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This year’s American Geophysical Union (AGU) Fall Meeting will be held online, making it one of the world’s largest virtual scientific conferences ever. Held December 1-17 (with most scientific programming taking place December 7-11) and presenting more than 1,000 hours of content, AGU20 will feature live and pre-recorded oral presentations and virtual posters from leading Earth and space science researchers. The conference theme is “Shape the Future of Science."

AGU Fall Meeting goes online for 2020

The Kingdom of Saudi Arabia (KSA) is at a crossroads. Recent long-term studies of the area indicate that rising temperatures and evaporation rates will likely further deplete scarce water resources critical to meeting the nation’s agricultural, industrial and domestic needs; more extreme flooding events could endanger lives, economic vitality and infrastructure; and a combination of increasing heat and humidity levels may ultimately render the Kingdom uninhabitable.

Saudi Arabia faces increased heat, humidity, precipitation extremes by mid-century
Mercury stories: Understanding sustainability through a volatile element

Summary: ​An interdisciplinary analysis of human interactions with mercury through history that sheds light on efforts to promote and achieve sustainability.

In Mercury Stories, Henrik Selin and Noelle Eckley Selin examine sustainability through analyzing human interactions with mercury over thousands of years. They explore how people have made beneficial use of this volatile element, how they have been harmed by its toxic properties, and how they have tried to protect themselves and the environment from its damaging effects. Taking a systems approach, they develop and apply an analytical framework that can inform other efforts to evaluate and promote sustainability.

After introducing the framework, which uses the lens of a human-technical environmental system and a matrix-based approach to analyze mercury use and exposure, the authors examine five topical mercury systems that each illustrate important issues in mercury science and governance: global cycling of mercury through the atmosphere, land, oceans, and societies; mercury's dangers to human health, including from occupational, medical, and dietary exposure; mercury emissions to the atmosphere from industrial sources; mercury in commercial products and production processes; and mercury use in artisanal and small-scale gold mining. Finally, looking across the five mercury systems, they distill insights for sustainability analysis more broadly, and draw lessons for researchers, decision-makers, and concerned citizens.

Use of natural gas and oil as a source of feedstocks

Abstract: Greenhouse gas (GHG) implications of natural gas and oil differ when they are used for combustion or as a feedstock. In addition to the growing demand for feedstocks that are converted into products (such as plastics and fertilizers), climate policies that penalize GHG emissions may incentivize a switch from burning natural gas and oil to their feedstock use.

Using an enhanced version of the MIT Economic Projection and Policy Analysis (EPPA) model, we examine several scenarios to assess natural gas and oil use as feedstock and find that global feedstock use grows 2-3 times by 2050 relative to 2015 levels.

In a scenario consistent with reaching 2°C goal set by the Paris Agreement, the share of natural gas used as a feedstock grows from about 5% in 2015 to about 15% in 2050 and the share of oil used as a feedstock grows from about 10% in 2015 to about 17% in 2050. In a scenario consistent with reaching 2°C goal set by the Paris Agreement, the share of natural gas used as a feedstock in 2050 is 86% larger than in the no-policy Reference. The corresponding increase in a share of oil used as a feedstock is 40%. USA, Europe, and the Middle East remain as the major regions for feedstock use, but China, India, and Africa grow fast to become major feedstock use centers. 

Mid-century changes in the mean and extreme climate in the Kingdom of Saudi Arabia and implications for water harvesting and climate adaptation

Abstract: The Kingdom of Saudi Arabia (KSA) is a water-scarce region with a dry, desert climate, yet flood-producing precipitation events and heat extremes lead to loss of life and damages to local infrastructure, property and economy. Due to its distinctive natural and man-made spatial features (e.g., coastal features, wadis, agricultural areas) studying changes in the mean climate and extreme events requires higher-resolution climate projections than those available from the current generation of Earth System Models.

Here, a high-resolution convection-permitting regional climate model is used to downscale the middle of the 21st century (2041–2050) climate projections of the Community Earth System Model (CESM) under representative concentration pathway (RCP) 8.5 and for a historical time period (2008–2017) focusing on two months (August and November) within KSA’s dry-hot and wet seasons, where extreme events have historically been observed more frequently. Downscaling of climate reanalysis is also performed for the historical time period (2008–2017) to evaluate the downscaling methodology.

An increase in the intensity and frequency of precipitation events is found in August by mid-century, particularly along the mountainous western coast of KSA, suggesting potential for water harvesting. Conversely, the northern flank of the Empty Quarter experiences a noticeable reduction in mean and extreme precipitation rates during the wet season. Increasing August heat index is found to particularly make regional habitability difficult in Jeddah by mid-century.

A comprehensive quantification of global nitrous oxide sources and sinks

Abstract: Nitrous oxide (N2O), like carbon dioxide, is a long-lived greenhouse gas that accumulates in the atmosphere. Over the past 150 years, increasing atmospheric N2O concentrations have contributed to stratospheric ozone depletion1 and climate change2, with the current rate of increase estimated at 2 per cent per decade. Existing national inventories do not provide a full picture of N2O emissions, owing to their omission of natural sources and limitations in methodology for attributing anthropogenic sources.

Here we present a global N2O inventory that incorporates both natural and anthropogenic sources and accounts for the interaction between nitrogen additions and the biochemical processes that control N2O emissions. We use bottom-up (inventory, statistical extrapolation of flux measurements, process-based land and ocean modelling) and top-down (atmospheric inversion) approaches to provide a comprehensive quantification of global N2O sources and sinks resulting from 21 natural and human sectors between 1980 and 2016.

Global N2O emissions were 17.0 (minimum–maximum estimates: 12.2–23.5) teragrams of nitrogen per year (bottom-up) and 16.9 (15.9–17.7) teragrams of nitrogen per year (top-down) between 2007 and 2016. Global human-induced emissions, which are dominated by nitrogen additions to croplands, increased by 30% over the past four decades to 7.3 (4.2–11.4) teragrams of nitrogen per year. This increase was mainly responsible for the growth in the atmospheric burden.

Our findings point to growing N2O emissions in emerging economies—particularly Brazil, China and India. Analysis of process-based model estimates reveals an emerging N2O–climate feedback resulting from interactions between nitrogen additions and climate change. The recent growth in N2O emissions exceeds some of the highest projected emission scenarios, underscoring the urgency to mitigate N2O emissions.

Future energy: In search of a scenario reflecting current and future pressures and trends

Abstract: Growing societal pressures, technological trends and government and industry actions are moving the world toward decarbonization and away from “business-as-usual." As such, the concept of a single/obvious “business as usual” or “reference” scenario is no longer relevant. Instead, there are multiple plausible futures that should be explored.

We contribute one such scenario that carefully considers emissions-reduction trends and actions that are likely in the future, absent a globally coordinated mitigation effort. We explore the long-term implications for energy, emissions and temperature outcomes if the world continues to address climate change in the way it has so far—through piecemeal actions and growing social and technological pressures. This Growing Pressures scenario results in a central scenario outcome of about 3°C of surface temperature warming, which is higher than the “well below 2°C” level aspired to by the Paris Agreement, but lower than many widely used “no-policy” scenarios.

Ongoing and growing pressures of change, the roots of which are clearly visible today, could deliver a plausible energy transition scenario to near-zero emissions that plays out over the coming century. While a more aggressive transition is clearly required, this finding highlights the need to bring actions forward in time to achieve an improved outcome making use of clearly identifiable policies and technologies.

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