What is the estimated global investment needed to confront climate change according to the UN report?

The correct answer reflects the UN report's estimation that $90 trillion in investments is necessary over the next 15 years to effectively address and combat climate change. This figure signifies the immense financial commitment required across various sectors, including renewable energy, agriculture, infrastructure, and technology, to transition towards sustainable practices and mitigate the impacts of climate change. The report emphasizes the urgency of mobilizing these funds to ensure that countries can meet their climate goals and protect against the environmental and economic challenges posed by climate change.

The specific time frame of 15 years highlights the need for timely action to avert the most severe consequences of climate-related issues. In contrast to the other options that suggest either shorter or longer timelines or different amounts, this answer aligns closely with the UN's calls for immediate and substantial financial investment to support global efforts in this critical area.