OBJECTIVETo determine if global warming has an impact on the evolution of hemagglutinins from influenza A viruses, because both global warming and influenza pandemics/epidemics threaten the world.

METHODS4 706 hemagglutinins from influenza A viruses sampled from 1956 to 2009 were converted to a time-series to show their evolutionary process and compared with the global, northern hemisphere and southern hemisphere temperatures, to determine if their trends run in similar or opposite directions. Point-to-point comparisons between temperature and quantified hemagglutinins were performed for all species and for the major prevailing species.

RESULTSThe comparisons show that the trends for both hemagglutinin evolution and temperature change run in a similar direction.

CONCLUSIONGlobal warming has a consistent and progressive impact on the hemagglutinin evolution of influenza A viruses.