ntil it was eventually deposited on land. While the vast majority of grounded radioactive material has been detected in Japan, smaller traces have been detected as far away as North America and Europe.
"As you move away from Japan, you get an exponential decrease in radioactivity concentration," said Jacobson.
In the case of Fukushima, no deaths have yet been identified as the direct result of radiation exposure. But according to Jacobson, those effects can take years, even decades, to manifest.
"We know that there were 600 deaths that resulted from the evacuation," due primarily to stress and fatigue, he said. "There were also between 10 and 12 worker fatalities at the Fukushima plants. Our estimate looks at the expected deaths over a lifetime of exposure to low levels of radiation."
Simulating particle physics on a global scale
While the effects of radiation are highly variable, he said, exposure is particularly dangerous for children, for whom any exposure constitutes a proportionally larger concentration of radioactive material.
The model shows that a failure to evacuate the area immediately surrounding the Fukushima power plant would have resulted in, at most, an extra 245 radiation-induced deaths.
Considering that about 600 deaths are currently attributed to the evacuation process itself, it is possible that the government's security measures cost more lives than they saved, Jacobson said.
In the months preceding the Fukushima disaster, Jacobson, whose work focuses on chemical transportation, had been preparing computer programs to model pollution movement from Asia to the United States. When disaster struck on March 11, 2011, he realized his opportunity to put his models to work.
Adjusting his programs to accommodate radionuclide data and emissions data from Japan, Jacobson and Hoeve began running their simulations shortly after the meltdown.
So complex were the models -- which account for atmospheric and oceanic circulation, as well as the processes of dissolution, coagulation and decay that characterize aerosol particles -- that they required the computing power of supercomputer clusters at both NASA and Stanford University.
Even so, each simulation required four to six months to run, said Jacobson.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500