Impacts of Climate Change on the Lives of Riverine Farmers on the Lower Rio Negro, Amazon

Abstract

Global climate change, although gradual, is already clearly perceptible for the whole society; however, its impacts affect individuals and regions in diverse ways. Riverine communities in the Brazilian Amazon are highly vulnerable to this change, as seasonal hydroclimatic cycles govern their daily lives, integrate their way of life with the environment, and determine the organization of social and agricultural calendars. This work aimed to understand the impacts caused by climate change on the lives of riverine family farmers on the lower Rio Negro. Initially, through the analysis of changes in hydroclimatic trends and, later, through the description of perception, we tried to present the impacts on the ways of life to then know the climate adaptation strategies. The research was carried out in the state of Amazonas, in the riverine communities Tiririca, Marajá, Santo Antônio, and Terra Preta, located in the Rio Negro Sustainable Development Reserve, with 43 subjects through semi-structured and focus group interviews. Historical trends in the seasonality of the hydrological regime, precipitation, and temperature were analyzed, while qualitative data from environmental perception were analyzed using the technique of content analysis. Physical records of local climate variability and environmental perception are, in most cases, compatible and indicate that hydroclimatic cycles are changing. For the riverine people, the rains have been decreasing and there is unanimity in the perception that the increase in temperature is a reality that has affected their way of life at work, education, health, and food. Although communities have been developing spontaneous adaptive strategies to mitigate the effects of climate change, effective public policies need to reinforce these local responses to climate variability, contributing to the quality of life of populations.

1. Introduction

The effects of global climate change have become a reality in the daily lives of Amazonian populations. Such effects appear in the form of abnormal floods and ebbs of rivers, changes in the duration of the rainy season, in addition to days and nights with higher extreme temperatures. These changes generate direct impacts on fundamental economic and subsistence activities, namely fishing and plant production. Losses in fishing and agriculture cause various problems for riverine populations that depend directly on these activities and the assured and abundant access to natural resources.

In the Sustainable Development Reserve (RDS) of Rio Negro, populations perceive extreme weather events, as being the most recurrent among residents of rural communities, due to the increase in the frequency and intensity of extreme temperatures or the increase in thermal discomfort. Such climate changes expose workers to extreme environmental conditions, which in response have been modifying their ways of life, such as working in agriculture and fishing, and their social activities, such as leisure.

Certain groups of workers already show concern about the heat and although research on farmers is limited, it is known that excessive heat can generate substantial social and economic impacts on them [1]. Family farmers are the most vulnerable agents. Family farming is responsible for the production of much of the food produced nationally [2], and as a result, losses caused by weather-related events within family farming cause unforeseen impacts, not only the economic security of farmers but also the food security of consumers of cultivated products.

In this context, the climate perception of populations impacted by the effects of climate change has been the subject of several studies that have already shown that people who work in outdoor activities, such as agriculture and fishing, already perceive an increase in diseases caused by sun exposure [3] and reduced productivity [4]. It is also worth mentioning that it is the perception of climate change that triggers the spontaneous adaptive adjustments essential for the maintenance of local socio-ecological systems [4].

Adaptation refers to the process of adapting, as well as to the condition of being adapted [5]. Adaptation is any action, whether anticipatory or reactive, process or condition, which reduces sensitivities or increases the adaptive capacity of socio-ecological systems, which means reducing vulnerabilities [6]. Adaptation has been defined as the “adjustment in the behavior and characteristics of a system that improves its ability to deal with external stress” [7]. There are already important initiatives to adapt to climate change in governmental, business, and community spheres around the world; however, their effectiveness has been more difficult in developing countries [8]. In Brazil, there is a national climate change adaptation plan that recommends important measures to be taken to reduce the risks and impacts caused by extreme weather events [9], but its effectiveness is far from reality in both urban and rural areas of the country. The fact is that the measures described in the national plan are not articulated with the local plans, nor do they provide for a dialogue with the spontaneous adaptations already carried out by local communities such as the riverine populations in the Amazon.

Humans’ adaptability to environmental conditions occurs through regulatory adjustments, which can be social, behavioral, or cultural, and are important for humans’ stable relationship with the environment, including the Amazon [10]. The current intensity and frequency of extreme hydroclimatic events generate the need for new forms of adaptability to be developed by the riverine populations of the Amazon, and these can be characterized through empirical work, seeking to raise and describe the perceptions of communities. Aspects of social life such as fishing and agriculture must be considered, as well as strategies for the social organization of work and subsistence.

This study presents an innovative interdisciplinary approach to the studies of climate change issues by correlating and proposing a dialogue between the different perspectives of climatology (climate series trends), cultural anthropology (environmental perception), and sociology (social behavior), on a local scale and in intense dialogue with traditional populations. In this research, the focus was on vulnerabilities, since adaptive responses always have an eminently local character, while mitigating actions necessarily require global responses, in terms of risks associated with climate change from the perspective of riverine communities of the Amazon region. In this context, this work aimed to analyze the perception of the residents of the lower Rio Negro about the climate changes that have occurred in the region vis-à-vis the historical meteorological records of the place. We present the results on the perceptions of the air temperature parameter, known locally as “quentura” (hot and humid air), in addition to the events of prolonged droughts that have been occurring in the region. In this study, we also seek to record the spontaneous adaptations that these populations are developing in response to climate change.

2. Materials and Methods

2.1. Description of the Study Sites

The research was carried out in the Sustainable Development Reserve of Rio Negro—SDS Rio Negro (Figure 1), located in the municipality of Novo Airão, in the state of Amazonas. It is a region characterized by rich biodiversity and the presence of traditional populations distributed in the nineteen communities existing in the place. Most families live close to rivers and were adapted to living harmoniously with the seasonality of hydroclimatic phenomena. Being a region historically occupied by traditional riverine farmers and enjoying the status of a nature conservation unit were the main constraints that led us to choose the RDS as the research site. Communities located in the most remote portions of the Unit were selected, that is, the most distant from urban centers and land access roads. The communities selected were Terra Preta in Iranduba, Tiririca, Santo Antônio, and Marajá.

The RDS do Rio Negro is a conservation unit for sustainable use, created from the dismemberment of the Environmental Protection Area on the right bank of the Rio Negro, formally regulated through State Law No. 3355 of 26 December 2008. It has a total area of 102,978.83 ha and is in the micro-region of the middle Amazon, lower Rio Negro [11]. The Reserve is located on the right bank of the Negro River, covering the municipalities of Iranduba, Novo Airão, and Manacapuru. This unit is part of the Central Amazon Biosphere Reserve which is part of the Central Ecological Corridor of the Amazon.

The criteria used to choose similar and comparable communities were: Access only by river, looking for communities that have a greater relationship and dependence on the Negro River; larger population centers, enabling greater data sampling; older communities, as they have residents who have lived for a longer period, therefore, have more experience with extreme events; and communities closer to the riverbanks, as they possibly suffer greater impacts as a result of extreme hydrological events.

This information was gathered through a conversation with the RDS manager and reading the area’s management plan. The Tiririca community was officially created in 1985, Santo Antônio in 1988, Marajá in 1982, and Terra Preta in 1990. According to the RDS Management Plan, the Tiririca community has 13 resident families, Santo Antônio has 10, Marajá with 18, and Terra Preta has 58 in total. Among the four communities, only Santo Antônio and Tiririca have religious temples, including Catholic, Adventist, and Presbyterian. Regarding the education system in the communities studied, Terra Preta has a school with all levels of education, from Kindergarten to High School, including youth and adult education—EJA. The Santo Antônio community has Elementary Schools I and II.

There are no schools in Tiririca and Marajá communities, therefore, students need to travel to other communities to study. In terms of health, none of the four communities in this research have a health post; however, except for the Santo Antônio community, the others have health agents. In the Terra Preta community, in addition to the health agent, there is an endemic disease agent who visits the families of the RDS.

Another issue observed is that of the 19 communities in the reserve, three do not have an electricity supply, namely Tiririca, Santo Antônio, and Marajá, all of which are part of this research. The communities use a light engine that is turned on overnight for 3 h but is not always in operation due to technical problems.

2.2. Research Subjects

The research subjects were residents of riverine communities, men, and women over 18 years of age, with a minimum time of residence of one year in the community, for having experienced the complete seasonal cycles of the river and climatic conditions in the place. The project was previously presented to all selected communities and all participants signed the Consent and Free Clarification Term (ICF) to clarify doubts and authorize possible subsequent publication of data and results collected. The TCLE was submitted to the Ethics Committee of the Federal University of Amazonas (UFAM) to meet the requirements of Resolution No. 466 of 12 December 2012, to protect the integrity of those involved, and was approved with CAAE 88672418.7.0000.5020 and opinion 2,872,385 in September 2018. Thus, all ethical procedures necessary for the research were followed.

The selection of research subjects in the communities studied took place through reference chains of Snowball sampling [12]. Primary data collection began in August 2018, shortly after the project was approved by the Research Ethics Committee (CEP).

The research is qualitative–quantitative, exploratory, and has a multi-method approach [13]. The guiding concept of the study is that the change in the patterns of hydroclimatic phenomena and their direct effects on subsistence and social activities, especially those resulting from the intensification in the magnitude and frequency of extreme events are perceived by riverine farmers who begin to develop spontaneous adaptive responses to mitigate the negative impacts of climate change. For the tabulation of primary and secondary data and the generation of graphs, electronic spreadsheets were used. In the statistical analyses, the free program Past version 3.25 was used [14]. The location map was prepared in ArcGis 10.7 with a license provided by the University of Aveiro—Portugal.

2.3. Collection and Analysis of River Data

Data on the Rio Negro quotas were collected from the National Water Agency—ANA and the Port of Manaus. With the information from the flood and ebb period of the Negro River, the thresholds between normal and critical fluvial events in the period from 1903 to 2018 (115 years) were established. Extreme fluvial events were calculated from the following equation [11]:

$$X=\frac{\left({\displaystyle \sum }\mathrm{r}\right)}{\mathrm{Nr}} \pm \sigma f$$

(1)

where:

• ∑r is the sum of all records in the sub-basin;
• Nr is the number of records
• σf is the standard deviation (σ) by a frequency factor (f).

To identify the thresholds of flood events, we used addition and subtraction for ebb events. The frequency factor is a function of the return time and the probability distribution used in the analysis [15]. We integrated the physical results (secondary data) with the results of the interviews (primary data) through the rescue of memory and perceptions throughout the research, always seeking to correlate them and avoiding comparisons. For the studies of trends, we applied techniques of graphic analysis of historical series based on the pattern of variation of moving averages, and linear trend lines defined by the regression technique and by the application of statistical tests of Mann–Kendall [16].

2.4. Collection and Analysis of Climate Data on Temperature and Precipitation

In Amazonas, fourteen official meteorological stations are operating since 1910; however, digital data are available online from 1961 onwards. Therefore, for the study area, we used the Manaus station due to its proximity and data history. The World Meteorological Organization—WMO states that the meteorological station for the most isolated locations can represent a range of up to 150 km of radius from its place of installation [17].

To generate temperature and precipitation results, secondary data from the historical series of the Conventional Surface Observation Meteorological Station of the National Institute of Meteorology were used—INMET, number 82331, in the Municipality of Manaus, with coordinates −3.1 and −60.01. In the precipitation and temperature studies, we used data from the INMET historical series, from which a database for the period from 1961 to 2018 (57 years) was structured, seeking to observe trends in the results. Seeking to detect climate change, the World Meteorological Organization (WMO) created a working group that developed 27 (twenty-seven) indices with this objective, some of which are applied to medium latitudes, others to the tropics, and part of them are valid for any location.

In this research, the indices of temperature extremes were used: (1) number of days in the year with maximum temperature above the annual average, (2) number of days in the year with a temperature above the 90th percentile, and (3) number of days in the year with temperature minimum temperature above the 90th percentile. The indices used for the extremes of precipitation were: (1) R10 mm—number of days of the year with rain above 10 mm; (2) R20 mm—number of days of the year with rain above 20 mm and (3) R50 mm—number of days of the year with rain above 50 mm, (4) annual percentage of wet days (PDU) with precipitation greater than or equal to 1 mm, and (5) number of consecutive dry days (DCS).

2.5. Collection and Analysis of Perception Data

The fieldwork was accompanied by a team of invited researchers who acted both in the application of the interviews and in the conduction of the focus group. Thus, a total of forty-three community members were interviewed, each one representing a family, distributed among the four communities of the RDS. In Terra Preta, there were twenty-two interviews, eight in Tiririca, six in Santo Antônio, and seven in Marajá.

Primary data collection was performed using the following research techniques: semi-structured interviews and focus groups. The interview forms were composed of forty-eight questions, divided into four distinct sessions: (1) Socioeconomic characterization of the interviewee; (2) Socio-environmental concepts; (3) Perception of environmental events; (4) Socio-environmental problems.

Focus group workshops were held in the four selected communities. This activity had the participation of a moderator who facilitated the interaction of the groups and an observer who had the function of capturing verbal and non-verbal information. In the end, both evaluated the activity to detect biases caused by problems arising in the application of this [18].

The first group took place in Tiririca at the community restaurant and sixteen people participated. In the community of Santo Antônio, the workshop was held at the social center and had 08 participants. In Marajá, the workshop took place in front of the community president’s house, in which the participants gathered around a wooden table fixed to the floor, as there was no other space available for the meeting and we had eighteen people in total. The Terra Preta community provided a school classroom, with tables, chairs, a whiteboard, and air conditioning, and 08 community members were present.

For operationalization, two groups were divided (Figure 2A,B), in each workshop, one composed of men and the other of women.

Each focus group were asked about their climate perceptions, activities impacted by extremes, and adaptations made to current and future changes due to extreme events.

The data collected in the interviews were examined using the content analysis technique [19], which was initiated by “floating reading” which sought to appropriate the text of the open questions of the interviews. Subsequently, the material was coded into categories, with internal validity, that is, exclusive (each registration unit covers only one category) and exhaustive (all registration units must be classified in some category) [20].

Categories can be created a priori or a posteriori, that is, from theory alone or after data collection. The definition of the categories was elaborated from the interviewee’s verbalization (speeches and answers) with a certain grammatical refinement whenever necessary [21].

3. Results

3.1. Seasonality of the Rio Negro and Extreme Events between 1903 and 2018

In regions close to Manaus, levels above 29 m are considered major floods, on the other hand, levels below 16 m are classified as severe floods (Figure 3). Of the ten largest floods and ebbs that have occurred in the last fifty years, five have occurred since the year 2000. The years with the highest occurrences of extreme flood events in the Amazon were 1998, 2005, and 2010, while flood events outside the threshold of normality had higher occurrences in the years 2009, 2012, 2013, 2014, and 2015 [22,23] (Figure 3).

3.2. Precipitation and Temperature Variability of the Rio Negro between 1961 and 2018

The average annual precipitation over the Amazon is estimated at 2124 mm [24], of which more than 30% of the rainwater is recycled and returns to the atmosphere through the process of evapotranspiration [25]. The average annual discharge from the Amazon River to the Atlantic is 168,200 m³/s [26], which is equivalent to one-fifth of the world’s freshwater reserves. Therefore, knowing the variability of precipitation in the Amazon region is vital for understanding the response of forests to the future climate [27].

The analysis of historical trends in a previous or parallel way to studies with the populations of the Amazon about extreme climatic events is an important support tool in the interdisciplinary discussion on the subject, as well as a subsidy for decision makers who currently seek solutions through complex research involving both dimensions.

For that, the temporal precipitation data from the INMET database were used in the formulation of extreme precipitation event indices used in this study. The R50 mm index, which indicates days with precipitation above 50 mm, when observing the upper threshold (mean + standard deviation) 10.238 and lower (mean−standard deviation) 3.933, an increase in the number of events above 10 days after 1990 and the non-occurrence of years smaller than 4 days before 1990 were observed (Figure 4).

Another index elaborated in this study was the annual percentage of wet days in the year (PDU), with precipitation greater than or equal to 1 mm, based on temporal data from 1961 to 2018 (Figure 5). There was a decrease in the number of wet days after 1990, that is, while the results of extreme rainy days increased, so did the dry days, indicating a concentration of precipitation events to days considered to be extreme events of short duration. A recent study reported a 17% increase in total rainfall with a greater occurrence of extreme rainfall that can lead to more frequent floods [28]. However, there is a trend towards drier days in southern Amazonia when shorter periods are analyzed.

When analyzing the data from the historical period, the average maximum daily temperature found for the period from 1961 to 2018 was 31.8 °C. For this study, the mean was rounded to 32 °C and then the analysis of the number of annual days of temperature above this value was performed (Figure 6, Figure 7 and Figure 8).

3.3. Farmer’ Perceptions and Adaptation Strategies to the Rio Negro Climate Variability

The questions on this topic focused on community members’ perceptions of extreme hydro climatological events. Regarding the changes in the seasonality of the Negro River, about the extremes of flood and ebb, most of the interviewees believe that they are within the normal range, whether the large floods or large ebbs (Figure 9). About a third of community members believe that extreme floods and ebbs have occurred more frequently. Less than a fifth of those interviewed disagreed and believed that there was a reduction in extreme events.

Community members were asked about the behavior of rain and heat, that is, whether these climatological parameters are within the normal range or are changing (Figure 10). About the rain events being different, the vast majority responded positively. However, a quarter of respondents believe that the rains are normal. More than half believe that it has rained less, a quarter thinks that the rains are still normal, and the rest said it is raining more frequently. Concerning heat, all said that the event has changed. For most heat events are much more intense, a quarter believes they are more intense.

For respondents from the communities of Tiririca and Marajá, extreme floods do not affect life in the communities. We identified a division of opinions between positive and/or negative impacts (

Table 1. Impacts of the great floods.

Negative

Positive

Difficulties in fishing and hunting, as the animals, disperse in the water and the forest. This generates food insecurity due to lower protein consumption; Excessive water makes it difficult to remove wood for various constructions; The school calendar is interrupted because of the risks of commuting and the venomous animals that are on the way home; Water floods land paths and makes it difficult for residents to move within communities. Major floods cause physical damage to communities’ homes, churches, and schools.

Water facilitates travel to more distant places; The canoes, which are the means of transport for the community members, are closer to the houses, something considered positive for them.

). The impacts cited by residents as the most intense are related to the availability of animal protein. During the great floods, there is a reduction in the catch as the shoals are very dispersed in the enlarged floodplains. In the case of wild fauna, the capture of game animals is also harmed. In addition, large floods cause damage to houses and other buildings, as has already occurred in the Terra Preta community and the church in the Tiririca community. Among the positive impacts, the highlight is the ease of travel and easy access by the river to more distant areas.

The scarcity of water hinders domestic work, including washing dishes, according to residents. A large ebb is considered worse than a flood because community members have no access to water and must walk to the canal, where boats are stranded during these events. The good side is that there is a lot of fish when they do not die due to lack of water in lakes and rivers (

Table 2. Impacts of great ebbs.

Negative

Positive

Large floods cause a shortage of drinking water for communities; They make access to health and school difficult, as they make the paths more distant; Extreme ebbs cause the geographic isolation of communities that need the rivers to move around; The lack of water makes it difficult to work on the swidden, both when moving to the site and when watering the plantation; Extreme events cause the death of fish in rivers and lakes.

In normal ebbs, there is greater availability of fish, something positive for the community. However, extreme ebbs cause fish to die.

).

The statements made by most interviewees about the consequences of heating are related to impacts on work, especially domestic activity, agriculture, and fishing (

Table 3. Impacts of “quentura” (extreme air temperature).

Categories	Verbalizations
Labour and Health	The heat causes physical discomfort, but the farmer must endure the work of harvesting. In addition, he suffers from high blood pressure (Community member/Maraja 3, male). The heat impacts domestic and swidden work. The community member has already felt short of breath due to the heat (Community member/Terra Preta 2, male). The heat impacts agriculture, and plant growth and causes the death of the swidden (Community/Tiririca 11, female).
Other dimensions	The hottest nights make it difficult to rest (Community/Maraja 2, female). The intense heat made the “terral”, which is the wind from the forest, disappear (Community member/ Tiririca 4, male). The heat impairs student learning during class at school (Community/Terra Preta, male).

).

For the four riverine communities of the RDS of the Rio Negro surveyed, the main impact felt was the sensation of increased heat. Therefore, most adaptations are associated with this category. However, adaptations due to extreme events of floods and ebbs of rivers were also mentioned. Most community members reported having changed their working hours, a fifth made changes to their housing, a smaller part cited adaptations related to education and a minority indicated the need to make changes to the hours of leisure activities (Figure 11).

For the four riverside communities of the Rio Negro RDS, the main perceived impacts were related to the sensation of increased heat, so most adaptations were around this category. However, adaptations due to extreme events of floods and ebbs of rivers are also mentioned. Most community members (57.5%) reported having changed their working hours, as testified by community members: “Before, we used to go to the fields early and stayed until 11:30 am, but today we only last until 9:30 am because of the heat” (Community/Maraja 4, female); “Today it is difficult to go to the fields and you can only stay until 9 am” (Community worker/Tiririca 5, male). Of the total number of respondents, 20% made changes to the housing, as the resident stated: “In 2014, I had to move my house back to the back of the community because it was flooding with the great flood” (Community/Terra Preta 16, male); 15% adapted questions related to education, as observed in the following statement: “The great flood broke the community school and when the river is too full it is dangerous for children to move around” (Community/Tiririca 8, male); “The great droughts make it difficult for children to go to school in another community and travel by canoe” (Community/Maraja 1, female); Due to the lack of electricity during the day, on hotter, students need to be released earlier from school (Community/Terra Preta 17, male) 7.5% needed to change their leisure time, as in the statement: “In the community, we like to play football, but with the heat, we also reduced the time in the field” (Community/Santo Antônio 2, male) (Figure 11).

4. Discussion

4.1. Climate Variability Trends in the Rio Negro

In the Amazon, life, in all its dimensions, is related to the flood and ebb pulses of rivers, which are sensitive to environmental changes in other parts of the planet [29]. The rainfall regime governs the natural and anthropic aspects of the Amazon and the dynamics of the hydrological regime, as its reflection, modifies the space, as well as the landscape, with seasonal ebb and flow regimes [30,31].

In the Negro River, the flood and ebb pulse is influenced by a wide spectrum of geomorphological conditions, the spatial and temporal distribution of rainfall, and the hydrological conditions of the basin itself, by the influence of the Solimões River basin [32]. The floods and inundations of the Rio Negro vary in frequency, magnitude, and duration, being important to distinguish the terrestrial and aquatic phases of the fluvial forms in time and space [33]. Therefore, it is important to know the annual dynamics of rising and falling waters of the Rio Negro basin to describe the magnitude of the quotas and the duration of each phase to determine a year with an extreme hydrological event in its physical concept.

The 2005 and 2010 extreme ebbs caused the isolation of several riverine communities that, with the scarcity of proteins, from fishing, had major nutritional problems [34,35] Such problems were confirmed by the residents of the communities interviewed in the Rio Negro RDS, who listed problems caused by the difficulty of commuting to work and school. Although the impact on the reduction in river levels reached its record in 2005, the reduction in precipitation that began in previous years was the fundamental factor for a gigantic decrease in river volume, contributing to the worsening of the occurrence of fires [36]. In 2010, the reduction in the river level also started with the reduction in rainfall in 2009.

Floods and ebbs affect the quality and access to water, which in turn can worsen the health of the population due to the proliferation of diseases, in addition to bringing losses in social and economic dimensions [37]. Records of social damage from extreme flood events are related to health issues, access to schools, and the need to relocate families. The economic effects are impacts on fishing activities, the practice of subsistence agriculture, and the transport and flow of production by the river. For extreme ebb events, the biggest problems are the isolation of communities, fish mortality, and waterborne diseases [38]. However, it is worth mentioning that the impacts related to extreme events are presented in diverse ways, which can be positive or negative, according to the location of the occurrence, that is, in the floodplain or upland environments.

Due to the enormous territorial extension of the Amazon basin, there is variability in its climatic regimes, both in the spatial and temporal aspects of precipitation, in which extreme events of ebb or flood cause important socio-economic consequences to the various sectors of society [39]. Rainfall and river flow are also influenced by the Intertropical Convergence Zone (ITCZ), entry of steam from the Atlantic Ocean by trade winds, and exchanges of heat and humidity between vegetation and the atmosphere in the region itself [40,41].

In the Amazon basin, rainfall is influenced by annual changes in the Intertropical Convergence Zone (ITCZ) and the South Atlantic Convergence Zone (SACZ) over the Andean region, as well as in certain years by the effects of the El Niño Southern Oscillation (ENSO) [2]. Specifically for the extreme event of the Negro River, the La Niña phenomenon is pointed out, with characteristics opposite to El Niño, with the abnormal cooling of the surface waters of the tropical Pacific Ocean with impacts in Brazil of increased precipitation and river flow. It is worth mentioning that the 2009 flood was attributed to La Niña when the Negro River reached an elevation of 29.77 m in Manaus [2].

Thus, the analysis of historical trends in a previous or parallel way to studies with the populations of the Amazon about extreme climatic events is an important support tool in the interdisciplinary discussion on the subject, as well as support to decision makers who currently seek solutions through complex research involving both dimensions.

The 50 mm precipitation events are considered short duration since they occur intensely and in a short time interval. These events have been given greater focus by climatologists, as some climate models and studies of climate projections for the future indicate higher frequencies and intensities of these events, such as intense rains, heat waves and cold, periods of droughts, in addition to storms and hurricanes, in scenarios of global warming such as the Amazon [42].

In this study, a decrease in the number of wet days (rainfall above 1 mm) after 1990 is observed, that is, while the results of extreme rainy days increased, the dry days also increased, indicating a concentration of precipitation events at days considered as short-term extreme events. As already reported by other authors [28], such an increase in total rainfall with a greater occurrence of extreme rainfall can lead to more frequent floods. However, there is a trend towards drier days in southern Amazonia when shorter periods are analyzed.

Studies indicate that the increase in dry days, especially in the period from September to November, causes delays at the beginning of the rainy season and leads to extreme ebbs. When compared to the 1970s, this delay reaches a month [28]. Changes in rainfall intensity and distribution are associated with the warming of the tropical Atlantic Ocean, as it produces an inflow of humid air masses in the north of the Amazon basin [28]. Some analyses of climate modeling for the Amazon expected a greater drought trend in the region, but studies point to an increase in rainfall in the watershed since approximately 1990. The consequences of these changes can be serious for local populations, affecting the hydrology of rivers and generating ecological and economic impacts. Furthermore, another concern regarding the greater occurrence of extreme hydroclimatic events is the increase in temperature and its consequences for the populations of the Amazon.

The waters coordinate and guide the lives of Amazonian populations [43,44], either by the seasonality of the rivers or by the variability of rainfall. We have noticed so far, there is much talked about the interdependence of the environmental system, because when there is a reduction in the amount of rain, there is consequently a change in the river quota and this phenomenon is something perceived by the Amazonian populations due to their experience and strong relationship with nature. Another factor cited among the populations interviewed for this study is the heat, that is, the increase in temperature, which is currently the greatest regulator of the activities carried out by the rural populations of the lower Rio Negro, Amazon.

This phenomenon generates potentially catastrophic impacts on the Amazon, and the maintenance of the Amazon Forest offers one of the most valuable and inexpensive options to mitigate climate change because if the forest is deforested, much of its carbon stock is released into the atmosphere. in the form of greenhouse gases [45].

For the Rio Negro region, a change in trend is observed after 1990, in which every year there is an increase in the number of hotter days, making it evident that extreme heat is a recent phenomenon. According to the IPCC projections indicate an increase in the number of hot days and heat waves on all continents [46]. The results indicate an increasing trend in the number of days with temperatures above 35 °C from the 2000s onwards. Between 1961 and 2000, the average number of days with temperature above 35 °C was 11, passing to 49 days in the period between 2001 and 2018. In 2009 and 2015, respectively, 79 days and 98 days with elevated temperatures were observed. The results showed the statistical significance of the data with values of s: 499, z: 3.6226, and p: 0.000292.

In the Amazon, the warming observed between 1949 and 2017 varies from 0.6 to 0.7 °C, according to several sources of temperature data and, despite some differences, most sources indicate an increase in warming in recent decades, with 2017 being the hottest year since the mid-20th century [47]. In addition, the trend of increasing minimum temperatures evidences the occurrence of warmer nights and increases in maximum and minimum temperatures may result in greater occurrences of heat waves in the region, which may indicate a trend of change and not only of variability. Changes in air temperature directly affect populations that work outdoors, such as those living in rural areas in the Amazon. Some studies show the need for care in thermal overload for the proper functioning of the human organism, since unfavorable temperature conditions lead to thermal stress, which results in health weakness, and changes in the physical and psycho-sensory system, generating falls. production and, therefore, the lack of food security for these populations [48].

4.2. Climate Perceptions and Adaptations by Populations of the Rio Negro

From the 19th century onwards, the issue of perception has intensified due to the consequent changes in the modern world, with this impacting human perceptive and cognitive faculties, constituting great interest to philosophers, anthropologists, cultural theorists, and psychologists [49]. One of the arms of human perception that is widespread in academia is environmental perception.

Environmental perception as an area of study had its conceptual basis in Humanistic Geography, which since the end of the 1960s and beginning of the 1970s rescued a new way of valuing the perceptions of individuals [50], and the theory brought feelings and ideas about space and place, seeking to understand the human world through man’s relationships with nature [51]. Environmental perception is the response of the senses to environmental stimuli (sensory perception) and the mental activity resulting from the relationship with the environment (cognitive perception) [51].

The landscape can be rescued in memory and can be analyzed for its visual aspects; these memories mesh affection or contempt, since places and feelings give important characteristics to personal and social identity [51]. Thus, landscapes result from the fusion of natural components and those built by the world experienced by everyone, becoming a cultural reality [52,53].

In the Amazon, the annual fluvial seasonality brings sociocultural dynamics to the landscape with the rise and fall of rivers. This dynamic has always been something trivial in the lives of riverine populations who have developed adaptive strategies that respond to new environmental conditions. It is known that after 2006 the extreme episodes of floods and ebbs became more frequent in the Negro River and that this perception of greater events of the ebb tide by the community is related to the greater negative impacts felt in the communities, as we can see in the very definition of the event presented by them.

In a study that evaluated the perception of climate change by rural producers in the Amazon, it was found that the most frequent response (58%) pointed to a warmer climate [54], contributing to the results of a previous study that found similar responses by small farmers in other biomes in the country [55]. One of the challenges of environmental perception studies is to compare social data with physical data [56]. According to what was observed in the results of the analysis of trends in the historical period, there is an indication of the increase in temperatures for the Rio Negro region.

Perception studies with riverine people through their sociocultural experiences with the environment can contribute to improving the quality of life of communities by helping to implement local public policies when there is support from managers. The perception of climate change accompanies other elements (risk and adaptation) in the family farming scenario, and immediately, the risk that is perceived with climate change is that of not producing food and gives rise to the need for adaptation [57]. These perceptions coincide with scientific data and differ in the time scale, in which riverine dwellers observe short-term events more easily, but can perceive the moments of pauses in the rise and fall of the waters [58].

The populations of the Rio Negro RDS perceive negative impacts when related to extreme events of large floods. The biggest impacts cited by residents are related to the availability of protein from fish due to shoals spread in rivers and lakes and game meat. In addition, the great flood has already damaged houses in the Terra Preta community and the church in the Tiririca community. Among the positive impacts, the highlight is the ease of displacement and access that the waters bring.

Artisanal fishing is of great importance for the food security of riverine populations, as fish is the main source of protein for families and the activity is carried out in lakes, igapós, streams, and rivers, by young men and adults, both during the high and low seasons, while hunting is the most important food composition in the high season [59].

As for the events of large river ebbs, most reported causing negative impacts on the lives of community members. In a study carried out in the municipality of Silves in Amazonas and the Tapajós National Forest in Pará, the greatest impacts found concerning extreme ebb events were related to the interruption of river transport, which made access to local markets difficult for residents, aggravating food insecurity and making access to health services and schools impossible [60].

Regarding the impacts of the change in rainfall, the majority stated that they harmed work, and a minority mentioned that they harmed Education. The change in the rains causes a series of impacts on the ways of life of the communities and even though they have the river as an important water resource, they claim that river water is quite different from rainwater for planting. In this process, work was one of the aspects cited as the most harmed since the community depends on the plants in the swidden because without the rains, the stem ends up burning as verbalized “[...] the lack of rain it gets in the way because the plants depend on it and the community depends on the plants” (Community member, Terra Preta 1, female).

Problems related to work in the fields directly affect the food security of the populations of the RDS of the Rio Negro due to the decrease in production and availability of food. Regarding production, the cultivation of cassava is the most common, being a basic component in the agricultural culture system in the Amazon in the production of flour, both in solid ground and in floodplain areas, and is characterized by its use in subsistence and marketing [61].

The heat generates discomfort, such as suffocation and shortness of breath, especially in some hypertensive community members. Added to this, the heat impairs the growth of plants until harvest time. The effects on hydrological cycles caused by climate change, such as changes in the water balance, make agriculture a vulnerable activity, given its natural sensitivity to climate [62]. Another important report concerning the negative impacts due to the heat is the displacement of schools to less warm and deeper waters and when they manage to fish, they need to return home soon, as the fish has spoiled faster, something that did not happen in the past.

Some interviewees mentioned the episodes of fires because of fires carried out inside and outside the RDS of the Rio Negro in drier periods and with high temperatures. In addition to the occurrence of stronger and more frequent storms accompanied by lightning, which roofed some houses in the communities. In a study carried out in the States of Pará and Acre, the perception of the increase in temperatures by farmers was unanimous, which they related to the deforestation of the surrounding areas and the riparian forest, causing a decrease in fish available in the areas of estuaries close to the lake margins and floodplain areas [63]. Therefore, assessing impacts is an important analysis tool in the identification of adaptive strategies currently developed by rural communities in the Amazon.

In Brazilian action, adaptation has been treated as secondary since the beginning of negotiations on the climate change agenda, currently being inserted and connected to the idea of climate justice, recognizing that the causes of climate change, their impacts, and adaptive capacity and response are not equally distributed in the world [6].

In this study with the communities of the RDS of the Rio Negro, after defining and pointing out the impacts of extreme hydroclimatic events, the communities were questioned about the strategies used as a form of adaptability in the face of these events. The riverine people recognize the harm that exposure to the sun can bring to their health; in this case, they adopted clothing that guarantees skin protection, such as long pants, long-sleeved shirts, hats, and the application of sunscreen.

Extreme events cause a series of changes in the lives of community members. On the other hand, the adaptation strategies for this period of the year reveal a dynamic of articulation typical of the Amazonian communities. Among these adaptations, the modification of the school calendar stands out, considering that among the communities studied, Marajá, Tiririca, and Santo Antônio, only the latter has a school, which makes it difficult and often impossible for students to travel to class in periods of the high ebb of the river since the main means of transport is the river.

Regarding the houses, the interviewees say that they are impacted by the events of large floods, as was the case in 2012 and 2014 when some houses were damaged and later moved to other locations. Riverine people adjust their systems after experiencing consecutive years of ebb (responsive adaptation), intending to be better prepared for similar conditions in the future (anticipatory adaptation) [64]. In the case of the houses damaged in 2009 and 2012, the community reported that they were helped by the civil defense, but always in a mitigating way through the donation of materials for the construction of new houses and non-perishable groceries. Pinho et al., 2015 list as problems: (i) the delay of the government to offer any kind of support to the inhabitants of the Amazon region; (ii) the absence of trained technical staff; (iii) delay in actions and lack of preventive measures by the Civil Defense, which is responsible for implementing such actions, performing risk assessment, and providing support when emergencies occur [60].

Through multivariate linear regression analysis, in which the relationship between the independent variable (be able to answer: 1 = yes; 0 = no) and the variables dependent on occupation, gender, and age of the interviewees, one can say that the ability to know how to respond and identify patterns is associated with the type of occupation of the observer. In this sense, family farmers were able to identify the patterns of temperature increase more easily, because they experience daily work that exposes them to the open environment (R² = 0.2366, p = 0.001). There is no difference between men and women, therefore it is not a matter of gender (R² = 0.0036, p = 0.835). Age seems to influence to a lesser extent (R² = 0.1486 p = 0.011), as younger people tend not to respond, since the older ones are usually the ones who have the occupation of farmer.

With the increase in atmospheric temperature, adaptations are also necessary, in the reduction in working time, as the community members say that during this period they need to leave earlier and return well before the time they are used to, as they cannot withstand the heat and for fear of skin cancer. The impacts of climate change on family farming have varied dimensions and depend on the adaptation strategies adopted in response to the changes [65]. In this case, the reduction in working time in fishing and agriculture poses a risk to the food security of community members, who are currently also building more beds for smaller-scale production that serve for family consumption and the purchase of ice for the conservation of fish during and on return from fishing, which means an extra expense.

The traditional soccer game, an activity widely practiced in the communities studied, is scheduled at various times than usual. The perception of climate change and its impacts on the various sectors is a prerequisite for the search for adaptive and mitigation strategies [66]. In addition, they can assist in the elaboration of public policies to improve governance and ensure the well-being of these populations, as well as investments in roads and alternative means of transport, schools, and well drilling [60]. Additionally, in the communities of the Rio Negro RDS, there are pre-existing socio-environmental problems that make the events and consequently the impacts more intense.

5. Conclusions

In the fluvial component, it was evidenced by the historical physical records that there was an increase in the occurrence of extreme events of floods and ebbs in the Negro River in the last two decades. In the rainfall component, there was an increase in the frequency of extreme events of short duration, such as intense rains with values above 50 mm, which can cause damage to the residents of the Negro River, which can lead to loss of productivity and products in the countryside. In addition to causing commuting and transportation difficulties for residents further away from the urban area.

There is also evidence of an increase in the minimum and maximum temperature indices. Hotter days and nights, added to drier days, may cause a loss of agricultural production, as well as a reduction in working time, due to thermal discomfort and consequent losses in productivity, leading the populations, who live on subsistence, to take risks in food security. Furthermore, more isolated communities with less infrastructure and availability of basic services are more vulnerable to these climate changes. However, the category of perception with the greatest prominence in the individual and collective research was heat, which is related to deforestation, burning, and environmental pollution, in addition to having as evidence in the speech of subjects to climate change.

The perception of impacts caused by extreme hydroclimatic events reveals important challenges considered by the residents of the Rio Negro RDS, who seek and develop through their knowledge the best adaptive alternatives in the face of events. Adaptive strategies of communities are conditioned by their environmental, social, cultural, and economic limits, often requiring the support of public policies that respond to the stresses caused by hydroclimatic events. The search for more adequate adaptive responses to the communities of the Rio Negro needs work among public managers who understand the reality and local needs and not just the imposition of adaptive models from other regions.

We believe that the results brought important contributions regarding the environmental perceptions and adaptive responses of the populations of the lower Rio Negro about extreme hydroclimatic events. These results can encourage further research on this topic in the Rio Negro region, in addition to contributing to the formulation of public policies for adaptive strategies in the face of climate change.