"The good news is that no existential catastrophe has happened," declared Nick Bostrom. "Not one. Yet. " Bostrom, director of Oxford"s Future of Humanity Institute, opened what he thinks might be the first ever conference to comprehensively consider the gamut of Global Catastrophic Risks. By existential catastrophes Bostrom means that humanity has survived extinction so far. However, he quickly pointed out 99. 9 percent of all species are extinct. Bostrom cited the Toba super-eruption 73,000 years ago which may have produced a global winter that reduced the population of human ancestors to fewer than 500 fertile women(though some disagree). Our Neanderthal relatives died out between 33,000 and 24,000 years ago. In Our Final Hour, Lord Martin Rees predicted that there was only a 50 percent chance that our civilization would survive to 2100. Bostrom justified the broad topic of global catastrophic risks by pointing to common causal links, e. g. , super-volcanoes, asteroid strikes, and nuclear wars all have the potential to produce disastrous global cooling. Catastrophic scenarios also present common methodological, analytical, and cultural challenges. And, argues Bostrom, a wider view of potential catastrophes is necessary for the adoption of proper policies and informed prioritization. To assist in this effort, the conference is launching the eponymous volume, Global Catastrophic Risks. Bostrom did note that people today are safer from small to medium threats than ever before. As evidence he cites increased life expectancy from 18 years in the Bronze Age to 64 years today(the World Health Organizations thinks it"s 66 years). And he urged the audience not to let future existential risks occlude our view of current disasters, such as 15 million people dying of infectious diseases every year, 3 million from HIV/AIDS, 18 million from cardiovascular diseases, and 8 million per year from cancer. Bostrom did note that, "All of the biggest risks, the existential risks are seen to be anthropogenic, that is, they originate from human beings". The biggest risks include nuclear war, biotech plagues, and nanotechnology arms races. The good news is that the biggest existential risks are probably decades away, which means we have time to analyze them and develop countermeasures. Tomorrow, the Oxford conference on Global Catastrophic Risks will have more edifying presentations on proposals for recovering from social collapses occasioned by catastrophes: how to rationally consider the end of the world; how to avoid Millennialist cognitive biases; how to insure against catastrophes; how ecological diversity could affect human prospects; and the tragedy of the uncommons.

单选题 By saying "existential catastrophe", Bostrom refers to the catastrophe which ______.

单选题 Bostrom cited the Toba super-eruption to illustrate that ______.

单选题 Bostrom argues that a wider view of possible catastrophe ______.

单选题 Bostrom noted that future existential risks ______.

单选题 The dominant theme of the Oxford conference on Global Catastrophic Risks is______.