A stacked piston subsurface safety valve configured for being disposed in a wellbore through a fluid-producing formation, the subsurface safety valve comprising: a closure mechanism configured to be positioned in a passageway defined by a tubing string, wherein the closure mechanism is configured to selectively prevent a flow of fluid to a portion of the passageway that is closer to a surface of the wellbore than the closure mechanism; a piston assembly configured for actuating the closure mechanism, the piston assembly comprising: a first piston and a first rod disposed in a first chamber having a first diameter, wherein the first piston is positioned adjacent to the first rod; and a second piston and a second rod disposed in a second chamber adjacent to the first chamber and having a second diameter, wherein the second piston is positioned adjacent to the second rod, wherein the first rod is positioned adjacent to the second piston, and wherein the second diameter is smaller than the first diameter; and a flow tube comprising a spring-loaded retention mechanism, the spring-loaded retention mechanism configured to bias the flow tube, the first piston, the first rod, the second piston and the second rod in an uphole direction to close the closure mechanism, wherein the second rod is positioned adjacent to the flow tube; wherein the first piston is arranged uphole of the second piston; wherein a first control line is configured to selectively communicate a first pressure to the first piston to create a pressure differential across the first piston to move the first piston in a downhole direction, wherein the first piston is configured to apply a force to the second piston in response to the pressure differential, and wherein the second piston is configured to apply a force to the flow tube and the spring-loaded retention mechanism in response to the force applied to the second piston to open the closure mechanism; wherein a second control line is configured to communicate a second pressure to the first piston in the uphole direction and to the second piston in the downhole direction to reduce the pressure differential across the first piston to reduce an amount of force required by the spring-loaded retention mechanism to displace the first piston, second piston and flow tube in the uphole direction to close the closure mechanism; and wherein the first control line is configured to communicate the first pressure from a first pressure source and the second control line is configured to communicate the second pressure from a second pressure source different from the first pressure source. a closure mechanism configured to be positioned in a passageway defined by a tubing string, wherein the closure mechanism is configured to selectively prevent a flow of fluid to a portion of the passageway that is closer to a surface of the wellbore than the closure mechanism; a piston assembly configured for actuating the closure mechanism, the piston assembly comprising: a first piston and a first rod disposed in a first chamber having a first diameter, wherein the first piston is positioned adjacent to the first rod; and a second piston and a second rod disposed in a second chamber adjacent to the first chamber and having a second diameter, wherein the second piston is positioned adjacent to the second rod, wherein the first rod is positioned adjacent to the second piston, and wherein the second diameter is smaller than the first diameter; and a flow tube comprising a spring-loaded retention mechanism, the spring-loaded retention mechanism configured to bias the flow tube, the first piston, the first rod, the second piston and the second rod in an uphole direction to close the closure mechanism, wherein the second rod is positioned adjacent to the flow tube; a first piston and a first rod disposed in a first chamber having a first diameter, wherein the first piston is positioned adjacent to the first rod; and a second piston and a second rod disposed in a second chamber adjacent to the first chamber and having a second diameter, wherein the second piston is positioned adjacent to the second rod, wherein the first rod is positioned adjacent to the second piston, and wherein the second diameter is smaller than the first diameter; and wherein the first piston is arranged uphole of the second piston; wherein a first control line is configured to selectively communicate a first pressure to the first piston to create a pressure differential across the first piston to move the first piston in a downhole direction, wherein the first piston is configured to apply a force to the second piston in response to the pressure differential, and wherein the second piston is configured to apply a force to the flow tube and the spring-loaded retention mechanism in response to the force applied to the second piston to open the closure mechanism; wherein a second control line is configured to communicate a second pressure to the first piston in the uphole direction and to the second piston in the downhole direction to reduce the pressure differential across the first piston to reduce an amount of force required by the spring-loaded retention mechanism to displace the first piston, second piston and flow tube in the uphole direction to close the closure mechanism; and