Climate Change is Weakening the Ocean Currents That Shape Weather on Both Sides of the Atlantic The change in the main ocean heat pump could bring more heat waves to Europe, increase sea level rise in North America and force fish to move farther north. Related Share this article Since the end of the last ice age, a swirling system of ocean-spanning currents has churned consistently in the Atlantic, distributing heat energy along the ocean surface from the tropics toward the poles, with heavy, cold water slowly flowing back toward the equator along the bottom of the sea. Collectively known as the Atlantic Meridional Overturning Circulation, the currents played a key role in shaping the climate of eastern North America and Western Europe, and thus the development of civilizations there. But in the 20th century, the circulation has weakened more than at any other time during at least the last 1,000 years, new research shows.