An animal crisis caused by pollution, deforestation, and warming in the late 21st century and exacerbation by nuclear war

Abstract

An environmental-animal crisis is currently ongoing and is becoming increasingly severe due to human activity. However, the magnitude, timing, and processes related to this crisis are unclear. This paper clarifies the likely magnitude and timing of animal extinctions and changes in the contribution rates of select causes (global warming, pollution, deforestation, and two hypothetical nuclear conflicts) of animal extinctions during 2000-2300 CE. This paper demonstrates that an animal crisis marked by a 5-13% terrestrial tetrapod species loss and 2-6% marine animal species loss will occur in the next generation during 2060-2080 CE if humans do not engage in nuclear wars. These variations are due to magnitudes of pollution, deforestation, and global warming. The main causes of this crisis will change from pollution and deforestation to deforestation in 2030 under the low CO₂ emission scenarios but will change from pollution and deforestation to deforestation in 2070 and then to deforestation and global warming after 2090 under the medium CO₂ emissions. A nuclear conflict will increase animal species loss up to approximately 40-70% for terrestrial tetrapod species and 25-50% for marine animal species, including errors. Therefore, this study shows that the animal species conservation priority is to prevent nuclear war, reduce deforestation rates, decrease pollution, and limit global warming, in this order.

Keywords: Anthropocene; Deforestation; Global warming; Mass extinction; Nuclear war; Pollution.

Graphical abstract

Fig. 1

Changes in global surface temperature anomalies (a) [12], mercury concentrations (relative to 1800 CE) as a proxy for pollution (b), deforestation area percentages (relative to 4000 BCE) (c), and amounts of stratospheric soot introduced by nuclear war, which would reduce sunlight penetration and induce global cooling (d) [11] from 1700 to 2300 CE. The four curves for global warming and pollution correspond to SSP1-1.9, SSP1-2.6, SSP2-4.5, and SSP4-6.0 (the 21st century scenarios simulated by the Scenario Model Intercomparison Project [ScenarioMIP]), respectively [12,13], (a, b). Dotted lines: SSP1-1.9. Thick lines: SSP1-2.6. Thin lines: SSP2-4.5. Dashed lines: SSP4-6.0. A nuclear war is simulated in 2060 and 2300 (d). These data are shown in Supplementary Table A2 (for a–c).

Fig. 2

Animal species extinction percentages in the marine (blue circle) and terrestrial (tetrapods, red square) environments from 1700 to 2300 CE under four causal contribution rate sets, four CO₂ emission scenarios, and no nuclear war. See Materials and Methods on contribution rates and extinction percentages. Dotted lines: SSP1-1.9. Thick lines: SSP1-2.6. Thin lines: SSP2-4.5. Dashed lines: SSP4-6.0. The final species extinction percentage in each figure is thought to be similar to the maximum species extinction percentage or slightly higher. These data are shown in Supplementary Tables A4 and A5. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 3

Animal species extinction contribution rates (global warming, pollution, and deforestation) for animal extinctions during 2000–2300 CE under a no nuclear war scenario. Marine animals under SSP1-2.6 (a). Terrestrial tetrapods under SSP1-2.6 (b). Marine animals under SSP4-6.0 (c). Terrestrial tetrapods under SSP4-6.0 (d). Figures a–d correspond to the contribution rates in Fig. 2b (high pollution and high deforestation contributions). These data are shown in Supplementary Table A6. Figures for the four extinction cause contribution sets are shown in Supplementary Fig. A3 and Supplementary Tables A6–A9.

Fig. 4

Animal species extinction percentages in the marine (blue circle) and terrestrial (tetrapods, red square) environments from 1700 to 2300 CE under four CO₂ emission scenarios and two different nuclear war magnitudes on two different dates for the high extinction contribution rates of pollution and deforestation. A nuclear war is simulated in 2060 (a) and 2300 (b). Dotted lines: SSP1-1.9. Thick lines: SSP1-2.6. Thin lines: SSP2-4.5. Dashed lines: SSP4-6.0. These data are shown in Supplementary Tables A4, A5, and A10. Extinction percentages during a major nuclear war include a ±13% error for marine animals and a ±15% error for terrestrial tetrapods shown in Supplementary Fig. A2d. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 5

Comparison between extinction percentages in the Phanerozoic mass extinctions and current Anthropocene animal crisis. Numbers 1 to 5: the five major mass extinctions. Closed bars in the Anthropocene show minimum values. Hollow bars in the Anthropocene show maximum values. The variations are due to different extinction contribution rates of pollution and deforestation (Supplementary Tables A10–12). O: Ordovician. F–F: Frasnian–Famennian boundary. G: Guadalupian. P: Permian. T: Triassic. J–K: Jurassic–Cretaceous boundary. K–Pg: Cretaceous–Paleogene boundary. Nc war: nuclear war case. Each silhouette shows a representative vertebrate animal from each age. These data in geological ages are shown in Kaiho [4,7]. These data in the Anthropocene are shown in Supplementary Table A12. Extinction percentages during a major nuclear war include a ±13% error for marine animals and a ±15% error for terrestrial tetrapods shown in Supplementary Fig. A2d.