Overview

Even if it is true that human activities have enhanced the natural greenhouse effect, it can be argued that natural climate variability is much stronger. This conclusion can be drawn from the history of our planet. Scientists who study climate changes in the past do not know who is in the drivers seat, carbon dioxide or temperature. It is the proverbial chicken or egg problem. Is it carbon dioxide that causes temperature changes, such as the predominant hypothesis of today wants us to believe, or might it just be the opposite and is it the temperature change that determines the concentration of carbon dioxide?

First of all, it is a fallacy that the concentration of carbon dioxide was fairly stable until the industrial revolution. This idea is partly based on the analysis of air bubbles in ice cores from Greenland and Antarctica. The idea behind this historical record is that the air has stayed more or less stable since the time the snow was compressed to ice. Several authors have pointed to the chemical processes taking place in these air pockets which influence the concentration of carbon dioxide. As Dutch geologist Priem states: There is reason to doubt that the air bubbles in glacier ice always reflect the atmospheric composition during precipitation. ^[1]

It has been suggested that the number of pores in vegetal leaves, the stomatal frequency, is a better indication of past carbon dioxide concentration. Contrary to popular belief, a study of these pores indicated that the...