The abyssal ocean is warming as a response to climate change. The coldest and most dense water is the Antarctic Bottom Water (AABW) with a potential temperature of < 2°C. In the western South Atlantic it spreads northward from the Argentine Basin to the Brazil Basin. The coldest AABW flows therefore through the Vema Channel which has a sill depth of over 4800m at ~31°S, ~ 39°W. Since the 1970’s a decadal warming trend of the coldest Antarctic Bottom Water has been observed in the Vema Channel and Vema Extension. This study will investigate the short and long term variability in observed temperature and attribute it to tides and topographic waves.