A field experiment on Antarctica's Ardley Island found that cutting ultraviolet light by 20% reduced the carbon uptake of moss and lichen tundra by roughly half. A 50% cut reduced uptake by about 80%, and at times the tundra released more CO2 than it absorbed. The results, published in Atmospheric and Oceanic Science Letters, suggest that the healing ozone layer may weaken part of Antarctica's carbon sink even as it removes a major health threat. The study covered small plots in two areas, one near penguin colonies and one without. In the western marsh, lower UV hurt photosynthesis. In the penguin-fertilized east, soil respiration rose instead. The authors note the findings are site-specific, but with about 72,000 square kilometers of Antarctic tundra, the mechanism could matter for carbon cycle models that currently ignore UV effects.
