Thompson, B.N.; Gregory, G. 1993 Climate change - what the rocks tell us. Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences information series 11 16 p.
Abstract: On the whole, world temperatures have been slowly rising this century. although this may be hard to believe on a wintry day, to geologists this comes as no big surprise. Much more dramatic swings between desert and polar conditions have occurred across the earth's surface over geological time. Moreover, although for much of the last 2 million years (the ''Ice Age'') temperatures have been colder that at present, they were up to 10deg.C warmer for the whole of the previous 150 million years. In this respect, it would have been surprising if modern temperatures had not risen in relation to those of the immediate geological past. The difficulty is to separate the increases caused by human activities from those that would have occurred anyway. (auths)