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Highlights

Global & regional analysis of all GHG drivers (1820–2050)

Economic growth (+81Gt) overwhelmed efficiency gains (−31Gt)

Carbon intensity must immediately fall 3 × faster (−2.25 %/yr) to 2050.

Regional drivers: population vs affluence patterns vary sharply.

Reveals unprecedented gap between trends and climate needs.

Abstract

Identifying the socio-economic drivers behind greenhouse gas emissions is crucial to design mitigation policies. Existing studies predominantly analyze short-term CO2 emissions from fossil fuels, neglecting long-term trends and other GHGs. We examine the drivers of all greenhouse gas emissions between 1820–2050 globally and regionally. The Industrial Revolution triggered sustained emission growth worldwide—initially through fossil fuel use in industrialized economies but also as a result of agricultural expansion and deforestation. Globally, technological innovation and energy mix changes prevented 31 (17–42) Gt CO2e emissions over two centuries. Yet these gains were dwarfed by 81 (64–97) Gt CO2e resulting from economic expansion, with regional drivers diverging sharply: population growth dominated in Latin America and Sub-Saharan Africa, while rising affluence was the main driver of emissions elsewhere. Meeting climate targets now requires the carbon intensity of GDP to decline 3 times faster than the global best 30-year historical rate (–2.25 % per year), which has not improved over the past five decades. Failing such an unprecedented technological change or a substantial contraction of the global economy, by 2050 global mean surface temperatures will rise more than 3 °C above pre-industrial levels.

Abstract

In contrast to most integrated assessment models, with limited transparency on damage functions and recursive temporal dynamics, we use a unique large-dimensional computational global climate and trade model, GTAP-DynW, to directly project the possible intertemporal impacts of water and heat stress on global food supply and food security to 2050. The GTAP-DynW model uses GTAP production and trade data for 141 countries and regions, with varying water and heat stress baselines, and results are aggregated into 30 countries/regions and 30 commodity sectors. Blue water stress projections are drawn from WRI source material and a GTAP-Water database to incorporate dynamic changes in water resources and their availability in agricultural production and international trade, thus providing a more general measure for severe food insecurity from water and heat stress damages with global warming. Findings are presented for three representative concentration pathways: RCP4.5-SSP2, RCP8.5-SPP2, and RCP8.5-SSP3 (population growth only for SSPs) and project: (a) substantial declines, as measured by GCal, in global food production of some 6%, 10%, and 14% to 2050 and (b) the number of additional people with severe food insecurity by 2050, correspondingly, increases by 556 million, 935 million, and 1.36 billion compared to the 2020 model baseline.

Abstract

Millions of non-producing oil and gas wells around the world are leaking methane and other contaminants, contributing to increased greenhouse gas emissions and polluting our water, soil, and air. Quantifying methane emissions and understanding the attributes driving these emissions are important for evaluating the scale of the environmental risks and informing mitigation strategies. With our national-scale direct measurement database of 494 non-producing wells across Canada, we find total annual methane emissions from non-producing wells in Canada to be 230 kt/year (51–560 kt/year) for 2023, which is 7 (1.5–16) times higher than estimated in Canada’s National Inventory Report (34 kt/year) and accounts for 13% of total fugitive emissions from oil and natural gas systems in Canada. We show that the role of well attributes in methane emissions is best evaluated by considering the emitting component (wellhead/surface casing vent) and the spatial scale (e.g., national, provincial, subprovincial). Large uncertainties in methane emissions from non-producing wells can be reduced not only with additional measurements but also with detailed well attribute analysis using direct measurements. Identifying attributes linked to high emitters can also be used to prioritize mitigation, thereby reducing methane emissions and broader environmental risks.

Highlights

Honeybee temporal removal on a small island increased nectar and pollen availability

Without honeybees, wild bees increased activity and changed hourly patterns

Without honeybees, wild bees increased nectar intake and optimized search time

Wild bee abundance declined ∼80% in 4 years, supporting trophic competition

Summary

High densities of managed honeybees (Apis mellifera) can threaten wild bees through exploitative competition, thus leading to population declines of the latter. Although reviews have outlined key steps to demonstrate these impacts—measuring resource overlap, changes in wild bee behavior, and population trends—studies that comprehensively address these aspects are virtually absent. We were granted access to the entire protected island of Giannutri (2.6 km2) and to the apiary (18 hives) located there during the early phase of coexistence between honeybees and wild bees. Using the island as an open-air laboratory, we experimentally manipulated honeybee pressure by closing the hives on selected days during the peak of the wild bee foraging period. In the plants most visited by pollinators, even short-term honeybee removals (11 h per day) increased nectar volume (∼60%) and pollen availability (∼30%). In the absence of honeybees, target wild bees (Anthophora dispar and Bombus terrestris) became dominant in the insect-plant visitation network, and the potential apparent competition significantly decreased. Accordingly, both species intensified their foraging activity and increased nectar suction time, a recognized proxy for the quantity of probed nectar, and Bombus terrestris also shortened the time of pollen searching. Transect monitoring revealed an alarming ∼80% decline in both species over 4 years, consistent with honeybee monopolization of floral resources, thus reducing availability for wild pollinators and altering their foraging budget. These findings underscore the risks of introducing high densities of honeybees into protected areas and emphasize the need for rigorous preventive ecological assessments.

Abstract

In this work, the electroreduction of carbon dioxide (CO2) to oxalate is enabled by incorporating trace metallic lead (Pb) on carbon-based supports (CBS) with polymer overlayers. These composite materials serve as an efficient electrocatalytic system for the facile conversion and storage of CO2, a pernicious atmospheric pollutant. Results from controlled potential electrolysis experiments indicate that 1) trace metallic Pb on the ppb scale is active toward the reductive coupling of CO2 to oxalate at comparable Faradaic efficiencies to bulk metallic Pb and 2) polymer encapsulation of this trace metallic Pb leads to promotion of CO2 reduction (CO2R) selectively to metal oxalates over other products such as CO. Importantly, metal oxalates are important alternative cementitious materials and precursors for other materials’ synthesis applications. The solid products undergo rigorous spectroscopic characterization, including 13CO2 labeling experiments, to ensure the metal oxalates are in fact produced from CO2R. These findings serve as a model for leveraging microenvironment effects to enhance activity and selectivity for CO2R using trace-metal catalysts for carbon utilization and storage technologies.