KM-B2 The threats from invasive alien species are 
increasing markedly in all regions of Earth, with 
the current unparalleled high rate of introductions 
predicted to rise even higher in the future {B10} 
(Figure SPM.4). The number of alien species has been 
rising continuously for centuries in all regions, and the global 
economic costs of invasive alien species have quadrupled 
every decade since 1970. Even without the introduction 
of new species, already established alien species given 
the opportunity, may continue to expand their geographic 
ranges into new countries, regions and ecosystems, 
including remote environments. Under a "business-asusual" scenario, which assumes that trends of drivers will 
continue as observed in the past, by 2050 the total number 
of alien species globally is expected to be about one-third 
higher than in 2005. However, the number of alien species 
worldwide is expected to increase faster than predicted 
under the business-as-usual scenario.
SUMMARY FOR POLICYMAKERS
The thematic assessment report on
INVASIVE ALIEN SPECIES
AND THEIR CONTROL
B. Globally, invasive alien species 
and their impacts are increasing 
rapidly and are predicted to 
continue rising in the future