A system for modifying the operation and/or performance of a gas turbine comprising one or more combustors, the system comprising: at least one sensor for determining a gas exhaust temperature for the gas turbine; and a controller configured to: receive the gas exhaust temperature from the at least one sensor; estimate a transient heat transfer rate for the gas turbine based at least in part on the gas exhaust temperature; and control the one or more combustors based at least in part on the estimated transient heat transfer rate for the gas turbine, wherein to estimate a transient heat transfer rate for the gas turbine based at least in part on the gas exhaust temperature, the controller is further configured to: estimate a bulk gas temperature for the gas turbine based at least in part on the gas exhaust temperature; estimate a bulk turbine rotor metal temperature for the gas turbine; determine a first adjustment factor based at least in part on a heat transfer rate for the gas turbine, the estimated bulk turbine rotor metal temperature, and the estimated bulk gas temperature; and calculate the estimated heat transfer rate based at least in part on the estimated bulk gas temperature, the estimated bulk turbine rotor metal temperature, and the first adjustment factor, wherein to estimate a bulk turbine rotor metal temperature, the controller is further configured to: determine a second adjustment factor based at least in part on a bulk turbine rotor metal temperature for the gas turbine and a bulk gas temperature for the gas turbine; and estimate a bulk turbine rotor metal temperature based at least in part on the second adjustment factor. at least one sensor for determining a gas exhaust temperature for the gas turbine; and a controller configured to: receive the gas exhaust temperature from the at least one sensor; estimate a transient heat transfer rate for the gas turbine based at least in part on the gas exhaust temperature; and control the one or more combustors based at least in part on the estimated transient heat transfer rate for the gas turbine, receive the gas exhaust temperature from the at least one sensor; estimate a transient heat transfer rate for the gas turbine based at least in part on the gas exhaust temperature; and control the one or more combustors based at least in part on the estimated transient heat transfer rate for the gas turbine, wherein to estimate a transient heat transfer rate for the gas turbine based at least in part on the gas exhaust temperature, the controller is further configured to: estimate a bulk gas temperature for the gas turbine based at least in part on the gas exhaust temperature; estimate a bulk turbine rotor metal temperature for the gas turbine; determine a first adjustment factor based at least in part on a heat transfer rate for the gas turbine, the estimated bulk turbine rotor metal temperature, and the estimated bulk gas temperature; and calculate the estimated heat transfer rate based at least in part on the estimated bulk gas temperature, the estimated bulk turbine rotor metal temperature, and the first adjustment factor, estimate a bulk gas temperature for the gas turbine based at least in part on the gas exhaust temperature; estimate a bulk turbine rotor metal temperature for the gas turbine; determine a first adjustment factor based at least in part on a heat transfer rate for the gas turbine, the estimated bulk turbine rotor metal temperature, and the estimated bulk gas temperature; and calculate the estimated heat transfer rate based at least in part on the estimated bulk gas temperature, the estimated bulk turbine rotor metal temperature, and the first adjustment factor, wherein to estimate a bulk turbine rotor metal temperature, the controller is further configured to: determine a second adjustment factor based at least in part on a bulk turbine rotor metal temperature for the gas turbine and a bulk gas temperature for the gas turbine; and estimate a bulk turbine rotor metal temperature based at least in part on the second adjustment factor. determine a second adjustment factor based at least in part on a bulk turbine rotor metal temperature for the gas turbine and a bulk gas temperature for the gas turbine; and estimate a bulk turbine rotor metal temperature based at least in part on the second adjustment factor.