1. Undid the Ottoman Empire. If the Ottomans had limped around for 20 more years, they would have found themselves in a century drunk on oil, while in charge of the majority of the world's oil reserves. The Ottomans would have been the global superpower of the latter half of the 20th century.
2. Rise of Communism. Lenin was an outcast living in Switzerland when the Tsar was overthrown. He arrived in Russia -- delivered there by Germany and with significant German funding -- two months after the interim government had taken over. It was a liberal democracy, not unlike the government of the US or France, that had the most power when Lenin arrived. Even if the Russian Empire had still fallen, the century probably wouldn't have fallen under the shadow of communism.
3. The center of world banking moved from London to New York City. After the end of 1916 or so, Britain was pretty much broke, and the war effort was to a significant extent funded by NYC bankers. London indebted themselves greatly to the US, and wherever you were in the world, if you wanted something to do with money, you went to New York City to get it, because England didn't have any. Of course, for these loans to mean anything, Britain would have to win the war (and reparations) which leads us to...
4. USA as world police. The US wanted nothing to do with European, Asian, or African politics. Even Teddy Roosevelt's "imperialist" attitudes were limited to North and South America. If Wilson wanted all the NYC banks to not go bankrupt, he'd have to enter the war- which he did. And thus began America's role as world police rather than a regional power.
5. The Belfast declaration and the catastrophic carving of the Arab world on arbitrary lines. Israel's foundation was laid down in 1917 by England declarating their intention to create a Jewish state in Palestine. And the borders drawn up on meaningless lines in the desert rather than along ethnic boundaries plunged the Arab world into a century of sectarian violence and chaos.
6. The Ottoman Empire would have gladly sold oil to Japan during their wars with China. (which likely still would have happened) Japan never would have had the quarrel with the United States that lead to the attack on Pearl Harbor.
While I'm not trying to minimize the human life cost of WWI, I actually don't think the death toll of the war was really all that significant. China's had a dozen or so civil wars with higher death tolls. More people died of the flu in 1918 and 1919 than all combat deaths from 1914 to 1918 combined. But WWI had an outsized effect on world history. I think it's probably the most transformational event in human history since... I dunno, Columbus introducing the Americas to Europe.
I don't know what the world would look like if WWI didn't play out the way it did. But it wouldn't look like this.
1. Undid the Ottoman Empire. If the Ottomans had limped around for 20 more years, they would have found themselves in a century drunk on oil, while in charge of the majority of the world's oil reserves. The Ottomans would have been the global superpower of the latter half of the 20th century.
2. Rise of Communism. Lenin was an outcast living in Switzerland when the Tsar was overthrown. He arrived in Russia -- delivered there by Germany and with significant German funding -- two months after the interim government had taken over. It was a liberal democracy, not unlike the government of the US or France, that had the most power when Lenin arrived. Even if the Russian Empire had still fallen, the century probably wouldn't have fallen under the shadow of communism.
3. The center of world banking moved from London to New York City. After the end of 1916 or so, Britain was pretty much broke, and the war effort was to a significant extent funded by NYC bankers. London indebted themselves greatly to the US, and wherever you were in the world, if you wanted something to do with money, you went to New York City to get it, because England didn't have any. Of course, for these loans to mean anything, Britain would have to win the war (and reparations) which leads us to...
4. USA as world police. The US wanted nothing to do with European, Asian, or African politics. Even Teddy Roosevelt's "imperialist" attitudes were limited to North and South America. If Wilson wanted all the NYC banks to not go bankrupt, he'd have to enter the war- which he did. And thus began America's role as world police rather than a regional power.
5. The Belfast declaration and the catastrophic carving of the Arab world on arbitrary lines. Israel's foundation was laid down in 1917 by England declarating their intention to create a Jewish state in Palestine. And the borders drawn up on meaningless lines in the desert rather than along ethnic boundaries plunged the Arab world into a century of sectarian violence and chaos.
6. The Ottoman Empire would have gladly sold oil to Japan during their wars with China. (which likely still would have happened) Japan never would have had the quarrel with the United States that lead to the attack on Pearl Harbor.
While I'm not trying to minimize the human life cost of WWI, I actually don't think the death toll of the war was really all that significant. China's had a dozen or so civil wars with higher death tolls. More people died of the flu in 1918 and 1919 than all combat deaths from 1914 to 1918 combined. But WWI had an outsized effect on world history. I think it's probably the most transformational event in human history since... I dunno, Columbus introducing the Americas to Europe.
I don't know what the world would look like if WWI didn't play out the way it did. But it wouldn't look like this.