Slide 6: Temperature change
Other methods for determining past climates include dendroclimatology. In this paper, conclusions are based on the width of tree growth rings, sampled from the sites highlighted on the panel in the lower left. It can be seen that approximately 1000 years ago trees grew considerably faster, during a period known as the medieval warm period. 500 years ago, however, the growth rates dropped, as the northern hemisphere entered what is called the 'little ice age'