from 1950). In New Zealand and neighbouring regions of the Pacific, temperatures may have been further depressed during part of the Last Glacial Maximum by the world's most recent supervolcanic eruption, the Oruanui eruption, approximately 28,500 years BP. However, it is estimated that during the Last Glacial Maximum, low-to-mid latitude land surfaces at low elevation cooled on average by 5.8 °C relative to their present day temperatures, based on an analysis of noble gases dissolved in groundwater rather than examinations of species abundances that have been used in the past. World impact During the Last Glacial Maximum, much of the world was cold, dry, and inhospitable, with frequent storms and a dust-laden atmosphere. The dustiness of the atmosphere is a prominent feature in ice cores; dust levels were as much as 20 to 25 times greater than now. This was probably due to a number of factors: reduced vegetation, stronger global winds, and less precipitation to clear dust from the atmosphere. The massive sheets of ice locked away water, lowering the sea level, exposing continental shelves, joining land masses together, and creating extensive coastal plains. During the last glacial maximum, 21,000 years ago, the sea level was about 125 meters (about 410 feet) lower than it is today. Africa and the Middle East In Africa and the Middle East, many smaller mountain glaciers formed, and the Sahara and other sandy deserts were greatly expanded in extent. The Persian Gulf averages about 35 metres in depth and the seabed between Abu Dhabi and Qatar is even shallower, being mostly less than 15 metres deep. For thousands of years the Ur-Shatt (a confluence of the Tigris-Euphrates Rivers) provided fresh water to the Gulf, as it flowed through the Strait of Hormuz into the Gulf of Oman. Bathymetric data suggests there were two palaeo-basins in the Persian Gulf. The central basin may have approached an area of 20,000 km2, comparable at its fullest extent to lakes such as Lake Malawi in Africa. Between 12,000 and 9,000 years ago much of the Gulf's floor was not covered by water, only being flooded by the sea after 8,000 years ago. It is estimated that annual average temperatures in Southern Africa were 6 °C lower than at present during the Last Glacial Maximum. This alone would however not have been enough to create a widespread glaciation or permafrost in the Drakensberg Mountains or the Lesotho Highlands.