Interview, Webinar
Climate change, societal collapse, & nuclear energy | Mark Lynas (2020)
- 80,000 Hours anticipates climate change poses tail risks with long-lasting impacts extending beyond this century but considers it unlikely to cause total civilizational collapse or human extinction, expecting instead that neglected issues pose higher existential risks.
- The organization plans to prioritize neglected problems that have not yet broken through to the mainstream, targeting areas where less than 1% of current climate funding is directed to leverage low-hanging fruit for greater progress.
- Experts predict that four to six degrees of warming would render substantial parts of the tropics and subtropics biologically uninhabitable due to lethal heat and drought, leading to the loss of the Arctic Ocean ice cap and most global glaciers.
- At warming levels of four to six degrees, forecasts indicate a "geologically defined mass extinction" of a good proportion of current species, synchronous harvest failures in global breadbaskets, and the potential for a "Venus effect" scenario where oceans boil off if all fossil fuels are burned.
- Current infrastructure alone is expected to release about 450 gigatons of carbon, blowing through the 1.5-degree budget within 10 years, while a 2-degree scenario entails the loss of the Arctic ice cap, 10 million people flooded by sea level rise, and widespread lethal droughts.
- Self-reinforcing feedback loops are expected, such as permafrost melting to release CO2 and methane, and the removal of Arctic ice causing the ocean to absorb solar radiation and fast-forward global warming by a quarter century.
- Probability estimates for large-scale civilizational collapse range from 30 to 40 percent at three degrees, 60 percent at four degrees, 90 percent at five degrees, and 97 percent at six degrees, with societal collapse becoming "almost certain" at six degrees.
- Risks include intense intergroup conflict and refugee flows driven by water scarcity, a factor linked to the Syrian conflict, though nuclear-armed states may lower the rate of interstate climate warfare.
- Renewable energy solutions face constraints, with 100% renewables deemed physically impossible in densely populated regions like Korea or Japan and requiring vast land areas, such as covering over 1.5 times the size of Wales to replace UK oil consumption with solar.
- Nuclear energy is proposed as a scalable solution capable of delivering net-zero carbon at net-zero cost if modular and scalable designs like ThorCon are utilized, potentially running the planet for 10,000 years with abundant thorium.
- Specific nuclear capacity requirements are estimated at over 400 gigawatts produced annually to replace global oil consumption with nuclear-generated hydrogen, leveraging nuclear energy's density of approximately one million times that of hydrocarbons.
- Carbon capture technologies are viewed skeptically, with point-source capture described as a "methadone option" and direct air capture deemed non-scalable due to thermodynamic challenges and immense energy requirements.
- Agricultural and water strategies include the potential for GMOs to bias a decade or two against supply shortages and desalination to produce large water quantities, though the latter's feasibility at continental scales remains uncertain.
- Sea level rise is expected to reach a maximum of 2.5 meters by 2100 in extreme scenarios, considered tolerable for most coastlines within a human timescale, though the Greenland Ice Sheet is already collapsing with a physical timeframe of centuries for full loss.
- Extreme weather events are getting worse with heavier rainfall and stronger hurricanes, even if death tolls are mitigated by better sheltering, and 99 percent of the world's coral reefs are expected to be lost before reaching two degrees of warming.