地球科学最新文献

Proglacial lakes along the retreating margin of the Laurentide ice sheet (LIS) significantly influenced the ice sheet's dynamics. This study investigates the interaction between proglacial lake drainage events and ice sheet evolution during deglaciation. Using a flowline ice sheet model, we demonstrate that abrupt lake drainage caused by the opening of spillways during the retreat of the ice sheet can temporarily reverse ice retreat and trigger rapid grounding line advance despite ongoing climate warming. We also show that ice shelf regrounding on a retrograde lake bed can follow lake drainage and further amplify ice sheet advance. These processes can decouple ice dynamics from climate forcing, offering a non-climatic mechanism to explain the observed highly irregular ice margin fluctuations of the LIS. Our findings suggest that proglacial lakes might play an important role in modulating ice sheet evolution in warming climates.

The moment-duration (M₀-T) scaling law reveals fundamental earthquake physics across various sizes and tectonic settings. However, the validity of the cubic relation (M₀ ∝ T³) inferred for large (Mw ≥ 7) megathrust events has been recently questioned due to the scarcity of observations and similarities to slow earthquakes. Here, by compiling events over the past 500 years from global subduction zones, we double the number of earthquakes studied (>260) compared to previous studies. A possible scale change is observed, at moment-magnitude and duration of ∼7.6 and ∼38.1 s, respectively. The new catalog reveals an accelerated decrease of the scaling exponent as a function of magnitude from 2.5 (Mw ≥ 7) to below 1 (Mw > 8.7), indicating increasingly longer durations than expected for larger events. The rapid increase in duration with earthquake size is interpreted as the interplay of seismogenic bounds, trench-breaching, and subevents, which delays lateral rupture propagation. Our study aids in understanding slow and fast earthquakes.

For centuries, forests have been considered a safeguard for drinking water quality. However, unprecedented pulses of forest dieback globally caused by the rising frequency and intensity of droughts may jeopardize the forests' crucial role in protecting water quality, potentially even turning forests into sources of contamination. To underscore the critical importance of the topic, here we provide the first comprehensive assessment of forest cover, type, and dieback across drinking Water Protection Areas (WPAs) in Germany, one of the countries hit by the unprecedented Central European drought of 2018–2020. Our findings reveal a high forest cover of 43% in WPAs, from which a substantial amount of 4.8% canopy cover got lost within only 3 years. Spruce-dominated forests were particularly susceptible, but other dominant tree species also experienced anomalously high mortality rates. Combining this assessment with exemplary records of nitrate concentrations in the groundwater of WPAs revealed that forest dieback can significantly impair drinking water quality. On average, nitrate concentrations more than doubled in WPAs with severe forest dieback, whereas concentrations did not significantly change in undisturbed WPAs. However, we also found pronounced differences between WPAs affected by forest dieback, underlining the need for further data and research to derive a generalizable understanding of the underlying mechanisms and controls. Based on this assessment, we deduce critical data and knowledge gaps essential to developing well-informed adaptation and mitigation strategies. We call for interdisciplinary research addressing the hidden threat forest dieback poses for our drinking water resources.

Wildfires cause large damage to natural and human systems. Despite the clear connection between human-induced climate change and increased fire weather risk, a global, systematic attribution of observed extreme fires to human-induced climate change is lacking. Here, we address this gap by first linking observed regional weekly burned area extremes (>85th percentile) to the fire weather index (FWI) during the fire seasons of 2002–2015 via a logistic regression model, and then using simulations from climate models to quantify the impact of human-induced climate change. Focusing on regions with good predictability of the statistical model, we find that human-induced climate change was responsible for a fraction equal to 8% (±4%, standard deviation across climate models) of the predicted probability of more than 700 regional fire extremes on average, thereby increasing the probability of experiencing a fire extreme across 15 out of 19 analysed regions. While higher temperature is the main driver of the increased fire extreme probability, shifts in precipitation, relative humidity, and/or wind speed substantially modulated fire changes across many regions. Mainly because of warming, the probability of extreme fires attributable to human-induced climate change increased by 5.2%/decade globally over 2002–2015, in line with an acceleration of the climate-driven enhancement of fire extremes over the last decades that may continue in the near future. These findings highlight the urgent need for sustainable fire management strategies.

Morphological scaling laws for basaltic lava flows, linking flow dimensions and eruption conditions, are essential for hazard assessment and geological analysis of basaltic eruptions. However, the governing factors influencing flow dimensions remain unclear. We developed a scaling law for lava dimensions based on natural observations, with insights obtained from numerical simulations. We found that lava flow dynamics transition from a volume-limited regime to a cooling-limited regime as the effusion duration increases. In the volume-limited regime, flow length increases with erupted volume raised to the power of 0.67, while in the cooling-limited regime, it increases with effusion rate raised to the power of 0.60. We also found that Mauna Loa's flows follow the volume-limited regime, while Mt. Etna's flows can follow either the volume-limited or cooling-limited regime, reflecting their differing cooling timescales. Consequently, we established a unified scaling law that quantitatively links flow length to erupted volume and effusion rate.

We investigated tsunamis of an Mw 7.1 earthquake in the Hyuganada Sea in 2024, observed by a new dense and wide seafloor observation network, N-net, installed in the western Nankai Trough. A joint inversion of the offshore tsunami and onshore GNSS data revealed a maximum slip of 2.4 m with a significant slip near the centroid from the teleseismic analysis. The joint inversion provided reliable constraints for both up-dip and down-dip extents of the fault, while the inversions using either data set showed limitations in the fault constraint. Comparisons with past earthquakes indicate the 2024 earthquake ruptured part of the asperity of the 1961 earthquake but not those of the 1996 earthquakes. Our fault modeling jointly using offshore and onshore data suggests the interplate seismic coupling ratio in this region is <0.4, which was much smaller than those in the anticipated megathrust earthquake source region in the Nankai Trough.

Recent research suggests atmospheric cloud radiative effect (ACRE) acts as an important feedback mechanism for enhancing the development of convective self-aggregation in idealized numerical simulations. Here, we seek observational relationships between longwave (LW) ACRE and the spatial organization of mesoscale convective systems (MCSs) in the tropics. Three convective organization metrics that are positively correlated with the area of MCS, that is, convective organization potential, the area fraction of precipitating MCS, and the precipitation fraction of MCS, are used to indicate the degree of convective organization. Our results show that the contrast in the LW ACRE inside and outside an MCS is consistent across different MCS precipitation intensities throughout the life cycle of an MCS, typically 90–100 W/m², and provides important positive feedback to the circulation of the given MCS. However, the LW ACRE inside and outside an MCS as well as their difference are not strongly related to the degree of organization, suggesting that the LW cloud radiative feedback may be supportive of MCS formation and maintenance without necessarily being a dominant factor for spatial organization of MCSs. The domain average vertical velocity does tend to be related to the measures of convective organization, suggesting that factors that favor large-scale low-level convergence may exert a leading effect in creating an environment favorable for mesoscale organization of deep convection.

Using the high-resolution data from the Magnetospheric Multiscale mission, we performed a statistical analysis on intense energy conversion events (IECEs) in the Earth's magnetotail. The results show that the average duration of IECEs is 0.14 s, and the spatial scale of more than 95% of IECEs is smaller than one ion inertial length. Intense energy conversion events can occur not only in flux ropes, magnetic holes, dipolarization fronts and magnetic reconnection region in the plasma sheet, but also in the plasma sheet boundary layer. Intense energy conversion events prefer to occur in the duskside and the northern hemisphere, showing obvious dawn-dusk asymmetry. The occurrence rate of IECEs is much higher when the interplanetary magnetic field is quasi-southward. Our results can deepen our understanding of energy conversion and dynamic processes in the planetary magnetotail.