Northern Iceland is a place of great interest for climatic studies. The land was fairly untouched by human activity until the Landnám period (870-930 AD), when humans first started to colonize the island. The study site is situated in the valley of Hjaltadalur close to the village Hólar, which after the settlement of humans became the religious and culture center of northern Iceland. Peat sediment cores were drilled to gain knowledge of the climatic fluctuations and environmental development in the area. Peat is a perfect archive of climatic and environmental changes due to its ability to preserve material like pollen, tephra and insect fossils which can be identified and analyzed to gain a better understanding of the past climate. Out of four possible drilling sites in the valley of Hjaltadalur, northern Iceland, Viðvik peat land was chosen for climatic analyses. Pollen, loss on ignition, tephra and radiocarbon dating analyses were performed on the peat material and samples for future macrofossil analyses were collected. The analyses provided useful information and insights into temperature fluctuations during the late Holocene, which could be correlated with other palaeoclimate research made in the past decades in the northern regions of Iceland. The pollen diagrams presented in this thesis show a transition from a warm and dry forestlike landscape to a cooler, more humid, open landscape during the last 5000 years. This visible transition, which contributed to a reduction of the birch population, started before the european settlement and thus implies that humans were not solely responsible for the birch decline in Iceland after the Landnám period (870-930 AD).