It’s official — effective Jan. 1, António Guterres will take on the “world’s most impossible job.” In a straw poll held Oct. 5, the United Nations Security Council voted 13 to 0 with two abstentions to give the former Portuguese prime minister and U.N. high commissioner for refugees the job of U.N. secretary general. The U.N. General Assembly is expected to approve the Security Council’s decision shortly.

The Security Council passed on appointing the first woman to head the United Nations and decided not to give Eastern Europe a turn at the helm. What does this role involve exactly, and what challenges will the 9th U.N. Secretary General confront? Here are five things to know:

1) Multitasking skills are essential

The U.N. secretary general needs considerable leadership capabilities to coordinate and cajole the 193 U.N. member states. Manager, crisis mediator and global emergency response coordinator are just some of the many hats Guterres will wear.

The world sees the secretary general as a “secular pope,” someone who gives voice to the U.N. Charter and its aspiration for a peaceful and law-based order that protects human rights and the environment and promotes economic development. It will be no simple task to do all that without stepping on the toes of powerful governments — and with few financial resources and little formal authority to push U.N. members to make compromises and take collective action.

2) Leading the U.N. isn’t easy

A secretary general may have minimal power over member governments — but must push forward important issues such asoverlooked civil wars, the effects of climate change and the suffering of refugees. As a peacemaker, the secretary general channels information between belligerents, proposes possible solutions and helps both sides make concessions. When negotiations break down, the secretary general keeps the peace process alive by arranging cease-fires, keeping communications lines open and developing options for the Security Council.

The secretary general can also be an internal change agent, by setting the United Nations’ policy priorities, proposing budgets and organizing senior management and the U.N. Secretariat. Secretary General Dag Hammarskjold (1953-1961) effectively fostered a culture of independence among U.N. staff. Outgoing Secretary General Ban Ki-moon (2007-2016) used his first year to restructure the U.N. Peacekeeping Department.

3) With crisis comes opportunity

My research argues that member governments give the secretary general greater freedom and authority during crises. For example, Hammarskjold used the 1953 downing of U.S. airmen in China to expand his office’s peacemaking authority and the 1956 Suez Canal crisis to deploy and manage the first modern U.N. peacekeeping force.

The secretary general occasionally spearheads new global commitments to solve common challenges. Climate activists applaud Ban’s contribution to the recently signed Paris Climate Agreement, while Secretary General Kofi Annan (1997-2006) helped facilitate the Millennium Development Goals and the Responsibility to Protect doctrine.

4) What’s within the secretary general’s power?

An overly ambitious agenda risks producing a backlash from member governments. And the secretary general has an incentive to let governments and independent experts guide the thought leadership, especially when it comes resolving politically sensitive issues.

But the secretary general does have the power to harness the U.N.’s considerable expertise and moral authority to spotlight important global issues. This is what Annan’s 1999 speech to the General Assembly did for humanitarian intervention, for instance.

The secretary general can shape negotiations and reforms by commissioning recommendations from prominent statesmen and experts — and separating out the touchy “third rails” that impede progress. The office also sits at the center of a web of global policy networks that can be leveraged to build a multi-stakeholder coalition of like-minded governments, companies and activists to make reform commitments and lobby governments to adopt and implement these recommendations.

And the United Nations can step in to demonstrate the benefits of proposed changes early on. For instance, as Ian Johnstone argues, Annan incorporated civilian protection into U.N. peace operation planning and proposals — even before member states adopted the Responsibility to Protect doctrine in 2005.

The secretary general can convene national leaders to create a sense of urgency — and push negotiators to come to agreement before their bosses arrive. Ban’s 2014 Climate Summit and Annan’s 2000 Millennium Summit are two such examples.

5) What specifically can we expect from the next secretary general?

Guterres’s record has earned him substantial praise and some criticism — and suggests he will be an outspoken and active reformer, at least by U.N. standards. He is the first officeholder to have led both a government and a major U.N. agency. At the Office of the U.N. High Commissioner of Refugees, he pressed the agency to rediscover its protection mission while insisting that wealthy governments do more to finance humanitarian operations and meet their legal obligations.

This experience will come into play as Guterres faces the challenge of leading the international response to a global refugee crisis on a scale not seen since World War II. There will be pressure to demonstrate U.N. relevance in intractable civil wars like the one in Syria and slower-moving crises like climate change. He also will have to decide how the United Nations can support implementation of the Sustainable Development Goals that governments negotiated last year.

And then there is peacekeeping. The secretary general is responsible for about 117,000 uniformed personnel and civilians deployed across 16 peacekeeping operations — and some of these missions go where there is little or no peace to keep.

Looking ahead, Guterres can expect pressure from troop-contributing countries, among others, to push back if the Security Council keeps sending blue helmets into ongoing civil wars. At the same time, the Security Council continues to favor peacekeeping missions, particularly in places where the five permanent council members have no vital national interests at stake. Consequently, the secretary general has little choice but to look for ways to make U.N. forces better equipped and trained for such missions.

The world will also look to Guterres to restore faith in the United Nations and its ideals, after a number of reports criticizing U.N. military units for putting their own protection ahead of civilian protection. And the United Nations was slow to take responsibility for a 2010 cholera outbreak in Haiti.

At the top of the to-do list is implementing a recent Security Council resolution bolstering the world body’s long-standing “zero-tolerance policy” on sexual exploitation and abuse. Recent peacekeeping scandals have eroded the United Nations’ moral authority. And, as discussed here in the Monkey Cage, cases of sexual abuse perpetrated by peacekeepers continue to pile up.

The United Nations has weathered past institutional crises — thanks to determined leadership. After tragic mission failures in Rwanda and the Balkans, Annan restored confidence in peacekeeping by pushing the United Nations to prioritize human security. Likewise, Hammarskjold restored the United Nations’ perceived impartiality by evicting the FBI from U.N. headquarters, publicly rejecting Soviet calls for his resignation and forcefully arguing for an independent international civil service.

Like his predecessors, the next secretary general will have his work cut out to cover existing mandates, as well as coordinate and fund the U.N. response to the world’s next crises and conflicts.

Michael Schroeder is professorial lecturer and director of the Global Governance, Security & Politics Program at the School of International Service at American University.