According to Wikipedia, the Tsar Bomba, detonated in 1961, was the most powerful bomb ever tested. It was a hydrogen bomb with a yield about 1,350–1,570 times the combined power of the bombs that destroyed Hiroshima and Nagasaki.
As dangerous as the Tsar Bomba sounds, it's destructive force is probably peanuts compared to what could be built today. And who's to say that some bigger and more destructive bomb might not be built in the future? The only way to protect ourselves from this potential threat is to go ahead and build the biggest most dangerous bomb we can and then try to figure out what sort of bomb shelters we might need just in case someone actually detonates something like it someday in the unforeseeable future. The explosion in the photo above from the U.S. hydrogen bomb test on the Bikini Atoll is a pipsqueak; we need to be ready, we need to build the biggest bomb imaginable, no, even bigger!
Sound stupid? Mental? Needlessly and obviously too dangerous? Well, you just don't understand science.
The precise number of people killed in the Hiroshima and Nagasaki blasts isn't known but estimates of about 200,000 are common. Most died almost instantly, vaporized by the intense heat. The actual number, over the ensuing years from radiation-related causes, must be much larger. But whatever the number, it's much smaller than the number of people who have died from other causes.
The greatest number of human deaths over the shortest period of time was due to the 1918 Spanish flu. The Great Influenza says:
Although the influenza pandemic stretched over two years, perhaps two-thirds of the deaths occurred in a period of twenty-four weeks, and more than half of those deaths occurred in even less time, from mid-September to early December 1918. Influenza killed more people in a year than the Black Death killed in a century; it killed more people in twenty-four weeks than AIDS has killed in twenty-four years.Estimates of the number of deaths range from between 20 and 100 million. This puts the 1918 Spanish flu on a par with World War II. But in the case of WW II, the deaths occurred over a period of about six years. Quite simply, humans have never encountered anything else as deadly as the Spanish flu. But that might change in the very near future.
It now appears that scientists with a history of biosafety violations and questionable judgement working at institutions with faulty biosafety oversight and a history of lying to the public and hiding their violations are going to be given permission (and paid) to continue to create particularly virulent strains of influenza. The reasons they give to justify gambling with our species' very existence are very nearly the same ones I mentioned above to justify the creation of the biggest bomb imaginable.
We should have learned by now from things like the Challenger disaster, Japan's Fukushima Daiichi nuclear disaster, the multiple biosafety melt downs at the USDA's "secure" Plum Island labs, the 2011 foot and mouth disease virus escape in Pilbright, UK, the many other laboratory accidents and mistakes that have occurred in just the past few years, and the matter-of-fact tendency of universities to lie about what they do and the problems and violations that plague their labs, that no guarantee of safety should be given much credence.
The likelihood of an eventual accident or personnel problem (like the lab tech murdering the Yale scientist in 2009) amounts to a time bomb that could explode at any moment. As more labs invent more and ever more dangerous versions of influenza viruses, the likelihood of an escape through natural disaster, accidental and unrecognized infection of a lab worker, or even an intentional release of the virus becomes ever more likely.
And once out of the lab and spreading in the population, containment is probably impossible. People infected and spreading flu viruses often remain asymptomatic for a while. By the time it is recognized by the victim or someone else that they are sick, they've already had the opportunity to infect other people, who then infect others, with the rate increasing exponentially. Were something as deadly and fast moving as the Spanish flu to escape or be released, the consequences would dwarf the death rate that occurred in 1918/19 due to increased air travel and higher population densities.
Worse, many knowledgeable scientists are frightened at the prospect of labs around the world working to create such dangerous germs. They're not taken seriously enough and those who want to get in line for the hefty NIH grants that will fuel this endeavor tell them to compromise, that the labs can be made safer, that better safeguards can be put in place. They are winning the argument.
Worse, the traditional watchdogs have all ceded the battlefield to the eager influenza creators or else have gotten into step behind them and are helping delude the public about the safety of the labs that will be doing this work. The article linked to here portrays the Kawaoka lab as "half a notch below the top level anywhere" in safety, but that is very misleading and never does the paper alert the public to the lab's biosafety violations or the university's inability to adequately monitor the biosafety and compliance with federal biosafety regulations in the many labs on campus. If and when a disaster occurs, the responsibility will be shared by the labs, the universities hosting them, and local media outlets that have opted to keep the public confused or in the dark.
The creation of ever more virulent influenza strains makes the outlook for humans on the planet somewhat bleak. Maybe that's a silver lining for the rest of Earth's inhabitants.