Are companies using Twitter to greenwash and hide bad environmental performance?

Companies and related consumer behaviours contribute significantly to global carbon emissions. However, consumer behaviour is shifting, with the public now recognising the real and immediate impact of climate change. Many companies are aware and seemingly eager to align to consumer’s increasing environmental consciousness, yet there is a risk that some companies could be presenting themselves as environmentally friendly without implementing environmentally beneficial processes and products (i.e. greenwashing). Here, using longitudinal climate leadership, environmental messaging (Twitter) and stock price data, we explore how climate leadership (a relative climate change mitigation metric) and environmental messaging have changed for hundreds of UK companies. Using the environmental messaging, we also assess whether companies are simply greenwashing their true climate change performance. Finally, we explore how climate leadership and environmental messaging influence companies’ stock prices. We found that companies (on average) have increased their climate leadership (coef: 0.14, CI 0.12–0.16) and environmental messaging (coef: 0.35, CI 0.19–0.50) between 2010 and 2019. We also found an association where companies with more environmental messaging had a higher climate leadership (coef: 0.16, CI 0.07–0.26), suggesting messaging was proportionate to environmental performance, and so there was no clear pattern of using Twitter for greenwashing across UK companies. In fact, some companies may be under-advertising their pro-environmental performance. Finally, we found no evidence that climate leadership, environmental messaging or greenwashing impacts a company’s stock price.

Widespread natural methane and oil leakage from sub-marine Arctic reservoirs

Parceling the anthropogenic and natural (geological) sources of fossil methane in the atmosphere remains problematic due to a lack of distinctive chemical markers for their discrimination. In this light, understanding the distribution and contribution of potential geological methane sources is important. We present empirical observations of hitherto undocumented, widespread and extensive methane and oil release from geological reservoirs to the Arctic Ocean. Methane fluxes from >7,000 seeps significantly deplete in seawater, but nevertheless reach the sea surface and may transfer to the air. Oil slick emission spots and gas ebullition are persistent across multi-year observations and correlate to formerly glaciated geological structures, which have experienced km-scale glacial erosion that has left hydrocarbon reservoirs partially uncapped since the last deglaciation ~15,000 years ago. Such persistent, geologically controlled, natural hydrocarbon release may be characteristic of formerly glaciated hydrocarbon-bearing basins which are common across polar continental shelves, and could represent an underestimated source of natural fossil methane within the global carbon cycle.

Carbon cycle perturbation and mercury anomalies in terrestrial Oceanic Anoxic Event 1b from Jiuquan Basin, NW China

The Oceanic Anoxic Event (OAE) 1b is well documented in western Tethys, however, records in Eurasia are still lacking. Here, we carried out high-resolution organic carbon isotope (δ13Corg), total organic carbon (TOC) contents and mercury (Hg) concentrations analysis of the lacustrine sediments from the Xiagou and Zhonggou formations in the Hanxiagou section, Jiuquan Basin, northwestern China. The lacustrine δ13Corg curve presents three stages of negative excursions above the basalt layer dated at 112.4 ± 0.3 Ma in the lowermost Zhonggou Formation. The three negative δ13Corg excursions, well corresponded with the three subevents (Kilian, Paquier, and Leenhardt) of the OAE1b in Poggio le Guaine (central Italy), Vocontian Basin (SE France) and St Rosa Canyon (NE Mexico) sections, supporting the record of the terrestrial OAE 1b in the Jiuquan Basin. Five mercury enrichment (ME) intervals in Hg/TOC ratios were recognized, indicating that the pulsed volcanism from the southern Kerguelen Plateau likely triggered the OAE 1b. However, the decoupling between NIE shifts and mercury enrichments signifying other carbon reservoir (with no link to mercury) probably contributed to the global carbon cycle perturbation during the OAE 1b period. Our results provide direct evidence to link the OAE 1b and terrestrial ecosystem in the Eurasia.

The Variability of Air-sea O2 Flux in CMIP6: Implications for Estimating Terrestrial and Oceanic Carbon Sinks

The measurement of atmospheric O2 concentrations and related oxygen budget have been used to estimate terrestrial and oceanic carbon uptake. However, a discrepancy remains in assessments of O2 exchange between ocean and atmosphere (i.e. air-sea O2 flux), which is one of the major contributors to uncertainties in the O2-based estimations of the carbon uptake. Here, we explore the variability of air-sea O2 flux with the use of outputs from Coupled Model Intercomparison Project phase 6 (CMIP6). The simulated air-sea O2 flux exhibits an obvious warming-induced upward trend (∼1.49 Tmol yr−2) since the mid-1980s, accompanied by a strong decadal variability dominated by oceanic climate modes. We subsequently revise the O2-based carbon uptakes in response to this changing air-sea O2 flux. Our results show that, for the 1990–2000 period, the averaged net ocean and land sinks are 2.10±0.43 and 1.14±0.52 GtC yr−1 respectively, overall consistent with estimates derived by the Global Carbon Project (GCP). An enhanced carbon uptake is found in both land and ocean after year 2000, reflecting the modification of carbon cycle under human activities. Results derived from CMIP5 simulations also investigated in the study allow for comparisons from which we can see the vital importance of oxygen dataset on carbon uptake estimations.

Soil Organic Carbon and Geochemical Characteristics on Different Rocks and Their Significance for Carbon Cycles

Soil organic carbon (SOC) is significant for soil quality and global carbon cycles. SOC was observed to be related to soil geochemistry, and soils originating from different bedrocks have different geochemical properties, but the effect of bedrock on SOC is still undefined. Soils overlying different bedrocks in Zhenxiong County and Weixin County were sampled. Specifically, soils in the mineral horizon, which are less affected by the external environment than surface soils, are focused on to reveal the effect of bedrock on SOC. Al/Ti, Fe/Ti, and Al/Fe indicate a soil–rock successive relationship. SOC contents in the mineral horizon are 0.19–2.74% (1.24% on average), and those in the surface horizon are 1.26–4.01% (2.63% on average). SOC contents in the surface and mineral horizons of the same bedrock are significantly positively correlated, implying that the bedrock is an important factor affecting SOC. SOC in the mineral horizon is related to the first transition metal ions. Significantly, positive correlations of SOC (p < 0.01) with Co, Cu, Ti, V, and Zn, and a positive correlation (p < 0.05) with Ni were observed in the mineral horizon. Organic transition metal complexation seems to play an important role in governing SOC in the mineral horizon. That is, the complexation maintains organic carbon stability, slows down its decomposition rate, and accumulates organic carbon. The Ca–SOC positive correlation in the mineral horizon exits because Ca also can complex with organic carbon. Co, Cu, and V–SOC positive correlations (p < 0.05) were also observed, but there were no significant positive correlations (p < 0.01) in the surface horizon because surface SOC had diversified sources. An SOC evolution model influenced by the bedrock was forwarded. Thus, the different soil geochemistry originating from different bedrocks should be noticed when SOC and global carbon cycles are discussed.

Unravelling microalgal-bacterial interactions in aquatic ecosystems through 16S co-occurrence networks

Microalgae and bacteria have a wide spectrum of associations in aquatic environments. Since their interactions can directly influence global carbon and nutrient cycling, understanding these associations help us evaluate their influence on ecosystem productivity. Algal biodiversity is large, and bacterial associations have been characterised for a small fraction of them. While experiments based on algal-bacterial co-culturing are commonly used to infer interactions, deciphering all associations present in nature through such methods is impractical and approaches based on co-occurrence network analysis can help infer associations. In this study, we used microbial co-occurrence networks built from Earth microbiome project 16S metabarcoding data to detect microalgal-bacterial associations in aquatic environments. We analysed marine and freshwater environments to understand what groups of bacteria are tightly co-occurring with different algal groups in both aquatic environments, to see patterns of interactions, and to evaluate the overall use of co-occurrence networks to infer meaningful algal-bacterial interactions. In line with expectations from co-culturing work, our results show that the phyla Proteobacteria and Bacteroidetes are the major bacterial associates of microalgae and the co-occurring bacteria may be specific to the algal host. From the independent analysis of environments, we also show that sample origin may be an important determinant of these interactions. By unravelling previously established microalgal-bacterial links as well as identifying a range of previously unknown interactions, we show that co-occurrence network analysis is a promising hypothesis-generating framework to study microalgal-bacterial interactions that can guide future research into the functional nature of interactions.

Structural Analysis of Lignin-Based Furan Resin

The global “carbon emission peak” and “carbon neutrality” strategic goals promote us to replace current petroleum-based resin products with biomass-based resins. The use of technical lignins and hemicellulose-derived furfuryl alcohol in the production of biomass-based resins are among the most promising ways. Deep understanding of the resulting resin structure is a prerequisite for the optimization of biomass-based resins. Herein, a semiquantitative 2D HSQC NMR technique supplemented by the quantitative 31P NMR and methoxyl group wet chemistry analysis were employed for the structural elucidation of softwood kraft lignin-based furfuryl alcohol resin (LFA). The LFA was fractionated into water-insoluble (LFA-I) and soluble (LFA-S) parts. The analysis of methoxyl groups showed that the amount of lignin was 85 wt% and 44 wt% in LFA-I and LFA-S fractions, respectively. The HSQC spectra revealed the high diversity of linkages formed between lignin and poly FA (pFA). The HSQC and 31P results indicated the formation of new condensed structures, particularly at the 5-position of the aromatic ring. Esterification reactions between carboxyl groups of lignin and hydroxyl groups of pFA could also occur. Furthermore, it was suggested that lignin phenolic hydroxyl oxygen could attack an opened furan ring to form several aryl ethers structures. Therefore, the LFA resin was produced through crosslinking between lignin fragments and pFA chains.