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Abstract

Where is humanity going? How realistic is a future of fusion and space colonies? What constraints are imposed by physics, by resource availability, and by human psychology? Are default expectations grounded in reality?

This textbook, written for a general-education audience, aims to address these questions without either the hype or the indifference typical of many books. The message throughout is that humanity faces a broad sweep of foundational problems as we inevitably transition away from fossil fuels and confront planetary limits in a host of unprecedented ways—a shift whose scale and probable rapidity offers little historical guidance.

Salvaging a decent future requires keen awareness, quantitative assessment, deliberate preventive action, and—above all—recognition that prevailing assumptions about human identity and destiny have been cruelly misshapen by the profoundly unsustainable trajectory of the last 150 years. The goal is to shake off unfounded and unexamined expectations, while elucidating the relevant physics and encouraging greater facility in quantitative reasoning.

After addressing limits to growth, population dynamics, uncooperative space environments, and the current fossil underpinnings of modern civilization, various sources of alternative energy are considered in detail— assessing how they stack up against each other, and which show the greatest potential. Following this is an exploration of systemic human impediments to effective and timely responses, capped by guidelines for individual adaptations resulting in reduced energy and material demands on the planet’s groaning capacity. Appendices provide refreshers on math and chemistry, as well as supplementary material of potential interest relating to cosmology, electric transportation, and an evolutionary perspective on humanity’s place in nature.

Corrections and feedback can be left at https://tmurphy.physics.ucsd.edu/energy-text/

Abstract

The year of 2023 was the warmest on record globally and the second warmest in Europe. Here we applied epidemiological models to temperature and mortality records in 823 contiguous regions from 35 countries to estimate sex- and age-specific heat-related mortality in Europe during 2023 and to quantify the mortality burden avoided by societal adaptation to rising temperatures since the year 2000. We estimated 47,690 (95% confidence interval 28,853 to 66,525) heat-related deaths in 2023, the second highest mortality burden during the study period 2015–2023, only surpassed by 2022. We also estimated that the heat-related mortality burden would have been +80.0% higher in absence of present-century adaptation, especially in the elderly (+100.7% in people aged 80+ years). Our results highlight the importance of historical and ongoing adaptations in saving lives during recent summers and the urgency for more effective strategies to further reduce the mortality burden of forthcoming hotter summers.

But why on earth? Rejoice, rather.

Abstract

Landscape drying associated with permafrost thaw is expected to enhance microbial methane oxidation in arctic soils. Here we show that ice-rich, Yedoma permafrost deposits, comprising a disproportionately large fraction of pan-arctic soil carbon, present an alternate trajectory. Field and laboratory observations indicate that talik (perennially thawed soils in permafrost) development in unsaturated Yedoma uplands leads to unexpectedly large methane emissions (35–78 mg m−2 d−1 summer, 150–180 mg m−2 d−1 winter). Upland Yedoma talik emissions were nearly three times higher annually than northern-wetland emissions on an areal basis. Approximately 70% emissions occurred in winter, when surface-soil freezing abated methanotrophy, enhancing methane escape from the talik. Remote sensing and numerical modeling indicate the potential for widespread upland talik formation across the pan-arctic Yedoma domain during the 21st and 22nd centuries. Contrary to current climate model predictions, these findings imply a positive and much larger permafrost-methane-climate feedback for upland Yedoma.