Robert B. Jackson

Soil organic matter decomposition and its interactions with climate depend on whether the organic matter is associated with soil minerals. However, data limitations have hindered global-scale analyses of mineral-associated and particulate soil organic carbon pools and their benchmarking in Earth system models used to estimate carbon cycle–climate feedbacks. Here we analyse observationally derived global estimates of soil carbon pools to quantify their relative proportions and compute their climatological temperature sensitivities as the decline in carbon with increasing temperature. We find that the climatological temperature sensitivity of particulate carbon is on average 28% higher than that of mineral-associated carbon, and up to 53% higher in cool climates. Moreover, the distribution of carbon between these underlying soil carbon pools drives the emergent climatological temperature sensitivity of bulk soil …

Direct air capture has gained traction as a method for carbon dioxide removal. How and whether direct air capture can be deployed requires securing social license to operate, and increasingly demands environmental justice and just transition principles. Here we use a nationally representative survey to evaluate public perceptions of direct air capture, paired with focus groups to assess community perceptions across four communities in the United States: Houston, Texas; Monaca, Pennsylvania; Bakersfield, California; and Rock Springs, Wyoming. We find conditional support for direct air capture deployment among focus group participants, and majority support for direct air capture deployment among national survey respondents. The most important determinants of project support were procedural justice elements—in particular community involvement in planning and implementation—and anticipated community …

Climate warming is expected to increase global methane (CH4) emissions from wetland ecosystems. Although in situ eddy covariance (EC) measurements at ecosystem scales can potentially detect CH4 flux changes, most EC systems have only a few years of data collected, so temporal trends in CH4 remain uncertain. Here, we use established drivers to hindcast changes in CH4 fluxes (FCH4) since the early 1980s. We trained a machine learning (ML) model on CH4 flux measurements from 22 [methane‐producing sites] in wetland, upland, and lake sites of the FLUXNET‐CH4 database with at least two full years of measurements across temperate and boreal biomes. The gradient boosting decision tree ML model then hindcasted daily FCH4 over 1981–2018 using meteorological reanalysis data. We found that, mainly driven by rising temperature, half of the sites (n = 11) showed significant increases in annual …

Wetland methane (CH4) emissions over the Boreal–Arctic region are vulnerable to climate change and linked to climate feedbacks, yet understanding of their long-term dynamics remains uncertain. Here, we upscaled and analysed two decades (2002–2021) of Boreal–Arctic wetland CH4 emissions, representing an unprecedented compilation of eddy covariance and chamber observations. We found a robust increasing trend of CH4 emissions (+8.9%) with strong inter-annual variability. The majority of emission increases occurred in early summer (June and July) and were mainly driven by warming (52.3%) and ecosystem productivity (40.7%). Moreover, a 2 °C temperature anomaly in 2016 led to the highest recorded annual CH4 emissions (22.3 Tg CH4 yr−1) over this region, driven primarily by high emissions over Western Siberian lowlands. However, current-generation models from the Global Carbon …

The photocatalytic decomposition of atmospheric methane (CH4) and nitrous oxide (N2O) could be valuable tools for mitigating climate change; however, to date, few photocatalyst deployment strategies have had their costs modeled. Here, we construct basic cost models of three photocatalytic CH4 and N2O decomposition systems: 1) a ground-based solar system with natural airflow over photocatalyst-painted rooftops, 2) a ground-based LED-lit system with fan-driven airflow, and 3) an aerosol-based solar system on solid particles dispersed in the atmosphere. Each model takes as inputs the photocatalyst’s apparent quantum yield (AQY; a measure of how efficiently photons drive a desired chemical reaction) and the local CH4 or N2O concentration. Each model calculates an overall rate of greenhouse gas drawdown and returns a levelized cost of greenhouse gas removal per equivalent ton of carbon dioxide …

Nutrients are essential regulators of the structure and function of natural ecosystems and play a key role in constraining future terrestrial productivity and carbon sequestration in response to rising CO2 concentrations and climate change. Nitrogen (N) and phosphorus (P) widely limit plant growth in global terrestrial ecosystems. Therefore understanding spatial patterns and future trends of N and P limitation can shed light on the future dynamics of forests and other terrestrial biomes. Based on current literature, here we (1) review the concept and mechanisms of nutrient limitation and how vascular plants adapt to nutrient limitation, (2) summarize the direct and indirect approaches to diagnose nutrient limitation, (3) synthesize the current understanding of global patterns of N and P limitation, and (4) discuss the future trends in N and P limitation in boreal, temperate, and tropical forests. Phosphorus limitation mainly …

Nitrous oxide (N2O) is the most important stratospheric ozone-depleting agent based on current emissions and the third largest contributor to increased net radiative forcing. Increases in atmospheric N2O have been attributed primarily to enhanced soil N2O emissions. Critically, contributions from soils in the Northern High Latitudes (NHL,> 50 N) remain poorly quantified despite their vulnerability to permafrost thawing induced by climate change. An ensemble of six terrestrial biosphere models suggests NHL soil N2O emissions doubled since the preindustrial 1860s, increasing on average by 2.0±1.0 Gg N yr-1 (p< 0.01). This trend reversed after the 1980s because of reduced nitrogen fertilizer application in non-permafrost regions and increased plant growth due to CO2 fertilization suppressed emissions. However, permafrost soil N2O emissions continued increasing attributable to climate warming; the interaction of …

NIST, Stony Brook University, and the Environmental Defense Fund (EDF) organized and held a workshop at the EDF offices in Washington, DC, on June 15 and 16, 2022 to discuss the current state of knowledge and to define productive courses of action in better determination and source apportionment of methane emission rates and, specifically, natural gas emission rates, in urban environments. The workshop involved 56 attendees from universities, government agencies, non-governmental organizations (NGOs) and the private sector, including representatives from relevant utilities. This report covers discussion of the knowledge base to date about urban sources of natural gas methane emissions, their relative magnitudes, and areas of uncertainty. Specific suggestions and ideas for future experiments to be conducted that could improve our understanding are presented. Next steps, including the creation of working groups for field experiments and/or a research coordination network are discussed.