climate change

Geosciences Column: climate modelling the world of Game of Thrones

Geosciences Column: climate modelling the world of Game of Thrones

Disclaimer: This article contains minor spoilers for Season 8 of “Game of Thrones.” A basic understanding of the world of Game of Thrones is assumed in this post.

The Game of Thrones world of ice and fire is an unpredictable place both politically and environmentally. While the fate of the Iron Throne is yet to be confirmed, a humble steward has been working diligently to make some sense of the planet’s peculiar climate. The results could help scholars assess when future winters will be coming or how wind patterns may influence where eastern attacks on Westeros from invading dragons and ships would occur.  

It is known that the realms of Westeros and Essos are subject to long-living seasons, with many extending over several years, but Samwell Tarly, the former heir of House Tarly and current steward of the Night’s Watch, has developed a new theory to explain this long seasonal cycle.

His research suggests that the seasons’ extended lifespans could be due to periodic changes in the planet’s tilt as it orbits around the Sun. The results were published in the Philosophical Transactions of the Royal Society of King’s Landing in the Common Tongue, with translations available in Dothraki and High Valyrian.

Tarly carried out his analysis while on sabbatical at the Citadel in Oldtown, Westeros. In the published article he notes that his study was “inspired by the terrible weather on the way here to Oldtown”.

Uncovering climate observations and models

Tarly’s first developed his theory after studying observational climate records stored in the Citadel library’s collections. Many of these manuscripts contain useful information on a number of climate conditions present within the Game of Thrones world, including the multiyear length of seasons.

Seasons occur when regions of a planet receive different levels of sunlight exposure throughout a year. The southern and northern hemispheres experience opposite degrees of sunlight exposure due to the natural tilt of the planet’s axis as it orbits around the Sun. For example, when the southern hemisphere is tilted closer to the Sun it experiences a warmer season; at the same time the northern hemisphere is tilted away from the Sun, so it experiences a colder season.

When a planet is consistently tilted on one side as it orbits around the Sun, the world experiences four seasons during one year. Tarly proposed that seasons could last over several years if the tilt of a planet changes during its orbit: “so that the Earth ‘tumbles’ on its spin axis, a bit like a spinning top”, he explains. If a planet were to only change the side of its tilt once a year, it would experience permanent seasons.

Caption: an example of Earth’s orbit in which (a) the angle of tilt of the spinning axis of the Earth stays constant through the year (Credit: Dan Lunt, University of Bristol)

Caption: an example of Earth’s orbit in which (b) the tilt “tumbles” as the planet rotates round the Sun, such that the angle of tilt changes, so that the same Hemisphere always faces the Sun, giving a permanent season (Credit: Dan Lunt, University of Bristol)

Tarly put this theory to the test with the help of a climate model that he discovered on a computing machine stored in the Citadel cellars. “Luckily I learned how to code when I was back in Horn Hill avoiding sword practice,” Tarly explains in the text.

By running climate simulations with the proposed parameters of his theory, Tarly found that his model was consistent with much of the observational data present within the Citadel library. The models also estimated many climatic features of the world of Game of Thrones, including the seasonal change in temperature, precipitation and wind direction across Westeros.

In the published article, Tarly notes that his theory doesn’t explain how the planet transitions between summer and winter. He guesses that the tumbling pattern of the planet’s tilt persists for a few years, but then flips at one point so that the hemispheres experience new seasons. “The reasons for this flip are unclear, but may be a passing comet, or just the magic of the Seven (or magic of the red Lord of Light if your name is Melisandre),” Tarly writes.

Caption: The Northern Hemisphere winter (top row (a,b,c)) and summer (bottom row (d,e,f)) modelled climate, in terms of surface temperature (◦C; left column (a,d)) precipitation (mm/day; middle column; (b,e)) and surface pressure and winds (mbar; right column (c,f)). (Credit: Dan Lunt, University of Bristol)

The world of Game of Thrones compared to ‘real’ Earth

Tarly then compared the climate of the world of the Game of Thrones to that of a fictional planet called the ‘real’ Earth; Gilly, his partner and research associate, had found records of this planet’s climate in the Citadel library. The analysis revealed that in winter, The Wall, the northern border of the Seven Kingdoms, was similar in climate to many areas of the ‘real’ Earth, including parts of Alaska in the US, Canada, western Greenland, Russia, and the Lapland region in Sweden and Finland. “I always suspected that Maester St. Nicholas was a member of the Night’s Watch,” Tarly noted.

Caption: High-resolution (0.5◦ longitude ×0.5◦ latitude) mountain height for the whole planet. (b) Model-resolution (3.75◦ longitude ×2.5◦ latitude) mountain height for the region of Westeros and western Essos. (Credit: Dan Lunt, University of Bristol)

On the other hand, the models showed that the climate of Casterly Rock, the southern home of House Lannister, was similar to that of the Sahel region in Africa, eastern China, and a small region nearby Houston, Texas in the US.

Climate sensitivity in a world of ice and fire

Finally, Tarly used the climate models to investigate how climate change might impact the world of Game of Thrones. The simulations were done in response to some “worrying reports from monitoring stations on the island of Lys”; the stations have recently observed increasing concentrations of methane and carbon dioxide in the world’s atmosphere. It is suggested that this spike in greenhouse gas emissions could be due to the rising dragon population in Essos, deforestation from global shipbuilding, and excessive wildfire.

Tarly found that, by doubling the level of atmospheric carbon dioxide in his models, the world would warm on average by 2.1°C over 100 years. The results showed that the greatest warming would occur in the polar regions, since warming-induced sea ice and snow melt can trigger additional warming as a positive feedback.

By comparing this level of warming to the Pliocene period of the ‘real’ Earth 3 million years ago, Tarly predicted that the sea level of the world of Game of Thrones could rise by 10 metres in the long term. This degree of sea level rise is sufficient to flood several coastal cities, including King’s Landing.

In the paper, Tarly stresses that climate action from all the Kingdoms is needed to prevent even more social instability and unrest from climate change. He suggests that all governing bodies should work on reducing their greenhouse gas emissions and invest in renewable energy, such as windmills.

If he survives the war for Westeros, Tarly expects that improving his climate analysis will keep him busy for years to come.

By Olivia Trani, EGU Communications Officer

This unfunded work was carried out by Dan Lunt, from the University of Bristol School of Geographical Sciences and Cabot Institute, Carrie Lear from Cardiff University and Gavin Foster from the University of Southampton during their spare time, using supercomputers from the Advanced Centre for Research Computing at the University of Bristol. You can learn more about the climate models online here.

Imaggeo on Mondays: The changing landscape of Patagonia

Imaggeo on Mondays: The changing landscape of Patagonia

Pictured here is a snapshot of an environment in transition. Today’s featured photo was taken at the foot of Monte Fitz Roy, a jagged Patagonia mountain located in Los Glaciares National Park on the border between Argentina and Chile.

The Patagonia region in South America is the second biggest source of glaciers in the southern hemisphere, behind Antarctica, but the region is losing ice at a rapid rate.

Satellite imagery analysis over the last few years has suggested that the Patagonia region is losing ice more than any other part of South America, with some glaciers shedding ice faster than any place in the world.

A recent study reported that the northern and southern Patagonia ice fields in particular are losing roughly 17 billion tons of ice each year. Los Glaciares National Park alone is home to around 50 large glaciers, but because of warming temperatures, almost all of these large ice masses have been shrinking over the last 50 years.

This level of glacial ice loss can be hard to fully imagine, but in 2017, Shauna-Kay Rainford, a PhD student at Pennsylvania State University in the United States and photographer of this featured image, got a first-hand glimpse of Patagonia’s changing landscape.

“Ensconced between the granite boulders I felt like I was at a pivotal moment of continued change,” said Rainford. “While the peaks of Mt. Ritz Roy remain and will likely remain tall and majestic, with each passing year the glacier continues to retreat further towards the peak and the glacial lake continues to expand more and more.”

Rainford had reached this scenic yet tragically ephemeral view after a strenuous hike up the mountain. “It was very emotional to think about what this view will look like in the future if I should ever visit the mountain again,” Rainford recalls. “It is always striking to be confronted with the adverse consequences of human actions.”

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

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


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,, 2018.

GeoPolicy: COP24 – key outcomes and what it’s like to attend

GeoPolicy: COP24 – key outcomes and what it’s like to attend

Earlier this month, the 24th Conference of the Parties (COP24), was held in Katowice, Poland.  COPs are held annually and provide world leaders, policy workers, scientists and industry leaders with the opportunity to negotiate and determine how best to tackle climate change and reduce emissions on a global level. With so much at stake, these negotiations can be tense.

Some COPs see more action than others. COP24 had relatively high stakes with delegates having to establish a rulebook that will allow the 2015 Paris Climate Agreement to be put into practice in 2020 [1]. The Paris Climate Agreement was established during COP21. It acknowledges climate change as an international threat and that preventing the Earth’s temperature from rising 2°C above pre-industrial levels should be a global priority. Creating a rulebook that will instruct countries on what they must do to achieve this is no easy feat.

This blog will give you some details about what was achieved at COP24, and perhaps more importantly, what wasn’t. But firstly, it will outline what it’s actually like to attend a COP with some personal insights from Sarah Connors, Intergovernmental Panel on Climate Change (IPCC) Science Officer and former EGU Policy Fellow.

Initial impressions from COP24

What struck me (as a first timer) was all the different levels of meetings, you have the top-level negotiations, which lots of observers can join and even ask questions at some bits (rather than just the official delegates). Sometimes it would be students speaking – which was cool to see. Then there’s smaller negotiation levels going on that are closed”

Activities for COP participants outside of the negotiations and high-level sessions

The whole meeting is mostly in two halves. There’s the official negations bit and then there are official side events and pavilions that several countries or organisations have paid for where they will have their own smaller events. The IPCC pavilion was something I worked on.”

Then there’s load of other events going on around the city, hosted by NGOs and charities. There’s also the occasional protest. It all felt a bit disjointed at times actually – not sure that’s a good thing.

It’s a bit like EGU in the fact your need to study all the different schedules to see which events you’d like to see/attend.”

Interacting with the policymaking delegates

“In terms of the science-policy interface, the SBSTA events or official side events were opportunities for the IPCC lead scientists to present the findings from the IPCC special report. Delegates got to ask questions there to help understanding.”

A few delegates also came to the IPCC pavilion to ask more about the what the science was saying about the differences between a 1.5°C and 2°C increase in temperature.”

So… What did the COP24 achieve?

The rulebook, which was the key task of COP24 and which will be used as an operating manual after 2020 was, for the most part, agreed upon. This is a positive step because, as UN Secretary General António Guterres, states “A completed work programme will unleash the potential of the Paris Agreement. It will build trust and make clear that countries are serious about addressing climate change” [1].

From 2024, all countries will have to report their emissions (and progress in reducing them) every two years. However, instead of requiring countries to adhere to a single, scientifically sound method of reporting their emissions, the text permits countries to use “nationally appropriate methodologies”. This could result in countries under-reporting their emissions with the land use sector being particularly susceptible to creative accounting [1].

A number of countries pledged to increased their climate pledges in 2020, including: the EU, UK, Argentina, Mexico, India, Canada, Ukraine and Jamaica. Some large private sector companies also made ambitious pledges including Maersk, the world’s largest shipping company, which pledged to eliminate its carbon impact by 2050.

What wasn’t achieved?

  1. The IPCC’s Special Report on Global Warming of 1.5ºC wasn’t fully embraced: Although the vast majority of national representatives wanted to “welcome” the report which was commissioned as part of the Paris Agreement, the US, Russia, Saudi Arabia and Kuwait only wanted to “note” the report. This resulted in a watered-down statement which welcomed the “timely completion” of the report and “invited” countries to make use of it. Although this may seem like semantics, it demonstrated the differing levels of engagement in climate action that countries are willing to have and pressed the issue of whether new legislation is effectively using the scientific evidence commissioned by policymakers.
  2. Lack of clarity on climate finance: During the Paris Climate Agreement, donor nations committed to mobilising $100 billion annually from 2020 to fund climate action in developing countries. Not only is it uncertain whether donor countries will be able to reach this contribution target by 2020, but there is a lack of clarity as to what constitutes “climate finance”. Can countries report aspects of their development add as “climate action aid” or should this be separated? What are the impacts of this?
  3. No agreement on Article 6, voluntary carbon markets: The final decision on Article 6 which sets the rules for voluntary carbon markets (such as carbon credits) will be made during COP25 next year. Carbon credits are given to countries based on their emissions-cutting efforts and carbon sinks, subsequently helping countries to meet their emissions targets. During the COP, Brazil pushed for a change in the wording of the final document which would have allowed each party in the carbon credit trade to make a “corresponding adjustment” to their emissions inventories. There was concern that this clause may allow countries to “double count” the emissions traded and as a result a final decision was not agreed upon this year.

What comes next?

COP25 will now be held in Chile rather than Brazil after Brazil’s president-elect Jair Bolsonaro reneged on hosting the event. During this meeting the final elements of the Paris rulebook will be finalised and work will begin on emissions targets for 2030 and beyond.

Additional reading