In their paper, The Discovery of ETI as a high-consequence, Low-probability event, Iván Almár and Jill Tarter suggest that the impact of the confirmed discovery of extraterrestrial intelligence depends on the kind of potential consequences that arise from the discovery and the credibility of the confirmation. The authors compare the news of aliens to the news of the approach of a large asteroid that would produce enormous damage upon impact. They cite the two-dimensional Torino scale, which calculates potential damage from an asteroid against the probability that it will happen. As a result, a lower score attaches to less-certain impacts and those that would produce less damage.
Almár and Tarter presented their paper to the 51st International Astronautical Congress in Rio de Janeiro. They proposed a numerical formula, the “Rio Scale,” to identify the level of impact related to the discovery of extraterrestrial intelligence. The Rio Scale incorporates the method of communication, the content of communication, and whether the contact was intentional or accidental. If the contact is confirmed and authentic with high confidence, the societal impact will be greater and have a higher number. A lower number would be assigned to contact, and any possible threat, that is far distant in the universe. A higher number would identify a contemporary sighting or contact on earth.