A plane is heated in an uneven fashion. The coordinates (x, y) of the points on this plane are measured in centimeters and the temperature T(x, y) at the point (x, y) is measured in degrees Celsius. An insect walks on this plane and its position after t seconds is given by x = sqrt(21 + 2t) and y = 1 + t. Given that the temperature on the plane satisfies T'x(5, 3) = 2 and T'y(5, 3) = 2, what is the rate of growth of the temperature along the insect's trajectory at time t = 2?