PORTUGAL – For three days in mid-September, wildfires rapidly tore through parts of Portugal, turning the sky a hellish, smoky red against the rolling green hills in the north. In central Portugal, a blaze engulfed a highway, cutting off the top half of the country from the bottom. Nine people were killed.

Few people in other parts of Europe and the US would have realized that some of their everyday products may have played a role in making these fires worse. Certain toilet paper, tissue and office paper brands are made with materials from eucalyptus trees, a non-native species to Portugal.

The eucalyptus globulus — also known as the Tasmanian blue gum — is an ideal tree for commercial cultivation because it’s faster-growing, has a larger amount of fiber and produces more pulp than most other species. That means it can be made into high-quality paper and tissue in an efficient and economical way.

The problem is eucalyptus trees are particularly flammable. That’s especially dangerous as the planet heats up from nearly two centuries of humans burning fossil fuels at an industrial scale.

The eucalyptus tree is native to Australia and provides food and shelter to koalas, among other wildlife. It has spread rapidly in other countries, too, including Portugal, where it was introduced in the early 19th century.

As the Portuguese paper and timber industries grew in the mid-1900s, so too did eucalyptus plantations, and the species now covers nearly 2 million acres. That’s almost one-tenth of the entire country, and a quarter of its total forested area.

Proportional to its size, Portugal has more eucalyptus than any country in the world. Miles and miles of the trees blanket the landscape like “green deserts,” as some Portuguese say. But it’s not the only nation to allow the species’ spread. In California, the eucalyptus tree has been naturalized, meaning it now grows beyond the places it was planted. (CNN)…[+]