreak occurring once in 300 years. Moreover, their retention of needles for 20 to 30 years provide a kind of stable photosynthetic capacity that can carry a tree over several years of stress. Some species have even shown drought-sensitivity records in their growth-ring sequences of almost 1700 years.

With the ongoing global warming, the effects that our changing climate will have on the bristlecone pine are assumed to be severe; increasing temperatures can lead to a higher pine mortality rate and can introduce invasive weeds and lower elevation conifers. This can in turn change the composition of organic material on the soil surface, and as a result, make the region more prone to wildfire.

Generally, the ecosystem of the bristlecone pine is still not fully understood, and the tree’s longevity remains a mystery. More research must be done to better understand the pine’s relationship with its environment and create appropriate adaption strategies to manage this species within a human-introduced changing climate. On that the trees continues to be the longest-lived life forms on Earth.

By Raphael Knevels, Friedrich-Schiller-University Jena (Germany)

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Wildfires in the wake of climate change

Wildfires in the wake of climate change

Last year saw some of the biggest blazes in history, and may be a sign of things to come.

2017 was a record year for wildfires. California and neighboring western states saw the most destructive fire in US history, with an estimated 18 billion dollars worth of damage over the season. In central Portugal, fires caused 115 deaths over the same period. Researchers presenting at a press conference at the European Geosciences Union General Assembly in Vienna, Austria, suggest this may be a sign of things to come.

With climate change, wildfires are expected to be on the rise, as fire-prone regions become hotter and drier. But how did weather and climate contribute to this disastrous season? Strong winds and warm temperatures are thought to be responsible for last year’s fires in California, but it remains unclear how much climate change contributed to these conditions. Etienne Tourigny, of the Barcelona Supercomputing Centre, has been on the case.

“Would this event have been possible with or without climate change?” Tourigny asks. “It’s hard to say. What we can say is that there is a high chance that these kinds of events will be more present and more frequent in the future, especially if we see temperatures increasing as they have”

Central Portugal is already very susceptible to wildfires. It’s hot, it’s dry and it’s forested: a recipe for the perfect storm. The 2017 season was particularly tragic due to an unusual set of circumstances: a tropical cyclone passed as the Portuguese Centro Region was ablaze. The nation hoped that the hurricane would bring rain to put out the fires, but, instead, the storm passed the area by, bringing strong winds and spreading the flames.

200 thousand hectares were burned in two days. Even if this was spread throughout an entire season, it would be a very bad year. Speaking at the conference, António Ferreira, a scientific coordinator at the Research Centre for Natural Resources, Environment and Society in Coimbra, Portugal, puts it frankly: “that’s hell as it was taught in Sunday School.”

The region is also vulnerable to climate change, and an increased risk of wildfires is expected by the end of the century. New strategies are needed to prevent such losses in future. Ferreira emphasised that there is no quick fix and, to reduce the risk, policies, plans, habits and investment have to change.

Even in the high Arctic, fires present a threat. This time, it’s not a direct risk to life or infrastructure, but a threat to the environment. Nikolaos Evangeliou, from Norwegian Institute for Air Research, stated that, even in icy regions, wildfires have the capacity to alter the Earth’s climate and accelerate melting.

Thawing permafrost during the 2017 summer left Greenland’s peatlands vulnerable to wildfires and between 31 July and 21 August about 2300 hectares of peatland were burned. Seven tonnes of black carbon generated by the fires rained down on the ice sheet, making the surface darker and causing it to absorb more heat.

If the ice sheet darkens, it reduces Earth’s ability to deflect solar radiation, allowing more of the sun’s energy to warm the planet. The change in Earth’s reflectivity following last year’s wildfires was small, but it is a warning. With larger fires predicted as the climate warms, we could expect much bigger changes to the Earth’s reflectivity towards the end of the century. Such warming spells further trouble for wildfire-sensitive regions.

By Sara Mynott, EGU 2018 General Assembly Press Assistant

References

Evangeliou et al. Open Fires in Greenland: An Unusual Event and its Impact on the Albedo of the Greenland Ice Sheet. Geophysical Research Abstracts, Vol. 20, EGU2018-12383, 2018, EGU General Assembly 2018.

Leitão et al. Dealing with climate change: how to cope with wildfire threat in a climate transition region. Geophysical Research Abstracts, Vol. 20, EGU2018-16640, 2018, EGU General Assembly 2018.

Tourigny et al. An observational study of the extreme wildfire events of California in 2017: quantifying the relative importance of climate and weather. Geophysical Research Abstracts, Vol. 20, EGU2018-9545-1, 2018, EGU General Assembly 2018.