Broad threat to humanity from cumulative climate hazards intensified by greenhouse gas emissions

Abstract

The ongoing emission of greenhouse gases is triggering changes in many climate hazards that can impact humanity. We found traceable evidence for 467 pathways in which human health, water, food, economy, infrastructure, and security have been recently impacted by climate hazards such as warming, heatwaves, precipitation, drought, floods, fires, storms, sea level rise, and changes in natural land cover and ocean chemistry. By 2100, the world's population will be exposed concurrently to the equivalent of the largest magnitude in one of these hazards if greenhouse gasses are aggressively reduced or three if they are not, with some tropical coastal areas facing up to six hazards concurrently. These findings highlight that greenhouse gas emissions pose a broad threat to humanity by simultaneously intensifying many hazards that have been harmful to numerous aspects of human life.Ongoing greenhouse gas emissions are simultaneously shifting many elements of Earth's climate beyond thresholds that can impact humanity 1 . By affecting the balance between incoming solar radiation and outgoing infrared radiation, man-made greenhouse gases are increasing the Earth's energy budget ultimately leading to warming 1 . Given interconnected physics, warming can affect other aspects of the Earth's climate system 2 . For instance, by enhancing water evaporation and increasing the air's capacity to hold moisture, warming can lead to drought in commonly dry places, in turn ripening conditions for wildfires and heatwaves when heat transfer from water evaporation ceases. There are opposite responses in commonly humid places where constant evaporation leads to more precipitation, which is commonly followed by floods due to soil saturation. The oceans have the added effect of sea warming, which enhances evaporation and wind speeds, intensifying downpours and the strength of storms, whose surges can be aggravated by sea level rise resulting from the larger volume occupied by warmed water molecules and melting land ice. Other inter-related changes in the ocean include acidification as CO2 mixes with water to form carbonic acid, and reduced oxygen due to warming reducing oxygen solubility and affecting circulation patterns and the mixing of surface waters rich in oxygen with deeper oxygen-poor water. These climate hazards and their impacts on human societies occur naturally but are being nontrivially intensified by man-made greenhouse gas emissions, as demonstrated by an active research on detection and attribution (discussed under Caveats in the Methods section). With few exceptions 3 , changes in these hazards have been studied in isolation whereas impact assessments have commonly focused on specific aspects of human life. Unfortunately, the failure to integrate available information most likely underestimates the impacts of climate change because i) one hazard may be important in one place but not another, ii) strong CO2 reductions may curb some but not all hazards (See Fig. S1), and iii) not all aspects of human systems are equally challenge...

Assessing the limitations of transparent conducting oxides as thermoelectrics

“…2. The curvature, or dispersion, of the bands indicates the mobility of charge carriers in those bands: Table 3 The converged k-point meshes used for most the calculations here, the denser meshes used in BoltzTraP calculations, the supercells used for the second and third order force constant calculations in Phono3py, the number of VASP calculations required to calculate the third order force constants and the q-point mesh sampled in Phono3py for BaSnO 3…”

“…Using the lattice thermal conductivity from Phono3py and the electronic transport properties from BoltzTraP, the ZT was calculated. Maximum ZTs occur at high doping concentrations of $1 Â 10 19 carriers per cm 3…”

“…Despite the primary global energy consumption of around 160 PW h this decade 1,2 and the numerous negative effects this will bring, 3 an estimated 50% of all generated energy is wasted as heat. 4 One h of this wasted heat is theoretically recoverable, 4 and that recovery could reduce the effects of global heating in at least three ways: reducing energy consumption, generating emissions-free electricity and reducing the local increase of temperatures in urban areas caused in part by anthropogenic waste heat (the urban heat island effect) 5 by utilising some of said heat.…”

“…for BaSnO 3 , $2 Â 10 19 carriers per cm 3 for CdO, $3 Â 10 19 carriers per cm 3 for SnO 2 and $8 Â 10 19 carriers per cm3 for ZnO. In order for a material to be an efficient thermoelectric, it must also be a degenerate conductor, i.e.…”

Understanding Interdependent Climate Change Risks Using a Serious Game

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