( ( The discovery ) ( ( suggests ( that ( ( while ( ( ( the ( Earth 's ) ) ( lower atmosphere ) ) ( is warming ) ) ) ( , ( ( ( ( ( ( its ( upper atmosphere ) ) , ) or ) thermosphere ) , ) ( is cooling ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN discovery)) (VP (VBZ suggests) (SBAR (IN that) (S (SBAR (IN while) (S (NP (NP (DT the) (NN Earth) (POS 's)) (JJR lower) (NN atmosphere)) (VP (VBZ is) (VP (VBG warming))))) (, ,) (NP (NP (PRP$ its) (JJ upper) (NN atmosphere)) (, ,) (CC or) (NP (NN thermosphere)) (, ,)) (VP (VBZ is) (VP (VBG cooling)))))) (. .)))
The discovery suggests that while the Earth's lower atmosphere is warming, its upper atmosphere, or thermosphere, is cooling.
(ROOT (S (NP (NNP Thermosphere)) (VP (VBZ is) (NP (DT the) (JJ upper-most) (NN atmosphere))) (. .)))