Pope Leo's stance on key issues, from climate change to LGBTQ+ rights to U.S. politics

Your request is inconsistent in some way. Pope Leo XIII held the papal office from 1878 to 1903. During that time, there wasn't much discussion or debate on climate change, LGBTQ+ rights, or the present-day political context of the United States. These issues became institutionalized and came to the forefront of discussion in the late 20th and 21st centuries.
Perhaps you wanted to know about the views of the current Pope Francis, as these topics are highly relevant during his pontificate. If so, I am presenting Pope Francis's opinions below. If you genuinely want to know about Pope Leo XIII regarding these specific issues, it must be said that these topics were not even raised during his time.
However, Pope Leo XIII is known for his famous encyclical "Rerum Novarum" (1891), where he spoke about workers' rights, fair wages, and social justice. It is regarded as an essential component of Catholic social teaching. These principles can indirectly be relevant to some of today's debates, such as economic inequality or the rights of the poor who are victims of environmental exploitation.
Now, if your intention is to know Pope Francis's opinions, his positions are as follows:
The Fundamental Values and Position of Pope Francis on Various Topics Since his election in 2013, Pope Francis has been known for his straightforward talk, his empathy for the poor and marginalized, and his bold steps in addressing complex global problems. His thinking is deeply centered on Jesus's mercy, social justice, and the protection of creation.

Climate Change:
Pope Francis views climate change as one of the most serious challenges of our time. He discussed this in detail in his influential 2015 encyclical "Laudato Si': On Care for Our Common Home."
Main Argument: He states that the Earth is our "common home" and caring for it is our moral responsibility. Climate change is primarily caused by human activity, and its worst effects are borne by the poor and vulnerable populations.
Critique: He strongly criticizes over-reliance on fossil fuels, consumerist culture, and environmental destruction for short-term economic gain.
Call to Action: Pope Francis calls for an "ecological conversion," where humanity reconsiders its relationship with nature. He emphasizes international cooperation, increased use of renewable energy, and changes in lifestyle. He encourages individuals, businesses, and governments to collaborate. In his 2023 Apostolic Exhortation "Laudate Deum," he again criticized global inaction in tackling the climate crisis and called for swift measures.
LGBTQ+ Rights:
This is a sensitive and complex issue for the Catholic Church. Pope Francis's stance is considered somewhat more lenient and compassionate than previous Popes, although there has been no change in the fundamental teachings of the Church.
Attitude Towards Individuals: Pope Francis has repeatedly said that homosexual individuals should be treated with respect and compassion and should not face unjust discrimination. His famous quote, "If a person is gay and seeks God and has goodwill, who am I to judge?" reflects his perspective on this matter.
Church Teaching: However, he upholds the traditional Catholic teaching that marriage can only be between a man and a woman. He has criticized "gender ideology," which he believes denies the natural differences between men and women and harms the family.
Recent Steps: In December 2023, the Dicastery for the Doctrine of the Faith issued a declaration titled "Fiducia Supplicans," which permits pastoral blessings for same-sex couples under specific circumstances. However, this does not alter the Church's doctrine on marriage, and such blessings are not to be equated with liturgical or formal matrimonial blessings. This step has generated mixed reactions.
U.S. Politics and Other Political Issues:
Pope Francis does not directly interfere in the internal politics of any country nor does he endorse any specific political party. However, he often comments on various policies and political trends from a moral perspective.
Immigration: He is a vocal advocate for the rights of migrants and refugees. He has criticized the building of border walls and harsh immigration policies, calling on nations to be more humane and compassionate.
Economic Inequality: He has criticized the unbridled expansion of capitalism and the "idolatry of money," which creates vast disparities in society. He advocates for an inclusive economy where the poor are prioritized.
Political Polarization: Pope Francis has expressed concern about political polarization and the culture of conflict. He emphasizes dialogue, mutual understanding, and "building bridges," not "building walls."
Pro-life Stance: Consistent with Catholic Church teaching, Pope Francis strongly opposes abortion and euthanasia, calling for the protection of human life's sanctity from conception to natural death.
War and Peace: He condemns war and violence worldwide and tirelessly calls for diplomacy and dialogue for peace. He is also a staunch critic of the arms trade.
Conclusion (Regarding Pope Francis):
Pope Francis's positions are primarily based on Gospel values and Catholic social teaching. He seeks to be a voice for the poor and marginalized and tries to inspire world leaders and ordinary people to build a more just, peaceful, and environmentally sustainable world. His message often challenges conventional political and economic structures and calls for profound spiritual and moral transformation.