VATICAN CITY (CNS) -- In a world torn by strife, diplomacy offers hope by promoting dialogue, solidarity and cooperation for the common good, Pope Francis said.

Welcoming new ambassadors to the Holy See from Ethiopia, Zambia, Tanzania, Burundi, Qatar and Mauritania June 8, the pope said they are "signs of hope" because they "seek to build bridges between peoples, not walls."

People need signs of hope, especially given that "the family of nations is today torn by the tragedy of civil, regional and international strife," the pope told them during a ceremony in the Clementine Hall of the Apostolic Palace. "We have only to think of what is taking place in Sudan, Ukraine, Gaza and Haiti, to name but a few examples."

The situation is aggravated, he said, by the "multiple humanitarian crises that result from such conflicts, including a lack of access to adequate shelter, food, water and medical supplies."

In addition, the pope said, "we must be attentive to the problems of forced migration and the increasing number of internally displaced persons, the scourge of human trafficking, the effects of climate change, especially upon the poorest and most vulnerable, and global economic imbalances that contribute to a loss of hope, especially among young people."

Pope Francis also said that "the decline in the birthrate, experienced by many countries, is a cause for grave concern."

The problems require "a farsighted, constructive and creative dialogue, based on honesty and openness," in order to find shared solutions that reflect and strengthen people's realization that they are all brothers and sisters, the pope said. "In this regard, we must also bear in mind our obligations to future generations, asking ourselves what kind of world we want to leave to our children and those who will come after them."

The challenges the world is facing and the fast pace of change have left many people "discouraged, pessimistic and even cynical," he said, "yet hope leads us to recognize the goodness present in our world and provides the strength needed to meet the challenges of our day."

Pope Francis told the ambassadors -- four women and two men -- that he hoped their service would "contribute not only to the consolidation of the good relations existing between your nations and the Holy See, but also to the building of a more just and more humane society in which all are welcomed and given the necessary opportunities to advance together along the path of fraternity and peaceful coexistence."