Joint Program studies featured in this year’s talks and posters showcase advanced modeling methods for projecting global and regional change—and, in some cases, results that could inform decision-making. Topics include modeling energy-water-land interactions, assessing water-stress risk, projecting regional climate change, evaluating modeling uncertainties under emissions scenarios consistent with the long-term goals of the Paris Agreement, and assessing the climatic impacts of aerosols. (All presenters are current or recent members of the Joint Program and, unless otherwise indicated, lead authors of studies co-authored by Joint Program and affiliated researchers.)

Modeling energy-water-land interactions

Former Principal Research Scientist Erwan Monier will serve as primary convener of a conference session on coupled human–natural systems and global environmental change. The session focuses on innovative approaches for developing predictive understanding of coupled human-Earth system dynamics across spatial and temporal scales. Such understanding is critical to informing sustainable responses to global environmental change. Topics may include interactions across the energy-water-land nexus, the influence of extreme events on critical infrastructure systems, connections between climate and human activities, or feedbacks associated with population dynamics and human health.

A poster by Monier describes the structure and potential applications of a new model that can simulate the impact of changes in climate, atmospheric chemistry and land use on the land system and the impact of human activity on global and regional cycles of energy, water, carbon and nutrients. To simulate the impact of climate change on land productivity and subsequent land-use change decisions, Monier and his co-authors aim to link the model to an existing water resource model for basin-scale assessment of water availability along with the MIT Economic Projection & Policy Analysis (EPPA) model of the world economy.

Assessing water-stress risk

A poster by Deputy DIrector C. Adam Schlosser summarizes numerical experiments with the MIT Integrated System Modeling (IGSM) framework linked to a Water Resource System (WRS) model. These experiments assess the effectiveness of both large-scale adaptation and mitigation pathways in reducing the risk of water stress and unmet water demands over a large portion of southern and eastern Asia. The researchers find that climate mitigation can reduce, but not eliminate, the risk of increased water stress for hundreds of millions, and that adaptation measures can overcome both climate and socioeconomic factors that increase the risk and severity of unmet water demands.

A talk by Research Scientist Xiang Gao presents a risk-based assessment of water availability and use in response to future climate change and socioeconomic growth in the U.S. with and without a global carbon-pricing policy. The study quantifies changes in (1) an index of managed water stress by midcentury resulting from projected climate change and socioeconomic growth, and (2) the total (additional) populations affected by increased stress—and assesses risks potentially averted under the aggressive climate mitigation pathway. The results may provide actionable insights for water-related strategic planning and risk management in the face of unavoidable and preventable global changes.

Projecting regional climate change

An invited talk by Erwan Monier evaluates possible implications of the Paris Agreement for climate change projections in Northern Eurasia. Representing nationally determined contributions (NDCs) of all major economic regions in the IGSM framework and testing various scenarios extending beyond 2030, Monier and his co-authors downscale projections of future global mean climate change into regional projections of temperature and precipitation over Northern Eurasia. The resulting set of climate projections provides the basis for updated climate risk assessment for the region.

A talk by Joint Program Research Scientist Muge Komurcu explores a modeling approach aimed at producing higher-resolution simulations of the local effects of climate change than what coupled Earth-system models (ESMs) can produce. Using a high-resolution regional climate model, Komurcu and co-authors show that they can improve historical simulations of temperatures and precipitation for the Northeastern U.S. They apply the same methodology to downscale climate projections of ESMs to obtain high-resolution regional climate projections for the Northeastern U.S. with enhanced spatial detail for the middle and end of this century.

Evaluating modeling uncertainties under 2oC and 1.5oC emissions scenarios 

A poster by Research Scientist Andrei Sokolov evaluates uncertainty in regional climate change projections using the IGSM framework. To that end, Sokolov’s study runs 400-member ensembles of climate simulations under two emissions scenarios that reflect the long-term goals of the Paris Agreement using the Joint Program’s latest probabilistic distributions of climate parameters. The first caps global warming at 2oC by 2100 with a 66% probability, the second at 1.5oC with a 50% probability, both relative to the 1861-1880 mean global surface temperature. Taking a statistical downscaling approach, the study calculates regional distributions of surface warming, and then estimates probability distributions of surface temperature increase for different regions.

A talk by Research Scientist Jennifer Morris evaluates economic uncertainties associated with meeting long-term Paris goals. Morris and her co-authors plan to simulate the 2oC and 1.5oC scenarios as a global cap-and-trade policy, running a 400-member ensemble of the EPPA model for each using the Joint Program’s latest probabilistic distributions of key economic parameters. These range from population to energy efficiency trends to the costs of advanced technologies. The study explores the resulting uncertainty in the cost of meeting the Paris goal, along with the relative contribution of different parameters to that uncertainty.

Assessing climatic impacts of aerosols 

A talk to be presented by Senior Research Scientist Chien Wang explores the impact of biomass-burning aerosols on the atmospheric convection system above the Maritime Continent in Southeast Asia, where biomass burning has long produced massive fire aerosols with peak concentrations of about 40 times that of background aerosols. Using a modeling system to conduct multiyear simulations with or without biomass-burning aerosols, Wang and the lead author of the study, Hsiang-He Lee (a research scientist in Wang’s group), investigate aerosol-cloud interactions associated with these aerosols in the region.

A second talk presented by Wang examines the impacts of anthropogenic aerosols emitted from Asia on the precipitation and hydrology of mainland Southeast Asia. This study, which was completed by Wang’s graduate student Lik-Khian Yeo, uses a regional weather-climate-hydrology model to dynamically interpret the results of a global climate model at the regional scale. Results indicate that anthropogenic aerosol emissions from East and Southeast Asia lead to an overall decrease in precipitation in the Southeast Asia mainland, an effect that becomes more evident during inter-monsoon seasons. The aerosols’ impact on precipitation also propagates to the streamflow of the Lower Mekong River, particularly during those seasons.

A poster by former Joint Program research assistant Qinjian Jin investigates the climatic response to international shipping emissions in a near-stable climate using a coupled Earth-system model that incorporates a model representing aerosol processes and aerosol-cloud interactions. Based on 100-year simulations with or without shipping emissions, Jin and co-author Chien Wang show that international shipping emissions result in cooling effects that are stronger in the Northern Hemisphere than in the Southern Hemisphere, with the strongest occurring in the Arctic.

Photo: AGU Fall Meeting Poster Hall (Source: AGU)