Now, a study published in the journal Npj Climate and Atmospheric Science reveals that the NAO shift may be a consequence of natural variability in the atmospheric system rather than anthropogenic effects altering global climatology. The new study is led by experts María Santolaria-Otín and Javier García-Serrano, from the Faculty of Physics and the Group of Meteorology at the University of Barcelona.
Why does the NAO move longitudinally?
The North Atlantic Oscillation was first identified in the early 20th century, although its consequences were known to the people of northern Europe much earlier. The NAO is one of the most studied climate variability phenomena in the scientific community. However, many aspects of the dynamics and processes controlling its variability, both temporally and spatially, are still unknown, and the evidence for its past and expected future trends is still being debated.
Javier García-Serrano, professor at the UB's Department of Applied Physics, says that "the atmosphere is a fluid system and shows a very chaotic and unpredictable behaviour. The study reveals that we can rule out some factors that explain this NAO pattern, namely anthropogenic forcing - i.e. the impact of greenhouse gases - or ocean coupling. Factors that could help to understand these shifts in the NAO are, for example, the interaction of winds with orography or the land-sea contrast. However, we need more research studies to confirm these hypotheses".
On a global scale, the effects of this NAO shift are likely to be small, although they could affect Arctic Sea ice variability and, consequently, other remote areas of the planet. According to the findings, this process would not alter anthropogenic global warming trends.
