News - Belfer Center for Science and International Affairs, Harvard Kennedy School

Impacts of Brexit on the UK, EU, and the World

At 11:00pm (London time) on Friday, January 31st, the long-awaited or long-feared Brexit will take place. The United Kingdom will no longer be part of the European Union.

What will Brexit mean to the UK, EU, and the rest of the world? What lessons does it hold for Europe and for UK internal politics? What dangers and pitfalls lie ahead? Brexit experts from the Belfer Center’s Project on Europe and the Transatlantic Relationship and Future of Diplomacy Project shared their thoughts on this major event.


Adrien Abecassis, Fellow, Project on Europe and the Transatlantic Relationship, career French diplomat and former Advisor to the President of the French Republic:

“Three years of efforts to avoid Brexit on both sides were unsuccessful, leading to Johnson’s landslide victory. The ‘populist wave’ has not receded. Fractures between the working and middle classes and the ruling elites remain deep and multifaceted across Europe. They are the most important threat to the EU and the transatlantic relationship.

Though no longer in the EU, the UK remains a European country – one can’t change geography, nor culture. Scenarios in which the United Kingdom would establish close relationships with the outside world without maintaining strong links with the continent are unrealistic.

Eleven months are a short time to settle all the issues of the UK-EU relationship, frictions will occur and priorities will have to be set, but these ‘normal’ negotiation issues don’t suggest that they could fail. They must proceed in a spirit of openness, without punitive energy – that would only increase difficulties and political frustrations. This is in the fundamental interest of both parties. 

Short-term internal instabilities in the United Kingdom (Scottish independence movement, destabilization of Northern Ireland politics) are the main risks to the negotiations. Expect strong pressure from other European states – especially those affected by secessionist claims – to calm these tensions.

Brexit will force the EU to change. The agreement on the ‘future relationship’ between the EU and the UK will be the first of its kind. New forms of cooperation will open, which could inspire others and push towards a more flexible Union. It is difficult, though unavoidable, to imagine the contours of a less uniform and more adaptable union that would maintain the level of coherence and unity necessary for it to function smoothly. This is the EU’s greatest challenge.”


Douglas Alexander, Senior Fellow, Future of Diplomacy Project at Harvard Kennedy School;  Visiting Professor at King's College, London and former UK Shadow Foreign Secretary:

“I will feel great sadness on 31st January when the United Kingdom's 47-year membership of the European Union comes to an end.

The EU without the UK will be smaller, poorer, and less influential on the international stage. The UK without the EU will soon discover the reality and the constraints of being a medium sized power in a world increasingly shaped by rising regional powers.

The roots of the British people’s decision to leave the EU lay more in domestic politics than in foreign policy: An unequal economy that leaves too many people behind, and a politics that left too many communities unable to see their place in the country's future. Brexit is predominantly an English Nationalist project wrapped in the Union Jack.

The challenge for those of us who continue to believe in a politics of cooperation, solidarity and internationalism, is to be informed by the lessons of Brexit but not paralyzed by them. In an age of common threats, the case for international cooperation is part of a progressive political project, not distinct from it.

Next week the UK will still be a top table member of NATO, the G7 and the G20, the Commonwealth, and the United Nations Security Council. From promoting a vision of responsible capitalism to tackling the climate crisis and working to secure peace and security while defending democracy and human rights, there is much work to be done. Many of us will be working to ensure the UK steps up rather than steps back in the years ahead.”


Nicholas Burns, Roy and Barbara Goodman Family Professor of the Practice of Diplomacy and International Relations at the Harvard Kennedy School; Faculty Chair, Project on Europe and the Transatlantic Relationship; former U.S. Ambassador to NATO:

“When the United Kingdom leaves the European Union this Friday, Prime Minister Boris Johnson will have pulled off a political miracle, against great odds, by bringing his divided country to a final decision after three and a half years of excruciating existential debate. Still, the UK faces a substantial challenge in separating from its major trade partner while seeking to maintain economic growth and a successful future. Its most compelling challenge will be the likely secession of Scotland and the possible loss of Northern Ireland to an eventual united island with a Catholic majority and capital in Dublin. That would effectively consign this remarkable country, assembled by the Act of Union in 1707, to become the United Kingdom of England and Wales.

Brexit’s impact will also be felt on the Continent. The EU will lose Friday its second largest economy, strongest military power and most globally sophisticated member state. Too little attention has been paid to how the EU will be diminished by the UK’s exit.

Finally, the U.S. must think creatively of how best to recreate and modernize our Special Relationship with the UK in a new trade agreement, expanded military ties in NATO and in reinforcing the West to deal with an assertive Russia and China.

Brexit is a strategic mistake by Britain. The task now, however, is for the British people to implement it in such a way that does the least damage and that provides for an eventual rebirth of this still vital democratic country.”


Cathryn Clüver Ashbrook, Executive Director, Project on Europe and the Transatlantic Relationship; former legislative advisor at the European Parliament and the UK House of Commons:

“The ironies in the United Kingdom’s exit from the European Union are many, but none more bitter than this: The Union is large and comparatively weak institutionally because of the UK’s longtime resistance to ‘an ever closer union’ – and now the UK is gone.

This is also an opportunity. Europe’s four decades of accommodating the UK’s independent streak within the EU – the rebate, the opt-outs – are definitively behind it. Europe can now define itself on its own, continental terms. And it will need to, to thrive in the big power era upon us.

The UK will bear the greatest burden of Brexit. Its economy is at greatest risk, its internal political rift is deepest, its very integrity as a United Kingdom in question. Watch Scotland and the Irish question. Boris Johnson, the glory of his parliamentary majority notwithstanding, will now have to deliver real devolution domestically and a complex post-Brexit negotiation with Brussels at the same time, and quickly.

Despite its chagrin at Brexit, continental Europe needs the UK to succeed. In defense, in intelligence, for connected responses to the transnational challenges of the 21st century, the UK and its decisions going forward will matter enormously to its European neighbors. Even as it negotiates hard over the next eleven months, Brussels will be an odd ally in wanting the UK to hang together and prosper.

The divorce process has been painful. With the papers signed, now it’s time for the EU to consolidate its gains to become the ‘ever closer union’ its founders intended and Westminster resisted. Without the UK as a convenient scapegoat, the work will be all the more necessary, all the more honest and unfortunately much harder.”


Jolyon Howorth, Fellow, Project on Europe and the Transatlantic Relationship; Jean Monnet Professor ad personam and Professor Emeritus of European Politics at the University of Bath (UK):

“Political leaders should shun referenda and revitalize representative democracy. Brexit epitomizes the power of populists and foreign agents to manipulate public opinion. The traditional right/left divide – throughout the EU – is on life support. The volatility of voter preferences flummoxes pollsters and academics. Party politics must respond to the new transnational challenges posed by globalization and climate change.

Serious economists predict a decline in the UK’s economic and marketplace clout. Few outside the tiny coterie of hard Brexiteers believe in the promise of ‘Global Britain’. The UK will struggle to negotiate beneficial trade agreements with the giants of the emerging multipolar world. Johnson is delusional if he imagines he can negotiate a satisfactory EU trade deal in eleven months. Painful trade-offs are unavoidable. Brexit is nowhere near ‘done.’

The UK will be forced, from a position of institutional weakness, to adapt to emerging transatlantic and European defense arrangements. Franco-British cooperation will intensify.

Light at the end of the tunnel? After several decades of international marginalization, the English must face up to the question they have avoided since 1945: what is their true identity in the post-imperial order – Island nation or European power? The key challenge of the 2040s will be ‘Bre-entry’.”


Karl Kaiser, Senior Fellow, Project on Europe and the Transatlantic Relationship, former advisor to German Chancellors Schmidt and Brandt:

“The most important lesson for Europe: fight populism and external interference right from the beginning. Sensible people both in the rest of the European Union and Britain underestimated and neglected the impact of these forces. Two consequences are imperative: coalitions that transcend traditional party lines to counteract these forces and a transnational and intergovernmental effort to block the outside interference, notably from Russia.

Brexiters will claim the act of leaving as a success but in reality it is a calamity on many fronts and the task of both sides in the forthcoming EU-UK negotiations consists of minimizing the damage. Britain’s economy is much more dependent on the EU than vice versa and full access to the EU market is vital for Britain’s future. Hopefully both sides can negotiate a curtain which hides the reality of integration while satisfying the Brexiters’ yearning for tokens of British independence.

Britain, the only other country besides France with a major capacity for military action outside Europe, remains vital for the future of European security. As the EU advances in developing its own security policy and capacities – hopefully in some coordination with NATO – it is vital that it develops mechanisms to associate Britain to such efforts.”


Álvaro Renedo, Rafael del Pino-Spanish Ministry of Foreign Affairs Fellow, Project on Europe and the Transatlantic Relationship; former Director of the Department of European Affairs and G20 in the Presidency of the Government of Spain:

“Brexit shows that European integration is not irreversible, nor are the major achievements it has facilitated in Europe - peace, development, prosperity, free trade, common policies, and freedom of movement of people, among others. In more general terms, multilateralism and international institutions cannot be taken for granted. Leaders must communicate, in a smart and effective way, the need for such institutions, and strive to ensure that they earn the trust and support of citizens.

Brexit also indicates that, in current the age of globalization, nationalism is an ever-luring phenomenon. Leaders must continue to reflect on the factors which have pushed citizens towards inward-looking political movements.

Brexit also underscores the cumulative psychological effect on society of public discourse. As Denis Macshane, former UK Minister for Europe, points out: ‘Europe is what the people are told it is by their press and many of their leading politicians, both Conservative, and Labour, over the four decades of British membership. That vision has been mainly negative, increasingly so in this century. Persuading the British to have warm feelings for Europe is hard.’

If Brexit is deemed a success – and public opinion somehow perceives that a Member State of the EU can obtain absolute gains from a EU withdrawal –  then eventual subsequent replications cannot be excluded.”


Lord Peter Ricketts, former Fisher Family Fellow, Future of Diplomacy Project; life peer in the House of Lords in the United Kingdom; former UK’s National Security Adviser (2010-2012):

“I write this on my last Eurostar journey as a citizen of the EU, deeply sad that opportunities like the right of free movement will be denied to the next generation. 

Brexit is a massive failure of the British political system. In never selling the benefits of EU membership. In failing to spot the anger and alienation at the impact of austerity and immigration. In hinging the country’s future on a one word answer referendum. In blundering into a divorce negotiation unprepared and divided.

Brexit diminishes Britain and the EU at a time when the mid-sized democracies are under real pressure. The twin pillars of British strategy, European and transatlantic, are both wobbly. The Brits need to redefine their role in the world. Let’s hope the Strategic Review achieves that. 

The EU must learn to live with an ex-member which is also the largest military power in the neighborhood. Success would be pragmatic alignment on defense and security, as is already happening on foreign policy. Failure would be rhetoric about strategic autonomy masking disagreement about the EU’s global ambitions. 

My hope? When that next generation are in power, they will rebuild the close partnership we are tearing up!”


Amanda Sloat, Fellow, Project on Europe and the Transatlantic Relationship; Senior Fellow in the Center on the United States and Europe at the Brookings Institution:

“The UK’s decision to leave the European Union has deeply polarized the British electorate, which will continue as the reality of divorce becomes apparent and decisions are made about the contours of the future relationship. Johnson’s large parliamentary majority gives him considerable leeway to make decisions, but he will continue to confront internal divisions.

In particular, Brexit has raised questions about the longevity of British constitutional arrangements. There are increasing calls for a second Scottish independence referendum (as Brexit has qualitatively changed the question since the 2014 poll), while likely deviation between Northern Ireland and Great Britain on regulatory standards as part of the Brexit deal could intensify debate about a referendum on Irish unification.

Externally, the UK must establish a new role within Europe and address changing dynamics in the transatlantic alliance. As London embarks on trade talks with Brussels and Washington, it will struggle to secure comprehensive deals with both partners and will need to choose between their regulatory models. On foreign policy, London may feel squeezed between its ideological affinity with the continent on some issues (e.g., climate change and Iran) and its special relationship with the United States.”

For more information on this publication: Belfer Communications Office
For Academic Citation: Abecassis, Adrien, Rt. Hon. Douglas Alexander, Nicholas Burns, Cathryn Clüver Ashbrook, Jolyon Howorth, Karl Kaiser, Álvaro Renedo , Lord Peter Ricketts and Dr. Amanda Sloat. “Impacts of Brexit on the UK, EU, and the World.” News, Belfer Center for Science and International Affairs, Harvard Kennedy School, January 30, 2020.

The Authors

Nicholas Burns