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The Gulf Stream proper is a western-intensified current, driven largely by wind stress. The North Atlantic Drift, in contrast, is largely thermohaline circulation–driven. In 1958 the oceanographer Henry Stommel noted that "very little water from the Gulf of Mexico is actually in the Stream". By carrying warm water northeast across the Atlantic, it makesWestern and especially Northern Europe warmer than it otherwise would be.

However, the extent of its contribution to the actual temperature differential between North America and Europe is a matter of dispute, as there is a recent minority opinion within the science community that this temperature difference (beyond that caused by contrasting maritime and continental climates) is mainly due to atmospheric waves created by the Rocky Mountains.

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