SHARM EL-SHEIKH - More than 150 countries have now signed up to a global pact to reduce methane emissions, some 50 more than signed on when the initiative launched last year, the United States and European Union announced on Thursday.

The pledge to cut emissions of the powerful greenhouse gas 30% this decade is seen as critical to global efforts to limit planetary warming to 1.5 degrees Celsius, a threshold scientists say must be maintained to avoid the worst of climate change.

The United States and the EU launched the Global Methane Pledge during the Glasgow climate talks last year.

"As of today, we will have 95% of countries that have included methane in their nationally determined contributions," Rich Duke, U.S. deputy special envoy on climate change, told Reuters ahead of the announcement, referring to the promises countries make to slash emissions.

China and India, the top two methane emitters, have not signed up for the pact, he said.

Duke told Reuters he was hopeful that China, the world's biggest methane polluter, will join the partnership and attend a Global Methane Pledge ministerial that will be led by the United States and EU before next year's COP28 climate summit in Dubai.

"I am hopeful that they will show up. We encourage them to join," he said, standing outside the China delegation office.

China is developing its own methane strategy but has not yet said whether it will join the global effort.

Fifty of the signatories to the Global Methane Pledge have so far unveiled detailed strategies to cut emissions.

The United States and EU will also launch other initiatives on Thursday under the Global Methane Pledge that tackle oil and gas, agriculture and waste sectors.

Among them is an effort to help smallhold farmers in Kenya, Rwanda, Tanzania, Uganda, Costa Rica, Uruguay, Colombia, Pakistan and Vietnam reduce methane in their dairy systems.

Another is a program providing $70 million for research on enteric fermentation - the digestive process in which some animals produce gas and the largest single source of methane emissions from agriculture.

The United States and EU also announced that Carbon Mapper, which tracks methane by satellite, will develop a global waste sector methane baseline assessment on landfills and dumpsites. The waste sector accounts for 20% of methane emissions.

(Reporting by Valerie Volcovici; Editing by Janet Lawrence)