Skeptical Science New Research for Week #30 2025

Posted on 24 July 2025 by Doug Bostrom, Marc Kodack

Open access notables

Calculating the Temperature Trend Bias Induced by Inhomogeneities Into Climate Data Without Running a Homogenization Algorithm, Lindau, International Journal of Climatology

Inhomogeneities are known to induce sudden jumps into the time series of climate stations. If these jumps tend to be upwards, a spurious positive trend will be inserted into the data, which would falsify the true climate trend. The classic method to identify such biases is to run a homogenisation algorithm and to assess the statistics of the found jump heights. However, in the past it was shown that already small detection errors lead to a strong systematic underestimation of such trend biases. Therefore, an alternative method is proposed that calculates the trend bias directly from the original data without previous homogenisation. First, the Composite Reference (CR) technique is applied where networks of neighbouring stations are compiled and one station is selected as a candidate from which the average of the others is subtracted. In this way, not only the common climate signal is eliminated, but also the common trend bias. However, we do not use the CR data directly, but consecutive differences of it, thus the change from year-to-year within the CR time series. In this way, large data volumes are available which are of course dominated by noise, but also the effect of a possible trend bias is traceable. Every break occurring in the candidate arises also in the reference of all other stations, where it is attenuated by averaging and with opposite sign, as the reference is subtracted. In this way, every inhomogeneity produces one large jump and many small ones with reversed sign so that the median is shifted. This effect is exploited in the proposed method. An application to temperature data from U.S. climate stations shows that there is no significant trend bias caused by inhomogeneities.

Unprecedentedly high global forest disturbance due to fire in 2023 and 2024, Potapov et al., Proceedings of the National Academy of Sciences

Global forests provide key ecosystem services, from climate regulation to biodiversity habitat, but are under increasing pressure from the combined impacts of climate and land use change. Here, we show that forest disturbance due to fire is growing globally, with the most dramatic increases in intact forest landscapes, highlighting an existential threat to remaining high biomass, high biodiversity forests. The global annual area of forest disturbance due to fire for 2023 and 2024 was highest since the beginning of monitoring in 2001. Compared to 2002–2022 average annual forest disturbance due to fire, the 2023–2024 average was 2.2 times higher globally and 3 times higher in the Tropics. More than ¼ of all 2024 forest disturbance from fire occurred in tropical forests. We found a statistically significant increasing trend of forest disturbance due to fire from 2002 to 2024 in all climate domains except Subtropical. High forest, low deforestation tropical countries were not exempt, with Guyana and the Republic of the Congo experiencing record forest disturbance due to fire. Our results agree with recently estimated increases in global forest fire emissions and active fire detections. The unprecedented scale of fires in the world’s most remote forests is a potential harbinger of ecosystem tipping points. Protecting these remaining unfragmented high conservation value forests from this threat poses a daunting and as yet undeveloped policy and capacity challenge.

Svalbard winter warming is reaching melting point, Bradley et al., Nature Communications

The Arctic is at the forefront of global climate change and is encountering unprecedented winter warming. In February 2025, exceptionally high air temperatures and rainfall over Svalbard triggered widespread snowmelt and pooling of meltwater. Increasingly frequent winter thaw events are reshaping Arctic landscapes, signaling a dramatic shift towards a new Arctic.

Strengthening Atmospheric Greenhouse Effect at the Arctic North Slope of Alaska Site Evidenced by Long-Term Records of the Downwelling Longwave Radiance Spectrum, Riot-Bretêcher et al., Journal of Geophysical Research: Atmospheres

Arctic amplification, the accelerated warming of the Arctic compared to lower latitude, remains poorly understood, particularly regarding the role of clouds. In this study, we analyze 26 years of downwelling longwave radiation (DLR) measurements from an Extended-range Atmospheric Emitted Radiance Interferometer (E-AERI) at the US Department of Energy’s North Slope of Alaska site. Our analysis reveals a pan-spectral increase in DLR under all sky conditions, primarily driven by an enhanced greenhouse effect from thick/low clouds and greenhouse gases. We find that the observed DLR trends are primarily driven by radiance changes within individual sky conditions, rather than changes in cloud fraction, suggesting fundamental shifts in atmospheric emissivity and/or temperature. Comparative analysis between the Southern Great Plains (mid-latitude) and North Slope of Alaska (high-latitude) sites demonstrates that clouds impact the longwave surface energy balance differently between the two locations. In the Arctic, the pan-spectral increase in DLR trend dampens out the radiative cooling of the warming surface, contributing significantly to Arctic amplification. Consistent positive trends are found in the far-infrared, a spectral region sensitive to even small changes of the dry and cold Arctic’s atmosphere and of significant interest in the current warming context. Additionally, we observe a relatively weaker DLR trend in the ozone absorption band under every sky condition, indicating a tropospheric ozone radiative forcing in the Arctic climate. 

Calibrated sea level contribution from the Amundsen Sea sector, West Antarctica, under RCP8.5 and Paris 2C scenarios, EGUSphere, Rosier et al.

The Amundsen Sea region in Antarctica is a critical area for understanding future sea level rise due to its rapidly changing ice dynamics and significant contributions to global ice mass loss. Projections of sea level rise from this region are essential for anticipating the impacts on coastal communities and for developing adaptive strategies in response to climate change. Despite this region being the focus of intensive research over recent years, dynamic ice loss from West Antarctica and in particular the glaciers of the Amundsen Sea represent a major source of uncertainty for global sea level rise projections. In this study, we use ice sheet model simulations to make sea level rise projections to the year 2100 and quantify the associated uncertainty. The model is forced by climate and ocean model simulations for the RCP8.5 and Paris2C scenarios, and is carefully calibrated using measurements from the observational period. We find very similar sea level rise contributions of 19.0 ± 2.2 mm and 18.9 ± 2.7 mm by 2100 for Paris2C and RCP8.5 scenarios, respectively. A subset of these simulations, extended to 2250, show an increase in the rate of sea level rise contribution and clearer differences between the two scenarios emerge as a result of differences in snow accumulation. Our model simulations include both a cliff-height and hydrofracture driven calving processes and yet we find no evidence of the onset of rapid retreat that might be indicative of a tipping point in any simulations within our modelled timeframe.

From this week’s government/NGO section

The Impact of Climate Change on Occupational Safety and Health in Selected Sectors. A Scoping Review, Maistrello et al, Lloyds Register Foundation

A review of the evidence on the impacts of climate change on worker safety and health found that climate change is a global phenomenon, but not all regions will be equally affected; approaches to protect workers need both global data and local knowledge to be effective; workers across all sectors will be affected, but not all sectors or occupations carry the same risks or have been researched equally; and ocean workers are represented across several high-risk sectors which are particularly affected by climate change including fishing and aquaculture, energy, and transport.

Hot for Six: The Danger Zone, FrontRunners, British Association for Sustainability in Sport (BASIS), Climate Central, and The Next Test

No major cricketing nation is unaffected by our changing climate. India, Pakistan, Bangladesh, Australia, New Zealand, South Africa, the Caribbean and the UK are all facing a variety of climate extremes that impact the game at all levels, from the professional to the grassroots. The authors analyze 65 matches played in the 2025 Indian Premier League to reveal that more than half were played in conditions classified as meriting either “Extreme Caution” or “Danger” on the Heat Index — a measure that combines air temperature and humidity to assess heat related risk. 27 of those took place under “Extreme Caution” conditions – where heat exhaustion becomes a serious threat. A further nine reached the “Danger” zone, where sunstroke, muscle cramps, and even heat exhaustion are likely, and heatstroke possible with prolonged exposure. These fresh data uncover a stark picture of one of the world’s biggest sporting leagues edging deeper into a climate danger zone.

94 articles in 44 journals by 536 contributing authors

Physical science of climate change, effects

Decomposing Cloud Radiative Feedbacks by Cloud-Top Phase, Wall et al., Journal of Climate 10.1175/jcli-d-24-0538.1

Explaining Observed Daily Variations and Decadal Trends in the Diurnal Air Temperature Range, Ghausi et al., Open Access 10.22541/au.174664163.35072035/v1