Short answers, pulled from the story.
Heavy industry emits about 22% of global greenhouse gas emissions. High-temperature heat processes in heavy industry account for roughly 10% of global emissions on their own, and the steel industry alone contributes 7-9% of all global carbon dioxide output.
Certain high-heat processes in heavy industry, particularly metalworking and cement production, are inherently difficult to decarbonize because the core chemical reactions are hard to run without generating carbon dioxide. Carbon capture and storage is considered a viable path because heavy industry emissions are concentrated at fixed point sources, making capture less energy-intensive than direct air capture.
China's Great Leap Forward of 1958-1960 was an attempt by Mao Zedong to rapidly industrialize and collectivize the economy, with heavy industry as the central focus. The effort failed to increase the output of usable-quality industrial goods and caused the largest famine in human history, killing up to 50 million people, while also severely depleting agricultural production.
Plants absorb heavy metals from contaminated soil, beginning the transfer up the food chain to animals and humans. Heavy metals cannot be chemically degraded, so they persist in soil and water indefinitely. Once concentrations pass certain thresholds, they cause plant poisoning and spread through bioaccumulation across multiple levels of the ecosystem.
Japan's Mitsubishi Heavy Industries and Fuji Heavy Industries are aerospace manufacturers and defense contractors to the Japanese government. South Korea's Hyundai Rotem, a joint project of Hyundai Heavy Industries and Daewoo Heavy Industries, follows the same model of combining industrial scale with national defense production.
From the mid-19th century through the early 20th century, traditional heavy industries included steelmaking, artillery production, locomotive manufacturing, machine tool building, and heavier forms of mining. By the late 19th century, the chemical and electrical industries developed with characteristics of both heavy and light industry, followed by the automotive and aircraft industries.