Star formation is an inefficient process and in general only a small fraction of the gas in a giant molecular cloud ( GMC ) is turned into stars .
This is partly due to the negative effect of stellar feedback from young massive star clusters .
In a recent paper , we introduced a novel 1D numerical treatment of the effects of stellar feedback from young massive clusters on their natal clouds , which we named warpfield .
Here , we present version 2 of the warpfield code , containing improved treatments of the thermal evolution of the gas and the fragmentation of the feedback-driven shell .
As part of this update , we have produced new cooling and heating tables that account for the combined effects of photoionization and collisional ionization on the cooling rate of the gas , which we now make publically available .
We employ our updated version of warpfield to investigate the impact of stellar feedback on GMCs with a broad range of masses and surface densities and a variety of density profiles .
We show that the minimum star formation efficiency \epsilon _ { \mathrm { min } } , i.e .
the star formation efficiency above which the cloud is destroyed by feedback and further star formation is shut off , is mainly set by the average cloud surface density .
A star formation efficiency of 1-6 % is generally sufficient to destroy a GMC .
We also find star formation efficiencies per free-fall time \epsilon _ { \mathrm { ff } } \sim 0.3 % , in good agreement with recent observations .
Our results imply that stellar feedback alone is sufficient to explain the low observed star formation efficiencies of GMCs .
Finally , we show that very massive clouds with steep density profiles – possible proxies of the giant clumps observed in galaxies at z \approx 2 – are more resilient to feedback than typical GMCs , with \epsilon _ { \mathrm { min } } between 1 and 12 % .