Climate change drivers of migration are a contemporary economic, political, and security concern that has surfaced in academic and policy discourses in recent years. The growing number of research reports on climatic drivers of migration in various parts of the world reflects this. For instance, the World Bank Report 2018 cautions that climate change will primarily drive human migration in Africa and other developing regions (Rigaud et al., 2018). Similar warnings have also been echoed by the European Union, which considers climate change-driven migration a matter of national security (Parsons & Nielsen, 2020). Regarding displacement, the Stern review on the economics of climate change (Warner & Boas, 2019) claimed that climate change has already forced 24 million people to relocate. Other scholars, such as (Geisler & Currens, 2017), have further projected that by 2050, up to 1 billion people will be displaced by the effects of climate change.

Such views on mass migration due to climate change are held mainly by climate activists who seek to amplify climate change risks to influence climate change policy (Risbey, 2008). In the views of the activists, the people compelled to migrate due to climate change are called environmental migrants or environmental refugees. (Burrows & Kinney, 2016) attempted to debunk the climate activist view by arguing that the estimated 1 billion climate migrants are uncertain and unrealistic due to a lack of data. Furthermore, emerging research indicates that the linkage between migration and climate change effects such as drought and floods is complex, indirect, and mediated by various social and economic drivers [(Suckall et al., 2017); (Smirnov et al., 2022)]. For example, it is argued that drought reduces the ability to migrate due to a lack of resources, forcing people to stay within their vulnerable environment [Foresight, 2011; (Haas, 2010)]. Moreover, research evidence by (Findley, 1994), citing an example of Mali, pointed out that when the country experienced a prolonged drought from 1983 to 1985, migration did not rise. Instead, there was a shift to short-cycle circulation where 'migrants' stayed in their destinations for a short period, with 64 percent adopting a circular migration pattern (Findley, 1994).

Similarly, (Haas, 2021) claimed that for smallholder farmers who rely on rain-fed agriculture, the effect of drought on migration is paradoxical. He further argues that drought decreases migration by eroding resources needed to move out for long distances. This claim is also echoed by (Quiñones et al., 2021), who conducted a study in 115 countries and concluded that out-migration is reduced with increased drought. Empirical studies have also suggested that migration decisions hinge upon the severity of climate events and the ability of households to afford migration (Kaczan & Orgill-Meyer, 2019). For example, in rural farm economies, relatively well-off farmers are incentivized to migrate due to the decline in farm production due to drought (Cattaneo & Peri, 2016). Other studies, such as the one by (Gray & Mueller, 2012) in Ethiopia, have reported the opposite by suggesting that labor migration increases twice during intense drought. Many scholars have also suggested that climatic-related hazards can facilitate and limit households' migration capacity [(Riosmena et al., 2018); (Bohra-Mishra et al., 2017); (Cattaneo & Peri, 2016)]. Such varied contentions on the climate change migration nexus imply some lack of consensus among migration scholars because the subject is complex due to the heterogeneity of migration contexts.

African Countries contribute less to global climate change through the emission of greenhouse gases. Still, they are more vulnerable to climate change effects because of various factors, including their geographical location in the tropics, limited adaptive capacity due to poverty, and social vulnerability [(Ibrahim & Mensah, 2022); (Coulibaly et al., 2020)]. For instance, Africa is warming at a more concerning rate than other regions, making it more susceptible to floods and drought (Aberman et al., 2015). Additionally, Africa's over-dependence on the natural environment for livelihood activities and low adaptive capacity motivate studying migration driven by climate change. With projections indicating that Africa will be one of the regions most affected by climatic hazards (Gemenne, 2011), studying the climate change migration nexus becomes relevant.

Recent reviews of climate change and migration nexus have focused on a broader scope, notably, the whole world, the African continent or sub-Saharan Africa [(Borderon et al., 2019); (Hoffmann et al., 2020); (Priovashini & Mallick, 2022)]. The reviews have also employed bibliometric and meta-analysis approaches to analyze the drivers of environmental migration, focusing on slow-onset climate impacts and fast-onset disasters. This review focuses on East Africa since not much attention has been given to this region by the previous reviews. The quest to conduct this review is also attributed to the fact that much human movement in the East Africa region happens in the form of nomadic pastoralism and seasonal migration. Furthermore, climate change stressors, such as changes in rainfall patterns, have also been endangering the resilience of the population in the region and have affected migration patterns (Rigaud et al., 2018).

This study uses an integrative review of literature methodology to examine how climate change affects migration in East Africa. This integrative study is entirely qualitative and is not meant to be a comprehensive evaluation of all papers that have been written (Snyder, 2019). Nonetheless, by fusing many points of view on the subject, it seeks to present an overview of the literature. Thus, this study aims to respond to the following query. What drivers related to climate change have influenced migration in East Africa? It is crucial to comprehend the relationship between climate change and migration so that the region's nations can implement the appropriate policies and measures.

This review is guided by theories explaining how climatic changes and associated hazards such as frequent drought, floods, and livestock diseases drive human migration. The theories include the push and pull, the social capital, and the adaptive capacity concept. The push and pull theory describes migration as a result of negative factors that push people towards areas with favorable climatic conditions or life opportunities. Rapid onset environmental factors such as floods and wildfires are push factors and are known to displace people globally (I.D.M.C., 2018). Although the literature review does not pinpoint a specific theory of involuntary migration, push factors of this nature may be categorized under forced migration. The risk of loss of life and properties is higher than in the case of slow-onset hazards (Erdal & Oeppen, 2018). Chronic environmental stresses such as drought also act as a push factor, although less risky than rapid onset factors, while places with favorable environmental conditions are pull factors that attract migrants (Hunter & Simon, 2023). These push and pull factors have dominated much of the migration literature in explaining the drivers of migration. Environmentalists and climate activists have warned the world of the potential mass migration due to climate-related push factors. However, scholars on climate migration do not ascribe to environmental push factors as the only drivers without the interaction with social and economic factors.

On the other hand, the social capital theory claims that formal and informal relationships between family members and friends are essential in explaining migration drivers (Ryan, 2011). Through the networks of friends or relatives, potential migrants receive financial support and information on settlements and jobs. In this way, the network plays a risk-lowering function for migrants arriving at their destination (Haas, 2010). For example, when confronted with climatic hazards such as drought, a potential migrant who decides to migrate to seek alternative income elsewhere will more likely choose destinations where there are family members or friends. The social network is also believed to set the stage for the subsequent migration of family members. As a result, migration becomes selfperpetuating, even after the original causes of migration no longer hold.

The adaptive capacity of a household is another crucial concept in understanding the climatic drivers of migration. It is the ability to adjust to climate change, moderate potential damages, or cope with the consequences (Fifth Assessment Report (AR5) Observed Climate Change Impacts Database, 2017). The ability to make adjustments or cope with the consequences is determined by many factors depending on the nature of climatic hazards. However, much of the adaptive capacity literature mentions resources such as financial, technology, health, and information as higher-order factors determining the capacity to deal with the effects of climate change (Adger et al., 2019). Such resources explain why some individuals can adapt more quickly and mitigate the damages caused by climate change than others (Adger et al., 2019). The resources crucial for adaptive capacity amid climatic change are linked with migration in two ways. First, those with financial resources and relevant technology may not migrate due to hazards such as drought since the resources enable them to make crucial adjustments needed to continue their livelihood activities. Similarly, financial resources are crucial for those who aspire to migrate, without which they may remain trapped.

The migration drivers related to climate change are examined in this literature-based research work. There are numerous methods for carrying out literature-based investigations, and they can be divided into three major groups: systematic reviews, semi-systematic reviews, and integrative reviews (Snyder, 2019). This paper employed an integrative review approach since it aligns with the nature of the topic of this study. An integrative review is a relevant approach for studying emerging topics in which some significant propositions remain contradictory (Torraco, 2005). Climate change migration nexus is one such topic. For instance, various competing strands of knowledge exist regarding whether and to what extent climate change influences migration. Different from the systematic review approach, an integrative review's goal is not to cover all articles that have been published, but rather, the focus is to provide an overview of the knowledge base, critically review, and potentially re-conceptualize the theoretical foundation of the phenomenon under study [(Torraco, 2005); (Snyder, 2019)].

The search for data was conducted through the Web of Science (WoS) and Scopus databases to obtain journal articles relevant to climate change and migration. These are two important academic databases in terms of the accuracy of their journal classification system (Wang & Waltman, 2016). A search strategy was conducted using boolean operators and search strings including "climate change*" AND "migrat*" AND "Tanzania*", "climate chang*" AND "migrat*" AND "Kenya*", "climate chang*" AND "migrat*" AND "uganda*". The short form "migrat" was used to capture all relevant derivatives of the noun migration, including terms such as migrants, migratory, or migrating. The short form for change, "chang" was also used for the same purpose to capture related derivatives such as change, changing, and changes. The search process also involved skimming through the list of references in journal articles to identify links to other papers relevant for inclusion in the literature.

Coastal zones are often studied as destination points of migrants from the hinterland and rarely as points of origin (Zickgraf, 2022). This is because coastal areas are usually more urbanized with economic incentives that pull migrants from the countryside. However, increased urbanization has put the most vulnerable people's livelihoods and the environment at risk due to the effects of climate change, such as rising sea levels, coastal erosion, and flooding (Nyadzi et al., 2020).

The East African coastal zones of Tanzania, Kenya, and Zanzibar islands face climate change risks. Mombasa City, for example, is already affected by extreme climatic events such as floods and strong winds (Awuor et al., 2008). Such events are projected to increase in intensity and frequency. The author further argues that rising sea levels and frequent flooding will render many areas inhabitable and unsuitable for agricultural production due to salinization. In extreme cases, this can disrupt essential services and infrastructure and impede economic activities. In the face of deteriorating infrastructure and declining opportunities, people may migrate inland. According to (Oyieke, 2000), a 0.3m increase in sea level rise will submerge 17% of Mombasa County if adaptation measures are not taken. The inundation will damage homes and businesses, driving people to escape the dangers and move to safer areas.

Flood risks in Tanzania's mainland coast and the islands are also high and might worsen in the future, given the rising sea level (Nassor & Makame, 2021). In Dar es Salaam, about 8% of the city lies within the Low Elevation Coastal Zone (LECZ), which exposes its inhabitants to coastal flooding. Under the sea level rise scenario, the number of people potentially exposed to flooding is set to increase, given rapid population growth (Kebede & Nicholls, 2012). In Zanzibar, the more vulnerable are in low-lying basins periodically inundated by runoff from the surrounding areas. Such areas were initially waterlogged but have been informally developed and flooded whenever it rains. This leads to the seasonal displacement of affected households [(Nassor & Makame, 2021); (Myers et al., 2020)].

Coastal zones in East Africa face risks that can push their dwellers to retreat from settlements near the coast or migrate further inland. Sea level rise and coastal flooding may be minor things to worry about now, but the risks are genuine as they threaten the built structures and livelihood of vast portions of the coastal population . For example, (Rigaud et al., 2018) argues that the rising sea level, compounded by storm surges in Mombasa, will submerge a significant part of the city and could lead to out-migration as early as 2030. To control this, participatory planned relocation from the low-lying zone is proposed as a long-term solution. According to (Yoo et al., 2022), relocating is the best option compared to expensive engineering solutions such as building seawalls, bulkheads, and revetments.

However, relocation operations are to be done carefully since they have limitations. On the Ivory Coast, the city of GrandLahou was relocated inland to a distance of 15 km to avoid the damage caused by the rising sea level. However, the project was only partially successful as some residents returned to the barrier beach to continue with traditional livelihood activities such as fishing (Alves et al., 2020). This implies that relocation can be a sustainable adaptation only if opportunities for alternative means of livelihood are available in the new location.

The review has also found that rising sea levels and related seawater intrusion contribute to soil salinity and make agriculture unsustainable. Elsewhere in Africa, studies by (Eswar et al., 2021) in Senegal and (Steyl & Dennis, 2010) in Mozambique have demonstrated how salinity intrusion is linked to the disruption of livelihood activities and drives migration inland. For example, seawater intrusion in Mozambique has caused salinity to go as far as 82 km inland.

Crop production is potentially unsustainable within the 82km perimeter, leading to migration considerations to nonsaline soils. Similarly, in Benin, where tomatoes are produced along the coast, increased soil salinity has caused tomato producers to move from their fields close to the sea to faraway fields (Ezin et al., 2012). Salinization has not only been a problem in coastal zones. In Ethiopia, increased length of dry periods and reduction in rainfall amounts are also believed to contribute to salinity development (Asad et al., 2019). The result of increased salinization has been repeated yield loss, leading farmers to abandon their land and migrate to cities for non-farming livelihood activities (Asad et al., 2019).

However, other scholars have reported opposing observations regarding migration and its linkage with slow-onset events such as salinity intrusion. (Borderon et al., 2019) argue that such long-term events are unlikely to lead to migration since individuals prefer localized adaptation instead of uncertain and costly migration. Such differences in responses to slow-onset events may be because of variations in adaptive capacity, social networks of migrants, and the level of natural resource dependence for livelihood.

The overarching aim of this review was to investigate how climate change has influenced migration in the East African countries of Tanzania, Kenya, and Uganda. The reality that climate change has severely affected many areas in the region, and of which most people have a low adaptive capacity, has prompted the quest for this review. The review has found that climate change effects such as drought, livestock, and crop diseases have been contributing to the migration of farmers and livestock keepers. However, such climate change effects have been impacting farmers and livestock keepers' by destroying their means of livelihood. As a result, farmers have been responding by migrating to areas with favorable farming conditions or seeking other sources of income in urban areas.

The review has also found that rapid onset floods have displaced the most vulnerable, who often live in poorly constructed structures in low-elevation areas. Other climate change effects, such as rising sea levels, and the associated impacts, such as salinization, have also been putting risks to many residents of low-lying coastal areas and could potentially cause relocation to safer zones inland. The review has further revealed that migrating in response to climate change effects is mediated by factors such as household adaptive capacity and social networks. This study generally points out that climate change effects, if not well managed and considering the low adaptive capacity of most people in East African countries, can cause displacements and endless migration to cities or rural areas. This review recommends the following. First is lessening the need for migration by promoting alternative non-farm livelihood activities through vocational skills training. This can potentially help to reduce the direct impact of climate change on the livelihood of farmers and livestock keepers. Alternative livelihood could also enhance adaptive capacity through the generated non-farm income. Second, when migration is the only reasonable option, such as during climate change-induced disasters, strengthening climate change adaptation policy by incorporating mobility options in National Adaptation is essential. This will help ensure that migration in response to climate change is well governed and coordinated.

Not applicable.