Despite global warming, a region in the North Atlantic ocean has been observed to cool, a phenomenon known as the warming hole. Its emergence has been linked to a slowdown of the Atlantic meridional overturning circulation, which leads to a reduced ocean heat transport into the warming hole region. Here we show that, in addition to the reduced low-latitude heat import, increased ocean heat transport out of the region into higher latitudes and a shortwave cloud feedback dominate the formation and temporal evolution of the warming hole under greenhouse gas forcing. In climate model simulations of the historical period, the low-latitude Atlantic meridional overturning circulation decline does not emerge from natural variability, whereas the accelerating heat transport to higher latitudes is clearly attributable to anthropogenic forcing. Both the overturning and the gyre circulation contribute to the increased high-latitude ocean heat transport, and therefore are critical to understand the past and future evolutions of the warming hole.

尽管全球变暖，但仍观察到北大西洋一个地区变冷，这种现象被称为变暖洞。它的出现与大西洋子午倾覆环流的减缓有关，这导致海洋热量向增温孔区域的传输减少。在这里，我们表明，除了减少低纬度的热量输入外，海洋热量从该地区向更高纬度的传输增加，并且短波云反馈主导了温室气体强迫下暖洞的形成和时间演变。在历史时期的气候模式模拟中，低纬度大西洋经向翻转环流的下降并非源于自然变化，而向高纬度的热传递加速显然是由于人为强迫。