In fact, this cycle is now thought to bury heat deep in the oceans periodically. And, because it existed even before humans put significant carbon into the atmosphere, it is likely natural.
事实上，现在人们认为这一循环定期将热量埋入深海。而由于该循环在人类向大气中大量排放碳之前就已存在，它很有可能是自然变量。