That the climate is changeable is not new, but the current accuracy of the predictions is altering our understanding of the subject. A study led by the Swiss meteorologist Raphael Neukom in which scientists from all over the world have participated has analyzed the climatic variability between the two hemispheres, based on comparing numerous data. In it it is seen that although a similarity was assumed in the atmospheric circulation processes between the two hemispheres, the southern hemisphere does not have the same internal dynamics as the north. Among other values, more than 300 studies were analyzed on the evolution of the width of the Patagonian tree rings, various marine records, sediments accumulated at the bottom of lakes, ice remnants from Antarctica, coral reefs and various documentation historical, such as ship logs from the colonial era.
All this information allowed the researchers to deduce that previous models overestimated the synchrony between both hemispheres by underestimating the influence of ocean-atmosphere dynamics, a determining factor in the southern hemisphere. Ignacio Mundo and Ricardo Villalba, two Argentine researchers who participated in the study. work, analyzed the width of the arboreal rings of Patagonia: “ Trees, like all living beings, respond to variations in the environment in which they grow and develop . The width of the growth rings allows us to indirectly deduce what the temperatures and rainfall were like and from these sequences to carry out climatic reconstructions even of the river flows ”, they explain.
Trees grow more when environmental conditions are favorable depending on the requirements of the species, and dedicate more of the energy obtained from photosynthesis in wood. On the other hand, when the conditions are more adverse, rigorous or extreme, they contribute less energy to radial growth. “Comparatively, there is greater synchrony in the climatic variability of the hemispheres in the last century than in the last millennium . This similarity of the last hundred years, visible in the temperature records, has to do with anthropic or human activity, ”says Mundo. Variations in the world meteorological system result from the interactions between the internal and specific dynamics of each hemisphere, characterized by factors such as El Niño or the circulation of the oceans, and external factors, such as solar radiation, volcanic eruptions that affect both halves of the planet and the emission of greenhouse gases by human action.
The researchers point out that since in the past the anthropic influence was lower, the variability of each hemisphere was greater. “In the work we conclude that climate variability is basically of endogenous origin, which would explain the relative autonomy of each hemisphere throughout the last millennium. But the previous models overestimated the influence of external factors on climate variability, which resulted in the fact that the predictive meteorology was highly biased towards the general atmospheric circulation, taking into account the known data from the north ”, highlights Villalba.
For its part, Mundo points out that in the last 40 years there has been a tendency to a sustained increase in temperature in both the North and the South, which can be seen in more detail now, although since the beginning of the last century there was a a marked trend in this sense, related to the industrialization process on a global scale.
