Population exposure to droughts in China under the 1.5 ºC global warming target Earth System Dynamics DOI 10.5194/esd-9-1097-2018 29 August 2018 Results show that an additional 6.97 million people will be exposed to droughts in China under a 1.5 ºC target relative to reference period, mostly in the east of China. Demographic change is the primary contributor to exposure. Moderate droughts contribute the most to exposure among 3 grades of drought. Our simulations suggest that drought impact on people will continue to be a large threat to China under the 1.5 ºC target. It will be helpful in guiding adaptation and mitigation strategies. Read more
Improving the representation of anthropogenic CO2 emissions in climate models: impact of a new parameterization for the Community Earth System Model (CESM) Earth System Dynamics DOI 10.5194/esd-9-1045-2018 21 August 2018 Earth system models provide simplified accounts of human–Earth interactions. Most current models treat CO2 emissions as a homogeneously distributed forcing. However, this paper presents a new parameterization, POPEM (POpulation Parameterization for Earth Models), that computes anthropogenic CO2 emissions at a grid point scale. A major advantage of this approach is the increased capacity to understand the potential effects of localized pollutant emissions on long-term global climate statistics. CESM)">Read more
A quantitative approach to evaluating the GWP timescale through implicit discount rates Earth System Dynamics DOI 10.5194/esd-9-1013-2018 17 August 2018 The 100-year GWP is the most widely used metric for comparing the climate impact of different gases such as methane and carbon dioxide. However, there have been recent arguments for the use of different timescales. This paper uses straightforward estimates of future damages to quantitatively determine the appropriate timescale as a function of how society discounts the future and finds that the 100-year timescale is consistent with commonly used discount rates. GWP timescale through implicit discount rates">Read more
Using network theory and machine learning to predict El Niño Earth System Dynamics DOI 10.5194/esd-9-969-2018 23 July 2018 The prediction of the El Niño phenomenon, an increased sea surface temperature in the eastern Pacific, fascinates people for a long time. El Niño is associated with natural disasters, such as droughts and floods. Current methods can make a reliable prediction of this phenomenon up to 6 months ahead. However, this article presents a method which combines network theory and machine learning which predicts El Niño up to 1 year ahead. Read more
Moisture transport and Antarctic sea ice: austral spring 2016 event Earth System Dynamics DOI 10.5194/esd-9-939-2018 4 July 2018 In austral spring 2016 the Antarctic region experienced anomalous sea ice retreat in all sectors, with sea ice extent in October and November 2016 being the lowest in the Southern Hemisphere over the observational record (1979–present). The extreme sea ice retreat was accompanied by the wettest and warmest spring on record, over large areas covering the Indian ocean, the Ross Sea, and the Weddell Sea. Read more
Climate sensitivity estimates – sensitivity to radiative forcing time series and observational data Earth System Dynamics DOI 10.5194/esd-9-879-2018 21 June 2018 A key question in climate science is how the global mean surface temperature responds to changes in greenhouse gases. This dependency is quantified by the climate sensitivity, which is determined by the complex feedbacks in the climate system. In this study observations of past climate change are used to estimate this sensitivity. Our estimate is consistent with values for the equilibrium climate sensitivity estimated by complex climate models but sensitive to the use of uncertain input data. Read more
On the social dynamics of moisture recycling Earth System Dynamics DOI 10.5194/esd-9-829-2018 14 June 2018 Moisture recycling is the atmospheric branch of the water cycle, including evaporation and precipitation. While the physical water cycle is well-understood, the social links among the recipients of precipitation back to the sources of evaporation are not. In this work, we develop a method to determine how these social connections unfold, using a mix of quantitative and qualitative methods, finding that there are distinct types of social connections with corresponding policy and management tools. Read more
Hazards of decreasing marine oxygen: the near-term and millennial-scale benefits of meeting the Paris climate targets Earth System Dynamics DOI 10.5194/esd-9-797-2018 13 June 2018 Human-caused, climate change hazards in the ocean continue to aggravate over a very long time. For business as usual, we project the ocean oxygen content to decrease by 40 % over the next thousand years. This would likely have severe consequences for marine life. Global warming and oxygen loss are linked, and meeting the warming target of the Paris Climate Agreement effectively limits related marine hazards. Developments over many thousands of years should be considered to assess marine risks. Read more
Two drastically different climate states on an Earth-like terra-planet Earth System Dynamics DOI 10.5194/esd-9-739-2018 7 June 2018 Using climate simulations, we investigate the role of water recycling in shaping the climate of low-obliquity Earth-like terra-planets. By such a mechanism feeding water back from the extra-tropics to the tropics, the planet can assume two drastically different climate states differing by more than 35 K in global temperature. We describe the bifurcation between the two states occurring upon changes in surface albedo and argue that the bistability hints at a wider habitable zone for such planets. Read more
Assessing the impact of a future volcanic eruption on decadal predictions Earth System Dynamics DOI 10.5194/esd-9-701-2018 6 June 2018 The likelihood of a large volcanic eruption in the future provides the largest uncertainty concerning the evolution of the climate system on the timescale of a few years, but also an excellent opportunity to learn about the behavior of the climate system, and our models thereof. So the following question emerges: how predictable is the response of the climate system to future eruptions? By this we mean to what extent will the volcanic perturbation affect decadal climate predictions and how does the pre-eruption climate state influence the impact of the volcanic signal on the predictions? Read more
