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The New Year has rung in with one of the most horrific wildfire events in world history: an urban firestorm in the Los Angeles metro area that has killed at least five people and reduced thousands of homes to smoking rubble. Two major fires in excess of 10,000 acres – the Palisades fire in the western suburbs of Los Angeles, and the Eaton fire in the northern suburbs – were intensified by severe drought and driven by winds gusting up to 100 mph (161 km/hr) from a severe Santa Ana wind event.

Climate scientist Daniel Swain said on CNN that the Pacific Palisades fire alone may end up as the most expensive wildfire in history, and that he expected that collectively, the fires ravaging the region will be the costliest wildfire event in history. According to NOAA, the most expensive wildfire season on record (in 2024 USD, to account for inflation) was the $30 billion 2018 season, mostly because of severe fires in California. This included the most destructive wildfire on record – the November Camp Fire, which devastated Paradise, California, killing 85 and destroying over 18,800 buildings. That fire cost $20 billion (2024 USD), according to EM-DAT, making it the most expensive single fire in world history.

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2025 SkS Weekly Climate Change & Global Warming News Roundup #02

Posted on 12 January 2025 by BaerbelW, Doug Bostrom

A listing of 23 news and opinion articles we found interesting and shared on social media during the past week: Sun, January 5, 2025 thru Sat, January 11, 2025.

This week's roundup is again published soleley by category. We are still interested in feedback to hone the categorization, so if you spot any clear misses and/or have suggestions for additional categories, please let us know in the comments. Thanks!

Stories we promoted this week, by category:

Climate Change Impacts

Climate Change Mitigation and Adaptation

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Skeptical Science New Research for Week #2 2025

Posted on 9 January 2025 by Doug Bostrom, Marc Kodack

Open access notables

Large emissions of CO2 and CH4 due to active-layer warming in Arctic tundra, Torn et al., Nature Communications:

Climate warming may accelerate decomposition of Arctic soil carbon, but few controlled experiments have manipulated the entire active layer. To determine surface-atmosphere fluxes of carbon dioxide and methane under anticipated end-of-century warming, here we used heating rods to warm (by 3.8 °C) to the depth of permafrost in polygonal tundra in Utqia?vik (formerly Barrow), Alaska and measured fluxes over two growing seasons. We show that ecosystem respiration is ~30% higher in warmed plots than in control plots (0.99 μmol m−2 s−1 versus 0.67 μmol m−2 s−1, p < 0.0001, n = 79). Additionally, the observed temperature sensitivity (Q10 of 2.8) is higher than that imposed for soil in Earth system models or reported by arctic experiments warming only the surface. A shoulder-season warming experiment revealed that rapid snow melt, which is becoming a more common event, can result in large methane emissions that may have otherwise been oxidized to carbon dioxide. Thus, warming promotes greenhouse gas emissions from the whole, deepening active layer and may contribute to climate change amplification.

Accelerated Permafrost Thaw Linked to Rising River Temperature and Widening Channels, Zhao & Li, Geophysical Research Letters:

River-controlled permafrost dynamics are crucial for sediment transport, infrastructure stability, and carbon cycle, yet are not well understood under climate change. Leveraging remotely sensed datasets, in-situ hydrological observations, and physics-based models, we reveal overall warming and widening rivers across the Tibetan Plateau in recent decades, driving accelerated sub-river permafrost thaw. River temperature of a representative section (Tuotuohe River) on the central Tibetan Plateau, has increased notably (0.39°C/decade) from 1985 to 2017, facilitating heat transfer into the underlying permafrost via both convection and conduction. Consequently, the permafrost beneath rivers warms faster (0.37°C–0.66°C/decade) and has a ∼0.5 m thicker active layer than non-inundated permafrost (0.17°C–0.49°C/decade). With increasing river discharge, the inundated area expands laterally along the riverbed (16.4 m/decade), further accelerating permafrost thaw for previously non-inundated bars. Under future warmer and wetter climate, the anticipated intensification of sub-river permafrost degradation will pose risks to riverine infrastructure and amplify permafrost carbon release.

On the economic feasibility of tidal range power plants, Pappas et al., Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science:

The potential energy associated with tides presents a sustainable energy resource that remains largely untapped. Uncertainties on the economic case of tidal range power plants are a known obstacle. Research on tidal range structures suggests energy yield may be maximized through operation strategy optimization, and that impacts can be mitigated through design optimization. While instructive, these perspectives alone are insufficient to support the feasibility of individual projects. We integrate operation optimization and hydrodynamic impact analyses within a cost evaluation framework for tidal range structures focusing on capital costs (CAPEX) and levelized cost of energy (LCOE). Once benchmarked against 11 historic proposal cost projections, we perform a redesign of 18 tidal power plants to deliver a comprehensive comparative basis across a diverse range of sites in the UK. Tidal power plant operation is simulated in regional shallow-water equation models, acknowledging tide variability. The cost evaluation framework demonstrates the impact of geospatial variations on key cost components. The redesign process indicates transformative implications in that equivalent and lower LCOE values can be achieved for designs at a substantially lower CAPEX. Given how the latter hinder development, we show how tidal range schemes could be far more economically feasible than commonly perceived.

Rethinking the “Levelized Cost of Energy”: A critical review and evaluation of the concept, Emblemsvåg, Energy Research & Social Science:

The Levelized Cost of Energy (LCOE) is frequently used for policymaking worldwide, modeling and in assessing the cost competitiveness of technologies, but its formulation is deceptively simple. The result is that many caveats are obscured, but they are important to understand so that LCOE calculations can become more accurate and communicated more correctly to avoid misleading policymakers and decisionmakers. The paper discusses the approach, and how a handful of influential and reputable organizations calculate and communicate the LCOE. The conclusion is that the introduction of variable renewable energy sources into the grid has made the LCOE questionable towards it initial purpose of providing a sound basis for comparison, and most reputed organizations fail to address the issues both computationally and in their communication. However, significant improvements to regain relevance can be made by using realistic assumptions as shown by presenting a reconceptualized version of LCOE and communicate the unsolved shortcomings to stakeholders.

The changing language and sentiment of conversations about climate change in Reddit posts over sixteen years, Fariello & Jemielniak, Communications Earth & Environment:

Here, we analyze 16 years of Reddit discussions, encompassing 11.5 billion posts, to examine how language surrounding climate change has evolved over time from 2005 to 2021. We applied sentiment analysis, polarity, subjectivity, and readability metrics to discussions of “global warming” and “climate change”. We found that the use of “climate change” surpassed “global warming” in 2013, with “climate change” associated with more negative sentiment and higher subjectivity. Additionally, we observed a decline in the proportion of climate-related discussions over time despite the increasing total number of posts. These findings suggest that public engagement with climate topics on Reddit is waning, and the choice of terminology significantly influences the tone and complexity of the discourse. Our results have important implications for how climate issues are communicated and perceived by the public.

Reversal of the impact chain for actionable climate information, Pfleiderer et al., Nature Geoscience:

Escalating impacts of climate change underscore the risks posed by crossing potentially irreversible Earth and socioecological system thresholds and adaptation limits. However, limitations in the provision of actionable climate information may hinder an anticipatory response. Here we suggest a reversal of the traditional impact chain methodology as an end-user focused approach linking specific climate risk thresholds, including at the local level, to emissions pathways. We outline the socioeconomic and value judgement dimensions that can inform the identification of such risk thresholds. The applicability of the approach is highlighted by three examples that estimate the required CO2 emissions constraints to avoid critical levels of health-related heat risks in Berlin, fire weather in Portugal and glacier mass loss in High Mountain Asia. We argue that linking risk threshold exceedance directly to global emissions benchmarks can aid the understanding of the benefits of stringent emissions reductions for societies and local decision-makers.

From this week's government/NGO section:

Fueling the crisis. Climate consequences of the 2021 infrastructure lawSalerno et al., Transporation for America

In November 15, 2021, President Joe Biden signed the bipartisan Infrastructure Investment and Jobs Act (IIJA) into law. The IIJA included a five-year transportation authorization for U.S. Department of Transportation (USDOT) programs, plus a standalone infrastructure law representing the largest-ever infusion ($643 billion over five years) of federal funding for surface transportation, including highways, roads, and bridges. The White House hailed the IIJA as “a once-in-a-generation investment in our nation’s infrastructure and competitiveness,” along with making lofty promises that it would “repair and rebuild our roads and bridges with a focus on climate change mitigation, resilience, equity, and safety for all users.” Three years into this investment of infrastructure dollars, has that turned out to be the case? The authors extrapolate that states’ federal formula-funded investments made over the course of the IIJA could cumulatively increase emissions by nearly 190 million metric tonnes of emissions over baseline levels through 2040 from added driving. This is the emission equivalent of 500 natural gas-fired power plants or nearly 50 coal-fired power plants running for a year.“

Europe's state of water 2024. The need for improved water resilienceEuropean Environment Agency

Europe's water is under significant pressure, presenting serious challenges to water security, now and in the future. As such, Europe urgently needs to improve its resilience and ensure sustainable freshwater supplies for people and the environment. Water stress is already occurring in Europe. It affects 20% of Europe's territory and 30% of the population every year, figures that are likely to increase in the future due to climate change. As climate change unfolds in Europe, managing flood risk affordably and sustainably will become increasingly important. Intense rainfall has already increased in parts of Europe, leading to floods and growing flood risks. Flooding affects human well-being and ecosystems, with potential loss of life and significant economic losses.

148 articles in 51 journals by 1047 contributing authors

Physical science of climate change, effects

Changes in Teleconnection Patterns and Land–Atmosphere Coupling Amplify the Spring–Early Summer Heatwaves Over Southwestern China, Zheng et al., International Journal of Climatology 10.1002/joc.8732

Changes in urban heat island intensity with background temperature and humidity and their associations with near-surface thermodynamic processes, Park et al., Urban Climate Open Access 10.1016/j.uclim.2024.102191

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Exploring the drivers of modern global warming

Posted on 8 January 2025 by Zeke Hausfather

This is a re-post from the Climate Brink

Global surface temperatures have risen around 1.3C since the preindustrial (1850-1900) period as a result of human activity.1 However, this aggregate number masks a lot of underlying factors that contribute to global surface temperature changes over time.

These include CO2, which is the primary driver of long-term warming, as well as non-CO2 greenhouse gases like CH4, N2O, and halocarbons. But it also includes planet-cooling aerosols that have masked a sizable portion of the warming of our greenhouse gas emissions to-date. Rounding out the list are other anthropogenic factors (tropospheric ozonealbedo changes due to land use change), and natural forcings (primarily volcanic eruptions and variations in solar output).

To disentangle the respective contributions of each of these requires a climate model. Here I will be using the latest version of FaIR, a reduced complexity climate model that has been used extensively by the community for assessing global-level changes. The implementation of FaIR used here is specifically designed to reproduce both observed climate change since pre-industrial and assessed climate metrics from the IPCC Sixth Assessment Report (AR6). This approach has the advantage of providing robust uncertainties that reflect the range of relevant parameters (e.g. climate sensitivity, carbon cycle feedback strength, ocean heat uptake rates, etc.) in-line with the ranges in the AR6.

However, unlike the climate simulations featured in the AR6, which only use climate forcings based on real-world observations through 2014 and explore different scenarios (SSPs) thereafter, these simulations use observationally-informed forcing estimate through the end of 2023 from Forster et al 2024. This has the advantage of allowing us to explore how actual changes in real-world emissions (e.g. including factors like rapid Chinese aerosol declines and low-sulfur shipping rules) have impacted global temperatures.

The figure below shows the output of 841 different emission-driven FaIR model runs across the range of constrained parameter values. It simulates both the global surface temperature response to all forcings (in yellow), as well as estimates of each forcing in isolation (calculated by comparing the difference between runs containing all forcings and those excluding one type of forcing).

Observed global surface temperatures since 1850 (black), along with modeled temperatures (yellow) and separate temperature components (other colors).

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