Prime Minister Justin Trudeau arrived today in Hamburg for the G20 Summit, having already staked out firm positions on free trade, migration and climate change that are at odds with U.S. President Donald Trump.

All three issues top an ambitious agenda set by the summit's host, German Chancellor Angela Merkel.

"One shouldn't expect any easy conversations in Hamburg," Merkel said in address to the German parliament last week.

"Whoever believes that the world's problems can be solved by isolationism and protectionism is mistaken," she added in remarks clearly directed at Trump.

Trudeau can't afford to be so blunt, especially given the interconnectedness of the Canadian and United States economies.

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Merkel repeats: Europe can no longer fully rely on U.S. "We do have clear disagreements regarding the United States or from the United States on climate and trade issues among others," Trudeau told reporters travelling with him this week in Europe. Even so, Trudeau said the world can still work with the U.S. on prickly issues such as meeting the goals of the Paris climate change agreement, even if the president isn't on board. German Chancellor Angela Merkel aims to generate more momentum on the United Nations 2030 Agenda for Sustainable Development, (Fabrizio Bensch/Reuters) "We certainly see from the American people, whether it's through their state-level actors, their governors or their large municipalities or indeed American businesses, there is still a very clear will to move forward on climate action," Trudeau said. University of Toronto professor and G20 research group co-director John Kirton is keeping a close eye on the discussions on climate change. "Climate change could be a disaster if both sides continue to insist on the somewhat theological issue of the Paris Agreement that was forged in 2015, and from which Donald Trump has just said the United States would withdraw," Kirton told CBC News. At the outset, at least, Environment Minister Catherine McKenna said Canada will insist on seeing language about the Paris Agreement included in the G20 leaders' final communique. Police disperse G20 protesters with water cannon

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"We need to stand firm, that we are going to be working with all countries around the table to reinforce the importance of the Paris agreement," she said.

U.S. President Donald Trump waves Wednesday as he boards Air Force One with first lady Melania Trump for a trip to Poland before the G20 summit in Germany, at Andrews Air Force Base, Md. (Evan Vucci/Associated Press)

Women and sustainable development

Germany also aims to generate more momentum on the United Nations 2030 Agenda for Sustainable Development, with an emphasis on equal access for women to information and community technologies.

That aligns with Canada's feminist international assistance policy, announced last month, which would invest $150 million over five years to help local organizations in developing countries that work to promote women's rights.

On Thursday, Trudeau and his wife, Sophie Gregoire Trudeau, spoke briefly about that focus on women and girls on stage at the Global Citizen concert in Hamburg, before introducing the British band Coldplay.

Trudeau said the fight for fairness and equality starts with empowering women and girls before both Trudeau and Sophie Gregoire jointly said: "Given equal opportunities women and girls can change the world."

Prime Minister Justin Trudeau, right, and his wife, Sophie Gregoire Trudeau, speak from the stage at the Global Citizen concert in Hamburg, Germany Thursday. (Pool/CBC)

In March, the government also announced $650 million over three years for sexual and reproductive health rights around the world.

By 2022, the government hopes to have 80 per cent of its international assistance targeted at the empowerment of women and girls as well as the advancement of gender equality.

All that money comes from the existing foreign aid budget.

"Great policy, but there was no money behind it," said Kirton, "So this government is doing less well in putting its money where its mouth is than virtually every Canadian government in the last 50 years."

'Marshall Plan' for Africa

Strengthening free and fair trade is a perennial goal at these leaders' summits.

By specifically putting Africa on the agenda of this summit, Merkel is hoping to build on the last two G20 meetings, which also focused on the continent.

The dual approach includes a kind of "Marshall Plan" that aims to promote infrastructure development such as roads, ports and railroads. Then there's the G20 Compact with Africa, where member nations are expected to pair up with African nations with the goal of attracting private investors on a whole host of development projects.

Canada stands apart from its G20 counterparts when it comes to Africa — but not in a good way.

According to the United Nations Conference on Trade and Development, Canada ranks last on foreign direct investment in Africa.

"All of the attention has been focused in the new markets in Europe, across the Pacific in China," said Kirton. "So Africa has been left out … abandoned even under the current Canadian government."

The Africa focus will include the movement of migrants and refugees who are fleeing conflict, human rights violations or problems associated with climate change or globalization.

Jessie Thomson, senior director of CARE Canada's humanitarian assistance and emergency team, said the world is coming to the realization that migration is not a temporary phenomenon.

She said she hopes the G20 will be able to make progress on how to more equitably share responsibility for resettlement.

A demonstrator lights flares on top of the Rote Flora, a former theatre that has become a culture centre and political meeting spot, during a protest against the G-20 summit in Hamburg, Germany on Wednesday. The G20 leaders meet July 7 and 8. (Matthias Schrader/Associated Press)

Last year Canada settled 44,000 Syrian refugees, but in Uganda, three thousand people are arriving every day from South Sudan.

"Eight hundred thousand refugees have arrived in the last couple of years," said Thomson. "It's a massive responsibility on Uganda, a developing country."

She suggests a trigger in mass influx situations, where once a nation receives a certain number of refugees, it would be entitled to a guaranteed amount of assistance. Those funds would come from G20 nations, whose contributions would be based on their gross domestic product.

"Right now, the unpredictability is putting a huge burden on states and making it feel chaotic, making it hard for the public to buy into refugee protection and assistance, making it hard for states to manage," Thomson said.

"If it's more predictable, more equitable, it actually gets easier to manage."

Kirton said he anticipates Merkel and Trudeau will present an effective united front on the issue of migration.

"It's Justin Trudeau that's really in the lead, backed by Merkel, with a simple message that immigrants are really good for you," said Kirton, adding that he could imagine a new commitment from Canada to settle some of the migrants who've crossed the Mediterranean to reach European shores.