Record-breaking warming and extreme drought in the Amazon rainforest during the 2015–2016 El Niño

Desdemona Despair

[Translation by Google.]

8 September 2016 (Asociación RUVID) – A study led by researchers at the Global Change Unit of the University of Valencia (UV) in the Image Processing Laboratory (IPL-PCB) shows the impact on Amazon forests of the 2015/2016 El Niño in the current scenario of climate change. Areas in extreme drought and changes in the spatial distribution of these are the most obvious consequences. The work has been published in the journal Scientific Reports, from the Nature publishing group.

El Niño is a climate phenomenon that results in an abnormal warming of the equatorial Pacific Ocean. It manifests itself cyclically every three to five years, approximately. Together with the Southern Oscillation, it is one of the main modes of climate variability. Although its consequences are reflected at almost global scale, its impact on tropical forests and especially on the Amazon acquires a particular interest, as this ecosystem is considered as a major carbon sink on the planet.

In some cases, such as the 1982/83 event and especially in 1997/98, its magnitude was extraordinarily intense (“Mega-Niño”). In 2014, alarms sounded over the possibility of an impending intense episode, similar to the 1997/98 El Niño, but ultimately the necessary conditions for this to happen did not occur. However, in 2015, conditions were reactivated resulting in the extreme event of 2015/16, higher than the previous event.

The study published in Scientific Reports shows how, in the latest case, the phenomenon is associated with unprecedented warming of the Amazon forests, which reached the highest temperature of the last four decades and probably the last century, and to a greater extent extreme drought. The study also notes changes in the spatial distribution of drought-stricken areas, with wetter than normal conditions in the southwestern region of the Amazon and extremely dry conditions in the northwest, something that has already occurred in 2009/2010 although with less intensity.

According to scientists, this fact not observed in episodes 1982/83 and 1997/98, explains that further warming in the central Pacific equatorial – when the phenomenon is known as Niño Modoki – a different distribution occurs and well differentiated between the wetlands of the Amazon forests and areas of extreme drought.

Some studies associate the current scenario of climate change to a higher frequency of this phenomenon, although there is still no clear consensus among scientists. The biggest impact of these extreme drought conditions on tropical forests occurs because of a decrease in the uptake of atmospheric CO_2, as well as a greater likelihood of fires and consequent loss of biomass.

Currently the Pacific temperature anomalies show neutral conditions, with slightly more than 50% of entering a phase of “La Niña”, the cold phase of this global natural cycle of climate chance, although it is expected that the drought will endure over the coming months.

The research was conducted from climatic data and records of temperature and precipitation generated by the European Centre for Medium-Range Weather Forecasts (ECMWF), the Met Office Hadley Centre and the Climatic Research Unit at the University of East Anglia, and as satellite imagery. Some of these data are are available on the server Thermal Amazoni @ installed in the IPL.

In the study, researchers Juan Carlos Jiménez Muñoz and Jose Antonio Sobrino, Unit Global Change Laboratory Image Processing of the University of Valencia, in the Science Park of the academic institution, participated as well as scientists from the University of Chile, the University of Leeds, the University of Maryland, the Geophysical Institute of Peru, the University of Oxford, and the Dutch Meteorological Institute (KNMI).

C. Jiménez-Muñoz, C. Mattar, J. Barichivich, A. Santamaria-Artigas, K. Takahashi, Y. Malhi, JA Sobrino, G. Van der Schrier. “Record-breaking warming and extreme drought in the Amazon rainforest During the course of El Niño 2015-2016”, Scientific Reports, doi:10.1038/srep33130

‘El Niño’ y el calentamiento global llevan al extremo la sequía en los bosques amazónicos

ABSTRACT: The El Niño-Southern Oscillation (ENSO) is the main driver of interannual climate extremes in Amazonia and other tropical regions. The current 2015/2016 EN event was expected to be as strong as the EN of the century in 1997/98, with extreme heat and drought over most of Amazonian rainforests. Here we show that this protracted EN event, combined with the regional warming trend, was associated with unprecedented warming and a larger extent of extreme drought in Amazonia compared to the earlier strong EN events in 1982/83 and 1997/98. Typical EN-like drought conditions were observed only in eastern Amazonia, whilst in western Amazonia there was an unusual wetting. We attribute this wet-dry dipole to the location of the maximum sea surface warming on the Central equatorial Pacific. The impacts of this climate extreme on the rainforest ecosystems remain to be documented and are likely to be different to previous strong EN events.

Record-breaking warming and extreme drought in the Amazon rainforest during the course of El Niño 2015–2016