NASA: small nuclear war reverts years of global warming: "According to National Geographic,Small Nuclear War Could Reverse Global Warming for YearsSee also
New Design World.
NASA GISS' computer modelers (Luke Oman et al.) were trying to solve the 'global warming crisis' and they found a solution: a regional nuclear war, for example between India and Pakistan, would reduce floods and cool the Earth by 1.25 °C - some places by 3-4 °C. After a decade, the temperature would still be 0.9 °C lower than before the war.
The predictions are a humble version of the nuclear winter scenario.
You see, nuking Iran and a few other thug states away will also revert decades or a century of 'global warming' at the same moment. It has not yet been reported whether John Holdren has already asked Barack Obama to press buttons.
More seriously, it's kind of amazing what kind of research is being funded. If there were a nuclear war between similar countries, a cooling by a degree Celsius would clearly be one of the least significant consequences. We had minus 14 Celsius degrees in the morning, fine, so we would have minus 15 Celsius degrees. And irradiated, dying relatives across the world, too.
Concerning the impacts, well, it's very likely that there would be some cooling that would depend on the magnitude of the explosions and that would last for years. It isn't terribly useful to calculate the exact impact because the total size of the hypothetical nuclear war would remain uncertain until its peak - or until its end. Nuclear wars may differ by many orders of magnitude.
Hiroshima and Nagasaki haven't experienced much of a climate impact so one has to speak about much larger conflicts - about 100+ times larger. They would probably have to kill tens of millions of people. Do those people really think that a degree of temporary cooling or warming would be more important than those lives and other political impacts of the war?
I am surely among the top 10% of the Hawks who would use nuclear weapons e.g. against Iran under certain circumstances. But I don't mean carpet bombing without any good reason; what I mean are surgical operations meant to cripple their offensive military. A temperature change by a degree can't be the reason to start the bombing.
ME HERO DYD