• Dust, black carbon (from burning fossil fuels, particularly diesel, wood, and coal), ash, and some other aerosols help cool the atmosphere by reflecting sunlight when they are in the atmosphere. But when they fall on ice and snow they lead to increased warming.
• Blooms of dark pigmented glacier ice algae on southwest Greenland is accelerating warming (Fig. 6).
• This is because fresh snow and clean ice has an albedo of about 0.86, meaning it reflects 86% of sunlight. However, when aerosols fall on the white ice and snow, the albedo declines, sometimes dramatically. Dark ice and snow absorbs a much higher percentage of incoming sunlight, warming the surface faster, which hastens melting, indirectly causing warming through this feedback effect.
• The effects of ash on New Zealand glaciers is visibly evident (top image and Figs. 1-4).
• Research of the impacts is now underway; contact Lynda Petherick (Victoria University of Wellington) or Phil Novis (Manaaki Whenua Landcare Research).
• The effect on ice caps in Greenland (Fig. 6) and Antarctica is speeding the pace of melting, contributing to sea level rise.

While most aerosols in the atmosphere scatter incoming solar radiation, resulting in a net cooling effect on the atmosphere, BC [black carbon] absorbs significantly more light than it reflects, resulting in a net warming effect. Light absorbing particles radiate long-wave energy that heats the surrounding air which results in a positive (warming) forcing effect. Additionally, when BC is deposited on, or precipitated with snow, it lowers the albedo (reflective properties) and the absorbed light heats the snow causing it to melt which has important implications for permanent snowpack such as the Himalayan, Arctic and Antarctic regions. – GNS Science Consultancy Report