The Sahara Desert is expanding at a rate of roughly 10000 km^2 per year due to a combination of natural and human induced factors. Deforestation, climate change, and agricultural practices contribute to the desertification of these areas.
Tumbleweeds originated in Russia and Siberia and they were brought to the United States in the 1870s, hidden among imported flax seeds. It only took 20 years for the plants to spread throughout the western United States and parts of Canada.
