The Earth has been much warmer than it is now, it has also been much colder. These extreme events have happened on many occasions during the planet's lifetime, before humans evolved. The prevailing view at the time that was published was that a cooler period was overdue. Since then science has progressed and new evidence has arisen; this too has happened many times - at one point in time the Earth was thought to be flat, it was also thought to be at the centre of the Solar System, but both of these views have been superceded as new science has developed.