Short answers, pulled from the story.
Deforestation is responsible for about 11% of global greenhouse gas emissions. It is the second largest source of carbon dioxide from human activities, after the burning of fossil fuels.
Modeling studies identify two crucial thresholds for the Amazon: a temperature rise of 4 degrees Celsius and deforestation reaching 40% of the forest cover. Either could trigger devastating and potentially irreversible collapse of the forest ecosystem.
The Amazon rainforest once absorbed one-fourth of all carbon dioxide emissions on Earth. Due to deforestation, that absorption capacity has fallen by 30% compared to the 1990s.
The Billion Tree Campaign was launched in 2006 by the United Nations Environment Programme as a response to climate change and broader sustainability challenges. Its initial target was one billion trees planted in 2007; by December 2011, more than 12 billion trees had been planted and the program was handed to the Plant-for-the-Planet initiative in Munich, Germany.
Deforestation reduces evapotranspiration, which in turn reduces precipitation and produces a hotter, drier climate with longer dry seasons. A 2023 study projected that deforestation in the Congo could reduce regional precipitation by up to 8-10% by the year 2100.
The Bali Action Plan was developed in December 2007 in Bali, Indonesia, as a follow-up to the Kyoto Protocol of December 1997. It committed member countries to creating policy approaches that incentivize emissions reductions from deforestation and forest degradation in developing countries, and it linked sustainable forest management to additional resource flows for those nations.