Browsing by Author "Kummu, Matti, Prof., Aalto University, Department of Built Environment, Finland"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Freshwater change in the Earth system - A qualitative-quantitative outlook and implications for planetary boundaries
    (Aalto University, 2024) Virkki, Vili; Chrysafi, Anna, Dr., Q-Plan International P.C., Greece; Porkka, Miina, Assoc. Prof., University of Eastern Finland, Finland; Rakennetun ympäristön laitos; Department of Built Environment; Water and Development Research Group; Insinööritieteiden korkeakoulu; School of Engineering; Kummu, Matti, Prof., Aalto University, Department of Built Environment, Finland
    Human actions currently put many life-supporting Earth system processes at risk. The planetary boundaries framework illustrates how this environmental change is pervasive throughout the Earth system and demarcates biophysical boundaries to keep the Earth system stable. Although the framework conceptualisation is sound, especially the definitions of boundaries describing changes in the biosphere and the hydrosphere have been criticised. This thesis provides a comprehensive analysis of global freshwater change and relates this to the planetary boundaries framework. The freshwater cycle supports hydroecological (sustaining ecosystems) and hydroclimatic (regulating climate) functions, which integrally embed freshwater in the Earth system. However, the planetary boundary for freshwater has not captured many of these interconnections, and global-scale approaches have often been limited in analysing and interpreting human-driven freshwater change. Thus, the aim of this thesis is to address the research gap of capturing freshwater change in the Earth system in a way that enables a better representation of freshwater in the planetary boundaries framework. The results of this thesis comprise a thorough qualitative-quantitative assessment of global freshwater change. Using expert knowledge elicitation, blue and green water are shown to strongly interact with other Earth system processes, with variable roles in mediating these interactions. Moreover, associations between common changes in streamflow regimes and their direct and indirect drivers are analysed, using streamflow observations and multivariate global data of the drivers. In-depth analyses of modelled hydrological data further demonstrate the widespread extent and considerable degree of global freshwater change, first through the concept of environmental flow envelopes and then by assessing streamflow and soil moisture deviations beyond pre-industrial reference conditions. This leads to introducing a new planetary boundary for freshwater change, which is defined based on the work conducted for this thesis and parallel studies. Safeguarding freshwater as an integral part of the Earth system requires integrated approaches. The interactions between freshwater and other Earth system processes form a dense and complex network where changes – often anthropogenic in nature – affect more than one component of the freshwater cycle at a time. Thus, setting planetary-scale limits or aggregating freshwater change globally should use the knowledge on the role of freshwater in the Earth system as widely as possible. The findings of this thesis provide a solid background for further advances on understanding the causes and consequences of freshwater change – at local to global scales.
  • Thumbnail Image
    Item
    Resilience perspectives in global food systems - Exploring variability, localness and diversity
    (Aalto University, 2022) Kinnunen, Pekka; Taka, Maija, Dr., Aalto University, Department of Built Environment Engineering, Finland; Guillaume, Joseph H. A., Dr., Australian National University, Australia; Rakennetun ympäristön laitos; Department of Built Environment; Water and Environmental Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Kummu, Matti, Prof., Aalto University, Department of Built Environment, Finland
    Global food production and food availability has increased remarkably since the Green Revolution due to, for example, technological improvements in food systems. Despite the increase in production capacity, the food system's resilience is challenged by a multitude of systemic and environmental disruptions, as well as natural variation. To build stable and sufficient food systems, these disruptions have to be taken into account. While global food systems are frequently assessed from the perspective of physical food availability, such straightforward approach is rarely enough to capture the very the complex nature of food. Thus, this dissertation investigates various perspectives of resilience of global food availability and variability by using novel data-driven spatial assessments. Additionally, it examines the use of agricultural inputs in Finland, drawing attention also to the intricacies of a single country, which are not feasible to assess in global scale studies. The dissertation found substantial variation in lower-than-average crop yields between regions and climatic systems. The results also showed that anthropogenic indicators such as human development index, or fertilizer application rates explain 40-60% of the variation in lower-than-average crop yields but only 5-20% in mean yield anomalies during climatic shock years. Furthermore, the dissertation demonstrated that even with a theoretically optimum case, only a fraction of global population could currently fulfil their food demand using only local crop production. Uncertainty created by the variation in crop yields, as well as the limits of local food resources, reveal that relying only on local available food creates major resilience challenges. One option to increase resilience against the variation in food production and surpass local resource limitations is international trade. The findings of this dissertation showed that increasing food trade has boosted quantity and diversity in food supply for a large proportion of the world population. This dissertation showed that despite the increasing dependency on food trade, the number of import partners more often decreased than increased, highlighting the challenges that may occur with potential large scale trade shocks. Furthermore, food and agricultural inputs can differ substantially in their respective dependencies. This further emphasises how these often-neglected hidden dependencies can reveal additional levels of complexity that needs to be considered from a resilience perspective. Resilience within the global food systems intertwines closely with the broader theme of food security. Building understanding of the vulnerabilities and resilience with regards to food production, trade and consumption is necessary for providing resilience against changing world. At the same time, it is imperative that food system narratives are not reduced to overly simplistic views that do not account for complex interactions.