The deep impact of climate change

It is believed that relatively warm water flooding the continental shelf is causing high melt rates at the base of the Larsen C, George VI and Ronne ice shelves.

The BAS climate modellers used data collected from flow switches to determine how warm and how salty the water was, which allowed them to log how rapidly the ice is melting, helping predict the rate and effects of climate change.

Dr Keith Makinson, researcher from the BAS team, stated: “Ice melting sounds so simple, but we don’t know much about the effect it has (on the climate).”

The team implemented a hot-water drill to create access holes through parts of the shelf. The holes are fed with measurement instruments that make numerical models of the ice shelf and ocean that include turbulence and the transfer of heat towards the ice.

The collected data, stated Makinson, will provide a view of the boundary layer below the shelf, making it possible to compare and contrast melt rates with one another.

Makinson’s team then relocated to the Ronne Ice Shelf, where drilling depths increase to 1000m, an increase of 600m on the Larsen C and George VI shelves.

The team collected similar data for 12 months, allowing a cross section of information to be obtained from various parts of the Antarctic shelves.

However, a challenge faced by the team remained the weather conditions. The holes drilled refreeze as quickly as they are made, so drills had to be fitted with appropriate equipment.

The team used three heaters, each equipped with a MR1K flow and brass switch supplied by PVL, which helped pump the melt water into a tank that is then subsequently heated to 90°C, and fed into the drill hole at a rate of 80mm/ minute.

Working through the warmer summer months, the team collected data between 12 and 20 hours at a time to help determine the effect climate change is having across large parts of the Antarctic continent.