Found 2770 publications. Showing page 9 of 277:
State of the Climate in 2024: Global Climate
For the second year in a row, record-high global surface temperatures were set in 2024, according to all six global temperature datasets assessed in this report (Berkeley Earth, GISTEMP, HadCRUT5, the NOAA Merged Land Ocean Global Surface Temperature Analysis [NOAAGlobalTemp], ERA5, and the Japanese Reanalysis for Three Quarters of a Century [JRA-3Q]). The last time consecutive years set records was in 2015 and 2016 when a strong El Niño similarly boosted global temperatures. The last 10 years (2015–24) are now the warmest 10 in the instrumental record—warmer than the 2011–20 average—and hence “more likely than not warmer than any multi-century period after the last interglacial period, roughly 125,000 years ago” (Gulev et al. 2021). The increased energy within the climate system is detectable at the top of the atmosphere, with the outgoing longwave radiation anomaly continuing to be above the range of natural variability.
During 2024, El Niño conditions that had been present since the middle of 2023 faded to neutral by the end of the year. The warm conditions observed around the globe over the last two years had impacts across the climate system, as demonstrated by many of the metrics presented in this chapter. Other temperature metrics also reached record levels over the instrumental periods assessed in this chapter: over the oceans at night, on the surfaces of lakes, and in the lower troposphere as well as measures of equivalent temperature (which considers the moisture contribution to heat), and high and low temperature extremes.
The frozen parts of Earth responded with permafrost temperatures continuing to reach record-high levels in many locations, and the active-layer thickness (the portion that melts and refreezes annually) also increasing at most sites. Repeated high temperatures over the European Alps during recent summers has led to large increases in rock glacier velocities in that region. The Great Lakes had much-below-average ice cover over the 2023/24 winter, and there was below-average snow cover extent in the Northern Hemisphere. All 58 reference glaciers across five continents lost ice during 2024, resulting in the greatest average ice loss in the record, which began in 1970. One more glacier was also declared extinct during 2024.
Higher global temperatures impacted the water cycle. Although lower than 2023 values, water evaporation from land in the Northern Hemisphere reached one of the highest annual values on record, in line with the long-term increasing trend. Specific humidity reached record levels over land and ocean, and relative humidity over both domains was higher than 2023. There was little relief from high humid-heat conditions, with the frequency of high humid-heat days at a record level and intensity at the second-highest level in the record—only a fraction of a degree cooler than that of 2023. The global atmosphere contained the greatest amount of water vapor in the record, and over one-fifth of the globe recorded their highest values. This far exceeded 2023, where only one-tenth of the globe experienced record-high total column water vapor. Rainfall was globally high; 2024 was the third-wettest year since records began in 1983. However, rainfall over land was close to average, while over the ocean it was the fourth-wettest year on record (following 2015, 2016, and 1998). Extreme rainfall, as characterized by the annual maximum daily rainfall over land, was the wettest on record. Averaged globally (4190 lakes), lakes had a small increase in water storage, and regionally, over 40% of monitored lakes showed significant changes in storage and level.
The effects of ongoing droughts in southern Africa and in North and South America can be seen in the soil moisture and water storage patterns. They are also apparent in the river discharge and runoff levels, which are topics that will be covered in the chapter after a few years of absence. Globally, however, drought severity and extent decreased from the record set in 2023.
Atmospheric concentrations of the three main greenhouse gases (carbon dioxide [CO2], methane [CH4], nitrous oxide [N2O]) again all reached record levels, with a record-equal annual increase in the annual change of CO2 concentrations. However, concentrations of ozone-depleting substances continued to decline, corroborated by stratospheric ozone columns well above the 1998–2008 average, especially in the Northern Hemisphere. In contrast, stratospheric aerosols remained high because of the Ruang eruption in April 2024, affecting the atmospheric transmission of solar radiation over Hawaii later in the year, and the ongoing effects from the Hunga eruption in 2022. The latter eruption also caused the ongoing elevated stratospheric water vapor concentrations.
Our planet’s surface albedo continued to darken with increased plant growth and decreased snow and ice cover. Plants responded to the warmer temperatures with some of the earliest starts to spring in the record over Europe—one to two weeks earlier than the 2000–20 baseline—and a warm autumn resulted in a much longer leaf-on season. Severe wildfire seasons occurred in South America (the worst since 2010), Canada (for the second consecutive year), and the Arctic, contributing to the second-highest atmospheric carbon monoxide concentrations since 2003 and the highest tropospheric aerosol optical depth since 2019, at 550 nm.
This year’s iteration of the Global Climate chapter features two Sidebars, both of which present new topics that have not yet been explored in the report. The first covers the ability of satellite products to monitor changes in land surface temperature extremes and identify hotspots where regions of Earth are becoming uninhabitable. This Sidebar also discusses the importance of dataset stability for climate studies, as well as the correlation of land surface temperature and air temperature anomalies. The second Sidebar complements the section on greenhouse gas concentrations by examining short-lived climate forcers—compounds that have lifetimes ranging from a few hours to a few decades.
As usual in the Global Climate chapter, Plate 2.1 shows maps of global annual anomalies for many of the variables and metrics presented herein. Many of these variables are also presented as time series in Plate 1.1. Most sections now use the 1991–2020 climatological reference period, in line with the World Meteorological Organization’s (WMO) recommendations, although this reference period is not possible for all datasets due to their length or legacy processing methods.
2025
Industrial and public infrastructure as local sources of organic contaminants in the Arctic
Arctic pollution has been a focal point in environmental research over the past five decades. Recently, the number of pollutants identified as relevant to the Arctic has significantly increased. Consequently, the expert group on Persistent Organic Pollutants (POPs) and Chemicals of Emerging Arctic Concern (CEACs) of the Arctic Monitoring and Assessment Programme (AMAP) has prepared a series of assessments of contaminants in the Arctic, including influences of climate change. This review addresses local sources of Arctic organic pollutants associated with infrastructure in the Arctic. Industrial, military, and public infrastructures, including domestic installations, sewage treatment, solid waste management, and airports, were identified as significant local pollution sources. Additionally, operational emissions (e.g., from shipping, transportation, heating, and power production) contribute to the overall local pollution profile. Based on currently available scientific information, elevated POP and CEAC levels are mostly found in close proximity to identified local pollution sources. To date, hazardous effects have only been confirmed for a few selected chemicals, such as polycyclic aromatic compounds (PAC) and certain pharmaceutical residues. However, studies are biased in the sense that they often focus on well-known contaminants, at a risk of overlooking CEAC and their effects. The review identifies several measures to reduce human impacts on local Arctic environments, including (i) using local indicator pollutants in ongoing national monitoring schemes, (ii) harmonizing emission reduction policies and licensing of industrial activities in the region to minimize exposure risks and environmental pollution, (iii) encouraging local municipalities, industries, and related stakeholders to coordinate their activities to minimize pollutant emissions.
2025
Quantifying European SF6 emissions from 2005 to 2021 using a large inversion ensemble
Abstract. Sulfur hexafluoride (SF6) is a highly potent and long-lived greenhouse gas whose atmospheric concentrations are increasing due to human emissions. In this study, we determine European SF6 emissions from 2005 to 2021 using a large ensemble of atmospheric inversions. To assess uncertainty, we systematically vary key inversion parameters across 986 sensitivity tests and apply a Monte Carlo approach to randomly combine these parameters in 1003 additional inversions. Our analysis focuses on high-emitting countries with robust observational coverage – UK, Germany, France, and Italy – while also examining aggregated EU-27 emissions. SF6 emissions declined across all studied regions except Italy, largely attributed to EU F-gas regulations (2006, 2014), however, national reports underestimated emissions: (i) UK emissions dropped from 68 (47–77) t yr−1 in 2008 to 19 (15–26) t yr−1 in 2018, aligning with the reports from 2018 onward; (ii) French emissions fell from 78 (51–117) t yr−1 (2005) to 35 (19–54) t yr−1 (2021), exceeding reports by 88 %; (iii) Italian emissions fluctuated (25–48 t yr−1), surpassing reports by 107 %; (iv) German emissions declined from 182 (155–251) t yr−1 (2005) to 97 (88–104) t yr−1 (2021), aligning reasonably well with reports; (v) EU-27 emissions decreased from 403 (335–501) t yr−1 (2005) to 225 (191–260) t yr−1 (2021), exceeding reports by 20 %. A substantial drop from 2017 to 2018 mirrored the trend in southern Germany, suggesting regional actions were taken as the 2014 EU regulation took effect. Our sensitivity tests highlight the crucial role of dense monitoring networks in improving inversion reliability. The UK system expansions (2012, 2014) significantly enhanced result robustness, demonstrating the importance of comprehensive observational networks in refining emission estimates.
2025
Biomethanol as a Marine Fuel Within Land Use Sustainability Boundaries
Global shipping is an essential, energy-efficient enabler of trade, yet it remains a hard-to-abate sector. With shipping demand projected to continue to rise in the coming decades, identifying scalable and sustainable fuel alternatives is critical. Biofuels, and particularly biomethanol, offer a promising option due to their compatibility with existing infrastructure. However, their sustainability critically hinges on land use impacts. From this Perspective, we argue that biomethanol derived from a dedicated crop could contribute to maritime decarbonisation, with ~71–77% well-to-wake greenhouse gases (GHG) reductions under cropland-only constraints. We further point to the fact that a wider adoption faces challenges such as higher costs, limited availability, and lower energy density relative to fossil fuels. Continued research and monitoring are essential to ensure that biofuel production does not inadvertently contribute to deforestation or biodiversity loss. We underscore the need for spatially sensitive biofuel deployment strategies that align maritime decarbonisation with land-system sustainability and climate objectives.
2025
Fine particulate matter (PM) poses a major threat to public health, with organic aerosol (OA) being a key component. Major OA sources, hydrocarbon-like OA (HOA), biomass burning OA (BBOA), and oxygenated OA (OOA), have distinct health and environmental impacts. However, OA source apportionment via positive matrix factorization (PMF) applied to aerosol mass spectrometry (AMS) or aerosol chemical speciation monitoring (ACSM) data is costly and limited to a few supersites, leaving over 80% of OA data uncategorized in global monitoring networks. To address this gap, we trained machine learning models to predict HOA, BBOA, and OOA using limited OA source apportionment data and widely available organic carbon (OC) measurements across Europe (2010–2019). Our best performing model expanded the OA source data set 4-fold, yielding 85 000 daily apportionment values across 180 sites. Results show that HOA and BBOA peak in winter, particularly in urban areas, while OOA, consistently the dominant fraction, is more regionally distributed with less seasonal variability. This study provides a significantly expanded OA source data set, enabling better identification of pollution hotspots and supporting high-resolution exposure assessments.
2025
2025
Reliable quantification of polychlorinated alkanes (PCAs) remains a major challenge, hindering environmental research across diverse matrices. Each sample can contain over 500 homologue groups, collectively producing >1000 m/z ratios that require interference checks. High-resolution mass spectrometry methods vary in ionization signals and data formats and require specialized algorithms for quantification. CPxplorer streamlines data processing through the integration of three modules: (1) CPions generates target ion sets and isotopic thresholds for compound identification into the next module; (2) Skyline performs instrument-independent data integration, interference evaluation, and homologue profiling; and (3) CPquant deconvolves homologues and reports concentrations using reference standards and homologue profiles from Skyline. Evaluation of the workflow with NIST-SRM-2585 dust and ERM-CE100 fish tissue material yielded comparable results across raw data formats from different instruments. Further applications of CPxplorer across diverse matrices, including indoor dust, organic films, silicone wrist bands, and food samples, demonstrated the usefulness in biological and environmental monitoring. Compared to existing tools limited to qualitative detection, CPxplorer enables quantitative outputs, reduces processing time, and expands functionality to PCA-like substances (e.g., BCAs) and PCA degradation products (e.g., OH-PCAs). CPxplorer reduces learning barriers, empowers users to quantify PCAs across various analytical instruments, and contributes to generating comparable results in the field.
2025
Tidal Amplification in the Lower Thermosphere During the 2003 October–November Solar Storms
Abstract Using the National Center for Atmospheric Research's vertically extended version of the Whole Atmosphere Community Climate Model nudged with reanalyses, we examine the impact of the 2003 Halloween solar storms on atmospheric tides and planetary waves in the lower thermosphere (LT). One of the largest solar flares and fastest coronal mass ejections on record occurred on 30 October, resulting in significant energy transfer via Joule heating and auroral particle precipitation in the Earth's higher latitude thermosphere. In the simulation, that occurrence creates large zonally asymmetric heating perturbations, amplifying the diurnal migrating tide (DW1), semidiurnal migrating tide (SW2), as well as non‐migrating westward and eastward tides between 120 and 200 km. Large‐amplitude bursts of DW1 in the Northern Hemisphere and non‐migrating westward tides in the Southern Hemisphere lead to westward wave forcings, which strengthen the thermospheric wind. Planetary waves are also amplified, but their forcing is much weaker than the forcing exerted by tides in the LT. Non‐migrating tides are generated by nonlinear interactions between tides, or between tides and quasi‐stationary planetary waves, and in situ processes in the LT linked to Joule heating and auroral particle precipitation. The induced disruptions of the thermospheric mean meridional circulation reinforce the Spring thermospheric branch in the Southern Hemisphere at high latitudes and oppose the Fall branch in the Northern Hemisphere. Our examination could be relevant to understand the dynamical impact of recent geomagnetic storms that occurred in May 2024 and October 2024.
2025
The role of the tropical carbon balance in determining the large atmospheric CO2 growth rate in 2023
Abstract. The global annual mean atmospheric CO2 growth rate in 2023 was one of the highest since records began in 1958, comparable to values recorded during previous major El Niño events. We do not fully understand this anomalous growth rate, although a recent study highlighted the role of boreal North American forest fires. We use a Bayesian inverse method to interpret global-scale atmospheric CO2 data from NASA's Orbiting Carbon Observatory (OCO-2). The resulting a posteriori CO2 flux estimates reveal that from 2022 to 2023, the biggest changes in CO2 fluxes of net biosphere exchange (NBE) – for which positive values denote a flux to the atmosphere – were over the land tropics. We find that the largest NBE increase is over eastern Brazil, with small increases over southern Africa and Southeast Asia. We also find significant increases over southeastern Australia, Alaska, and western Russia. A large NBE increase over boreal North America, due to fires, is driven by our a priori inventory, informed by independent data. The largest NBE reductions are over western Europe, the USA, and central Canada. Our NBE estimates are consistent with gross primary production estimates inferred from satellite observations of solar-induced fluorescence and from satellite observations of vegetation greenness. We find that warmer temperatures in 2023 explain most of the NBE change over eastern Brazil, with hydrological changes more important elsewhere across the tropics. Our results suggest that the ongoing environmental degradation of the Amazon is now playing a substantial role in increasing the global atmospheric CO2 growth rate.
2025
Satellite instruments for measuring atmospheric column mixing ratios have improved significantly over the past couple of decades, with increases in pixel resolution and accuracy. As a result, satellite observations are being increasingly used in atmospheric inversions to improve estimates of emissions of greenhouse gases (GHGs), particularly CO2 and CH4, and to constrain regional and national emission budgets. However, in order to make use of the increasing resolution in inversions, the atmospheric transport models used need to be able to represent the observations at these finer resolutions. Here, we present a new and computationally efficient methodology to model satellite column average mixing ratios with a Lagrangian particle dispersion model (LPDM) and calculate the Jacobian matrices describing the relationship between surface fluxes of GHGs and atmospheric column average mixing ratios, as needed in inversions. The development will enable a more accurate representation of satellite observations (especially high-resolution ones) via the use of LPDMs and, thus, help improve the accuracy of emission estimates obtained by atmospheric inversions. We present a case study using this methodology in the FLEXPART (FLEXible PARTicle dispersion model) LPDM and the FLEXINVERT inversion framework to estimate CH4 fluxes over Siberia using column average mixing ratios of CH4 (XCH4) from the TROPOMI (TROPOspheric Monitoring Instrument) instrument aboard the Sentinel-5P satellite. The results of the inversion using TROPOMI XCH4 are evaluated against results using ground-based observations.
2025