Instanton molecules at high temperature - the Georgi-Glashow model and beyond

We show that correlators of some local operators in gauge theories are sens itive to the presence of the instantons even at high temperature where the latter are bound into instanton-anti-instanton "molecules". We calculate co rrelation functions of such operators in the deconfined phase of the 2+1 di mensional Georgi-Glashow model and discuss analogous quantities in the chir ally symmetric phase of QCD. We clarify the mechanism by which the instanto n-anti-instanton molecules contribute to the anomaly of axial U(1) at high temperature.