The Global Forest Resources Assessment 2010 is a new United Nations Food and Agriculture Organization (FAO) report on deforestation. It shows a decrease in deforesting over the past decade, but depletion continues at an alarming rate in many countries. Between 2000 and this year about 13 million hectares of forest were converted annually to other use or lost through natural causes, down from 16 million a year in the previous decade.

Satellite imagery provides a mine of information for such reports. True and false colour images are used to determine the earth surface covered by forest. Object-Based Image Analysis techniques are increasingly commonly used to recognise forest area, or even single trees in urban environments. An interesting contribution on this subject will be presented by the ‘Boom en Beeld Project' (Tree and Image Project) at the Geobia (GEOgraphic Object-Based Image Analysis) conference to be held in Ghent, Belgium from 29th June to 2nd July 2010.

Almost coinciding with appearance of the FAO report, severe sandstorms struck China. These storms are a product of worsening desertification in Inner Mongolia and other Gobi Desert regions caused by deforestation, but also by overgrazing, drought and urban sprawl. China's expanding deserts now cover one third of the country. Loose dust and dirt are picked up by strong winds that mix them with industrial pollution and transport the laden air over hundreds of miles to Beijing. The most recent storms even affected the regions of Xinjiang and Inner Mongolia, and the provinces of Shanxi, Shaanxi and Hebei.

As a sandstorm moved south-east, South Korea's national weather agency issued a ‘yellow-dust' advisory for Seoul and other parts of the country. The Chinese Academy of Sciences has estimated a six-fold increase in the number of sandstorms in the past fifty years, to two dozen a year.

The photograph shows the headquarters of China Central Television. On the right, the skyscraper blanked out by the sandstorm which hit China last March.

See also GIM International January 2010 feature ‘Object-based Image Analyses ' by Elisabeth Addink, Utrecht University, the Netherlands, and Frieke Van Coillie, Ghent University, Belgium.