QuickLinks -- Click here to rapidly navigate through this document

Exhibit 12.1

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES
(unaudited)

(in thousands, except ratio)	Three months ended March 31, 2013			Year ended December 31, 2012			Year ended December 31, 2011			For the period from Inception to December 31, 2010
Earnings:
Net income (loss)	$	39,996		$	131,919		$	53,232		$	(52,040	)
Add:
Provision (benefit) for income taxes		21,676			72,054			29,609			(8,875	)
Fixed charges		52,562			167,638			68,797			53,673
Less:
Capitalized interest		(6,899	)		(19,388	)		(10,390	)		(1,769	)
Earnings as adjusted (A)	$	107,335		$	352,223		$	141,248		$	(9,011	)
Fixed charges
Interest expense	$	45,440		$	147,413		$	57,692		$	51,743
Capitalized interest		6,899			19,388			10,390			1,769
Interest factors of rents(1)		223			837			715			161
Fixed charges as adjusted (B)	$	52,562		$	167,638		$	68,797		$	53,673
Ratio of earnings (loss) to fixed charges ((A) divided by (B))(2)		2.04			2.10			2.05			—

(1)

Estimated to be ¹/3 of rent expense.

(2)

For the period from inception to December 31, 2010, earnings were insufficient to cover fixed charges by $62.7 million.

QuickLinks

Exhibit 12.1

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES (unaudited)