While we do not know with any precision what the ambient average temperature of the whole earth is in any year there have been many markers emerge. Some are: the average extent of Arctic ocean ice at the end of the Arctic summer; the acceleration of the melt rate of tropical glaciers; the melt rates of continental glaciers in Greenland and Antarctica; the southward migration of the permafrost line in Alaska, Canada and Siberia; the reduction of tropical rain-forests and the acidification of the oceans. Some of these factors are associated with the storage or release of carbon in the earth's surface, all moving in the direction of warming.

"It is not necessary to have hope in order to persevere."