Reindeer may be best known for pulling Santa’s sleigh, but a new study suggests they may have a part to play in slowing down climate change too.A team of researchers, writing in the journal Environmental Research Letters, found that when reindeer reduce the height and abundance of shrubs on the Arctic tundra through grazing, the level of surface albedo – the amount of solar energy (shortwave radiation) reflected by the Earth back into space – is increased.