These extreme conditions can be analyzed through the use of the Standardized Precipitation Evapotranspiration Index (SPEI), where positive (negative) values represent wet (drought) conditions. The SPEI values in the Amazon Basin during the 2015/2016 El Niño (Fig 3a) show a widespread drought over the entire region up to the northernmost parts of South America. The spatial extent of the drought at this period was enormous to the point it has no parallel during the other extreme events in the 21st century in the Basin as the great droughts of 2005 and 2010. The decrease of rainfall levels during the wet season increased the window of opportunity for man-made fire outbreaks even outside the Arc of Deforestation.
The strong 2010/2011 La Niña, on the other hand, seems to be related to wet conditions at the eastern side of the Basin while drought conditions were observed at the west. This pattern hints to a lack of symmetry between ENSO events and their related effects in the rainfall regime of the region and also points to the difficulty to predict where and when these adverse effects will happen. During this specific event the river water levels in the western Amazon increased so much that many small communities and cities next to the (several) river banks became entirely submerged by the intense floods for months. 
ENSO activity, therefore, is a major factor for the functioning not just of the local amazonian human population, but its biodiversity of animals and the health of the forest itself as these extreme events can increase the mortality of many species especially during drought periods caused by El Niño. This poses a challenge for the world and future generations as the increase of global temperatures due to the anthropogenic emissions of Greenhouse Gases is set to increase the frequency and intensity of extreme drought and flood events, disturbing the natural ecosystem of the Amazon rainforest until it reaches a point of no return and the climate setting of the world is altered forever.