No abstract

Climate mitigation targets must involve the agricultural sector, which contributes 10%–14% of global anthropogenic greenhouse gas (GHG) emissions. To evaluate options for implementing mitigation measures in the agricultural sector, farmers’ knowledge, positions, and attitudes towards agricultural GHG emissions, their accounting, and reduction need to be understood. Using an online survey, we asked 254 German farmers about their motivation to reduce GHG emissions and their acceptance of possible regulation schemes. We examined differences between relevant farming sectors, i.e., conventional versus organic and livestock keeping versus crop-cultivating farms. Results show that German farmers are aware of climatic changes and feel a general commitment to reducing GHG emissions but lack sufficient information. We identified agricultural magazines as the most effective tool for disseminating relevant knowledge. German farmers would feel motivated to adopt climate-friendly farming styles if products were labeled accordingly and if they received subsidies and public acknowledgment for their effort. As long as there is no regulation of agricultural GHGs through taxes or subsidies, personal motivation is yet the strongest motivation for voluntary emission reduction. Our findings are timely for the further development of strategies and instruments that reduce agricultural GHG emission and account for the farmers’ views. The dataset is available for further investigations.

Human impacts can induce ecosystems to cross tipping points and hence unexpected and sudden changes in ecosystem services that are difficult or impossible to reverse. The world´s oceans suffer from cumulative anthropogenic pressures like overexploitation and climate change and are especially vulnerable to such regime shifts. Yet an outstanding question is whether regime changes in marine ecosystems are irreversible. Here we first review the evidence for regime shifts in the North Sea ecosystem, one of the heaviest impacted and best studied marine ecosystems in the world. We then used catastrophe theory to show that fishing and warming have caused a previously undetected and potentially irreversible regime shift. Our study emphasizes the combined effects of local and global human impacts in driving significant ecosystem shifts and suggests that adaptation is likely the central avenue forward for maintaining services in the face of global climate change.

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Consumers' preferences coupled with available fishing technology determine fisheries' harvests and impacts on the ecosystem. In this paper, I investigate the effects of unintended catch, or bycatch, on consumption decisions and harvests. To this end, a multi-species coupled ecosystem economy model including consumer preferences is extended to also include bycatch in harvesting. The resulting equilibria and dynamics of the model are solved analytically. This allows demonstration of the effects of bycatch not only on the ecosystem, which are comparatively well researched, but also on the economic actors harvesting and consuming fish stocks. The main results, besides replicating the finding that bycatch can increase harvesting mortality, are that even strong bycatch may have no effects on stocks and that the harvesting economy may change dramatically depending on bycatch intensity. Therefore, bycatch should indeed be taken into account in the economic modelling of fisheries. Furthermore, understanding the interrelation of bycatch and market forces is essential in designing overarching policy where economic effects, such as changing employment, need to be considered while also ensuring sustainable use of the ecosystem.