The eruption of the Indonesian island of Tambora was even larger than that of Krakatoa, yet the average world temperature did not drop as much as it did following the eruption of Krakatoa. In 1883, the ocean-atmospheric phenomenon La Nina occurred, an event that is always followed by a drop of several degrees in the world's average temperature. No volcanic eruption in the 20th century was close to the magnitude of the Krakatoa eruption, yet average world temperatures dropped between 1950 and 1960. According to sophisticated computer analysis, the eruption of Mt. Toba between 69, 000 and 77, 000 years ago, one of the most powerful ever, may have hastened an ice age.
In 1883, the Indonesian island Krakatoa, home to a massive volcano, seemingly disappeared overnight as an eruption rent the entire island apart, catapulting rock and debris into the atmosphere. For the next few years, as ash circled the entire globe, the average world temperature dropped by several degrees Fahrenheit. Ttherefore, an eruption of similar power in terms of the amount of debris ejected into the atmosphere will likely cause the average temperature around the world to drop by several degrees.
Which of the following, if true, best challenges the main claim of the argument?