Besides the low frequency variations, the Earth's orbital elements also exhibit variabilities at shorter time scales. This study investigates the quantitative impact of these high frequency orbitally induced insolation variations on climatic variables such as surface temperature as well as the dynamical change in vegetation. Moreover it aims to assess the extent to which these different factors (high frequency insolation variations and subsequent vegetation changes) may compete with the changes in solar activity. To this end, we have carried out a series of transient climate simulations over the last 1000 years using a climate model of intermediate complexity.