Historic opportunity, daunting task — The race to lead the United Nations at a critical moment

More than three decades ago, I had the privilege of working within the United Nations during the tenure of Secretary-General Boutros Boutros-Ghali. That experience profoundly shaped my understanding of global governance, diplomacy, and international cooperation. From those years, I remember not only the immense scale of the UN's work, but also its unique significance for millions worldwide. For many, the UN remains the last glimmer of hope in times of conflict, catastrophe, or political paralysis.

There is no other organization quite like the United Nations. As António Guterres prepares to conclude his second term, the world stands at a critical crossroads. The next Secretary-General will inherit what may be the most demanding leadership portfolio in the organization's history.

The challenges are staggering. First, the UN faces a profound crisis of reputation and credibility. Many question its effectiveness in preventing wars, enforcing international law, and responding to geopolitical tensions. As rivalries intensify and divisions among major powers deepen, the gap between aspiration and action has become increasingly visible, fueling public scepticism about the organization's relevance in addressing the pressing challenges of our time.

Second, the post-1945 international order is under growing strain. The Security Council, designed for a different era, urgently requires reform. Yet despite its shortcomings, the Council remains the world's most important mechanism for maintaining international peace and security. No other international body possesses its unique authority, legitimacy, and capacity to mobilize collective action in response to conflicts and threats to global stability. Reform should strengthen and modernize the Council, not weaken it.

Third, the rise of China and the growing influence of the Global South are reshaping global power dynamics. Institutions founded on Global North leadership must adapt to a multipolar world. The geopolitical landscape of the 21st century differs profoundly from that of 1945, when the United Nations was created under the leadership of victorious Western powers at the end of the Second World War. Today, China has emerged as a major economic, technological, diplomatic, and strategic actor with global reach, while countries across Asia, Africa, Latin America, and the Middle East increasingly demand a greater voice in international governance. Although the United States remains the world's foremost military, technological, and financial power, its ability to shape global outcomes unilaterally has diminished as alternative centers of influence gain prominence and nations pursue more autonomous foreign policies.

This transformation is reflected in the growing relevance of BRICS, the expansion of South-South cooperation, and the increasing willingness of developing countries to advocate for institutional reforms. The next Secretary-General will face the delicate task of managing a historic redistribution of power while preserving the principles of multilateralism. Success will require building bridges between established and emerging powers, fostering trust between North and South, and ensuring the UN remains a credible platform for dialogue and consensus-building.

Fourth, rapid developments in artificial intelligence and emerging technologies raise difficult questions regarding governance, ethics, security, and employment. Humanity is entering an era where innovation outpaces regulation. Artificial intelligence is already transforming economies, labour markets, education, healthcare, and military capabilities, offering enormous opportunities while also creating significant risks. The spread of disinformation, the emergence of autonomous weapons systems, cyber threats, and the potential displacement of millions of jobs illustrate the scale of the challenge. The next Secretary-General must promote international cooperation on AI governance, ensuring that progress remains guided by ethical principles, human rights, transparency, and inclusiveness.

Fifth, international public law faces unprecedented pressures as conflicts increasingly challenge established norms. For decades, international law has served as a pillar of global stability, providing the framework through which states manage disputes, protect human rights, and promote cooperation. The principles enshrined in the UN Charter—respect for sovereignty, peaceful settlement of disputes, and prohibition of the use of force—have helped prevent countless confrontations from escalating into wider conflicts. Yet these foundations are increasingly tested by geopolitical rivalries, regional wars, unilateral actions, and growing disagreements over the interpretation and application of international norms. The next Secretary-General will need to defend the integrity of international law while encouraging dialogue and peaceful conflict resolution among increasingly polarized actors.

Beyond these immediate geopolitical and technological challenges, the next Secretary-General must also confront rising migration flows, persistent concerns over disarmament and arms control, climate change, hunger, environmental degradation, and widening inequalities. The sustainability crisis facing humanity—from biodiversity loss to pollution and resource scarcity—demands urgent attention and coordinated global action.

Finally, beyond addressing these global challenges, the next Secretary-General must champion institutional reform. The United Nations must become more efficient, transparent, and responsive. The question, therefore, is whether the international community is prepared to empower a leader capable of restoring confidence in multilateralism at this moment of profound uncertainty. The world's next Secretary-General, whether woman or man, will inherit not only the toughest job in international diplomacy, but also the responsibility of redefining the UN's role for the 21st century. In an era of deepening fragmentation and mounting crises, effective leadership will be indispensable.

The author is an Associate Professor of the University of Macau