Neither the Ukraine war nor tough weather changes would threaten a global food shortage in a normal market environment. Unfortunately, world markets are riddled with regulations, killing production.
The scale of the sanctions which Washington has imposed on Russia (and Russians) should not distract us from a crucial fact. What Washington is doing against Moscow is not rare. It is something that happens every day.
It's unlikely that Putin had no idea of the immense costs that he and Russia as a whole would incur in undertaking this war, so he likely believed the alternative would have been even more costly.
Germany's government is pushing a new plan for massive spending on a "Climate Fund." This is justified with the usual Keynesian myths about the benefits of government spending.