Barroso's 10 years at the head of the commission were eventful to say the least. Since 2004, three more countries have joined the EU. Bulgaria and Romania became members in 2007, followed by Croatia in 2009, while six countries joined the eurozone.
Ten years ago, the world was a very different place. George W. Bush had just been re-elected as president of the United States. The Iraq war was in full swing. We did not yet have Facebook, Twitter or smartphones.
Observers have noted that Barroso's time at the head of the commission was marked by a series of crises, and the outgoing president himself described the past 10 years as "exceptional and challenging times". Just a few short months after the start of his mandate, Europe was rocked by a political crisis, with France and the Netherlands both rejecting the constitutional treaty. The crisis was eventually solved with the ratification of the Lisbon treaty.
At the start of his first mandate, Barroso called for a common communication strategy with the council and parliament and more cooperation between the institutions. This is why in 2005, when outlining the commission's priorities for the next five years, he announced a joint programme for strategic objectives with the parliament and council.
"[The Nobel peace prize was] a powerful reminder sent to us from the global community that we count in this world and that what we do is very important" - José Manuel Barroso
The partnership for prosperity, solidarity and security was aimed at stimulating growth and job creation, fighting discrimination and climate change, as well as improving Europe's ability to respond to threats and crises as quickly as possible. These have all been recurring themes throughout Barroso's mandate.
Growth, employment and the eurozone crisis
Stimulating growth and job creation has been a priority for every commission, and this will no doubt continue to be the case when Jean-Claude Juncker and his team take office. However, in Barroso's case, this has been an especially difficult goal to achieve, as Europe has faced the most serious financial and economic crisis in its history, starting in 2007.
Promoting growth and employment was at the heart of a new programme implemented by Barroso at the start of his second mandate in 2009. The Europe 2020 strategy was aimed at stimulating what the commission called "smart, sustainable and inclusive growth". Particular emphasis was placed on innovation and support measures for small and medium sized enterprises (SMEs).
Earlier this year, the commission carried out a midterm review of the strategy and found that growth remains sluggish, and SMEs still have trouble accessing financial resources such as bank loans. This is due to the economic crisis, which was in full swing when Barroso took on his second mandate. At the time, he vowed to get struggling economies back on track.
When Greece's economy came crashing down, many predicted it would exit the eurozone. Other countries such as Spain, Ireland and Portugal were also hit hard by the crisis, yet the outgoing commission president pointed out in his valedictory speech that despite being "under the imminent threat of collapsing, [they] are now in a much more stable mood". While Barroso admits that growth in Europe has been disappointing, he did say "we have won the battle of stability".
"[Barroso was] a real driving force behind Europe" - Manfred Weber
Leading the climate agenda
Barroso described himself as "extremely proud that it was [his] commission in [his] first mandate, in 2007, that put forward the most ambitious programme for climate protection in the world". The '20-20-20' targets laid out key objectives for 2020. Member states agreed to reduce their greenhouse gas emissions, increase their use of renewable resources and improve energy efficiency, all by 20 per cent. These targets were formally implemented within the Europe 2020 strategy in 2009.
Further signalling his commitment to the issue, Barroso added a commissioner for climate action to his team in 2010. Climate action was previously under the umbrella of the directorate general for environment. Speaking to MEPs, he claimed that the EU is "leading the world in terms of the climate agenda".
Unfortunately, members of parliament were left disappointed by the EU's latest climate change package, whereby member states will attempt to reduce their greenhouse gas emissions by at least 40 per cent by 2030.
"Serious policy mistakes [were made]" - Gianni Pittella
In one of his first speeches as president of the commission, Barroso underlined his commitment to fighting discrimination, particularly with regards to gender inequality. A European women's charter was implemented in 2010, and the commission introduced plans for a 40 per cent quota for women on company boards. However, he was criticised for having fewer women commissioners in his second team than in his first.
The outgoing president has often stressed that unity is key, saying that "the forces of integration are stronger than the forces of disintegration" and criticising "the intellectual glamour of pessimism", seemingly referring to those who do not believe in the future of Europe.
Parliament's take
Barroso admitted that relations with parliament "were not always perfect", but thanked the institution for its cooperation over the years. MEPs meanwhile offered up mixed reviews of his 10-year term at the head of the commission.
Manfred Weber, chair of the EPP group - part of Barroso's own political family - praised the outgoing president as "a real driving force behind Europe".
Gianni Pittella, chair of parliament's S&D group, said that the Portuguese offical had left office with "our continent is deep in unemployment". He admitted that this was partly due to external factors outside of Barroso's control, but that "serious policy mistakes" had been made.
Pavel Telička, second vice-president of ALDE, complained that "the outgoing commission […] lost the battle on competitiveness, reform and growth".
Barroso wished Juncker's incoming commission "all the best, […] they have a great challenge ahead of them", warning that "we cannot say that the crisis is completely over, because threats remain".
Yet he proudly remembered the day the EU received the Nobel peace prize, describing it as "a powerful reminder sent to us from the global community that we count in this world and that what we do is very important", urging the incoming commission to continue fighting for the values that shaped the EU and "to continue to do work for a united, open and stronger Europe".