An Atlantic Ocean current that helps regulate the global climate has reached an 1,000-year low, according to two new studies in the journal Nature. The shift could mean bad news for the climate. The Atlantic Meridional overturning circulation [AMOC] - often called the conveyor belt of the ocean - exchanges warm water from the equator with cold water in the Arctic. The AMOC plays a key role in the distribution of heat" across the Earth, but that is being disrupted by melting ice, particularly from Greenland, causing larger volumes of freshwater to flow through the oceans, says David Thornalley ... the lead author of one of the new studies. Some scientists are concerned the influx of freshwater could cause the current to shut down altogether. Scientists are worried about the AMOC shutting down "because evidence from the past suggests that it actually did happen during the last ice age, and it is possible that it could happen in the future," [Thornalley] says. While there is an ongoing dispute about what is causing the slowdown, scientists agree that it could have a dramatic impact on ocean ecosystems, such as coral reefs and deep-sea sponge grounds. "These delicate ecosystems rely on ocean currents to supply their food and disperse their offspring," Prof Murray Roberts, who co-ordinates the Atlas project at the University of Edinburgh, told BBC News. "Ocean currents are like highways spreading larvae throughout the ocean, and we know these ecosystems have been really sensitive to past changes in the Earth's climate."