A study published in 2014 found, rapid grounding line retreat in the years 1992–2011. Based on a study from 2005, the greatest retreat was seen in Sjogren Glacier, which is now further inland than where it was in 1953. There are 32 glaciers that were measured to have advanced; however, these glaciers showed only a modest advance averaging per glacier, which is significantly smaller than the massive retreat observed. Thwaites Glacier, which has also shown evidence of thinning, has been referred to as the weak underbelly of the West Antarctic Ice Sheet. A study published in 2014 found rapid grounding line retreat in the years 1992–2011. More recently, new satellite imaging data led to calculations of Thwaites Glacier "ice shelf melt rate of 207 m/year in 2014–2017, which is the highest ice shelf melt rate on record in Antarctica." Totten Glacier, is a large glacier draining a major portion of the East Antarctic Ice Sheet. A study in 2008 concluded that Totten Glacier is currently losing mass. A study published in 2015 concluded that Totten Glacier, has the largest contribution of ice thinning rate on the East Antarctic continent, and that the thinning is driven by enhanced basal melting, because of ocean processes, and affected by polynya activity. Additionally, warm Circumpolar Deep Water, has been observed during summer and winter months at the nearby continental shelf below 400 to 500 meters of cool Antarctic Surface Water.