Key Concepts Used in Climate Change Mitigation Strategies in the Coffee Sector

Abstract

Key concepts such as “carbon footprint”, “carbon neutral”, “carbon neutrality”, “low carbon”, and “net-zero emissions” have gained prominence in the context of climate change, a current issue that has become an urgent global challenge caused by anthropogenic activities, including agriculture. This bibliometric review analyzed the use of these concepts in mitigation strategies for the coffee sector, since coffee production significantly contributes to greenhouse gas (GHG) emissions, primarily due to land use change, fertilizer use, and processing methods, and therefore, sustainable approaches within the whole coffee value chain need to be implemented. A total of 105 documents from the Scopus database, covering publications from January 1988 to June 2023, were analyzed. Co-word analysis and co-occurrence mapping techniques, together with traditional bibliometric laws and historical evolution analysis using VOSviewer and Bibliometrix, were applied. The evolution of research over time revealed that the first concept introduced for documenting the reduction in greenhouse gas (GHG) emissions was “low carbon emissions” in 1909, but it was not until 2008 that the first document was published establishing a link between “low carbon emissions” and “coffee”. In 2015, two more concepts, “carbon neutral” and “carbon neutrality”, documented since 1968 and 1995, respectively, were used in articles related to coffee. So far, the most relevant concept in quantifying GHG emissions in the context of coffee production activities has been “carbon footprint”. When it comes to new documents linking key concepts to coffee, between 2015 and 2018, there was an average of six documents per year. Since 2019, the average has remained at 15, highlighting the need to continue documenting climate change mitigation strategies in the coffee sector. Practical application of our findings for coffee sustainability programs must include the adoption of on-farm sustainable agricultural practices that span the entire value chain. In conclusion, this study underscores the importance of concepts such as “carbon footprint” and “carbon neutrality” as key pillars in the development of effective climate change mitigation strategies in the coffee sector and the significance of their integration into future research and global policies with practical applications, with far-reaching implications for sustainable agriculture in the near future.

1. Introduction

Climate change has become an alarming global challenge, representing the primary issue humanity faces today [1]. One of the most visible impacts of climate change is global warming, manifesting as a rise in the average global temperature due to increased concentrations of greenhouse gases (GHG) [2]. The main GHGs are carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), perfluorocarbons (PFC), hydrofluorocarbons (HFC), and sulfur hexafluoride (SF₆) [3]. The excess GHG emissions released into the atmosphere by human activities have surpassed the atmosphere’s absorption capacity [4], altering Earth’s temperature and triggering extreme natural events [5].

In response to this climate crisis, the governments of 196 countries have initiated strategies to meet the goals set by the 2015 Paris Agreement, a legally binding agreement aimed at limiting global warming to 1.5 °C and achieving net-zero CO₂ emissions by 2050 [6,7]. These strategies encompass the following five key concepts: carbon footprint, carbon neutral, carbon neutrality, low carbon and net-zero emissions. While these terms are often used interchangeably, they differ in scope and application. For instance, carbon footprint is a metric that quantifies total GHG emissions associated with a product, process, or organization [8], whereas carbon neutral refers to balancing emissions released with those removed, maintaining atmospheric GHG concentrations [9]. In contrast, carbon neutrality emphasizes the role of offsetting mechanisms such as carbon credits to achieve balance [10].

The concept of low emissions highlights pathways toward reduced-carbon transitions in economic, political, or social systems without necessarily reaching zero [11], and net-zero emissions entails fully eliminating emissions within production systems, avoiding reliance on offsets [12]. Clarifying these distinctions is essential to reducing ambiguity in scientific and policy discussions, especially when these terms guide the formulation of mitigation strategies. By establishing clear boundaries among them, this study provides a framework for analyzing how such concepts have been employed in scientific documents related to coffee production, which is a sector increasingly scrutinized for its environmental impact. While coffee is the second most popular drink worldwide, just after water, the process from farming to the cup, including deforestation, fertilizer use, processing, and transportation, releases greenhouse gases and thus per se contributes to climate change [13]. Therefore, there is a dire need to address these concepts and terminology in order to deeply analyze the advances and gaps within the coffee sector.

The available bibliometric analyses covering one or more of the key concepts include that developed by Yue et al. (2020) [14], who compiled 3698 articles related to “carbon footprint” published between 2007 and 2018, highlighting the growth of research, interdisciplinary applications, and the international distribution of contributions in agricultural and energy systems. Other studies on the carbon footprint, focused on its consolidation as a core tool in sustainability research, have identified emerging topics such as land use changes, livestock systems, and emissions associated with international trade [15,16]. In addition, bibliometric studies show that carbon-neutral strategies have been primarily linked to municipal solid waste management and research on waste-to-energy technologies, emphasizing both technological advances and policy approaches that support emissions mitigation [17].

Analyses on carbon neutrality have focused on the utilization of coal-based industrial solid wastes, highlighting resource recovery strategies while revealing limitations in sustainable large-scale implementation [18]. Low carbon development has been systematically mapped, demonstrating its role as a foundation for neutrality, with emphasis on emission reduction, carbon sinks, and policy mechanisms such as carbon markets and renewable energy [19,20]. Finally, publications on net-zero emissions have been examined through comprehensive bibliometric analyses, showing sustained growth from 1991 to 2023, in the USA, the United Kingdom, and China as the main contributors, and underscoring emerging topics such as decarbonization, energy efficiency, and machine learning [21].

Bibliometric analyses on climate change mitigation strategies typically include publications related to carbon sinks and environmental governance [22,23]. Likewise, food production and the environmental impact generated throughout the value chain have been examined, considering the Sustainable Development Goals and the need to implement a sustainable food system with a holistic approach encompassing all activities involved [24]. Furthermore, GHG emissions from land use have been studied from the perspective of regional and global governance for the development of public policies [25]. Conversely, life cycle assessment reviews have focused on the impact of fuel use for energy generation and its relationship with the economy and agriculture [26]. Nonetheless, an in-depth analysis of main or pivotal concepts related to climate change mitigation strategies in the coffee sector is lacking. In this review, the key concepts documented in climate change mitigation strategies, which have been used in the analysis of coffee systems, are evaluated in terms of their impact and usefulness.

The search for a specific key concept related to climate change and its impact on the coffee value chain is crucial for standardizing the research methodology on the environmental impact of coffee production, marketing, and consumption. For this reason, this paper aimed to analyze the trajectory of strategies used to mitigate climate change, focusing on the key terms (carbon neutral, carbon neutrality, carbon footprint, low emissions, and net-zero emissions) employed by governments and academics in climate change mitigation research in the coffee sector through a bibliometric analysis. To this end, the following questions were posed:

Q1: What has been the trajectory of publications related to concepts for mitigating climate change?

Q2: What has been the trend and impact of publications related to concepts for mitigating climate change?

Q3: Which countries have been the most productive in using these concepts in climate change mitigation strategies?

Q4: Which journals have published the most articles related to concepts for mitigating climate change?

Q5: Who are the most prolific authors, and who has collaborated on research projects?

Q6: How has author recognition evolved over time for those who have used one or more of these concepts to mitigate climate change in coffee?

Q7: In which areas of knowledge have more works on climate change mitigation in coffee been published?

Q8: How have researchers’ topics of interest evolved over time?

Q9: What are the most relevant documents related to concepts for climate change mitigation in coffee?

Q10: What is the most used concept in coffee to study or propose strategies for mitigating climate change?

2. Materials and Methods

Bibliometric analysis allows for the examination of the evolution and trends of a specific topic through the exploration and analysis of large volumes of scientific data published in various databases [27]. For this publication, the procedure described in the SALSA (Search, Appraisal, Synthesis, and Analysis) framework was followed, which is a structured and systematic approach used in research to conduct literature reviews and analyses [28]. Although this method is commonly used in systematic reviews and meta-analyses, in this context, it was adapted to ensure a systematic exploration of the literature without seeking complete exhaustiveness. This approach is fundamental to ensure the credibility and replicability of findings in scientific studies [29] (Figure 1).

2.1. Data Collection

The documents used for the analysis were collected from the Scopus database due to its breadth of peer-reviewed scientific literature, facilitating the replicability of the review and minimizing bias [30]. The search was conducted for the period from 1988 (the date of the first appearance of a document with key concepts and coffee in the database) to 3 July 2023 (the date of the search). The following search strategy was employed:

• (TITLE-ABS-KEY (“carbon footprint”) OR TITLE-ABS-KEY (“carbon neutral”) OR TITLE-ABS-KEY (“carbon neutrality”) OR TITLE-ABS-KEY (“low carbon”) OR TITLE-ABS-KEY (“net-zero emission”) AND TITLE-ABS-KEY (coffee)) AND (LIMIT-TO (DOCTYPE, “ar”) OR LIMIT-TO (DOCTYPE, “ch”) OR LIMIT-TO (DOCTYPE, “re”)).

This query identified 128 documents. The selection process was conducted in several phases. First, filters were applied in Scopus to retain only research articles, reviews, and book chapters. Subsequently, a manual verification was carried out to ensure thematic relevance, leading to the exclusion of 23 records corresponding to conference papers, editorial notes, and short surveys, as they did not meet the inclusion criteria or were not peer-reviewed. After this refinement, the final corpus consisted of 105 documents that explicitly linked carbon-related concepts with coffee. The documentation of the process ensures both transparency and replicability of the review.

2.2. Data Cleaning and Curation

In order to minimize bias and ensure consistency in the analysis, the dataset was subjected to a process of cleaning and curation. Plural and singular forms were standardized (e.g., humans/human, emission/emissions) to avoid the dispersion of concepts in the co-occurrence maps. Generic terms such as priority journal, article, and review were removed, as they did not contribute relevant thematic information. In the keyword analysis conducted with VOSviewer, the search term coffee was excluded, since it appeared in all documents, and its inclusion would have generated a dominant central node. For each keyword, the total strength of co-occurrence links with the highest total link strength was selected. This procedure allowed for a more precise identification of emerging concepts and research trends relevant to the field [31].

2.3. Bibliometric Analysis

The analysis was carried out using VOSviewer software, version 1.6.19, which allows the visualization of bibliometric networks [32]. The science map was constructed with a minimum co-occurrence of five keywords, resulting in 42 words reaching the threshold of 1475 words. Additionally, the biblioshiny function of the Bibliometrix package in the statistical software R (https://www.bibliometrix.org/) was used to analyze and graph the results [33].

The bibliometric indicator for measuring journal productivity is based on Bradford’s Law of Scattering, which establishes an uneven distribution in the production of articles in scientific journals. According to this law, most articles are concentrated in a small number of journals, while a large number of journals publish only a few articles on the same topic [34]. The formula can mathematically express this observation:

$$\mathit{N}=\mathit{\kappa }·{\displaystyle \frac{1}{{\mathit{r}}^2}}$$

where $N$ represents the number of relevant articles in the core group of journals, $k$ is a constant that varies depending on the subject area, and $r$ is the rank of the journals in the productivity list. This relationship highlights the importance of identifying key journals in a research field to better understand the dynamics of scientific literature.

The concept known as Lotka’s Law was used as a bibliometric indicator to describe author productivity. This law is based on a discrete probability distribution to determine the quantitative relationship between scientific articles produced in a specific field and the authors; that is, most authors publish few papers, while a small number of authors are the most prolific, publishing the majority of works [35]. The mathematical expression of Lotka’s productivity law, also known as the Inverse Square Law, for identifying the distribution of authors according to their productivity, is as follows:

$${\mathit{A}}_{\mathit{n}}={\displaystyle \frac{{\mathit{A}}_1}{{\mathit{n}}^2}}$$

where $A_n$ represents the total number of publications by a specific number of authors, $A_1$ is the number of publications by a particular author and $n^2$ refers to the authors whose number of publications would be calculated according to the law of exponential growth squared.

A detailed list of all references analyzed is included as Supplementary Material 1 (SM1).

3. Results

3.1. Trajectory of Publications Related to Concepts for Climate Change Mitigation in Coffee

Each of the concepts documented in this review aims to serve as a reference for documenting the reduction in GHG emissions. The longest-standing concept, first introduced in 1909, is “low carbon emissions”, with 64,825 documents found in the Scopus database, of which only 32 are related to coffee. The first document establishing a link between “low carbon emissions” and coffee appeared almost 100 years after the concept was first introduced. The concepts of “carbon neutral” and “carbon neutrality”, documented since 1968 and 1995, respectively, appeared in 2015 in articles related to coffee, adding up to a total of 22 and 7 publications on the subject, respectively.

“Carbon footprint” is the concept with the shortest period between its first appearance in the database in 2002 and its first publication with coffee in 2009. Additionally, it is the concept with the most publications related to coffee, with a total of 73 documents. “Net-zero emissions,” despite being another concept used to mitigate climate change, has only added 1315 publications, of which only seven are related to coffee, with its first appearance in the Scopus database recorded in 2018 (Figure 2).

Even though the key concepts shown in Figure 2 have been used in scientific papers to analyze coffee-related topics since 2008, it was not until 2019 that annual paper production increased significantly (Figure 3), jumping from 6 to 15 documents, a level that has been maintained in recent years, highlighting the need to continue documenting climate change mitigation strategies in the coffee sector.

3.2. Annual Trend vs. The Impact of Publications

Figure 3 presents the annual trend in the number of publications compared to their impact, measured by citations. Although the number of publications related to key concepts in coffee climate change mitigation strategies has remained constant over time, the impact of these studies, reflected in the number of citations, has shown significant variations. In 2013, a notable increase in citations was observed, reaching a total of 863. This phenomenon can be attributed to an article published in the Nature journal, which, as of July 2023, has received 777 citations. This article discusses the effects on biodiversity caused by the logistics of distributing products originating from developing countries that are exported to developed countries [36]. This figure highlights the difference between the volume of publications and their academic impact, indicating that while the number of publications has been relatively low, certain studies have generated a high volume of citations and, therefore, a significant impact in scientific literature.

3.3. Country Productivity

Countries that have developed at least 50 publications using one or more of the key concepts and generated a minimum of 100 citations are shown in Figure 4, with Brazil being the country that has developed the most research. Over the years, more countries have joined this fight against climate change, with the United Kingdom and now China, India, and Indonesia being the most prolific countries. As can be noted, from 2012 the publication of articles has significantly increased.

Indonesia is the country that has developed the most research focused on the agricultural sector using the concepts of “low carbon” and “carbon footprint”. Brazil has mainly used “low carbon”, whereas the United Kingdom stands out for its use of “carbon footprint.” Indonesia has specialized in biomass utilization from hydrochloric acid as a green inhibitor to control metal corrosion [37] and sulfuric acid [38]. Research has also been developed using carbon footprint calculation in the transformation process from coffee cherry to parchment coffee [39]. In the case of “low carbon”, studies have focused on the decaffeination process [40] and total CO₂ emissions in mechanized farming systems [25].

Taiwan is the country that has published the most research on “carbon neutral”. Like Indonesia, it has focused on biomass utilization [41], but in this case through pyrolysis for bio-oil production [42] and biochar from coffee husk [43]. Another country, although not an agricultural coffee producer, that has developed research related to GHG emissions reduction is Germany. This country has funded initiatives in Latin America and the Caribbean, such as the one developed at Coopedota in Costa Rica, the first coffee mill to obtain carbon neutral certifications worldwide [44]. “Carbon neutral” has also been used in coffee marketing to raise consumer awareness of the efforts made by producers to mitigate climate change [45].

Germany leads the list of countries that have used the concept of “carbon neutrality” in their research, especially to analyze shaded coffee cultivation in agroforestry systems [46] and the role of trees as carbon reservoirs [47]. On the other hand, research focused on “carbon neutrality” has also concentrated on the use of coffee husk as a raw material for biofuel production [48]. In addition, progress has been made in understanding the microbiology involved in the degradation of switchgrass combined with spent coffee grounds, allowing the development of new production techniques that are more economical and have lower carbon emissions than conventional chemical products [49].

Research on the “carbon footprint” has focused particularly on agriculture in the face of climate change [50]. This analysis considers the environmental impact and incorporates the circular economy, highlighting the use of coffee husk [51] and the reduction in GHG emissions through the use of organic fertilizers produced by the anaerobic digestion of agricultural byproducts [52]. As an industrial coffee-processing country, Germany has focused on the environmental impacts of international trade [53,54], simultaneously analyzing the environmental benefits and economic viability of using coffee husk [55].

The concept of “net-zero carbon emissions” has been a part of research in the United States (an industrial coffee processor), focusing on the cost of carbon credits to achieve zero carbon emissions [56]. In the coffee sector, studies have related this to the use of rainwater harvesting systems [57] and wastewater treatment [58]. After the European Union committed to achieving net-zero carbon emissions by 2050, Austria has conducted research ranging from life cycle analysis to using coffee spent grounds in the production of biolubricants, as petroleum-based lubrication systems must adapt to meet established energy efficiency goals [59].

3.4. Outstanding Journals with Publications Related to Climate Change Mitigation Concepts in Coffee

The database reported a total of 80 journals that have published work developed by scholars using one or more of the concepts for mitigating climate change. According to Bradford’s Law, these journals are grouped into three zones to facilitate the identification of scientific journals with high-impact factors for authors, as well as easy access to new publications on a given topic. The results of this study showed that 12 journals were located in Zone One, led by the Journal of Cleaner Production, while 34 journals were grouped in Zone Two, with Waste Management as the first journal in that zone. Finally, Zone Three, with a total of 34 journals, was led by the International Journal of Consumer Studies. It is worth noting that the top 10 most outstanding journals were located in Zone One and account for 30% of all published works (Figure 5).

3.5. Prolific Authors and Collaboration Among Them

The results confirmed what Lotka’s Law predicts: most authors contribute very few papers, while a small number of authors produce the majority of the literature available on key concepts used in climate change mitigation strategies in coffee. For example, Peter Läderach from the International Center for Tropical Agriculture (Nicaragua) has published 3.81% of the total work related to key concepts. Meanwhile, Athena Birkenberg from the University of Hohenheim (Germany), Wei-Hsin Chen from National Cheng Kung University (Taiwan), Rahmat Pramulya from Teuku Umar University (Indonesia), and Henk van Rikxoort from UTZ Certified (a certification focused on sustainability and responsible agricultural production) have each contributed 2.86%. Additionally, Omar I. Awad from the University of Kirkuk (Iraq), Tajuddin Bantacut from IPB University (Indonesia), Regina Birner from the University of Hohenheim (Germany), Chin-Lung Chiang from National Chin-Yi University of Technology (Taiwan), and Matteo Cibelli from the University of Tuscia (Italy) each contributed 1.9% (Figure 6).

In bibliometrics, collaboration networks map the relationships and connections between authors who have worked together on scientific research. These maps also help understand research evolution and trends, facilitating the identification of the degree of collaboration, authors’ topics of interest, and collaborative processes over periods. Collaboration networks also provide information about the impact of partnerships, allowing researchers to identify potential research partners and journals where their work could be published. This is the case with Indonesia, where researchers have co-authored papers to contribute to developing research (Figure 7).

3.6. Historical Evolution

In the map (Figure 8), nodes or bubbles represent a scientific article. The size of the bubble indicates the number of citations received by that article, and colors represent different periods or categories. In this case, there are red and blue bubbles, indicating two distinct groups (e.g., different topics or received versus cited citations). Another element is the labels, which, along with the bubbles, show the authors’ names and the publication year of each article. Arrows indicate citations between articles. It is worth noting that an arrow from one article to another shows that the source article cites the target article.

3.6.1. Central Article

The article [60] is the largest node, indicating that it is the most cited article in this dataset. Many arrows originate from this node and point to other nodes, showing that [60] is cited by multiple subsequent articles.

3.6.2. Cited Articles

The articles directly connected to the [60] node are those that cite this article, for example [55,61,62], among others.

3.6.3. Secondarily Connected Articles

Some articles, such as [45,63], also cite [60] and are, in turn, cited by other articles, creating a citation network that expands from the central article.

3.6.4. Temporal Evolution

The labels’ dates allow us to observe how ideas and citations evolve over time. For example, we can see a progression from [60] through successive years until 2023. Additionally, the color helps distinguish between different periods or categories.

3.6.5. Different Thematic Groups or Periods

Blue bubbles like [64,65] seem to form a separate group from the red bubbles. This could indicate a thematic evolution or a different subcategory within the same field of study.

This map provides a clear visualization of how the article [60] has influenced subsequent work, showing both the central importance of this article and the connections between articles over time. Direct and secondary citations are highlighted through arrows and the citation network, helping to understand the historical evolution and influence of ideas within this research field (Figure 8).

3.7. Analysis of Knowledge Areas

In the global percentage of knowledge areas, environmental sciences, energy, and engineering stood out. Although the different concepts overlapped with these three areas, in the case of the “carbon footprint” concept, it has been primarily used in engineering, environmental sciences, and agriculture; “carbon neutral” and “carbon neutrality” showed the same order of importance, with energy ranking first, followed by environmental sciences, and finally engineering. The “low carbon” concept has been most used in environmental sciences, with energy in second place and engineering in third. Regarding “net-zero emissions”, it coincided with the global knowledge areas (Figure 9).

3.8. Research Interests and Themes

In the case of coffee, Figure 10 shows how the concepts for mitigating climate change are related. The proximities and distances between keywords help to understand the associations and thematic groupings within the dataset. Keywords that are closer together tend to be related and appear in similar contexts, whereas those that are farther apart tend to be less related.

3.8.1. Dimension 1 (Dim 1)

The horizontal orientation (Dim 1) captures the main differences in associations between keywords. For instance, terms such as “biofuel,” “biodiesel,” and “biofuel production” are grouped on the negative side of Dim 1, suggesting that these keywords are closely associated within the context of the analysis. Conversely, on the positive side of Dim 1, words such as “agriculture”, “developing country”, and “charcoal” appear, indicating another cluster of associations. In our study, Dim 1 reflects how anthropogenic activities have driven the increase in GHG emissions into the atmosphere, leading to climate change and its subsequent environmental impacts.

3.8.2. Dimension 2 (Dim 2)

The vertical orientation (Dim 2) captures secondary differences in associations. On the positive extreme of Dim 2, keywords such as “biofuel” and “biodiesel” are found, whereas the negative extreme includes terms like “chlorine.compound” and “carbon.sequestration.” Thus, Dim 2 emphasizes life cycle analysis aimed at quantifying GHG emissions and establishing initiatives for their mitigation, such as carbon neutrality, which includes leveraging coffee silver skin and other residues for energy generation.

In the upper-left quadrant of Figure 10, keywords such as “biofuel,” “biodiesel,” “extraction,” and “carbon.emission” appear to represent themes related to biofuel production and emission. In contrast, the upper-right quadrant includes terms like “temperature,” “moisture,” “charcoal,” and “energy.consumption,” which may be associated with energy and environmental factors. At the center of the figure, keywords such as “sustainability,” “environmental.analysis,” and “waste.management” suggest a focus on sustainability and environmental management.

The overlay visualization presented in Figure 11 was constructed following the strategy described in the Section 2, where keywords with a minimum co-occurrence of five were selected. Keywords were clustered into thematic groups using VOSviewer’s default clustering algorithm, with each cluster represented by a distinct color. The color gradient in the figure indicates the average publication year of each keyword, enabling the identification of both emerging and declining themes within the coffee and climate change literature. Warm tones, particularly yellow, highlight cutting-edge topics that have gained increasing relevance in recent years, such as bioenergy production from coffee residues and the application of organic fertilizers like biochar. In contrast, cooler tones correspond to older concepts that, while still relevant, have received comparatively less attention in the most recent publications.

Among the five key concepts analyzed in this study, only the carbon footprint is clearly reflected in the science mapping, standing out due to its larger node size compared to the others. This prominence indicates its frequency and significance in the field, underscoring its central role in research addressing the environmental impacts of coffee production. The carbon footprint serves as an important environmental indicator by quantifying GHG emissions that can be reduced through waste valorization technologies, such as the reuse of spent coffee grounds and the application of biochar, within broader strategies aimed at achieving carbon neutrality. Thus, the assessment of carbon footprint represents a fundamental step, while the subsequent reduction and offsetting of emissions constitute the strategic pathway toward mitigating the environmental impact of coffee production.

The thematic map (Figure 12) is based on networks of keyword associations grouped into four quadrants, each representing different characteristics of the topics in terms of their relevance (centrality) and degree of development (density):

3.8.3. Upper-Right Quadrant (Motor Themes)

This quadrant includes well-developed topics that are central to the research field. Themes such as fossil fuel, nonhuman, and agriculture demonstrate a high degree of development and are critical to studies on sustainability. Similarly, topics like carbon footprint, greenhouse gas emissions, and life cycle analysis stand out as highly relevant and fundamental to the core of current research. These themes form the backbone of investigations, highlighting their pivotal role in advancing strategies to mitigate climate change within the coffee sector.

3.8.4. Upper-Left Quadrant (Niche Themes)

The upper-left quadrant is characterized by peripheral themes that, while well-developed, hold limited central relevance to the broader research field. Examples include chlorine compounds, corrosion inhibitors, and electrochemical corrosion. Although these topics are technically advanced, their contribution to the sustainability discourse is less pronounced compared to the central themes, reflecting their specialized but isolated nature.

3.8.5. Lower-Right Quadrant (Basic Themes)

Basic themes occupy this quadrant, indicating foundational topics that are crucial for the field but underdeveloped. These include calorific value, higher heating value, and coal. While these topics are integral to understanding energy metrics and their implications for GHG emissions, they represent areas where significant gaps in research exist, offering substantial opportunities for further exploration and innovation.

3.8.6. Lower-Left Quadrant (Emerging or Declining Themes)

This quadrant encompasses topics with low centrality and limited development. These may represent emerging areas gaining traction or themes in decline within the field. For example, Escherichia coli, plant extract, consumption, and fructo-oligosaccharides could signify nascent research directions with potential relevance. Additionally, Fourier transform infrared spectroscopy may either be an emerging analytical tool or a declining focus in this context, depending on future trends and applications.

3.8.7. Additional Observations

Certain themes, such as biomass, spent coffee grounds, and emission control, lie closer to the central-right region, indicating growing relevance and active development. Meanwhile, topics like male, adult, and diet are positioned at the intersection of the upper quadrants, signifying moderate relevance and development within their respective contexts. These patterns highlight the dynamic nature of research trends and the interplay of established and evolving themes in the pursuit of sustainable coffee production.

3.9. Outstanding Documents

The production of publications over the years has been variable, with their impact being even more uneven. The most significant documents related to concepts for mitigating climate change are presented in

Table 1. Publications with the greatest impact utilizing one or more key concepts for mitigating climate change in the coffee sector.

Title	Author	Journal	Global Impact Factor	Impact Factor Per Year	Normalized Impact Factor
International trade drives biodiversity threats in developing nations	[36]	Nature	777	64.75	2.70
Addressing uncertainty in adaptation planning for agriculture	[50]	Proceedings of the National Academy of Sciences of the United States of America	197	17.91	2.84
Energy potential from rice husk through direct combustion and fast pyrolysis: A review	[66]	Waste Management	158	22.57	3.07
A better carbon footprint label	[67]	Journal of Cleaner Production	83	10.38	2.24
Organic solvents in sustainable synthesis and engineering	[68]	Green Chemistry: An Inclusive Approach	74	12.33	3.39
Climate change adaptation, mitigation and livelihood benefits in coffee production: where are the synergies?	[69]	Mitigation and Adaptation Strategies for Global Change	70	7.00	1.29
Health and sustainability outcomes of vegetarian dietary patterns: a revisit of the EPIC-Oxford and the Adventist Health Study-2 cohorts	[70]	European Journal of Clinical Nutrition	65	13.00	3.32
Greenhouse gas emissions in coffee grown with differing input levels under conventional and organic management	[71]	Agriculture, Ecosystems and Environment	56	4.67	0.19
Delayed addition of nitrogen-rich substrates during composting of municipal waste: Effects on nitrogen loss, greenhouse gas emissions and compost stability	[72]	Chemosphere	54	7.71	1.05
Characterization of residual biomasses from the coffee production chain and assessment of the potential for energy purposes	[73]	Biomass and Bioenergy	53	10.60	2.70

. Notably, despite the passage of time, no publication has surpassed the prominence of the article published in Nature in 2012.

3.10. Most Utilized Strategy in Coffee to Mitigate Climate Change

The analysis of the most frequently cited keywords revealed that among the five key concepts adopted by governments worldwide-low emissions, carbon neutral, carbon neutrality, net-zero emissions, and carbon footprint-only “carbon footprint” prominently stands out in the word cloud (Figure 13), highlighting its connection to the other terms. This observation is not coincidental, as the carbon footprint serves as an environmental indicator enabling the quantification of GHG emissions across one or more stages of the value chain, as outlined by life cycle assessment methodology. For this reason, “carbon footprint” emerges as one of the three most significant keywords in the analysis.

Additionally, other keywords reflect the activities undertaken in the coffee sector to mitigate and adapt to climate change, with the overarching goal of reducing environmental impact. These activities underscore the sector’s commitment to addressing climate challenges while promoting sustainable practices.

Operationalization of our results for coffee sustainability programs may include adoption of on-farm sustainable agricultural, as well as sustainable practices during transportation, processing, commercialization and final consumption. By spanning the entire chain, sustainable practices must apply methods like agroforestry, provision of shade, intercropping, soil fertility management and water conservation; processing by reducing energy use and waste; and transformation with energy-efficient processes. Environmental protection, including prevention of deforestation and conservation of soils, along with socio-economic fairness for farmers, need to be seriously taken into consideration in order to increase the resilience of the farming systems and reduce GHG emissions.

We recognize that use of Scopus-only data represents a limitation for our analysis and acknowledge the need for future studies aimed at considering a broad spectrum of databases for further analysis in the near future. Nonetheless, our study significantly contributes to the analysis of the main concepts in relation to mitigation strategies as an attempt to shed light on the farmers, academics and policy makers related to the coffee sector.

4. Conclusions

This review synthesized the key concepts underpinning strategies to mitigate climate change in the coffee sector, offering an integrative perspective on research trends, impacts, and methodological approaches. The analysis revealed a moderate but steady increase in publications, with citation patterns highlighting that the influence of research is determined more by quality and relevance than by volume. Leading contributions have come from countries such as Brazil, the UK, and China, whose diversity of approaches has strengthened the development of innovative sustainability strategies.

The findings also demonstrate the central role of high-impact journals, such as Nature and Sustainability, in disseminating multidisciplinary research on climate change mitigation in coffee. Collaboration networks show a strong international dimension, with prolific authors advancing concepts such as carbon footprint and agricultural sustainability in vulnerable coffee-growing regions. Sustainability, agriculture, and environmental sciences remain the dominant fields, while research topics have increasingly focused on adaptation, biodiversity, and sustainable practices. The major gaps are related to the lack of reports on specific case studies that evaluate the application of key concepts used in strategies to mitigate climate change in the coffee agroecosystem, considering, in the measurement and quantification, that coffee production systems are not uniform across producing countries. Future research should therefore address this need.

The carbon footprint has emerged as the most widely applied concept, serving as a fundamental tool for assessing and guiding environmental impact reduction in coffee production and processing. This emphasizes the need to integrate quantitative evaluation with practical strategies to enhance resilience and reduce greenhouse gas emissions. Continued research on the interplay between sustainable practices, climate resilience, and ecosystem conservation will be essential to secure the long-term viability of coffee production, ensuring practical benefits for both small-scale producers and the global market.