The new research took as its baseline one of the central forecasts of the Intergovernmental Panel on Climate Change, for a temperature rise of 2C above pre-industrial levels by 2050.

1. 主要结构：take sth. as...， 把......作为......

2. took 的宾语是 one of the central forecasts of the Intergovernmental Panel on Climate Change，因太长被后置，回到原位后：

3. ...as its baseline for a temperature rise of 2C above pre-industrial levels by 2050,

由此看出，划线部分是 its baseline 的定语。这里， for 表示为 a temperature rise of 2C 而设置的一条基准线。