Air travel and COVID-19: How effective are travel bans?

By Tamás Krisztin, researcher in the IIASA Ecosystems Services and Management Program

Tamás Krisztin discusses the air travel restrictions instituted by governments across the globe and how effective they really are in terms of curbing the spread of COVID-19.

© Potowizard |

Many Western countries are reaching, or have reached, the peak of COVID-19 infections, and policymakers are increasingly turning their attention to the next critical question: how to lift lockdown restrictions responsibly, while at the same time making sure that trade and travel can be restored to as close to “normal” as possible? Our research indicates that stoppage of airline traffic and border closures, which were some of the first modes of transport to be restricted, should also be some of the last to be restored because of their critical role in spreading infections.

Governments began to restrict airline traffic at the end of January this year, and by 21 March, over half of the EU had implemented flight suspensions. Our research confirms that this was a timely and necessary step. In the early stages of the pandemic, international flight linkages were actually the main transmission channel for the virus. In fact, flight connections proved to be an even more accurate predictor of infection spread between two countries than the presence of common land borders or trade connections. As country after country enacted travel bans, our research also shows a corresponding decrease in cross-country spillovers of the virus.

In Austria, for instance, our model demonstrates that if the shutdown of cross border traffic (flight connections and car border crossings) had been delayed by only 16 days, (25 March instead of 10 March), about 7,200 additional people would have been infected (see Figure 1).

Figure 1: Additional infections in Austria without border closures (Note: Shaded areas correspond to the 68th and 90th quantiles, respectively).

Additionally, our modeling shows the increased importance of flight connections over the initial period of the crisis, as seen in Figure 2. The top panel visualizes the relative importance of connectivity measures and demonstrates that, particularly in the beginning phases of the pandemic, flight connections were of the highest importance. The bottom panel shows infection spread between countries. Around the middle of March, when most border closure policies were implemented, the line drops to zero, indicating that these measures significantly reduced cross-border infections.

Figure 2: Importance of connectivity (top panel) and spatial spillovers (bottom panel)

Given the importance of air travel as a means for transmission of COVID-19, it stands to reason that governments and policymakers will have to continue to restrict air travel to prevent a second wave of the virus. As some parts of the world begin slowly to lift restrictions and ease lockdowns, while others are only now beginning to near the peak of the pandemic, it is likely that air travel will continue to be severely limited to prevent cross-border spread.

Note: This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.

More fish, less energy, less pollution – but only if all players cooperate

By Adriana Gómez-Sanabria, researcher in the IIASA Air Quality and Greenhouse Gases Program

Adriana Gómez-Sanabria discusses the results of a new study that looked into the impacts of implementing various technologies to treat wastewater from the fish processing industry in Indonesia.

© Mikhail Dudarev |

To reduce water pollution and climate risks, the world needs to go beyond signing agreements and start acting. Translating agreements and policies into action is however always much more difficult than it might seem, because it requires all players involved to participate. A complete integration strategy across all sectors is needed. One of the advantages of integrating all sectors is that it would be possible to meet different objectives, for example, climate and water protection goals in this case, with the same strategy.

I was involved in a study that assessed the impacts of implementing various technologies to treat wastewater from the fish processing industry in Indonesia when involving different levels of governance. This study is part of the strategies that the government of Indonesia is evaluating to meet the greenhouse gas mitigation goals pledged in its Nationally Determined Contribution (NDC), as well as to reduce water pollution. Although Indonesia has severe national wastewater regulations, especially in the fish processing industry, these are not being strictly implemented due to lack of expertise, wastewater infrastructure, budgetary availability, and lack of stakeholder engagement. The objective of the study was to evaluate which technology would be the most appropriate and what levels of governance would need to be involved to simultaneously meet national climate and water quality targets in the country.

Seven different wastewater treatment technologies and governance levels were included in the analysis. The combinations included were: 1) Untreated/anaerobic lagoons – where untreated means wastewater is discharged without any treatment and anaerobic lagoons are ponds filled with wastewater that undergo anaerobic processes – combined with the current level of governance. 2) Aeration lagoons – which are wastewater treatment systems consisting of a pond with artificial aeration to promote the oxidation of wastewaters, plus activated sludge focused solely on water quality targets with no coordination between water and climate institutions. 3) Swimbed, which is an aerobic aeration tank focusing mainly on climate targets assuming no coordination between institutions. 4) Upflow anaerobic sludge blanket (UASB) technology, which is an anaerobic reactor with gas recovery and use followed by Swimbed, and 5) UASB with gas recovery and use followed by activated sludge, which is an aerobic treatment that uses microorganisms forming particles that clump together. Both, 4 and 5 assume vertical and horizontal coordination between water and climate institutions at national, regional, and local level. It is important to notice that the main difference between 4 and 5 is the technology used in the second step. Two additional combinations, 6 and 7, are also proposed including the same technological combinations of 4 and 5, but these include increasing the level of governance to a multi-actor coordination level. The multi-actor level includes coordination at all institutional levels but also involves academia, research institutes, international support, and other stakeholders.

Our results indicate that if the current situation continues, there would be an increase of greenhouse gases and water pollution between 2015 and 2030, driven by the growth in fish industry production volumes. Interestingly, the study also shows that focusing only on strengthening capacities to enforce national water policies would result in greenhouse gas emissions five times higher in 2030 than if the current situation continues, due to the increased electricity consumption and sludge production from the wastewater treatment process. The benefit of this strategy would be positive for the reduction of water pollution, but negative for climate change mitigation. From our analyses of combinations 2 and 3 we learned that technology can be very efficient for one purpose but detrimental for others. If different institutions are, for example, responsible for water quality and climate change mitigation, communication between the institutions is crucial to avoid trade-offs between environmental objectives.

Furthermore, when analyzing different cooperation strategies together with a combination of diverse sets of technologies, we found that not all combinations work appropriately. For instance, improving interaction just within and between institutions does not guarantee proper selection and application of technologies. In this case, the adoption of the technology is not fast enough to meet the targets proposed in 2030, thus resulting in policy implementation failures. Our analyses of combinations 4 and 5 showed that interaction within and between national, regional, and local institutions alone is not enough to prevent policy failure.

Finally, a multi-actor cooperation strategy that includes cooperation across sectors, administrative levels, international support, and stakeholders, seems to be the right approach to ensure selection of the most appropriate technologies and achieve policy success. We identified that with this approach, it would be possible to reduce water pollution and simultaneously decrease greenhouse gas emissions from the electricity required for wastewater treatment. Analyzing combinations 6 and 7 revealed that multi-actor governance allows to simultaneously meet climate and water objectives and a high chance to prevent policy failure.

In the end, analyses such as the one shown here, highlight the importance of integrating and creating synergies across sectors, administrative levels, stakeholders, and international institutions to ensure an effective implementation of policies that provide incentives to make careful choices regarding multi-objective treatment technologies.


Gómez-Sanabria A, Zusman E, Höglund-Isaksson L, Klimont Z, Lee S-Y, Akahoshi K, Farzaneh H, & Chairunnisa (2019). Sustainable wastewater management in Indonesia’s fish processing industry: bringing governance into scenario analysis. Journal of Environmental Management (Submitted).

Note: This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.

Perspectives on transforming food and land use systems for sustainable development

By Frank Sperling, Senior Project Manager (FABLE) in the IIASA Ecosystems Services and Management Program

Food and land use systems play a critical role in managing climate risks and bringing the world onto a sustainable development trajectory.

The UN Secretary General’s Climate Action Summit in New York on 23 September seeks to catalyze further momentum for climate change mitigation and adaptation. The transformation of the food and land use system will play a critical role in managing climate risks and bringing the world onto a sustainable development trajectory.

Today’s food and land use systems are confronted with a great variety of challenges. This includes delivering on universal food security and better diets by 2030. Over the last decades, great strides have been made towards achieving universal food security, but this progress recently grinded to a halt. The number of people suffering from chronic hunger has been rising again from below 800 million in 2015 to over 820 million people today [1]. Food security is however not only about a sufficient supply of calories per person. It is also about improving diets, addressing the worldwide increase in the prevalence of obesity, and how we use and value environmental goods and services.

© Paulus Rusyanto |

Agriculture, forestry and other land use currently account for around 24% of greenhouse gas emissions caused by human activities [2]. Land use changes are also a major driver behind the worldwide loss of biodiversity [3]. Clearly, in light of population growth and the increasingly visible fingerprints of a human-induced global climate crisis and other environmental changes, business as usual is not an option.

Systems thinking is key in shifting towards more sustainable practices. A new report released by the Food and Land-Use System (FOLU) Coalition showcases that there is much to be gained. There are massive hidden costs in our current food and land use systems. The report outlines ten critical transitions, which can substantially reduce these hidden costs, thereby generating an economic prize, while improving human and planetary health.

The International Institute for Applied Systems Analysis (IIASA) contributed to the analytics underpinning the report [4], applying the Global Biosphere Management Model (GLOBIOM) [5]. A “better futures” scenario, which seeks to collectively address development and environmental objectives, was compared to a “current trends” scenario, which is basically a continuation of a business-as-usual scenario. The assessment illustrates that an integrated approach that acknowledges the interactions in the food and land use space, can help identify synergies and manage trade-offs across sectors. For example, shifting towards healthy diets not only improves human health, but also reduces pressure on land, thereby helping to improve the solution space for addressing climate change and halting biodiversity loss.

While understanding that the global picture is important, practical solutions require engagement with national and subnational governments. The challenge is to identify development pathways that address the development needs and aspirations of countries within global sustainability contexts. As part of FOLU, the Food, Agriculture, Biodiversity, Land and Energy (FABLE) Consortium was initiated to do exactly this. The FABLE Secretariat, jointly hosted by the Sustainable Development Solutions Network (SDSN) and IIASA, is working with knowledge institutions from developed and developing countries, to explore the interactions between national and global level objectives and their implications for pathways towards sustainable food and land use systems. Preliminary results from inter-active scenario and development planning exercises, so-called Scenathons, were recently presented in the FABLE 2019 report.

These initiatives highlight that acknowledging and embracing complexity can help reconcile development and environmental interests. This also entails rethinking how we relate to and manage nature’s services and their role in providing the foundation for the welfare of current and future generations. This is underscored by the prominent role nature-based solutions are given at the UN Secretary General’s Climate Action Summit. We need to move from silo-based, sector specific, single objective approaches to a focus on multiple objective solutions. In the land use space, this means embedding agriculture in the broader land use context, which accounts for and values environmental services, and linking to the food system where dietary choices shape human health and the demand for land.

Doing so will help bridge the international policy objectives of the UN Framework Convention on Climate Change (UNFCCC), the UN Convention on Combating Desertification (UNCCD), the Convention on Biological Diversity (CBD), and the Sustainable Development Goals (SDGs) enshrined in ‘The 2030 Agenda for Sustainable Development’. This represents an opportunity to create a new value proposition for agriculture and other land use activities where environmental stewardship is rewarded.


[1] Food and Agriculture Organization (FAO) et al. (2019). The State of Food Security and Nutrition in the World 2019. Safeguarding against economic slowdowns and downturns. Rome, FAO.

[2] Intergovernmental Panel on Climate Change (IPCC) (2019). Climate Change and Land. IPCC Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. Intergovernmental Panel on Climate Change (IPCC).

[3] Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) (2018). The IPBES assessment report on land degradation and restoration. Montanarella, L., Scholes, R., and Brainich, A. (eds.). Secretariat of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, Bonn, Germany. 744 pages.

[4] Deppermann, A. et al. 2019. Towards sustainable food and land-use systems: Insights from integrated scenarios of the Global Biosphere Management Model (GLOBIOM). Supplemental Paper to The 2019 Global Consultation Report of the Food and Land Use Coalition Growing Better: Ten Critical Transitions to Transform Food and Land Use. Laxenburg, IIASA.

[5] Havlik P, Valin H, Herrero M, Obersteiner M, Schmid E, Rufino MC, Mosnier A, Thornton PK, et al. (2014). Climate change mitigation through livestock system transitions. Proceedings of the National Academy of Sciences 111 (10): 3709-3714. DOI: 1073/pnas.1308044111 [].

Note: This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.

Lessons from 50 years of model-based policy advocacy

Monika Bauer, IIASA Network and Alumni Officer, interviewed alumnus Dennis Meadows during his recent visit to IIASA. 

Dennis Meadows with colleagues in the IIASA Water & RISK Programs © Monika Bauer | IIASA

“It’s a great pleasure to be back at IIASA because the institute really had a big impact on my professional life,” said Dennis Meadows, coauthor of the seminal book Limits to Growth, after his lecture to IIASA staff during a recent visit to the institute. “I came to IIASA, and it gave me so many new ideas and contacts. It became the fuel for my professional activities for a long time.”

Meadows visited the IIASA Energy Program in 1977 when Roger Levien was director, and he says that Levien greatly impacted the way he viewed problems. In his lecture titled, Lessons from 50 years of model-based policy advocacy, he pointed out that Levien looked at problems as universal or global, and that he uses the criteria Levien passed on to him in what he calls “problem selection” to this day. Meadows also spent some time at the institute from 1983-1984 when C.S. Buzz Holling was director.

During his lecture, Meadows highlighted the idea of using the concept of an “invisible college” as a strategy to implement academic work. He explained that an “invisible college” usually constitutes a group of about 50 people connected with an issue, who, while they do not necessarily all have to agree on the issue or do the same work, can collectively come up with a solution.

© Dennis Meadows

Meadows created his version of an invisible college through the Balaton Group, a global network for collaboration on systems and sustainability that he founded in 1982. He says that the network is meant to “connect and empower people who will go back home and do good things”. Meadows stopped by IIASA on his way to the group’s annual retreat in at Lake Belaton in Hungary, where 50 leading scientists, teachers, consultants, writers, and managers annually get together to discuss topical issues on their own costs. According to Meadows, this in itself shows the value individuals see in the meetings. The results of past meetings are outlined on the group’s webpage.

When asked about his key messages for IIASA, Meadows’ answers focused on the institute’s alumni network and exploring a deeper understanding of resilience.

“The incredible power of IIASA lies in its alumni, rather than in its models. You create the alumni network through the process of creating models. IIASA doesn’t have many models, but it has thousands of alumni. One of the first things I would look at is how to link alumni more strongly together, so they could help each other. I still have affection for the institute and respect for what it does, and I’m sure that my opinion is shared by many.”

His second take-away for IIASA concerns building a deeper expertise on resilience. “Sustainable development is something that is hard to realize, while there is no doubt that shocks will continue to occur, and there is no unified theory in resilience yet. In my opinion, IIASA has an opportunity to tap into a huge legacy of understanding that goes back to Buzz Holling’s work.”

Note: This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.

Facilitating sustainable energy transitions at the top of the world

By Pallav Purohit, researcher with the IIASA Air Quality and Greenhouse Gases Program

More than 300 million people in Hindu Kush Himalaya-countries still lack basic access to electricity. Pallav Purohit writes about recent research that looked into how the issue of energy poverty in the region can be addressed.

The Hindu Kush Himalayas is one of the largest mountain systems in the world, covering 4.2 million km2 across eight countries: Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, and Pakistan. The region is home to the world’s highest peaks, unique cultures, diverse flora and fauna, and a vast reserve of natural resources.

Ensuring access to affordable, reliable, sustainable, and modern energy for all – the UN’s Sustainable Development Goal (SDG) 7 – has however been especially elusive in this region, where energy poverty is shockingly high. About 80% of the population don’t have access to clean energy and depend on biomass – mostly fuelwood – for both cooking and heating. In fact, over 300 million people in Hindu Kush Himalaya-countries still lack basic access to electricity, while vast hydropower potentials remain largely untapped. Although a large percentage of these energy deprived populations live in rural mountain areas that fall far behind the national access rates, mountain-specific energy access data that reflects the realities of mountain energy poverty barely exists.

Source: Wester et al. (2019)

The big challenge in this regard is to simultaneously address the issues of energy poverty, energy security, and climate change while attaining multiple SDGs. The growing sectoral interdependencies in energy, climate, water, and food make it crucial for policymakers to understand cross-sectoral policy linkages and their effects at multiple scales. In our research, we critically examined the diverse aspects of the energy outlook of the Hindu Kush Himalayas, including demand-and-supply patterns; national policies, programmes, and institutions; emerging challenges and opportunities; and possible transformational pathways for sustainable energy.

Our recently published results show that the region can attain energy security by tapping into the full potential of hydropower and other renewables. Success, however, will critically depend on removing policy-, institutional-, financial-, and capacity barriers that now perpetuate energy poverty and vulnerability in mountain communities. Measures to enhance energy supply have had less than satisfactory results because of low prioritization and a failure to address the challenges of remoteness and fragility, while inadequate data and analyses are a major barrier to designing context specific interventions.

In the majority of Hindu Kush Himalaya-countries, existing national policy frameworks currently primarily focus on electrification for household lighting, with limited attention paid to energy for clean cooking and heating. A coherent mountain-specific policy framework therefore needs to be well integrated in national development strategies and translated into action. Quantitative targets and quality specifications of alternative energy options based on an explicit recognition of the full costs and benefits of each option, should be the basis for designing policies and prioritizing actions and investments. In this regard, a high-level, empowered, regional mechanism should be established to strengthen regional energy trade and cooperation, with a focus on prioritizing the use of locally available energy resources.

© Kriangkraiwut Boonlom |

Some countries in the region have scaled up off-grid initiatives that are globally recognized as successful. We however found that the special challenges faced by mountain communities – especially in terms of economies of scale, inaccessibility, fragility, marginality, access to infrastructure and resources, poverty levels, and capability gaps – thwart the large-scale replication of several best practice innovative business models and off-grid renewable energy solutions that are making inroads into some Hindu Kush Himalayan countries.

This further highlights an urgent need to establish supportive policy, legal, and institutional frameworks as well as innovations in mountain-specific technology and financing. In addition, enhanced multi-stakeholder capacity building at all levels will be needed for the upscaling of successful energy programs in off-grid mountain areas.

Finally, it is important to note that sustainable energy transition is a shared responsibility. To accelerate progress and make it meaningful, all key stakeholders must work together towards a sustainable energy transition. The world needs to engage with the Hindu Kush Himalayas to define an ambitious new energy vision: one that involves building an inclusive green society and economy, with mountain communities enjoying modern, affordable, reliable, and sustainable energy to improve their lives and the environment.


[1] Dhakal S, Srivastava L, Sharma B, Palit D, Mainali B, Nepal R, Purohit P, Goswami A, et al. (2019). Meeting Future Energy Needs in the Hindu Kush Himalaya. In: The Hindu Kush Himalaya Assessment. pp. 167-207 Cham, Switzerland: Springer. ISBN 978-3-319-92287-4 []

[2] Wester P, Mishra A, Mukherji A, Shrestha AB (2019). The Hindu Kush Himalaya Assessment: Mountains, Climate Change, Sustainability and People. Cham, Switzerland: Springer. ISBN 978-3-319-92287-4.

Note: This article gives the views of the author, and not the position of the Nexus blog, nor of the International Institute for Applied Systems Analysis.