Global catastrophe scenarios
The impact of these scenarios can vary widely, depending on the cause and the severity of the event, ranging from temporary economic disruption to human extinction.
[14] In 2009, the Association for the Advancement of Artificial Intelligence (AAAI) hosted a conference to discuss whether computers and robots might be able to acquire any sort of autonomy, and how much these abilities might pose a threat or hazard.
[15] Various media sources and scientific groups have noted separate trends in differing areas which might together result in greater robotic functionalities and autonomy, and which pose some inherent concerns.
Projections of future climate change suggest further global warming, sea level rise, and an increase in the frequency and severity of some extreme weather events and weather-related disasters.
Effects of global warming include loss of biodiversity, stresses to existing food-producing systems, increased spread of known infectious diseases such as malaria, and rapid mutation of microorganisms.
Christine Peterson, co-founder and past president of the Foresight Institute, believes a cyberattack on electric grids has the potential to be a catastrophic risk.
[38] An environmental or ecological disaster, such as world crop failure and collapse of ecosystem services, could be induced by the present trends of overpopulation, economic development, and non-sustainable agriculture.
Detected in the early 21st century, a threat in this direction is colony collapse disorder,[40] a phenomenon that might foreshadow the imminent extinction[41] of the Western honeybee.
[56] Others worried that the RHIC[57] or the Large Hadron Collider might start a chain-reaction global disaster involving black holes, strangelets, or false vacuum states.
Romanian American economist Nicholas Georgescu-Roegen, a progenitor in economics and the paradigm founder of ecological economics, has argued that the carrying capacity of Earth—that is, Earth's capacity to sustain human populations and consumption levels—is bound to decrease sometime in the future as Earth's finite stock of mineral resources is presently being extracted and put to use; and consequently, that the world economy as a whole is heading towards an inevitable future collapse, leading to the demise of human civilization itself.
[66]: 303f Ecological economist and steady-state theorist Herman Daly, a student of Georgescu-Roegen, has propounded the same argument by asserting that "all we can do is to avoid wasting the limited capacity of creation to support present and future life [on Earth].
"[67]: 370 Ever since Georgescu-Roegen and Daly published these views, various scholars in the field have been discussing the existential impossibility of allocating Earth's finite stock of mineral resources evenly among an unknown number of present and future generations.
[69] The only one that appears to pose a significant global catastrophic risk is molecular manufacturing, a technique that would make it possible to build complex structures at atomic precision.
Gray goo is another catastrophic scenario, which was proposed by Eric Drexler in his 1986 book Engines of Creation[76] and has been a theme in mainstream media and fiction.
The energy for the Green Revolution was provided by fossil fuels in the form of fertilizers (natural gas), pesticides (oil), and hydrocarbon-fueled irrigation.
Geologist Dale Allen Pfeiffer claims that coming decades could see spiraling food prices without relief and massive starvation on a global level such as never experienced before.
Should the world's large grain-producing areas become infected, the ensuing crisis in wheat availability would lead to price spikes and shortages in other food products.
The Chicxulub asteroid, for example, was about ten kilometers (six miles) in diameter and is theorized to have caused the extinction of non-avian dinosaurs at the end of the Cretaceous.
[122] Asteroids with around a 1 km diameter have impacted the Earth on average once every 500,000 years; these are probably too small to pose an extinction risk, but might kill billions of people.
"[127] Also in 2018, physicist Stephen Hawking, in his final book Brief Answers to the Big Questions, considered an asteroid collision to be the biggest threat to the planet.
[130][131][132][133][134] According to expert testimony in the United States Congress in 2013, NASA would require at least five years of preparation before a mission to intercept an asteroid could be launched.
[135] In April 2008, it was announced that two simulations of long-term planetary movement, one at the Paris Observatory and the other at the University of California, Santa Cruz, indicate a 1% chance that Mercury's orbit could be made unstable by Jupiter's gravitational pull sometime during the lifespan of the Sun.
Interstellar objects, including asteroids, comets, and rogue planets, are difficult to detect with current technology until they enter the Solar System, and could potentially do so at high speed.
[148] In around 1 billion years from now, the Sun's brightness may increase as a result of a shortage of hydrogen, and the heating of its outer layers may cause the Earth's oceans to evaporate, leaving only minor forms of life.
[160] An article in The New York Times Magazine discussed the possible threats for humanity of intentionally sending messages aimed at extraterrestrial life into the cosmos in the context of the SETI efforts.
Several public figures such as Stephen Hawking and Elon Musk have argued against sending such messages, on the grounds that extraterrestrial civilizations with technology are probably far more advanced than, and could therefore pose an existential threat to, humanity.
In 1969, the "Extra-Terrestrial Exposure Law" was added to the United States Code of Federal Regulations (Title 14, Section 1211) in response to the possibility of biological contamination resulting from the U.S. Apollo Space Program.
[citation needed] The amount of heat-trapping gases emitted into Earth's oceans and atmosphere will prevent the next ice age, which otherwise would begin in around 50,000 years, and likely more glacial cycles.
When the supervolcano at Yellowstone last erupted 640,000 years ago, the thinnest layers of the ash ejected from the caldera spread over most of the United States west of the Mississippi River and part of northeastern Mexico.
[183] According to a recent study, if the Yellowstone caldera erupted again as a supervolcano, an ash layer one to three millimeters thick could be deposited as far away as New York, enough to "reduce traction on roads and runways, short out electrical transformers and cause respiratory problems".
