Extreme fire weather in Chile driven by climate change and El Niño-Southern Oscillation (ENSO).

A string of fierce fires broke out in Chile in the austral summer 2023, just six years after the record-breaking 2017 fire season. Favored by extreme weather conditions, fire activity has dramatically risen in recent years in this Andean country. A total of 1.7 million ha. burned during the last decade, tripling figures of the prior decade. Six of the seven most destructive fire seasons on record occurred since 2014. Here, we analyze the progression during the last two decades of the weather conditions associated with increased fire risk in Central Chile (30°-39° S). Fire weather conditions (including high temperatures, low humidity, dryness, and strong winds) increase the potential for wildfires, once ignited, to rapidly spread. We show that the concurrence of El Niño and climate-fueled droughts and heatwaves boost the local fire risk and have decisively contributed to the intense fire activity recently seen in Central Chile. Our results also suggest that the tropical eastern Pacific Ocean variability modulates the seasonal fire weather in the country, driving in turn the interannual fire activity. The signature of the warm anomalies in the Niño 1 + 2 region (0°-10° S, 90° W-80° W) is apparent on the burned area records seen in Central Chile in 2017 and 2023.

Compound climate-pollution extremes in Santiago de Chile.

Cities in the global south face dire climate impacts. It is in socioeconomically marginalized urban communities of the global south that the effects of climate change are felt most deeply. Santiago de Chile, a major mid-latitude Andean city of 7.7 million inhabitants, is already undergoing the so-called "climate penalty" as rising temperatures worsen the effects of endemic ground-level ozone pollution. As many cities in the global south, Santiago is highly segregated along socioeconomic lines, which offers an opportunity for studying the effects of concurrent heatwaves and ozone episodes on distinct zones of affluence and deprivation. Here, we combine existing datasets of social indicators and climate-sensitive health risks with weather and air quality observations to study the response to compound heat-ozone extremes of different socioeconomic strata. Attributable to spatial variations in the ground-level ozone burden (heavier for wealthy communities), we found that the mortality response to extreme heat (and the associated further ozone pollution) is stronger in affluent dwellers, regardless of comorbidities and lack of access to health care affecting disadvantaged population. These unexpected findings underline the need of a site-specific hazard assessment and a community-based risk management.

NEDD4L represses prostate cancer cell proliferation via modulating PHF8 through the ubiquitin-proteasome pathway.

PURPOSE: Prostate cancer (PC) is a heterogeneous malignancy that greatly threatens man's health. E3 ubiquitin-protein ligase neural precursor cell expressed developmentally downregulated 4-like (NEDD4L) imparts an regulatory role in various malignancies. This study focused on the modulatory mechanism of NEDD4L in proliferation of prostate cancer cells (PCCs) via regulating histone demethylase plant homeodomain finger protein 8 (PHF8/KDM7B) through the ubiquitin-proteasome system. METHODS: The expression levels of NEDD4L, PHF8, H3 lysine 9 dimethylation (H3K9me2) and activating transcription factor 2 (ATF2) in PC tissues and cell lines were detected via real-time quantitative polymerase chain reaction and Western blotting. After transfection of pcDNA3.1-NEDD4L, pcDNA3.1-PHF8, and pcDNA3.1-ATF2 into PCCs, cell proliferation was assessed via the cell counting kit-8 and 5-ethynyl-2'-deoxyuridine assays. Interaction between NEDD4L and PHF8 was identified via the protein immunoprecipitation. The ubiquitination level of PHF8 was determined via the ubiquitination detection. The enrichments of H3K9me2 and PHF8 in the ATF2 promotor region were detected via the chromatin-immunoprecipitation assay. RESULTS: PHF8 and ATF2 were highly expressed while NEDD4L was poorly expressed in PC tissues and cells. NEDD4L overexpression reduced proliferation of PCCs. NEDD4Linduced degradation of PHF8 via ubiquitination. PHF8 limited the enrichment of H3K9me2 in the ATF2 promotor region and enhanced ATF2 transcription. Upregulation of PHF8 or ATF2 abolished the inhibitory role of NEDD4L in proliferation of PCCs. CONCLUSION: NEDD4L facilitated degradation of PHF8 to limit ATF2 transcription, thereby suppressing proliferation of PCCs.

Black carbon footprint of human presence in Antarctica.

Black carbon (BC) from fossil fuel and biomass combustion darkens the snow and makes it melt sooner. The BC footprint of research activities and tourism in Antarctica has likely increased as human presence in the continent has surged in recent decades. Here, we report on measurements of the BC concentration in snow samples from 28 sites across a transect of about 2,000 km from the northern tip of Antarctica (62°S) to the southern Ellsworth Mountains (79°S). Our surveys show that BC content in snow surrounding research facilities and popular shore tourist-landing sites is considerably above background levels measured elsewhere in the continent. The resulting radiative forcing is accelerating snow melting and shrinking the snowpack on BC-impacted areas on the Antarctic Peninsula and associated archipelagos by up to 23 mm water equivalent (w.e.) every summer.

Evaluation of MODIS-derived estimates of the albedo over the Atacama Desert using ground-based spectral measurements.

Surface albedo is an important forcing parameter that drives the radiative energy budget as it determines the fraction of the downwelling solar irradiance that the surface reflects. Here we report on ground-based measurements of the spectral albedo (350-2200 nm) carried out at 20 sites across a North-South transect of approximately 1300 km in the Atacama Desert, from latitude 18° S to latitude 30° S. These spectral measurements were used to evaluate remote sensing estimates of the albedo derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). We found that the relative mean bias error (RMBE) of MODIS-derived estimates was within ± 5% of ground-based measurements in most of the Atacama Desert (18-27° S). Although the correlation between MODIS-derived estimates and ground-based measurements remained relatively high (R= 0.94), RMBE values were slightly larger in the southernmost part of the desert (27-30° S). Both MODIS-derived data and ground-based measurements show that the albedo at some bright spots in the Atacama Desert may be high enough (up to 0.25 in visible range) for considerably boosting the performance of bifacial photovoltaic technologies (6-12%).