The United Nations says a record 155 countries will sign the landmark agreement to tackle climate change at a ceremony at U.N. headquarters on April 22, according to AP. U.N. spokesman Farhan Haq said Friday that five countries, Barbados, Belize, Tuvalu, Maldives and Samoa will not only sign but ratify the agreement reached in Paris in December. Secretary-General Ban Ki-moon, French President Francois Hollande and French Environment Minister Segolene Royal, who heads global climate negotiations, have invited leaders from all 193 U.N. member states to the event. The U.N. says more than 60 heads of state and government plan to attend. The previous opening day record of 119 signatures is held by the Law of the Sea treaty in 1994.