It's not really comparable... but they compared it anyways

Blog post 9

The video showing a controversial environment conservation advertisement

It's not really "one of the worst tragedies in history", honestly any natural disaster will cause more people to perish than this, but the 9/11 incident definitely caused one of the most serious consequences of terrorism in history. Aside from the international conflicts, the 9/11 incident has been (unfortunately) brought into mainstream culture as an icon of many things, from terrorism, racism, to the consequences of working in a highrise and power of airplanes.

What's interesting is that the advertisement shown in this video, about environmental conservation again, compares one disaster to another.  The logic behind this, although quite clear, does not explain the motive behind creating an advertisement like this. Yes it is true that a tsunami will kill many more people than an airplane, but a tsunami is not an act of terrorism, neither is terrorism an act of nature. These are two completely unrelated acts that both resulted in tragedies. It is as if the designers of the advertisements are saying "car crash is bad, but genocide is worse". The severities of different tragedies is incomparable, because one incident of suffering of mankind cannot be worse than another. In all cases of disasters, people lose their homes, lose their lives, and lose their loved ones. Just because one disaster killed more people than the other does not mean one should be compared to the other.

It's also interesting to note that although 9/11 has been used to iconize countless things in mainstream culture, this is the first time I've seen it used as a comparison of severity to other disasters. Perhaps it's one thing that it's not effective at iconizing.