Charles I of England was executed in January, 1649, after which Oliver Cromwell rose to power.
The Americans signed their Declaration of Independence in 1776.
The French got a late start in 1789, but a couple decades of crop failures and food shortages are undoubtedly to blame.
Revolutions and political upheavals swept Europe in 1848. " It remains the most widespread revolutionary wave in European history... The revolutionary wave began in France in February, and immediately spread to most of Europe and parts of Latin America. Over 50 countries were affected..."
The Russian Revolution, of course, was also prompted by suffering, death, and starvation, thought most likely due to World War I, rather than climate.
Some of these revolutions turned out well. Some turned out terribly. The Americans were quite lucky to have George Washington, and the Russians terribly unlucky to have Lenin and Stalin. But the Americans also had better access to land to feed their families, and no reactionary counter-revolution to deal with. The leaders of the French Revolution took advantage of the instability to reform the state, but (as far as I can tell,) could do little about the country's biggest problem, lack of food. The new government never had a chance. (As for the English, well, I don't know enough about the 1600s to really comment.)
When man is starving, the political order loses legitimacy and the wealthy--the folks with food--become his first targets.