By 2050, researchers predict alien species worldwide will increase 36% from 2005 numbers. Using a mathematical model, the team calculated how many nonnative species would arrive based on historical invasions under a business-as-usual scenario. They found that 36% more than the approximately 35,000 nonnatives reported in 2005 will be likely occur under this scenario, mostly insects, arthropods and birds. The largest increase is expected in Europe, where alien species will likely by 64%. The lowest increase of nonnative species is expected in Australia. The team also stresses that strict regulations and rigorous enforcement of international trade could slow the spread of these species.