Carbon dioxide levels have risen for decades and some scientists predict they will rise another 35 percent to 50 percent by 2050.
(Carbon dioxide levels; have risen; T:for decades) (some scientists; predict; they will rise another 35 percent to 50 percent by 2050)
Carbon dioxide levels some scientists
have risen predict
T:for decades
they will rise another 35 percent to 50 percent by 2050