The U.N. weather agency says the world and especially urban areas experienced a brief and sharp drop in emissions of air pollutants last year.

MIAMI – The smoke coming from the fires in southeastern Australia has spread high into the atmosphere, and during an eastward dispersal, it will be making at least one full circuit globally, which will be affecting air quality, according to NASA scientists. In New Zealand, the smoke was able to darken mountaintop snow. By Jan. 8, NASA satellites detected the smoke had traveled halfway around the earth and was turning the skies hazy. NASA released this animation showing how the smoke from the fires in Australia is affecting air quality around the world. (NASA)NASA scientists expect the smoke to affect atmospheric conditions and air quality globally, but they do not know with certainty if it will have a cooling or a warming effect.