It slows down the war effort by up to 3-6 months early in the war, then it may speed up the war. The Enterprise spent much of the first few months of the war harassing Japanese island defenses. It was great training for the USA naval aviation, but it did not accomplish a great deal in he larger picture. We have probably butterflied away the Doolittle raid. Japanese may do a bit better in New Guinea. Without Doolittle raid, the Japanese navy will not have the reason to get a Midway type operation approved. And with few carriers, you might butterfly away Guadalcanal. But by 1943, the Americans are steam rolling the Japanese with ships commissioned after Pearl. And here is where it gets interesting. If we follow the Central Pacific Strategy, the war is won faster.
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Following this, we'd see the SE Pacific battles of 1942 in a different form. With fewer carriers lost by the Japanese & few air crew lost. Perhaps the Hiei & Krishima not sunk. So there could still be some big naval battles in late 43 & 44 as the Essex class carriers & new US BB are confronted by a less reduced IJN.