What are the cause of thermosphere, stratosphere and troposphere?

The problem of malnutrition in bangladesh is caused in part by "over population."hope my answer has you : )

The us is first  the  u.s. economy  remains the  largest in the world  in terms of nominal  gdp. however, the  u.s. economy  loses its spot as the number one  economy  to china when  measured  in terms of  gdp  based on ppp. in these terms, china's  gdp  is $23.19 trillion exceeds the  u.s. gdp  of $19.42 trillion

Boreal forest another word for this is taiga.but it is a biomes, that stretches across the northern regions of north america, europe, and asia.~ hope this ! (if this is correct may i have brainy? )