(ACAFE - 2017) Answer the questions based on the text below. The Brazilian government has ratified its participation in the Paris agreement on climate change, a significant step by Latin Americas largest emitter of greenhouse gases that could spur other countries to follow suit. With a landmass larger than the continental US, Brazil emits about 2,5%of the worlds carbon dioxide and other polluting gases, according to United Nations data. Our government is concerned about the future, said President Michel Temer during a signing ceremony in Brasilia. Everything we do today is not aimed at tomorrow, but rather at a future that preserves the living conditions of Brazilians. Temer said Brazils ratification would be presented formally to the UN later this month. The Paris agreement will enter into force once 55countries representing at least 55%of global emissions have formally joined it. Climate experts say that could happen later this year. Countries set their own targets for reducing emissions. The targets are not legally binding, but nations must update them every five years. Using 2005 levels as the baseline, Brazil committed to cutting emissions 37%by 2025 and an intended reduction of 43%by 2030. In the last decade, Brazil has achieved significant emissions cuts thanks to efforts to reduce deforestation in the Amazon and increase in the use of energy from hydropower and other renewable sources including wind, solar and biomass. The Paris accord got a boost earlier this month when the US president, Barack Obama, and Chinas President, Xi Jinping, sealed their nations participation. Brazil is now the next major country to move forward. It will add even greater momentum, said David Waskow, director of the International Climate Initiative at the Washington, DC-based think tank the World Resources Institute. Source: https://www.theguardian.com/environment/2016/sep/13/brazil-ratifies-paris-agreement-with-pledge-to-sharplyreduce-emissions. Why has the author used the modal must in the sentence: The targets are not legally binding, but nations must update them every five years?
