The consequences of climate change are appearing in both social and ecological dimensions. As temperatures continue to rise, more damaging consequences are expected, including impacts on the Amazon, one of Earth's most important CO2 sinks.
The climate of Brazil varies significantly across regions. Figure 1 (left) shows the average distribution of temperature and precipitation across different states. The warmest parts of the country cover the North, with average temperatures decreasing towards Central and South Brazil. In the higher altitudes of Central and South-East Brazil, average annual temperatures range from 12 to 20 degrees Celsius. The annual rainfall map shows large differences, from semi-arid climates in the Northeast, with low rainfall sums of < 700 mm/year, while the Amazon basin in the Northwest has a very humid climate with up to 3000 mm/year.
A dry season is common in most parts of Brazil. Rainfall typically increases during the southern hemisphere's summer months, beginning in October and November. However, this year, we are observing significant anomalies for temperatures and precipitation. The November 2023 anomalies show above-average temperatures in the entire country (Figure 1, right). The highest anomalies are observed In central Brazil, one of the most important regions for agricultural production. The precipitation volumes in November 2023 were below average in most of Brazil. Particularly the Central region has experienced drought. Even humid regions, including the Amazon River basin, are drier than usual. An exception is the very South, which is experiencing extreme rainfall, continuing the high-precipitation trend that started in September 2023 with a cyclone causing severe flooding.
Our Climate Comparison diagrams offer a better and more detailed insight of the previous findings, representing different climate zones of Brazil (Figure 2).
Since April 2023, all locations have experienced above-average temperatures, up to 3°C above normal, whereas precipitation volumes have been below the average since June 2023 in most areas, except in the South, where October and November 2023 showed heavy rainfall, as shown in Muçum.
The phenomenon "El Niño" significantly influences current weather conditions in Brazil. During an "El Niño" phase, warm water moves into the Eastern Tropical Pacific Ocean and eastward winds weaken or reverse. Our map showing Sea Surface Temperature anomalies illustrates a typical El Niño phase (Figure 3). El Niño affects global weather patterns, typically causing higher temperatures and more drought in tropical areas. Regions like Southeast Asia, Australia, Central Asia, and parts of West Africa are especially impacted by drought, while East Africa and the South- and Central American Pacific coasts receive higher precipitation. Brazil commonly experiences drought during El Niño.
However, what seems like a recurring and 'normal' phenomenon is becoming more problematic. Eight Brazilian states recorded their lowest rainfall ever between July and September in over 40 years, according to the country's disaster warning center CEMADEN. Our Climate Change diagram (Figure 4) shows a clear intensification of drought and rising temperatures, especially since 2010.
The diagram for Manaus, the capital to the Amazonas state located in the centre of the Amazon River basin, show the increasing impact of climate change on the regional climate. The region has become hotter and drier over the years. The impacts of El Niño are becoming more frequent and intense. As temperatures continue to rise, ecosystems are increasingly stressed, becoming less resilient to climatic fluctuations and intensifying weather extremes such as floods, wildfires, and forest degradation. The situation in the Amazon River Basin is increasingly critical, considering deforestation and degradation by human activities. Extreme droughts in recent years have reduced the Amazon River to a record-low water level of 12.7 meters this year, causing numerous ecological, economic, and social problems. Communities reliant on the river have been isolated, and many fish have died due to high water temperatures. There is concern that the Amazon Forest, closely linked to the river, may reach a tipping point beyond which it cannot recover from longer droughts.
The potential loss of the Amazon Forest would mark the beginning of a self-reinforcing cycle of desertification. As one of our largest carbon sinks and reservoirs (Nobre et al., 2009), its protection is crucial in reducing the effects of climate change.
