A Bibliometric Analysis of World Issues—Social, Political, Economic, and Environmental Dimensions

: Globalization has taken place for several decades and the world has become a connected place. As researchers are on the frontline to explore world (or global) issues, it is crucial to understand what research has been done and what the emerging topics relating to social, political, economic, and environmental dimensions are. This study investigates the trend and emerging topics of world (or global) issues using a bibliometric approach. A literature search using Scopus identiﬁed 1201 related documents, including journal articles, review articles, conference articles, books, and book chapters published during the period 1975–2022. Bibliometric data were analyzed using Scopus tools and VOSviewer software. Results show that the number of publications on world (or global) issues has increased over the last ﬁve decades, particularly after 2001. Two major streams of research were identiﬁed based on co-occurrence of keywords. They were “sustainable development and climate change”, and “environmental protection, economics, and politics”. Additionally, corporate social responsibility, governance approach, and COVID-19 were identiﬁed as emerging keywords in recent years. global)


Introduction
The improvement of health care services and economic conditions has led to an increase in population in many developing countries over the past few decades [1][2][3]. According to the United Nations, the world's population increased continuously from 4 billion in 1975 to almost 7.9 billion in 2021 [3]. The largest population increases took place in Eastern and South-Eastern Asia (mainly in China), and Central and Southern Asia (mainly in India) [3]. Population growth, on the one hand, may further economic growth in the long run in some developing countries [4]. On the other hand, population growth has created tension in social, political, and public health care systems [5]. Moreover, human demands on energy, goods, services, and transport impose an enormous amount of pressure on the environment [6]. In the last three decades, globalization, including the advancement of transport systems and the advent of information and communications technology, has made the world a connected place where people can interact with each other face to face within a short period of time or virtually through different channels in real time [7]. As such, each person and country becomes a node in this interconnected world and his/her/their activities can either enhance or hinder the development of global human society. While globalization facilitates the exchange of capital, goods, people, knowledge, and cultures across countries and regions, it also exacerbates social and political conflicts, economic gaps, and environmental problems in many parts of the world [8][9][10].
Since 1980, researchers have started utilizing a multi-dimensional or holistic approach to address the world's various social, political, economic, and environmental issues and challenges [8,[11][12][13][14][15][16][17]. Nevertheless, research focuses change as a function of time and the topics widely studied in the past may no longer be hot topics in recent years. Therefore, it is important to use a systematic approach to review peer-reviewed literature on world (or global) issues using bibliometric techniques. Doing so helps us identify the trend of World 2022, 3 620 research on world (or global) issues, hot topics in the past, and emerging topics in recent years. A literature search using "bibliometric analysis" and ("world issues" or "global issues") within "Article title, Abstract, Keywords" in Scopus on 22 June 2022 identified only 13 articles [18][19][20][21][22][23][24][25][26][27][28][29][30]: 11 articles focusing on a particular topic of environmental research, such as climate change, land, renewable energy, food waste, ocean acidification, etc., 1 article about a social and health issue, and 1 article about economic and business research. In bibliometric analysis of world (or global) issues, using a multidimensional approach is still lacking; it is crucial to conduct a timely bibliometric analysis to understand the past, present, and future research of world (or global) issues in a more encompassing perspective. More specifically, this study aims to answer the following research questions: (1) What is the trend of world (or global) issues-related research? (2) Who are the most prolific authors? (3) Which are the most productive institutions and countries? (4) Which funding bodies are the most supportive and which subject areas are associated with this type of multidisciplinary research? (5) Which articles are the most influential ones based on the number of citations? (6) What are hot topics and emerging topics of world (or global) issues using cluster analyses? The present study identified the relevant literature on world (or global) issues by utilizing world (or global), social, political, economic, environmental, and issues in their keywords from an academic database-Scopus [31,32]. It was focused on journal, review, and conference articles, as well as books and book chapters. The data were analyzed using Scopus bibliometric tools and a popular bibliometric visualization tool-VOSviewer-was used to generate clusters of keywords [33,34]. The findings of the study show that the number of publications on world (or global) issues has increased over the last five decades, particularly after 2001. They revealed that world (or global) issues should be multidisciplinary in nature, as the identified articles were categorized into a wide range of subject areas, including: "Social Sciences", "Environmental Science", "Business, Management and Accounting", "Earth and Planetary Sciences", etc. Additionally, co-occurrence of keywords revealed two major streams of research, namely: "sustainable development and climate change" and "environmental protection, economics, and politics".
The rest of this paper is structured as follows. Section 2 presents a literature review. It is followed by Materials and Methods, Results, and Discussion in Sections 3-5. Section 6 concludes the paper.

Literature Review on World (or Global) Issues and Bibliometric Analysis
Globalization does not only facilitate the exchange of capital and goods, it also accelerates communication and understanding between people, knowledge, skills, and cultures. Globalization took place very rapidly at the turn of the 1980s and 1990s. It was primarily driven by large corporations looking for suppliers and new markets [8] and the modernization of many Asian economies, especially after the opening-up policy adopted by China since 1978 [35]. As different parts of the world are connected physically and/or virtually, Kaufmann et al. [7] proposed to use "motility"-referring to the overall potential capacity of goods, people, or information to be mobile both socially and geospatially-to characterize mobility as a capital. They suggested that access, competence, and appropriation are key features of motility [7]. Yet, globalization has also eroded social and environmental systems [8,10,11] and can put enormous pressure on host countries' political and economic structures [8,11]. Specifically, Korten [8], in his book, indicated that most of the current world (or global) issues (or problems) do not come from business or the market per se, but rather a corrupted global economic system mostly dictated by the world's largest corporations. As world (or global) issues become multifaceted and cross-disciplinary, researchers started applying a multi-dimensional/holistic approach to study them [12][13][14][15][16][17]. For example, Brechin et al. [13], in 1991, proposed that population, environment, and development planning/policy should not be studied in isolation because all of them are interrelated. Costello et al. [12] and Nightingale et al. [17] indicated that the task of transforming human behaviors and economies has become more urgent than ever because climate change has adversely affected our social-economic-environmental systems and human health at an accelerating rate. Udo et al. [14], Pereira [15], and Zhang [16] argued that social, economic, environmental, and/or political dimensions have to be considered holistically to evaluate global and regional sustainability.
A bibliometric analysis refers to the application of quantitative techniques (statistical analysis, citation, and co-citation analyses, etc.) on bibliometric data [36]. Although bibliometric methodologies are not new, the proliferation of bibliometric analyses and studies is rather recent due to the advancement and availability of academic indexing databases, such as Web of Science, Scopus and Dimensions, and bibliometric software, such as VOSviewer, Gephi and Leximancer [36]. Donthu et al. [36] compared bibliometric analysis with metaanalysis and systematic literature review. They highlighted that bibliometric analysis aims to summarize large quantities of bibliometric data and to reveal some underlying structures and emerging trends of a research topic/field. A bibliometric analysis is particularly useful when the scope is broad (such as world/global issues) and the dataset is too large for manual review (it is likely in the present study that the identified articles can be over 1000). Among academic indexing databases, Web of Science and Scopus are the two most popular multidisciplinary databases for bibliometric analysis [31,32]. Although Web of Science has stringent criteria for journal inclusion and is the most authoritative bibliometric source for quality publications, its core collection does not cover enough new and less-established open access journals in emergent disciplines and conference proceedings. Currently, Web of Science's core collection covers 21,100 journals in 254 disciplines, with about 74.8 million total records [37]. On the other hand, Elsevier launched Scopus in 2004. Initially, Scopus covered around 14,000 journals from 4000 publishers, with about 27 million abstract and citation records. Scopus has expended its coverage over the past two decades. As of January 2020, Scopus covered over 23,000 journals, 852 book series, and papers from over 120,000 international conferences. It has over 77.8 million records [38]. In fact, bibliometric analyses have been carried out in the fields of environmental science [18][19][20][21][22][24][25][26][27][28][29] and social responsibility [39][40][41][42]. Many of these bibliometric analyses used Scopus as the source of data and VOSviewer as a key visualization tool. Nevertheless, there is scant literature using bibliometric analysis to understand the trend and emerging topics of world (or global) issues that not only cut across the fields of environmental science and social responsibility, but also social sciences, economics and finance, and earth and agricultural sciences, etc.

Materials and Methods
Scopus has a good coverage in multidisciplinary journals and journals in emergent disciplines, and has a broader coverage in books and conference proceedings than Web of Science. Therefore, this study used it as the source of bibliometric data. More specifically, documents were searched in Scopus using [("world" OR "global") AND "social" AND "political" AND "economic" AND "environmental" AND "issues"] within [Article title,  The csv file was imported to VOSviewer (version 1.6.11). After that, co-authorship analysis, citation analysis, co-citation analysis, and co-occurrence of keywords analysis were conducted to reveal associations between key researchers, what sources researchers normally cited, and key topics of world (or global) issues, similar to other bibliometric studies in the field of environmental science [18][19][20]22,24,26,28] and social responsibility [39][40][41][42]. The default minimum number of co-occurrences in VOSviewer was 5. For the full set of identified documents, the minimum number of co-occurrences was set to 20 and all keywords including author keywords and index keywords were used in keyword cooccurrence analysis. The minimum cluster size was set to 10. Additionally, co-occurrence of keywords analysis was conducted for the identified publications during the periods 1980-1989, 1990-1999, 2000-2019-2022(up to 22 June 2022, in which the minimum number of co-occurrences was set to 10 in each one of the first four cases, while it was set to 5 for the case covering 2020-2022 (up to 22 June 2022). Additionally, the minimum cluster size was set to 3 in these cases. Figure 1 shows the process of this bibliometric study that followed closely the procedure as suggested by Donthu et al. [36].
Scopus offers a number of features for bibliometric study, such as (i) the number of publications in the selected documents during the studied period, (ii) the number of publications by authors, (iii) the number of publications by affiliations, (iv) the number of publications by countries, (v) the number of publications by funding sponsors, (vi) the number of publications by subject areas, (vii) the number of publications by source titles, and (viii) the number of citations for each document.
The csv file was imported to VOSviewer (version 1.6.11). After that, co-authorship analysis, citation analysis, co-citation analysis, and co-occurrence of keywords analysis were conducted to reveal associations between key researchers, what sources researchers normally cited, and key topics of world (or global) issues, similar to other bibliometric studies in the field of environmental science [18][19][20]22,24,26,28] and social responsibility [39][40][41][42]. The default minimum number of co-occurrences in VOSviewer was 5. For the full set of identified documents, the minimum number of co-occurrences was set to 20 and all keywords including author keywords and index keywords were used in keyword co-occurrence analysis. The minimum cluster size was set to 10. Additionally, co-occurrence of keywords analysis was conducted for the identified publications during the periods 1980-1989, 1990-1999, 2000-2019-2022(up to 22 June 2022, in which the minimum number of co-occurrences was set to 10 in each one of the first four cases, while it was set to 5 for the case covering 2020-2022 (up to 22 June 2022). Additionally, the minimum cluster size was set to 3 in these cases. Figure 1 shows the process of this bibliometric study that followed closely the procedure as suggested by Donthu et al. [36]. Process of bibliometric study. Note: 1 The keyword "issues" or "issue" produced the same search result. However, "issues" was used in the article because the study aimed to investigate "world (or global) issues" from a multi-dimensional perspective.  Process of bibliometric study. Note: 1 The keyword "issues" or "issue" produced the same search result. However, "issues" was used in the article because the study aimed to investigate "world (or global) issues" from a multi-dimensional perspective. In terms of the number of publications by authors, Scopus identified that each of the following seven researchers-Bertaux, N., Dredge, D., Hall, C.M., Lahiri-Dutt, K., Okunoye, A., Quinn, F., and Taylor, N.-had three publications. A total of 70 researchers contributed to two publications each and the rest of the researchers contributed to one publication each. Specifically, Bertaux and Okunoye of Xavier University in the United States co-authored three publications about a framework of knowledge management in global diversity [43][44][45], while Quinn and Taylor of the University of New England in Australia co-authored three publications about education for sustainability in primary schools [46][47][48].

Data Analysis Using SCOPUS Tools
In terms of the number of publications by affiliations, Table 1 shows that there were 10 publications with authors affiliated with the Australian National University and National University of Singapore each, and nine publications with authors affiliated with Wageningen University & Research and the University of Sussex each. They were followed by the University East Anglia and University College London, whose faculty members contributed to eight publications.

Rank
Affiliation The Australian National University 10 1 National University of Singapore 10 3 Wageningen University & Research 9 3 University of Sussex 9 5 University of East Anglia 8 5 University College London 8 7 Cornell University 7 7 University of Washington 7 7 University of Toronto 7 7 Monash University 7 7 University of California, Berkeley 7 7 North-West University 7 Table 2 shows the number of publications by countries. As expected, researchers in the United States were in the leading position to explore world (or global) issues, followed by researchers in the United Kingdom, Australia, and Canada. While many researchers in these countries started exploring world (or global) issues in the 1980s and 1990s, nearly all publications (except one each) from China and India were published after 2006. In terms of the number of publications by authors, Scopus identified that each of the following seven researchers-Bertaux, N., Dredge, D., Hall, C.M., Lahiri-Dutt, K., Okunoye, A., Quinn, F., and Taylor, N.-had three publications. A total of 70 researchers contributed to two publications each and the rest of the researchers contributed to one publication each. Specifically, Bertaux and Okunoye of Xavier University in the United States co-authored three publications about a framework of knowledge management in global diversity [43][44][45], while Quinn and Taylor of the University of New England in Australia co-authored three publications about education for sustainability in primary schools [46][47][48].
In terms of the number of publications by affiliations, Table 1 shows that there were 10 publications with authors affiliated with the Australian National University and National University of Singapore each, and nine publications with authors affiliated with Wageningen University & Research and the University of Sussex each. They were followed by the University East Anglia and University College London, whose faculty members contributed to eight publications. University of Washington 7 7 University of Toronto 7 7 Monash University 7 7 University of California, Berkeley 7 7 North-West University 7 Table 2 shows the number of publications by countries. As expected, researchers in the United States were in the leading position to explore world (or global) issues, followed by researchers in the United Kingdom, Australia, and Canada. While many researchers in these countries started exploring world (or global) issues in the 1980s and 1990s, nearly all publications (except one each) from China and India were published after 2006. In terms of the number of publications funded by different sponsors, Table 3 shows that the authors in 15 publications acknowledged funding support from the European Commission (EU). Ten publications had an acknowledgement of funding support from the National Science Foundation (US). The authors in nine publications acknowledged the funding support from the Horizon 2020 Framework Programme (EU), while the authors of eight publications acknowledged funding support from the National Natural Science Foundation of China. The United Kingdom supported 12 publications through its Economic and Social Research Council and Engineering and Physical Sciences Research Council. The Government of Canada also supported 12 publications directly and indirectly through its Social Sciences and Humanities Research Council. Engineering and Physical Sciences Research Council (UK) 5 8 Government of Canada 5 9 National Institutes of Health (US) 5 Table 4 shows the number of publications by subject areas. Over half of the publications (611) were categorized as social sciences. Thirty percent (361) of publications were categorized as environmental science. About one-eighth (152) of them were categorized as business, management, and accounting. Eleven percent of them were categorized as earth and planetary sciences (137), economics, econometrics and finance (132), and engineering (132), respectively. Table 5 shows the number of publications by source titles. Only seven source titles had five publications or more. Among the top seven source titles, Sustainability (Switzerland) ranked first with 14 publications. It was followed by Renewable and Sustainable Energy Reviews with eight publications and Ocean and Coastal Management with seven publications. Agricultural and Biological Sciences 104 10 Medicine 96 1 A publication could be assigned to more than one subject area in Scopus. Global Environmental Change 5 Table 6 shows the top 10 most frequently cited publications. Costello et al.'s [12] article ranked first with 1488 citations. This review article discusses how population growth and human consumption impact the global climate and in turn how climate change affects health by altering patterns of disease, morbidity and mortality, food production, and water and sanitation, etc. It has attracted over 100 citations per year since 2013. The second most highly cited publication was a book entitled "When corporations rule the world" by Korten [8]. This book discusses how global corporations focus on their own interest rather than interests of the public, producing devastating environmental and human rights consequences in many countries. It attracted 25 to 61 citations per year during the period 1997-2018. The third most highly cited publication was an article entitled "Biofuels: Environment, technology and food security" in Renewable and Sustainable Energy Reviews by Escobar et al. [49]. This review article highlights the rise in biofuels and how biofuels impact the environment and food production. It also argues that regulation mechanisms should be in place to regulate the use of land, and environmental impacts and social impacts due to biofuel production. The paper was cited close to 500 times since its publication in 2009. The fourth most highly cited publication was "Anthropological research on hazards and disasters" [50]. Oliver-Smith [50] conducted a thorough review about applied anthropological research on disasters due to natural and technologicalinduced changes in vulnerable regions, i.e., developing countries. The fifth most highly cited publication was "Determinants of voluntary CSR disclosure: Empirical evidence from Germany" in which Gamerschlag et al. report that CSR disclosures in German companies were affected by the size, shareholder structure, and relationship with stakeholders of the companies [51]. Additionally, profitability was positively associated with environmental disclosures [51].

Co-Authorship Analysis Using VOSviewer
Co-authorship analysis could be performed at the author and country levels in VOSviewer. When co-authorship analysis was carried out based on authors with three publications, results show that only two links (Bertaux-Okunoye) and (Quinn-Taylor) were identified, as expected. There was no link for Dredge, Hall, and Lahiri-Dutt. When co-authorship analysis was carried out at the country level, seven clusters were identified as shown in Figure 3 and Table 7.

Citation Analysis Using VOSviewer
Citation analyses were carried out at the document and country levels using VOSviewer. Figure 4a shows the result of citation analysis by documents with 100 citations or more. Thirty-six documents were identified and, as expected, the most frequently cited document was Costello et al.'s [12] article, followed by Korten [8] and Escobar et al. [49]. Figure 4b shows the result of the citation analysis by country. It shows 33 countries with 10 documents or more and one cluster linking the United States, the United Kingdom, Australia, Germany, Canada, and another 13 countries together.

Co-Citation Analysis Using VOSviewer
Co-citation analyses were carried out based on the cited references and authors using VOSviewer. It was found that only one article attracted more than 10 citations from more

Co-Citation Analysis Using VOSviewer
Co-citation analyses were carried out based on the cited references and authors using VOSviewer. It was found that only one article attracted more than 10 citations from more than one of the selected documents. The article was "The tragedy of the commons: The population problem has no technical solution; it requires a fundamental extension in morality" in Science by Hardin [57]. Figure 5 shows the co-citation analysis based on the cited authors. This analysis revealed whether two or more authors shared the same area of research, as their publications were jointly cited by the identified documents [58].

Co-Occurrence of Keywords Analysis Using VOSviewer
Co-occurrence of keywords analysis (i.e., all keywords) was carried out using VOSviewer. Sixty-eight keywords were identified, with the minimum number of occurrences at 20. The top 10 keywords are shown in Table 8. Figure 6 shows that two clusters were formed based on co-occurrence of keywords. Sustainable development was the core keyword in Cluster 1 (red color) and environmental protection was the core keyword in Cluster 2 (green color).    Figure 7a). These keywords still formed a cluster after 1990. However, another three clusters emerged during the period 1990-1999 (see Figure 7b). They were economics (with socioeconomic factors, human rights, women rights, etc.), environment (with politics, natural resources, health, etc.), and population (with population dynamics, demography, social policy, health care planning, population policy, etc.). Additionally, sustainability development started appearing and coupled with environmental protection, public policy, and conservation closely in the first cluster. During the period 2000-2009, sustainable development (with economic and social effects, environmental impact, environmental pro-   Figure 7a-d show the co-occurrence of keywords of the selected documents published in each decade from 1980 to 2019. Initially, many researchers focused on environmental protection, conservation of natural resources, policy, economic development, population, and developing countries, etc., in their studies, during the period 1980-1989 (see Figure 7a). These keywords still formed a cluster after 1990. However, another three clusters emerged during the period 1990-1999 (see Figure 7b). They were economics (with socioeconomic factors, human rights, women rights, etc.), environment (with politics, natural resources, health, etc.), and population (with population dynamics, demography, social policy, health care planning, population policy, etc.). Additionally, sustainability development started appearing and coupled with environmental protection, public policy, and conservation closely in the first cluster. During the period 2000-2009, sustainable development (with economic and social effects, environmental impact, environmental protection, etc.) formed a core cluster (see Figure 7c). Another three clusters were politics (with development countries, globalization, human, decision making, etc.), world (with eastern hemisphere, North America, United States, western hemisphere, etc.), and Eurasia (with Europe, sustainability, environmental issue, environmental policy, etc.). During the period 2010-2019, sustainable development and climate change (with decision making, environmental issues, economic and social effects, planning, etc.) formed a major cluster (see Figure 7d). Another three clusters were found. They were sustainability and environment (with environmental impact, developing world, governance approach, corporate social responsibility, ethics, etc.), human (with humans, public health, United State, international cooperation, etc.), and economics and environmental protection (with environmental management, ecosystem, biodiversity, etc.). Figure 8 shows the co-occurrence of keywords of the selected documents published from 2020 to 2022 (up to 22 June 2022). When the minimum number of occurrences was set to five, 32 keywords were identified and formed five clusters. Sustainable development formed a cluster (yellow color) with investments, and economic and social effects. Climate change formed a cluster (blue color) with COVID-19, pandemic, United States, and migration. Sustainability formed a cluster (red color) with human, economics, decision making, stakeholder, etc. Environmental protection formed a cluster (green color) with environmental economics, environmental policy, governance approach, etc. Finally, biodiversity, social justice, and South Africa formed the last cluster (purple color).  and migration. Sustainability formed a cluster (red color) with human, economics, decision making, stakeholder, etc. Environmental protection formed a cluster (green color) with environmental economics, environmental policy, governance approach, etc. Finally, biodiversity, social justice, and South Africa formed the last cluster (purple color).  Figure 2 demonstrates that publications about world (or global) issues were almost non-existent before 1985. The number of publications was between 2 and 20 during the period 1985-2000 and has an upward trend since 2001. This pattern was similar to the total number of academic publications during the period 1980-2018 [59]. It could be explained by the following reasons: (i) the rapid increase in number of university teachers cum aca-  Figure 2 demonstrates that publications about world (or global) issues were almost non-existent before 1985. The number of publications was between 2 and 20 during the period 1985-2000 and has an upward trend since 2001. This pattern was similar to the total number of academic publications during the period 1980-2018 [59]. It could be explained by the following reasons: (i) the rapid increase in number of university teachers cum academic researchers after 2000 [59], (ii) the culture of publish or perish becoming pervasive [59,60], (iii) most academic publishers switching to online submission systems that speed up the publication rate in the 2000s, and (iv) more researchers starting to work in multidisciplinary contexts and topics such as world (or global) issues. Among the 1201 documents identified in the study, a relatively high proportion of them were books (148 i.e., 12.3%) and book chapters (202 i.e., 16.8%). Scopus reports that among 77.8 million items, only around 210,000 (i.e., 0.27 percent) of them are books [38]. This is probably due to the fact that most traditional journals are specialized journals and only accept a small number of articles (or review articles) about world (or global) issues that are complex and across many fields of study. Although some multidisciplinary journals such as Sustainability (Switzerland) were launched in 2009, and Global Environmental Change in 2003, most published articles in these two journals still focus on a specific issue or relatively narrow range of sustainability/environmental issues.

Discussion
The identified documents showed that the majority of researchers contributed to one publication and only seven researchers contributed to a maximum of three publications. The highest number of publications based on affiliations was only 10, with authors affiliated with the Australian National University or National University of Singapore. Overall, researchers in the United States contributed to 289 (i.e., 24%) publications, followed by researchers in the United Kingdom contributing to 184 (i.e., 15.3%) publications. This was not surprising because researchers in the United States contributed to over 20% of the world's total academic publications in the last few decades and the United Kingdom was ranked second in terms of academic publications for several decades before, being surpassed by China in 2005 [59]. Although China became one of the top two countries producing the highest number of academic publications in the 2000s, China's research funding and outputs, i.e., academic publications, were primarily focused on science, technology, engineering, and mathematics (STEM). Social sciences, arts and humanities, and multidisciplinary research has been underfunded [61].
The EU was found to be the most supportive funding body/region directly and indirectly through its Horizon 2020 Framework Programme. It was followed closely by the US through the National Science Foundation and the National Institutes of Health. A total of 611 (i.e., 50.9%) of the identified documents were categorized as social sciences and 361 (i.e., 30.1%) of them were categorized as environmental science. Additionally, 96 (i.e., 8%) to 152 (i.e., 12.7%) were categorized as medicine, agricultural and biological sciences, arts and humanities, energy, engineering, economics, econometrics and finance, earth and planetary sciences, and business, management, and accounting, reflecting that world (or global) issues are complex and multidisciplinary in nature.
The top three highly cited publications were Costello et al.'s [12] review article, Korten's [8] book, and Escobar et al.'s [49] review article. They attracted 1488, 966, and 499 citations, respectively. Additionally, the fourth to sixth most highly cited publications included review articles by Oliver-Smith [50] and Henchion et al. [52] and an empirical research article by Gamerschlag et al. [51]. The seventh most highly cited publication was a book entitled "Sustainable development" by Baker [53], while the eighth and ninth most highly cited publications were review articles by Zimmet [54] and Sueyoshi et al. [55]. Therefore, review articles and books about world (or global) issues attracted more citations, particularly those about health-and food-related issues [12,49,50,52,54], and energy and the environment [49,55].
Co-authorship analysis based on the country level identified seven clusters. When the strength of co-authorship was considered, researchers in the United States had the largest number of publications, with researchers in the United Kingdom, followed by researchers in Canada, Switzerland, Australia, France, South Africa, Spain, and China. Likewise, researchers in the United Kingdom had the largest number of publications with researchers in the United States, followed by researchers in Canada, Australia, Germany, and the Netherlands. Although the relation between the United States and China has been strained over the last few years, collaborations between researchers in both countries has been resilient and the number of co-authored publications has increased [62]. The same situation is applicable to the United Kingdom-China research collaborations. Therefore, it is expected that the number of co-authored publications between these two countries and researchers in China would increase.
When co-occurrence of keywords analysis was carried out using all the 1201 documents, two clusters of 68 keywords were identified, with the minimum number of occurrences at 20. One cluster was centered on sustainable development and climate change, as well as its economic and social effects on humans. Another cluster was centered on environmental protection and economics, covering a wide range of political, social, and environmental issues impacting the world, particularly in developing countries. As research focuses, i.e., keywords, change temporally, the results of co-occurrence of keywords analysis in each decade spanning from 1980 to 2019 show that environmental protection, conservation of natural resources, policy, economic development, population, developing countries, etc., were research focuses in the identified 26 documents in the 1980s. In the 1990s, sustainable development became one of the keywords in the environmental protection cluster, while other clusters were centered on issues about economics, the environment, and population, respectively. The importance of sustainable development grew enormously in the 2000s and 2010s, making it the most prominent keyword and one cluster's focal point. During the same period, the importance of climate change grew and it became the second most prominent keyword in the 2010s. In the 2010s, corporate social responsibility and governance approach became two important keywords associated with the sustainability cluster. This is not unexpected because corporate social responsibility and its synonym (or a relatively new term)-corporate sustainability-has gained an increasing amount of attention in the last decade [63], while the number of publications about corporate social responsibility showed an increasing trend after 2007 [64]. Finally, co-occurrence of keywords analysis using the 187 documents published after 2020 showed that sustainable development and climate change were the two most prominent keywords, followed by sustainability and human. Additionally, COVID-19 and pandemic have become very important keywords since 2020, as COVID-19 has reshaped the world's social, political, economic, and environmental dimensions significantly [65][66][67].

Recommendation for Future Research
This study used a bibliometric approach to analyze the extant literature on world (or global) issues. I used "world or global", "social", "political", "economic", "environmental", and "issues" as search terms in "Article title, Abstract, Keywords". Although the study provides a general overview of world (or global) issues-related research in the last few decades, future research can use the same set (or slightly different sets) of search terms to repeat the study because search results on world (or global) issues change at a different times, knowing that globalization is changing the adoption of new technologies [9], while technologies in turn reshape globalization and our understanding of world (or global) issues [68,69]. Additionally, a systematic literature review can be conducted to provide a more in-depth understanding on the past, present, and future world (or global) issues from a multidisciplinary perspective.

Conclusions
World (or global) issues are complex and crosscut many fields of study. As such, researchers have adopted a multi-dimensional/holistic approach to explore how human and business activities impact their own social, political, and economic systems and the environment including its physical, chemical, biological, and climate systems. Climate change in turn affects ecosystems and causes health hazards, such as illnesses due to extreme weather incidents and infectious diseases, and natural disasters, such as storms and flooding, droughts and famine, and wildfires. This study adopted a bibliometric approach to examine what world (or global) issues-related research has been done, what the prominent research areas were, and what the emerging world issues are. Based on the data collected from Scopus and the analytical tools from Scopus and VOSviewer, the study identified 1201 related documents and found that research about world (or global) issues has an upward trend after 2001. Interestingly, even the most prolific authors only published three documents among the identified documents. The most productive institutions were the Australian National University and National University of Singapore, while US researchers produced the highest number of publications. Funding bodies in the EU and US were found as the most supportive ones for this type of multidisciplinary research. Costello et al.'s [12] review article was the top highly cited document, with 1488 citations and nearly all highly cited documents were either review articles or books. Co-occurrence of keywords analysis showed that sustainable development was the most prominent keyword, followed by climate change, and environmental protection. As these keywords (or research topics) are encompassing concepts, covering social, political, economic, and environmental dimensions, researchers have used a multi-dimensional/holistic approach to deal with these complex issues and their interactions. Additionally, researchers started investigating how the COVID-19 pandemic has influenced a wide range of world (or global) issues in the last two and a half years. In sum, the study contributes to the current body of knowledge by unveiling the trend, emerging topics, and multidisciplinary nature of world (or global) issues. Furthermore, it is suggested that world (or global) issues should be addressed by multidisciplinary and/or cross-disciplinary approaches, implying that researchers should expand their focus beyond traditional academic boundaries and work with fellow researchers from a diverse range of disciplines. It is particularly true that social, political, economic, and environmental interests from different stakeholders/groups cannot be easily reconciled and have to be tackled holistically/multi-dimensionally.
Like any cross-sectional analysis using secondary data, the study has some limitations. First, the bibliometric data were extracted and downloaded from Scopus on 22 June 2022. As there are over 3.2 million academic publications indexed by Scopus every year, i.e., >8700 publications/day in recent years [59], while the world/global issues continue to attract researchers from a wide range of disciplines, it is expected that new trends and hot topics will emerge in the near future. Researchers can carry out a new round of bibliometric analysis and systematic literature review in future. Second, micro-level bibliometric data may include some errors, such as inconsistencies in authors' last names and initials, authors' affiliations, book editions and years, and inconsistencies due to changes to journal names [70]. Yet, the data were checked and no obvious error was found. Third, a bibliometric analysis using a different database will produce different results. Future research can carry out a similar bibliometric analysis using Web of Science, Dimensions, etc., to re-evaluate the trends and hot topics of the world/global issues primarily based on journal articles.