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Abstract

Without rapid emission reduction, it is increasingly likely that global temperatures will overshoot 1.5°C before carbon dioxide removal may help reverse warming. Such temperature overshoots affect the future hydrological cycle, with implications for land water availability. However, the hydrological response to such temperature overshoots is not well understood. Here, we investigate regional and seasonal changes of precipitation minus evaporation (P − E) in an ensemble of Earth system model simulations of temperature overshoot. Most climate models broadly show P − E reversibility after overshoot. However, models exhibiting an irreversible shift of the intertropical convergence zone (ITCZ) during the temperature overshoot experience reduced wet-season and enhanced dry-season land water availability in tropical regions, which has long-lasting effects on the amplitude of P − E seasonality after the overshoot, constituting irreversible changes on human timescales. While some regions may experience alleviating seasonal hydrological conditions, others are subject to more intense seasonality. Half a century of CO2-stabilization after the temperature overshoot only halves the legacy effects of the overshoot on land water availability on over 23% of the world population in 12% of the global land area, covering regions of various hydrological regimes. Based on the model ensemble presented here, a strong irreversible shift of the ITCZ after an overshoot is a low-probability but high-impact outcome that would entail long-lasting hydrological changes with consequences for ecosystems and human societies.

Abstract

Aspergillus species cause severe infections in humans, livestock, and plants, and are widespread environmental saprotrophs. With rising global temperatures, climate change is expected to alter the ecological niches and spread of many fungal pathogens. Here, we use global metabarcoding data and Maximum Entropy (MaxEnt) modelling to predict the current and future environmental suitability of three pathogenic Aspergillus species: A. fumigatus, A. flavus, and A. niger. We show that A. fumigatus is more common in temperate climates, while A. flavus and A. niger dominate in warmer regions. Future climate scenarios (SSP126, SSP245, and SSP585) suggest northward shifts in suitability for all three species, particularly under severe warming. We combine the MaxEnt model with spatial models of crop growing areas and human population and show that geographical shift will occur on Aspergillus species along different climate scenarios. A literature review revealed that clinical prevalence of invasive aspergillosis correlates with environmental suitability and we show that different continents have differential expansion or reduction of Aspergillus suitable habitat.

Abstract

Climate extremes are escalating under anthropogenic climate change1. Yet, how this translates into unprecedented cumulative extreme event exposure in a person’s lifetime remains unclear. Here we use climate models, impact models and demographic data to project the number of people experiencing cumulative lifetime exposure to climate extremes above the 99.99th percentile of exposure expected in a pre-industrial climate. We project that the birth cohort fraction facing this unprecedented lifetime exposure to heatwaves, crop failures, river floods, droughts, wildfires and tropical cyclones will at least double from 1960 to 2020 under current mitigation policies aligned with a global warming pathway reaching 2.7 °C above pre-industrial temperatures by 2100. Under a 1.5 °C pathway, 52% of people born in 2020 will experience unprecedented lifetime exposure to heatwaves. If global warming reaches 3.5 °C by 2100, this fraction rises to 92% for heatwaves, 29% for crop failures and 14% for river floods. The chance of facing unprecedented lifetime exposure to heatwaves is substantially larger among population groups characterized by high socioeconomic vulnerabilities. Our results call for deep and sustained greenhouse gas emissions reductions to lower the burden of climate change on current young generations.

Abstract

To calculate the additional copper required for the electrical transition from fossil fuels to electric energy, we first establish a business-as-usual baseline, assuming continued growth in demand driven by global population growth and rising standard of living. We then project the extra copper needs of the electric transition relative to this baseline. The extra copper that cannot be supplied through recycling must be mined, and we determine the annual increase in mining necessary to support the electrical transition. Our analysis shows that, while there is enough discovered copper with resources close to being defined to meet demand for the next 25 years, the rate at which it needs to be mined poses significant challenges. The unavoidable conflict between the copper demands of electrification and achieving equitable living standards for the developing world underscores the importance of resource-realistic policies. Given that the sharp increase in copper demand is primarily driven by batteries, the extra copper needs for electrification can be significantly reduced if the need for electrical storage is minimized. This can be achieved by generating electricity through a mix of nuclear, wind, and photovoltaics; managing power generation with backup electric plants fueled by methane from abundant resources of natural gas; and transitioning to a predominantly hybrid transportation fleet rather than fully electric vehicles.

Abstract

Gaseous ammonia, while influential in atmospheric processes, is critically underrepresented in atmospheric measurements. This limits our understanding of key climate-relevant processes, such as new particle formation, particularly in remote regions. Here, we present highly sensitive, online observations of gaseous ammonia from a coastal site in Antarctica, which allows us to constrain the mechanism of new particle formation in this region in unprecedented detail. Our observations show that penguin colonies are a large source of ammonia in coastal Antarctica, whereas ammonia originating from the Southern Ocean is, in comparison, negligible. In conjunction with sulfur compounds sourced from oceanic microbiology, ammonia initiates new particle formation and is an important source of cloud condensation nuclei. Dimethylamine, likely originating from penguin guano, also participates in the initial steps of particle formation, effectively boosting particle formation rates up to 10000 times. These findings emphasize the importance of ecosystem processes from penguin/bird colonies and oceanic phytoplankton/bacteria on climate-relevant aerosol processes in coastal Antarctica. This demonstrates an important connection between ecosystem and atmospheric processes that impact the Antarctic climate, which is crucial given the current rate of environmental changes in the region.