The Sahel: Challenges and opportunities

Stretching 5000 km from the Atlantic Ocean in the West to the Red Sea in the East, the Sahel is home to over 150 million people from ten¹ countries. For the purposes of this edition, four Sahelian countries, Burkina Faso, Mali, Niger and Chad, have been the central focus. To varying degrees, Sahelians suffer from humanitarian issues brought about by armed conflicts and violent extremism in the region. In addition, although Sahelians are one of the smallest contributors of CO₂ globally, the region is among the worst hit by climate change,² further exacerbating already fragile humanitarian conditions in the region. The ongoing hostilities and food insecurity, fuelled by both armed conflicts and climate change, have also led to displacement and large-scale migration of Sahelians both within the borders of the States and throughout the region as a whole. In the beginning of the pandemic, COVID-19 had become an additional complicating factor, which had restricted humanitarian access in the region while armed conflict and violence have increased.³

Armed conflict in the Sahel

Ongoing clashes between armed forces and armed groups in the Sahel have forced millions of civilians to flee their homes in various countries within the Sahel region.⁴ Many of those who flee are farmers who can no longer till their land, thereby exacerbating an already existing food instability. As will be seen below, each conflict situation in the Sahel region is unique, with its own complex history and diversity in actors. However, even with such complex histories, international humanitarian law (IHL) must be respected. International humanitarian law is not merely a slogan, it is a responsibility.

Burkina Faso currently finds itself in a devastating state due to armed conflicts and other situations of violence, with various causes to the different conflicts. There was growing instability since the 2014 Uprising and subsequently from 2016 on, there were ongoing attacks against the Burkinabe military forces and civilians by extremist groups. These groups have had a strong presence in Burkina Faso and neighbouring Mali. These various extremist groups have also had conflicts with each other due to the ideological differences of the groups they have pledged their allegiance to (i.e. Al-Qaeda or the Islamic State). Since 2015, over 2000 people have been killed and 1.5 million displaced due to violence attributed to extremist groups in Burkina Faso. Additionally, communal violence is prevalent in Burkina Faso, "which threaten[s] to destroy all hope of cohabitation between the communities”.⁵

Moreover, the weak presence of State institutions outside the capital of Ouagadougou and the distrust the population has in them has led to the proliferation of many self-defence groups in areas threatened by extremist armed groups and other criminal groups. These groups have themselves been parties to several deadly ethnic or communal conflicts. Although considered legitimate at their formation, many have questioned their activities in respect of which it has been argued they violate the human rights⁶ of the people in the region.

Neighbouring Mali has been in a continuous armed conflict since 2012. With various peace agreements between the parties to the armed conflict failing to reach a decisive end to the conflict, it is estimated from May 2020 to June 2021, over 2000 people have been killed in the ongoing armed clashes in Mali.⁷ The underlying causes of the conflict go back decades and are highly intricate. The lack of trust among various ethnic groups, horizontal inequalities among the people, and environmental concerns, added to the concentration of power in the hands of the few, are among the issues that have been festering for decades and continue to play out until this day.

The post-colonial Mali of the 1960s saw rebellions and uprisings from the ethnic groups in the North against the government in Bamako. Economic disparities and other inequalities in the North have led to Northerners distrusting the Central government and supporting the communal defence groups and armed groups in their regions. This led to what has been known as the "Tuareg Rebellions" with stiff resistance from the government. Although various peace agreements were signed in the past decades, none have quelled the armed conflicts involving the Tuareg communities. In addition, even though not at the same level of intensity, other groups, such as the Arabs, Songhay and Fulani communities in post-colonial Mali, have been involved in armed violence as well. The past ten years have witnessed ongoing clashes between the Malian army and armed groups in the North. There have also been clashes between armed groups and other groups designated as “terrorist” groups in the region.

These conflicts were marred with international involvement of the French forces, the US military and the United Nations Multidimensional Integrated Stabilization Mission in Mali (MINUSMA).

By the end of 2021, there were over 350,000 internally displaced persons (IDPs) and over 50,000 Malian refugees.⁸

Niger, with shared borders with both Burkina Faso and Mali, has faced the catastrophic consequences of armed clashes among State forces, armed groups and extremist groups over the last decade. Armed violence within the country and the spillover effects from the conflicts in neighbouring Burkina Faso and Mali on one side and Libya on the other side have contributed to the instability and increasing security concerns in Niger. In the first half of 2021 alone, over 540 conflict-related civilian casualties were reported in Niger.⁹ The armed conflict has had a devastating impact on children in Niger: of the 3.8 million people in need of humanitarian aid in Niger, 2.1 million are children and 1.6 million children suffer from malnutrition.¹⁰ More than eighty children between the ages of 15 and 17 years living in towns on the Niger–Burkina Faso border have reportedly been recruited as child soldiers.¹¹ Over sixty children were killed in conflict-related violence in Niger in 2021 alone.¹²

Chad has also witnessed its fair share of violence and intercommunal tensions. The situation in this Sahelian country involves a complex, but devastating, political history. Armed conflicts and situations of violence due to politics, elections in particular, and land use between indigenous and non-indigenous people because of resettlement have been recorded in the past few decades.¹³ In the Lac Province of Chad, which is in the Lake Chad Basin, the insecurity due to armed conflicts has had catastrophic humanitarian consequences. In 2021 alone, over 60% of the population of the province (more than 406,500 people) were internally displaced due to prevailing armed conflicts in the province.¹⁴ In the same year over 1.8 million Chadians were affected by severe food insecurity. In addition, the spillover conflicts from other non-Sahelian neighbouring countries such as Libya and Central Africa Republic, and “terrorist” groups in other parts of the Sahel have also led to civilian casualties and displacement.¹⁵ Chad has been at the centre of violent operations of extremist groups, causing hundreds of civilian causalities, including in the capital N'djamena.

In 2021, there have been over 300 casualties in these conflicts in Chad.¹⁶ The country's political crisis and power struggles have also led to several incidents involving political violence during and after elections. The country's socio-economic problems – 42% of the population lives under the poverty line¹⁷ – have also caused indignation toward the government. This indignation, in turn, has added fuel to recruitment efforts by non-State armed groups (NSAGs).

Terrorism

The instability in the Sahel region has helped to pave the way for the emergence of some “terrorist” groups in the region. In their efforts to coerce the Sahelian people and government decision-makers for ransom or political concessions, these groups have employed various terrorist activities, including launching deadly attacks against civilians and military targets alike, attacking public and private property, kidnapping individuals, and more.¹⁸ Weak State institutions around the inter-State borders have enabled such groups to flourish in the peripheries and border towns, targeting people in multiple countries at once. Such groups also take advantage of the low security along the borders between the Sahelian States, freely moving between neighbouring countries.

Burkina Faso, Mali and Niger saw over 4000 casualties of terrorist attacks in 2019;¹⁹ these attacks led, in turn, to the displacement of over half a million people.²⁰ The growing presence of “terrorist” groups in the Sahel has also intensified organized crime and criminal networks that have served as routes for lucrative criminal activities such as drugs, arms trade, human trafficking and the kidnapping of persons for ransom.

The individual States in the Sahel have each put in place various counterterrorism measures at the national level in an attempt to confront these challenges. However, it has been argued that these counterterrorism measures have caused more civilian casualties than they were intended to prevent.²¹

There have also been regional efforts in the fight against terrorism in the Sahel. In 2017, Burkina Faso, Chad, Mali, Mauritania and Niger formed the G5 Sahel joint force to respond to the growing presence of armed and violent groups. The G5 was established for the founding countries to pool resources and efforts to fight common security threats and ensure the security of their citizens.²² In 2014–2015, several Lake Chad Basin countries, such as Cameroon, Chad, Niger and Nigeria, along with Benin, joined forces to create the Multinational Joint Task Force to fight against terrorism in these States.²³ This taskforce was authorized by the African Union in 2015.²⁴ To support the counterterrorism measures of Sahelian countries and at the invitation of Mali, France had launched Operation Serval in 2013 which was succeeded by Operation Barkhane in 2014 and deployed 5000 French troops.²⁵

Notwithstanding, there have been allegations of violations of IHL and international human rights law (IHRL)²⁶ by the national forces,²⁷ regional efforts such as the G5 joint force,²⁸ and France's Operation Barkhane.²⁹ Reports have surfaced that these forces have targeted civilians, carried out summary executions, and engaged in torture, rape, enforced disappearances and other reprisals.³⁰ Such violations risk undermining any counterterrorism gain made by the forces and further breaking the trust and social contract of the local population with the governments involved. Coupled with weak institutions that have not been able to protect them from armed groups and “terrorist” groups, gross human rights violations by national,³¹ regional, foreign and international armed forces will make Sahelians less likely to support counterterrorism operations.

Effects of regional violence on the civilian population

In addition to the usual consequences of armed conflicts that disrupt the lives of civilians, Sahelians have also faced harsher effects, with civilians becoming direct targets of attacks by various parties to the different armed conflicts taking place in the region. Various reports have shown that armed groups, community self-defence groups and security forces have directly targeted civilians.³² In the first six months of 2020 alone, in the Central Sahel region which includes Burkina Faso, Mali and Niger, there were over 4660 casualties due to armed conflicts and violence.³³ Between February 2021 and February 2022, nearly 2000 civilians were killed in Burkina Faso, Mali and Niger.³⁴ These attacks were based on ethnic and religious identity and perceived support to community defence groups. In addition to direct targeting of civilians, civilian objects such as farms, crops and food reserves have been destroyed, adding to the already existing food instability in the region.³⁵

Decades-long armed conflicts in the Sahel have also limited the accessibility of essential services and humanitarian assistance to the victims and those most vulnerable. The International Committee of the Red Cross has estimated that around 1.5 million Sahelians live in areas that are “virtually impossible to access humanitarian aid and essential services”.³⁶

Protracted armed conflicts in the Sahel also lead to prolonged disruption of education due to the lack of access. The ongoing hostilities have led to the closure or destruction of over 6000 schools,³⁷ infringing upon the right to education of children. Schools provide not only education but also a psychological safe harbour where children can be children and interact with their peers in a safe environment,³⁸ the destruction of which causes significant difficulty in the lives of children. For the seven million Sahelian children out of school due to armed conflicts and violence,³⁹ the destruction of schools jeopardizes not only their present but also their future lives.⁴⁰

Various reports have also shown that children in the region, especially young boys, have been direct targets of attacks by different armed groups and other parties to the conflicts,⁴¹ in violation of IHL and IHRL's rules safeguarding children from harm. Young children have also been recruited by armed forces and armed groups⁴² in the Sahel as fighters or other roles, notwithstanding the prohibitions on the recruitment and use of child soldiers under IHL and IHRL. This puts children at risk of being killed, wounded and detained in armed conflicts. Such involvement of children in armed conflicts also has long-term psychological effects, often impeding their re-integration into society post-conflict. The continued exposure to violence makes these children particularly prone to mental health problems, including post-traumatic stress disorder and depression.⁴³ In October 2021, the United Nations Security Council unanimously adopted a first-of-its-kind resolution put forward by Niger and Norway on the protection of education in armed conflicts.⁴⁴

Girls and women in the Sahel also face high rates of sexual and gender-based violence in the hands of armed forces and various armed groups. Rape, forced and child marriages, female genital mutilation and trafficking of girls and women have increased in the Sahel in the past decade.⁴⁵ Stories published in this edition of the Review of girls and women subjected to sexual violence highlight the severe impacts of sexual and gender-based violence in the Sahel and demonstrate the importance of strengthening the protection of girls and women in armed conflicts, and the respect of IHL in general.

Furthermore, impunity and lack of accountability for violations of IHL and IHRL in the Sahel continue to fuel existing grievances in the region. Although reports have shown serious violations of IHL and IHRL by national, foreign and international armed forces and various armed groups, there has been little to no accountability or redress to ensure respect for IHL and human rights. IHL violations in connection to the armed conflicts and human rights law violations must be investigated. This requires States to take domestic measures as well as international support to ensure that such investigations are effective. This will not only redress past violations but will also help maintain social cohesion in the Sahel in the future.

To reiterate, international humanitarian law is not merely a slogan; it is a responsibility. All States have an obligation to respect and ensure respect of this body of law. The violation of IHL, as well as human rights, first and foremost affects human dignity, based on which various international humanitarian and human rights laws were drafted upon. Therefore, human dignity requires respect and at least accountability in the cases of its violation.

Climate change

The Sahel region is at the core of the harsh reality of climate change, where temperatures are rising 1.5 times faster than the global average. For Sahelians whose main sustenance depends on agriculture and pastoralism, this has meant worse and frequent droughts and floods, crippling food production capabilities. In an already semi-arid environment, the farmlands and grazing lands in the Sahel have suffered deforestation and overgrazing, diminishing the capacity of the soil to retain water and making it susceptible to soil erosion.

With over 70% of the population in the Sahel⁴⁶ depending on agriculture and pastoralism as the primary source of income, the adverse impacts of climate change have further added to an existing problem. With differences in the economic development and capacity of the individual countries, the ability to cope with the effects of climate change differs. Weak governance institutions have further diminished this capacity, negatively impacting the lives of Sahelians and contributing to the underdevelopment of the region. With existing problems of weak institutions and poor governance, internal power struggles and corruption, the Sahelian governments have not been able to adequately respond to the questions and concerns of Sahelians regarding the negative impacts of climate change, economic development, food insecurity, violence and displacement. Former United Nations Secretary-General Ban Ki-Moon referred to climate change as a "threat multiplier” that worsens existing social, political and economic tensions and conflicts.⁴⁷ In the case of the Sahel, climate change has indeed contributed to driving existing socio-economic and political tensions farther and escalated the conflicts.

With limited access to land and water, which are scarce natural resources in the Sahel, and which are inadequate for the growing population in the region, migratory routes of pastoralists have increasingly gone through land traditionally used for cultivation by farmers. At the same time, farmers are increasingly expanding their cultivation into land traditionally used as pastoral corridors. This has led to violent clashes between farmers cultivating the land and pastoralists who often cross intra-State borders to feed their cattle. In the past decade, farmer–herder violence has led to over 15,000 casualties, with half that number reported in the past three years alone.⁴⁸ Although the root of the dispute is competition over scarce resources, these grievances have been fuelled and utilized by “terrorist” groups to drive recruitment into their own forces.

For Sahelian countries, climate change is an important, cross-cutting agenda, and this is reflected in the fact that all five members of the G5 Sahel have signed and ratified the Paris Agreement on Climate Change. However, due to the lack of adequate resources within the Sahel and the countries within the region being some of the smallest CO₂ contributors in the world, regional action alone cannot provide the necessary mitigation of the harsh effects of climate change. Therefore, Niger worked with Ireland to co-author a draft thematic resolution on climate change and security and brought it for a vote before the Security Council at the end of 2021. This draft resolution requested the “integration of climate-related security risk as a central component into comprehensive conflict-prevention strategies"⁴⁹ – though, ultimately, the Security Council failed to adopt it, with twelve votes in favour and two against with one abstention. This edition's interview with his excellency S.E. Abdoulaye Abarry Dan Bouzouwa, the Ambassador of Niger to the United Nations Security Council from 2020 to 2021, highlights the importance of recognizing the security implications of climate change, particularly in the Sahel.

Mobilizing the international community for improved and urgent action against climate change is more critical than ever. Climate change is a global problem affecting every country, although some countries, such as those in the central Sahel, are more affected than others. The harsh effects of the increase of temperature in the Sahel at a rate of 1.5 times the global average witnessed in the Sahel, such as heavy flooding and intense droughts, should be seen as a wake-up call for the international community to commit to effective action against climate change.

Displacement

Regardless of the location and parties to the Sahel's various armed conflicts and the differing effects of climate change, one fact remains the same throughout the region: millions of people have been displaced from their homes and forced to flee adverse conditions all over the Sahel region. Drivers of displacement – such as conflict and harsh climate conditions – are closely interlinked in the Sahel, often making it difficult to identify a single or proximate cause for displacement and related instability.

Although it is often overlooked, the Sahel has one of the fastest growing displacement crises in the world. By February 2022, over 2.6 million Sahelians were internally displaced – that is, they have been driven out of their homes but remain inside the same country. This represents a ten-fold increase in less than a decade: in 2013, there were 217,000 IDPs in the Sahel. More than half a million of the 2.1 million IDPs were displaced in 2021 alone. An additional 930,000 people have left the borders of their own countries and sought refuge in neighbouring States, such as Burkina Faso, Mali and Niger, driving the total number of displaced persons in the Sahel to 2.7 million people.⁵⁰

In just three years (from 2018 to 2021), Burkina Faso had more than tenfold IDPs, hitting 1.5 million people, making it one of the fastest-growing displacement crises in the world.⁵¹

Even after being forced to flee to escape the violence, in the very places these people have fled to, camps for IDPs and refugees in the Sahel have come under serious attack by armed groups,⁵² in violation of IHL.

It is well accepted that no one willingly chooses the path of exile or to abandon their homes to stay at IDP or refugee camps.⁵³ The millions of people in the camps all across the Sahel have been forced out of their homes due to the adverse conditions of armed conflicts and climate change. The stories of IDPs included in this edition of the Review put a human face to the Sahel region's displacement crisis and tell of their experience and resilience.

Displacement also brings along with it various factors that limit the enjoyment of the rights of IDPs and refugees. Many IDPs and refugees have difficulties accessing the basic necessities of life, such as food, water, shelter, clothing and health services. These persons have left their homes and livelihoods, often leaving them with little to no income to afford these basic necessities. For many Sahelians who already live below the poverty line, displacement leads them to extreme poverty, which causes still more abuses of their human rights and threatens their fundamental human dignity.⁵⁴

While there are many national, regional and international humanitarian efforts to alleviate at least some of the humanitarian needs of IDPs and refugees in the Sahel region, the displacement crisis requires a lasting solution. As the displacement crisis is a result of the armed conflicts and effects of climate change, Sahelian States along with regional and international organizations need to work together to solve these underlying causes of displacement.

Opportunities in the Sahel

Although the challenges mentioned above in the Sahel are numerous, it is also a region full of opportunities.

Focus on the youth

In 2020/2021, 64.5% of Sahel's 150 million people were young people under the age of 25 years.⁵⁵ This massive young population is an abundant human resource for development within the region and the global market. Effective investment in the education and potential of the Sahelian youth will serve to ensure steady economic development in the region. Increasing economic development, education and employment opportunities in the Sahel will help counter violent extremism and voluntary recruitment of youth by the armed groups that often attract young individuals with financial incentives.

However, this requires a thorough analysis and study of the factors that make the youth more vulnerable to violent extremism or voluntary recruitment into armed groups. No one is born a “terrorist”; rather, people are made into “terrorists”. Poor socio-economic backgrounds and educational status, marginalization and collective grievances, injustice, oppression, poor governance, misuse of belief, ideologies and ethnic or cultural differences could be some factors that make the youth more prone to take up violent extremism.⁵⁶

Including the Sahel's youth in decision-making, most importantly, will help remedy the deep-rooted grievances with and distrust towards the Sahelian governments. A particular focus on communities that have been socially, economically and politically marginalized will help strengthen the social cohesion of the diverse communities in the region as well.

African solutions to African problems

Similar to most parts of Africa, elders and religious leaders are community leaders of high importance in the Sahel. Elders are held in high regard and are respected for their experience and wisdom. Religious leaders, as spiritual guides for many people, likewise have enormous influence over their followers.⁵⁷ This helps explain why the customary and community-led initiatives aimed at conflict resolution have been quite successful in some parts of the Sahel. Since time immemorial, communities in the Sahel have developed knowledge on causes of conflicts and ways to mitigate them. By involving community leaders, such initiatives will have more meaning and, therefore, legitimacy within the local population than the government's policies, which are often considered top-down approaches.

The time has passed where IHL was just a concern of the military or governments. Now it is time to make IHL a part of the daily agenda of elders, religious leaders and other community leaders. It is important to have sustained dialogue with these community leaders with the aim of disseminating IHL and influencing the behaviour of armed groups to ensure respect for the law.

Meaningful conflict resolution processes should include the local communities' traditional rituals and initiatives to address conflicts, particularly related to intercommunal violence and agro-pastoralist violence.⁵⁸ In this regard, meaningful discourse should also involve local intermediaries facilitating and mediating discussions between local communities. Examples include griots,⁵⁹ traditional and community leaders, and women⁶⁰ in the Sahel.⁶¹ Such intermediaries should also be used to disseminate IHL and IHRL to raise awareness of these fields of law within the local community. In such cases, it is also essential to show how the basic principles of these fields of law are engrained in the local values of the communities.⁶²

In this context, the idea of involving traditional and religious leaders in the Sahel's crisis exit strategies is beginning to gain ground. In December 2021, a regional meeting led by the United Nations Office for West Africa and the Sahel (UNOWAS) was held in Dakar with conclusions on the need for better use of endogenous strategies,⁶³ with various innovative efforts presented on the mobilization of religious leaders in favour of the protection of the civilian population, in the context of humanitarian work and peace-building efforts.

Involving financial organizations

With immense natural resources, massive potential for renewable energy, culture and physical heritages and young human capital, the Sahel, even with its challenges, offers a multitude of opportunities for investment and development. This gives States, development partners and investors various opportunities for investment that could build the resilience of Sahelian countries to the effects of climate change and food insecurity. It also creates opportunities to empower women and the youth through development towards the goal of promoting peace.

Financial organizations can play a mammoth role in the development and peace building of the Sahel. These organizations have the opportunity to invest in the youth, female entrepreneurs, farms and pastoralists in the region. In most parts of the Sahel, where access to financial services is limited, such investments would empower individual entrepreneurs and build resilience within communities. The World Bank, the African Development Bank Group, the European Investment Bank and Agence française de développement are some of the organizations working to build resilience in the Sahel.

The engagement of the African Development Bank in the Sahel is a case in point: its investments in agriculture, energy, transportation, entrepreneurship and women's empowerment have had positive impacts on the local population. The interviews with Yero Baldeh⁶⁴ and Amel Hamza⁶⁵ from the African Development Bank included in this edition of the Review highlight how such support from financial organizations can apply on the ground and support the conflict resolution and peace-building agenda.

Although all of the above are commendable initiatives, these are not enough. Other financial organizations and even private banks should be involved in the security and development agenda of the Sahel. There is no return on investment without peace or respect of rules. These organizations and banks must also support the efforts on ensuring respect for IHL and IHRL in the Sahel, enabling the protection of civilians and civilian objects.

The Sahel in a decade

The past decade in the Sahel has carried unprecedented humanitarian challenges due to armed conflicts, climate change and displacement. We must now work together to ensure that the next decade promises Sahelians a significant, positive change: a Sahel built by Sahelians and Sahelian values, that will accommodate all others in peace and harmony. This future of the Sahel requires solid and effective leadership that respects human dignity and ensures that no one is left behind. Governments should respect both their IHL and IHRL obligations. Non-State actors should also understand, recognize and respect their commitments to protect human beings and human dignity both in times of armed conflicts and in peace.

This requires inclusive and participatory dialogues between governments and local communities to resolve conflicts and sustain the peace-building process.

It is now the time for Sahelians, both young and old, to carry IHL and IHRL as their own and hold violators of these branches of law accountable for their actions.

A sustainable peace-building process also requires accountability for atrocities and violations of international law. Ending the culture of impunity in the Sahel will play an essential role in respecting and ensuring respect of IHL and human rights, thereby ensuring the respect of human dignity. The role of domestic judiciary systems should be immense in this regard.

To successfully turn around the current humanitarian crisis in the region, Sahelians need to create a strong movement within the region instead of looking outward or being dependent on non-Sahelians for solutions. Scaling up local conflict resolution and peace-building initiatives will be a more sustainable form of ensuring peace in the region.

The announcement of the withdrawal of French troops in February 2022⁶⁶ after nine years in Mali should be seen as an opportunity for all Sahelian countries at large, and not only Mali and the members of the G5, to take the rule of law and the respect of IHL and IHRL into their own hands. Sahelian countries need to develop their leadership capacity to manage the security challenges and finally bring the mantra “African solutions to African problems” to reality.

Africa is indeed the continent of the future, and the Sahel is a model of that future. All stakeholders must come together to unlock the opportunities the region has to offer.

To this effect, this "Sahel" edition of the Review has brought together perspectives of diplomats, humanitarian actors, armed forces, think tanks, financial institutions as well as legal, agricultural and climate change experts in a unique collection of articles. The academic articles and interviews in this edition will help fill the literature gap and serve as an important reference point about the complex issues that Sahelians face. They will also be an important entry point within the Sahel and outside, into diplomatic, political, humanitarian and academic discussions that aim at permanently solving the complex humanitarian challenges in the Sahel region.

Written by twenty-one authors on a wide range of issues impacting the daily lives of Sahelians, this edition of the Review presents a starting point for action and motivation to ensure respect of IHL and IHRL in the Sahel. As explained above, the current situation in the Sahel is not solely attributable to a single factor. Instead, it needs analysis of each factor that has contributed to the instability and displacement, as the authors in this edition have done.