The landmark Paris agreement on climate change moved closer to reality on September 21 after 31 countries joined during the United Nations General Assembly. UN Secretary-General Ban Ki-moon voiced confidence that the accord, through which countries commit to take action to stem the planet’s rising temperatures, would come into force by the end of the year. The accord requires all countries to devise plans to achieve the goal of keeping the rise of temperatures within two degrees Celsius (3.6 Fahrenheit) above pre-industrial levels. The countries that joined the accord on September 21 included Latin American powerhouses Argentina, Brazil and Mexico as well as major fossil fuel powers Brunei and the United Arab Emirates. To come into force, the Paris agreement needs ratification from 55 countries that account for at least 55 per cent of the planet’s greenhouse gas emissions.