Nuclear Winter

[GrauGeist]

The most damaging nukes are the ones of high yield, which churn up debris and broadcast that matter into the stratosphere (like a volcano).
While an air-burst type detonation has it's strategic value, it won't present a significant threat to weather/climate.
It's the nukes that burrow and detonate or ground-burst, that present a problem globally.

 

[Zipper730]

The most damaging nukes are the ones of high yield, which churn up debris and broadcast that matter into the stratosphere (like a volcano).

That's correct, and there were warheads that were designed for lay-down delivery. There was also some war-plans from the 1950's that revealed proposals to use ground-bursts in some cases: Probably to produce a tremendous overpressure on a small area (like a hardened target) versus a large amount over a large area (area-target).

What really struck people as surprising was that "population" was sometimes specified as a target (I gotta say, I'm impressed with their candidness -- usually there's various euphemisms that obscure the nature of stuff like that), though I'm not sure if it was needed (several nukes would often be assigned to nearby targets).

It's the nukes that burrow and detonate or ground-burst, that present a problem globally.

I assume the ones that penetrate would probably be the worst, the B53 was designed to be able to dig into the ground before detonating. I'm not sure how far down it'd go, but if you could dig in 280 feet and detonate with just 5MT of force, you could make Meteor crater.

 

[mikewint]

In 1982, the journal of the Royal Swedish Academy of Sciences, Ambio, published an article that discussed the issue of smoke generated by the nuclear-ignited burning of forests and grasslands. The article discussed the effect of the smoke generated causing changes in continental weather patterns. As bad as that was, later studies found that the smoke from urban fires posed an even greater global hazard in the form of a "Nuclear Winter" that was capable of causing a worldwide collapse of agriculture. Modern climate models not only show that the nuclear winter theory is correct, but also that the effects would last for more than a decade because of an unexpected phenomenon: Smoke would rise to altitudes of 40 kilometers (25 miles). At such a height it would be protected from rain and would therefore take more than a decade to clear completely. Thus the smoke's climate impacts would be more extreme than had once been thought.

The new models show that a full-scale nuclear conflict, in which 150 million tons of smoke are lofted into the upper atmosphere, would drastically reduce precipitation by 45 percent gloabally, while temperatures would fall for several years by 7 to 8C (12 to 14F) and would remain depressed by 4C (7F) after a decade. Global temperatures have not been this low since the last ice age. In important grain-growing regions of the northern mid-latitudes, precipitation would decline by up to 90 percent, and temperatures would fall below freezing and remain there for one or more years.

For instance in a nuclear exchange between the major powers, the use of 4,000 weapons (the rough total for US and Russian arsenals in 2017 under New START), each with a yield of 100 kilotons (a typical yield for submarine weapons, but at the low end for most nuclear weapons), against urban or industrial targets would produce about 180 million tons of soot. A single US submarine carrying 144 weapons of 100-kiloton yield could produce 23 million tons of smoke if these weapons were used on densely populated Chinese cities.

Let's now consider a smaller scale regional nuclear war (India – Pakistan) involving the use of just 100 Hiroshima-size weapons. In these simulations, more than five million tons of smoke is lofted to high altitude, where it absorbs sunlight before the light can reach the lower atmosphere. As a result, surface temperatures fall and precipitation declines. The calculated results show a 10 percent global drop in precipitation, with the largest losses in the low latitudes due to failure of the monsoons. The predicted climate model also shows global average temperatures colder than any experienced on Earth in the past 1,000 years and growing seasons shortened by two to three weeks in the main mid-latitude agricultural areas of both hemispheres. These effects would persist for several years, threatening a significant fraction of the world's food supply. At present at least a billion people are now only marginally fed as it is. New simulations of the effects of these climate changes on crop production predict reductions of soybean and corn production in the US Midwest, and of rice production in China, of 20 percent for several years and 10 percent even after a decade. The smoke would also heat the upper atmosphere by as much as 50 degrees Celsius for several years. As a consequence, ozone levels over the mid-latitudes of both hemispheres would be reduced to values now found only in the Antarctic ozone hole allowing large amounts of UV-radiation to reach the surface.

 

[Zipper730]

For instance in a nuclear exchange between the major powers, the use of 4,000 weapons . . . . each with a yield of 100 kilotons

The bombs we had in 1962 were well above that on average.

The smoke would also heat the upper atmosphere by as much as 50 degrees Celsius for several years. As a consequence, ozone levels over the mid-latitudes of both hemispheres would be reduced to values now found only in the Antarctic ozone hole allowing large amounts of UV-radiation to reach the surface.

So there'd be radiation from the blasts, and radiation from the ozone depletion. I assume that would contribute to massive cancer deaths...

 

[mikewint]

The only real Nuclear Bomb data remains the effects of the bombs dropped on Hiroshima and Nagasaki. There were, of course only two bombs involved and they were, by today's standards, small low yield bombs: Little Boy 13-18 kt TNT and Fat Man 20-22 kt TNT. By comparison the USSR's Tsar Bomb, as tested with a lead damper yielded 500,000 kt TNT and with a depleted uranium damper should reach 100 Mega tons of TNT.

Approximately 200,000 people died in the bombings and their immediate aftermath, mainly from the explosive blast, the firestorm it sparked, and from acute radiation poisoning. Around half of those who survived subsequently took part in studies tracking their health over their entire lifespan. These studies began in 1947 and are now conducted by a dedicated agency, the Radiation Effects Research Foundation, The project has followed approximately 100,000 survivors, 77,000 of their children, plus 20,000 people who were not exposed to radiation.

Cancer rates among survivors were higher compared to rates in those who had been out of town at the time. The relative risk increased according to how close the person was to the detonation site, their age (younger people faced a greater lifetime risk), and their sex (greater risk for women than men). However, most survivors did not develop cancer. Incidence of solid cancers between 1958 and 1998 among the survivors were 10% higher, which corresponds to approximately 848 additional cases among 44,635 survivors in this part of the study. However, most of the survivors received a relatively modest dose of radiation. In contrast, those exposed to a higher radiation dose of 1 Gray (approximately 1000 times higher than current safety limits for the general public) bore a 44% greater risk of cancer over the same time span (1958-1998). Taking into consideration all causes of death, this relatively high dose reduced average lifespan by approximately 1.3 years.

Although no differences in health or mutations rates have yet been detected among children of survivors, However, more subtle effects might one day become evident, perhaps through more detailed sequencing analysis of their genomes. For the present it seems clear that even if the children of survivors do in fact face additional health risks, those risks must be very small.


The Gray is the unit of absorbed radiation dose and has replaced the rad. 1 Gray = 1 Joule/kilogram and also equals 100 rad. The Gray can be used for any type of radiation (e.g., alpha, beta, neutron, gamma), but it does not describe the biological effects of different radiations.
Biological effects of radiation are measured in units of "sievert" (or the older designation "rem").
Sievert is calculated as follows: gray multiplied by the "radiation weighting factor" (also known as the "quality factor") associated with a specific type of radiation.
To cause death within hours of exposure to radiation, the dose needs to be very high, 10Gy or higher, while 4-5Gy will kill within 60 days, and less than 1.5-2Gy will not be lethal in the short term.

 

[swampyankee]

There is also limited data from US servicemen exposed during testing (see Other Studies of Radiation Exposure of Military Personnel - The Five Series Study - NCBI Bookshelf) and accidents, such as the Lucky Dragon No. 5 (Godzilla: The "Lucky Dragon" of Bikini Atoll | Naval Historical Foundation). Some data on the behavior of smoke can be obtained from the Kuwait War Oil FIeld fires (Environmental impact of Kuwait oil fires: upper atmosphere) and forest fires.

 

[fubar57]

The bombing of Hamburg lasted until Aug. 3 '43 so I'm sure it would have burned into August.