ALBERT

Description: There is evidence that a self-sustaining ice discharge from the West Antarctic Ice Sheet (WAIS) has started, potentially leading to its disintegration. The associated sea level rise of more than 3m would pose a serious challenge to highly populated areas including metropolises such as Calcutta, Shanghai, New York City, and Tokyo. Here, we show that the WAIS may be stabilized through mass deposition in coastal regions around Pine Island and Thwaites glaciers. In our numerical simulations, a minimum of 7400 Gt of additional snowfall stabilizes the flow if applied over a short period of 10 years onto the region (−2 mm year−1 sea level equivalent). Mass deposition at a lower rate increases the intervention time and the required total amount of snow. We find that the precise conditions of such an operation are crucial, and potential benefits need to be weighed against environmental hazards, future risks, and enormous technical challenges.

Description: The Atlantic Meridional Overturning Circulation (AMOC) is likely the most well-known system of ocean currents on Earth, redistributing heat, nutrients and carbon over a large part of the Earth’s surface and affecting global climate as a result. Due to enhanced freshwater fluxes into the subpolar North Atlantic as a response to global warming, the AMOC is expected, and may have already started, to weaken and these changes will likely have global impacts. It is therefore of considerable relevance to improve our understanding of past and future AMOC changes. My thesis tries to answer some of the open questions in this field by giving strong evidence that the AMOC has already weakened over the last century, by narrowing future projections of this slowdown and by studying the impacts on global surface warming.

Description: Germany wishes to cut its greenhouse gas emissions by 80 to 95 per cent by 2050. However, despite the success to date, the measures which have already been planned and implemented are not sufficient for achieving this ambitious goal. In addition to the energy sector, the largest source of greenhouse gas emissions, German industry is also responsible for releasing considerable volumes of global warming gases. In its Climate Action Plan 2050, the Federal Government has for the first time set a sector target for industry. The present acatech POSITION PAPER analyses the options for (re)utilising and storing CO2 (Carbon Capture and Utilisation (CCU) and Carbon Capture and Storage (CCS)) which come into consideration for reducing greenhouse gas emissions from industrial processes. It is recommended that a wide-ranging public debate about the use of CCU and CCS be conducted in the near future. Only then will it be possible to take account of reservations about CCU and CCS, further develop suitable technology in good time and bring it to market maturity so that the necessary infrastructure can be planned, approved, funded and constructed.

Description: Climate change affects societies across the globe in various ways. In addition to gradual changes in temperature and other climatic variables, global warming is likely to increase intensity and frequency of extreme weather events. Beyond biophysical impacts, these also directly affect societal and economic activity. Additionally, indirect effects can occur; spatially, economic losses can spread along global supply-chains; temporally, climate impacts can change the economic development trajectory of countries. This thesis first examines how climate change alters river flood risk and its local socio-economic implications. Then, it studies the global economic response to river floods in particular, and to climate change in general. Changes in high-end river flood risk are calculated for the next three decades on a global scale with high spatial resolution. In order to account for uncertainties, this assessment makes use of an ensemble of climate and hydrological models as well as a river routing model, that is found to perform well regarding peak river discharge. The results show an increase in high-end flood risk in many parts of the world, which require profound adaptation efforts. This pressure to adapt is measured as the enhancement in protection level necessary to stay at historical high-end risk. In developing countries as well as in industrialized regions, a high pressure to adapt is observed - the former to increase low protection levels, the latter to maintain the low risk levels perceived in the past. Further in this thesis, the global agent-based dynamic supply-chain model acclimate is developed. It models the cascading of indirect losses in the global supply network. As an anomaly model its agents - firms and consumers - maximize their profit locally to respond optimally to local perturbations. Incorporating quantities as well as prices on a daily basis, it is suitable to dynamically resolve the impacts of unanticipated climate extremes. The model is further complemented by a static measure, which captures the inter-dependencies between sectors across regions that are only connected indirectly. These higher-order dependencies are shown to be important for a comprehensive assessment of loss-propagation and overall costs of local disasters. In order to study the economic response to river floods, the acclimate model is driven by flood simulations. Within the next two decades, the increase in direct losses can only partially be compensated by market adjustments, and total losses are projected to increase by 17% without further adaptation efforts. The US and the EU are both shown to receive indirect losses from China, which is strongly affected directly. However, recent trends in the trade relations leave the EU in a better position to compensate for these losses. Finally, this thesis takes a broader perspective when determining the investment response to the climate change damages employing the integrated assessment model DICE. On an optimal economic development path, the increase in damages is anticipated as emissions and consequently temperatures increase. This leads to a significant devaluation of investment returns and the income losses from climate damages almost double. Overall, the results highlight the need to adapt to extreme weather events - local physical adaptation measures have to be combined with regional and global policy measures to prepare the global supply-chain network to climate change.

Description: Airborne influenza virus transmission is depending on climate. Infected individuals are able to travel to any country in the world within one day. In this study we combine these two insights to investigate the influence of climate change on pandemic spreading patterns of airborne infectious diseases, like influenza. Well-known recent examples for pandemics are severe acute respiratory syndrome (SARS, 2002/2003) and H1N1 (Influenza A virus subtype, 2009), which have demonstrated the vulnerability of a strongly connected world.

Description: Climate change is arguably the most severe challenge facing our planet during the 21st century. Human interference with the climate system (mainly through the emission of greenhouse gases and changes in land use) has increased the global and annual mean air temperature at the Earth's surface by roughly 0.8 °C since the 19th century (IPCC, 2013). The year 2014 was the hottest one on record so far (NOAA, 2015a), and at the time of writing, 2015 appears to be on track to set a new record (NOAA, 2015b). This trend of increasing temperatures will continue into the future: by 2100, the globe could warm by another 4 °C or so if emissions are not decisively reduced within the next decades (IPCC, 2013). There is broad agreement that a warming of this magnitude would have profound impacts both on the environment and on human societies (IPCC, 2014a), and that climate change mitigation via a transformation to decarbonized economies and societies has to be achieved to prevent the worst of these impacts (IPCC, 2014b). The spatial and temporal extent of the climate challenge deeply connects it to ethical questions as well. These arise both from the fact that the poorest people on Earth are not significantly contributing to global emissions, but may well feel the impacts most severely, and from the long‐term commitment to future warming and climate change impacts – like sea level or the partial melting of the large ice sheets – which will be felt by future generations. In essence, past and future greenhouse gas emissions seriously affect a large fraction of the still growing human population on our planet and profoundly shape the environment in which our children and grandchildren will have to live in. Humanity therefore has a moral obligation to address the climate challenge. This will have to combine successful negotiations on a binding and effective international climate agreement and bottom‐up initiatives from individuals or communities. There is a wide range of global threats that certainly require humanity's urgent attention (see the recent report by the World Economic Forum, 2015). These global risks include water, food and energy security, population growth, infectious diseases, and international security, for example. However, climate change is often regarded as one of the most profound global problems. This is mainly due to the sheer scale of climate change impacts – both in terms of its global and temporal spread and of the variety of sectors affected by it – that sets it apart from other planetary challenges. Indeed, recent high‐level initiatives highlight the importance of climate change, including the ground‐breaking encyclical of Pope Francis, the G7 countries' pledge to phase out fossil fuels or Barack Obama's new climate mitigation proposal. But climate change cannot be considered isolated from other challenges. Indeed, climate change is a truly cross‐cutting issue affecting many sectors and connected to other global challenges. For example, climate change has the potential to impact global water supplies, agricultural production, human health, and our energy infrastructure. In turn, the way in which we produce our energy and food has a profound effect on the Earth's climate system. Finally, the impacts of policies in one of the fields on the other challenges need to be explored if truly sustainable solutions to global problems shall be achieved. These close connections – and the societal and technical challenges of climate mitigation (IPCC 2014b) and adaptation (IPCC 2014a) – require interdisciplinary and transdisciplinary thinking; we hope that our new journal Global Challenges can serve as a highly visible forum for research bridging classical scientific disciplines, for ideas which have the potential to directly influence future climate policy and for discussions about new research and different policy options. Within the climate change focus of Global Challenges , we therefore invite submissions related to climate change of the highest quality, with a clear focus on the global view of the climate problem and with relevance for (global) climate policy or bottom‐up initiatives which are a significant step towards a solution of the climate challenge. We explicitly invite submissions connecting climate change to the other challenges covered by the journal. In addition to original research papers, we will regularly commission commentary pieces and review articles highlighting the most relevant recent developments in climate research and policy as well as the most exciting open research questions. I firmly believe that a journal like Global Challenges with its broad scope, its cross‐cutting nature, its focus on policy relevance, and its open‐access publication model is an important and innovative outlet for high‐quality research work on global problems in general. Concerning climate change in particular, I am looking forward to working with the editorial team, the staff at Wiley and the global climate science community to develop Global Challenges into one of the major journals in the field.

Description: This paper describes the motivation for the creation of the Vulnerability, Impacts, Adaptation and Climate Services (VIACS) Advisory Board for the Sixth Phase of the Coupled Model Intercomparison Project (CMIP6), its initial activities, and its plans to serve as a bridge between climate change applications experts and climate modelers. The climate change application community comprises researchers and other specialists who use climate information (alongside socioeconomic and other environmental information) to analyze vulnerability, impacts, and adaptation of natural systems and society in relation to past, ongoing, and projected future climate change. Much of this activity is directed toward the co-development of information needed by decision-makers for managing projected risks. CMIP6 provides a unique opportunity to facilitate a two-way dialog between climate modelers and VIACS experts who are looking to apply CMIP6 results for a wide array of research and climate services objectives. The VIACS Advisory Board convenes leaders of major impact sectors, international programs, and climate services to solicit community feedback that increases the applications relevance of the CMIP6-Endorsed Model Intercomparison Projects (MIPs). As an illustration of its potential, the VIACS community provided CMIP6 leadership with a list of prioritized climate model variables and MIP experiments of the greatest interest to the climate model applications community, indicating the applicability and societal relevance of climate model simulation outputs. The VIACS Advisory Board also recommended an impacts version of Obs4MIPs and indicated user needs for the gridding and processing of model output.

Description: Climate change and socioeconomic developments will have a decisive impact on people exposed to hunger. This study analyses climate change impacts on agriculture and potential implications for the occurrence of hunger under different socioeconomic scenarios for 2030, focusing on the world regions most affected by poverty today: the Middle East and North Africa, South Asia, and Sub-Saharan Africa. We use a spatially explicit, agroeconomic land-use model to assess agricultural vulnerability to climate change. The aims of our study are to provide spatially explicit projections of climate change impacts on Costs of Food, and to combine them with spatially explicit hunger projections for the year 2030, both under a poverty, as well as a prosperity scenario. Our model results indicate that while average yields decrease with climate change in all focus regions, the impact on the Costs of Food is very diverse. Costs of Food increase most in the Middle East and North Africa, where available agricultural land is already fully utilized and options to import food are limited. The increase is least in Sub-Saharan Africa, since production there can be shifted to areas which are only marginally affected by climate change and imports from other regions increase. South Asia and Sub-Saharan Africa can partly adapt to climate change, in our model, by modifying trade and expanding agricultural land. In the Middle East and North Africa, almost the entire population is affected by increasing Costs of Food, but the share of people vulnerable to hunger is relatively low, due to relatively strong economic development in these projections. In Sub-Saharan Africa, the Vulnerability to Hunger will persist, but increases in Costs of Food are moderate. While in South Asia a high share of the population suffers from increases in Costs of Food and is exposed to hunger, only a negligible number of people will be exposed at extreme levels. Independent of the region, the impacts of climate change are less severe in a richer and more globalized world. Adverse climate impacts on the Costs of Food could be moderated by promoting technological progress in agriculture. Improving market access would be advantageous for farmers, providing the opportunity to profitably increase production in the Middle East and North Africa as well as in South Asia, but may lead to increasing Costs of Food for consumers. In the long-term perspective until 2080, the consequences of climate change will become even more severe: while in 2030 56% of the global population may face increasing Costs of Food in a poor and fragmented world, in 2080 the proportion will rise to 73%.