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Two separate systems interact to produce climate cycles

Researchers from the University of Alcala de Henares and the University of the Basque Country are answering some important questions about changing weather patterns. The interaction of two major climate trends affects weather cycles and ecosystems, according to the study.

The North Atlantic Oscillation (NAO), which is largely responsible for drought in Europe, is a large-scale fluctuation in the atmosphere located between the area of subtropical high pressures and the low polar pressure in the North Atlantic basin. The NAO impacts a range of activities in the environment, ranging from tree growth to forestry pest cycles.

The researchers have determined that inconsistencies in climate cycles – when events such as long-term forestry production did not match up to what was predicted by the NAO values – can be attributed to changes in the surface temperatures of the Atlantic Ocean. These periodic anomalies are known as the Atlantic Multidecadal Oscillation (AMO). The experts determined that the AMO significantly impacts the atmosphere, yet the effects are not seen immediately.

To test out this theory, the research team analyzed data from historical archives, climatology, statistical models, and forestry ecology.

“It has been a fascinating piece of work, dusting off archives of the end of the 19th century to get accurate estimates about how the productivity of forests across the Peninsula evolved over the last century and analyse them using 21st-century tools to understand the causes of the climate cycles and their consequences for the productivity of ecosystems,” said the authors of the study.

The research was primarily focused on pine forests in the Spanish regions of Castilla-La Mancha and in Castilla y Len. The study revealed for the first time that it is the interaction of the two climate modes, NAO and AMO, that largely controls the productivity of ecosystems.

“The monitoring of the climate modes analyzed may help to predict periods of severe drought, although it would not be an easy task, thus encouraging the applying of measures to adapt the forests more effectively,” said study co-author Asier Herrero.

The findings of this analysis could be utilized by land managers for water, agricultural, and forestry planning. The research could be particularly useful in assessing the climate vulnerability of ecosystems.

The study is published in the journal Nature Communications.

By Chrissy Sexton, Staff Writer

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