Seite - 6 - in options, Band winter 2017/2018

research news 6 iiasa research www.iiasa.ac.atoptions ◼ winter 2017/18 The costs of phasing down hydrofluorocarbons The Kigali Amendment of the Montreal Protocol aims to phase down the consumption of hydrofluorocarbons, chemicals that have strong global warming impacts. A new study by IIASA researchers Lena Höglund-Isaksson and Pallav Purohit provides the first analysis of costs and the importance of electricity savings and technological development for keeping implementation costs low. www.iiasa.ac.at/news/fgas-17 Water management interventions push scarcity downstream Human interventions to harness water resources, such as reservoirs, dams, and irrigation measures, have increased water availability for much of the global population, but at the same time, swept water scarcity problems downstream, according to IIASA research. The new study is one of the first to provide a global accounting of regional and local water impacts, taking into account seasonal changes and different types of intervention, including water withdrawals, reservoir regulation, land-use change, and irrigation. www.iiasa.ac.at/news/downstream-17 Optimal harvests without top-down planning From the air, Bali’s rice terraces look like colorful mosaics, because farmers plant their fields at different times. A new study shows that the resulting fractal patterns actually lead to optimal harvests, without overarching management. Under certain conditions, the study shows, it is possible to reach sustainable situations that lead to a maximum payoff for everybody, even as each individual makes free and independent decisions. The results could help inform sustainable resource management. www.iiasa.ac.at/news/bali-17 Uncertainty in the Paris climate pledges The pledges made by countries under the Paris Agreement on climate change mean that greenhouse gas emissions could range from 47 to 63 billion metric tons of CO2 equivalent (GtCO2e) per year in 2030, compared to about 52 GtCO2e in 2015, according to a new analysis. That range—caused by ambiguity in the pledges— has critical consequences for the feasibility of achieving the goal of keeping warming “well below 2°C” over preindustrial levels, according to a study led by IIASA researchers. www.iiasa.ac.at/news/pledges-17 Climate change could lead to a greater incidence of toxic algae blooms in Lake Taihu, the third-largest freshwater lake in China, according to a new study by researchers in China, the USA, and at IIASA. The lake supports a productive fishing industry, which is threatened by fast-growing algae that deplete oxygen in the lake. Since multiple factors contribute to algae growth, and there are interplays between these factors, it can be hard to pinpoint what tips the system over the edge—previous research has identified non-linear relationships between many of these factors and aquatic organisms. In the new study, scientists used a new systemic approach that draws from thermodynamics to better understand what drives algal growth to the point where it threatens ecosystem health. “We wanted to look at ecosystem health as a whole, and how it is affected by environmental and anthropogenic pressures,” says Brian Fath, a researcher who splits his time between IIASA and Towson University in the USA. Fath worked with two colleagues in China who took measurements of physical factors such as water temperature, pH, inorganic pollutants such as nitrogen compounds, and several algae species at 33 sites at the lake each month in 2013. To represent ecosystem health in the lake, the researchers built a new indicator that borrows from the theory of thermodynamics in physics, using the physical factors they measured as energy inputs. “Like a physical system, ecosystems also take in energy in different forms, which affects the health of the ecosystem,” explains Fath. The researchers found that water temperature, inorganic nutrients, and suspended solids (such as soil run-off) greatly contributed to the growth of algae. In addition, they found that high pH levels, driven by increased CO2, have the potential to fuel harmful algae growth even further. The new method provides quantitative relationships between physical factors and environmental health. The researchers say it could therefore be useful for predicting ecosystem changes in other shallow lakes. KL Further info Wang C, Bi J, & Fath B (2017). Effects of abiotic factors on ecosystem health of Taihu Lake, China based on eco-exergy theory. Scientific Reports 7: p. 42872. [pure.iiasa.ac.at/14417] Brian Fath Fath@iiasa.ac.at China’s Lake Taihu at risk from climate change