The global average footprint per person has increased from 2.2 to 2.7 hectares since 2008 including the footprints of many developing nations, such as india and china. this means that

our collective lifestyle is even more unsustainable than before

Explanation:

Footprint is express in a common unit called a global hectare

we are cutting trees faster than they maturing and we emitting more carbon in atmosphere than the than forest absorb

and harvesting more fishes than ocean replenish

but since 2008, global average footprint per person increase by 2.2 hectares to 2.7 hectares

so by that our collective lifestyle is even more unsustainable than before

the factors that the economies of the muslim empires prosper were:

1- land trade routes-located between three continents  

2- sea trade routes

trade contributed to the spread of muslim empires, and with that islamic culture led to a growing feeling of internationalism resulted in the transfer of technology, science, and other cultural forms.

answer; generalizability;