Since the end of the 19th century there has been a general recession in Iceland's largest glaciers, e.g. since then the volume of the Vatna glacier has decreased by about 10%, and over the last 10 years the volume of all glaciers has decreased by 2.7%. This is the result not only of climate change but also of geothermal and volcanic phenomena. Studies of glacier mass balance and dynamics suggest that by the mid-21st century, Iceland's main ice caps will have shrunk by 25-35%, and the remnants of small glaciers on the largest peaks may disappear after about 150-200 years.