Climate Changes Of The Recent Past In Southern Parts Of Brazil

Bore-hole temperature data from 23 localities in<br>southern Brazil were examined for identifying thermal<br>signals related to climate changes of the historic<br>past. Both forward and inverse modeling methods<br>were employed in the analysis of vertical distribution<br>of temperatures. The forward modeling approach is<br>based on the classical method of least square fits to<br>theoretical curves, with a priori assumption as to the<br>form of temperature variation. The inverse method<br>can handle non-linear problems and allows convenient<br>trade-off between model and data.<br>The data set examined so far reveal the following<br>information about recent climate changes in southern Brazil:<br>- the form of temperature variation is indicative of a<br>warming trend in all of the 23 localities;<br>- the magnitudes of temperature variations are in the<br>range of 1 to 40C while the time elapsed vary from<br>20 to 200 years;<br>- the climate change seem to be more pronounced in<br>coastal areas compared to that in inland and semiarid<br>zones;<br>- there is a progressive increase in the age of climatic<br>perturbation, as one moves from the coastal area<br>towards the interior of the continent;<br>- changes in vegetation cover have marked effects on<br>surface temperatures in southern parts of Brazil;<br>- the changes found in semi-arid zones, being unaffected<br>by changes in vegetation cover, appears to be<br>indicative of global climate changes.