NAIROBI, Nov 17 (Reuters) - Climate change and security in Ethiopia, Sudan and the Sahel are set to top the agenda as U.S. Secretary of State Antony Blinken arrives in Nairobi on Wednesday to visit three of the continent's major players: Kenya, Nigeria and Senegal.

Blinken's first Africa trip follows the COP26 climate talks in Glasgow, where poorer nations called on wealthy governments to do more to help them combat climate change.

His visit will likely seek to underscore the difference between President Joe Biden's administration and his predecessor Donald Trump. Trump dismissed some African nations as "shitholes", left key diplomatic posts to Africa empty and scoffed at climate change science.

Blinken's first stop will be Kenya, where President Uhuru Kenyatta will want to discuss security following last month's coup in Sudan and a widening war in Ethiopia, Africa's second most populous nation and the headquarters of the African Union.

Blinken said last week that Ethiopia could "implode", a prospect that would widen famine there and send millions of refugees around an already unstable region.

Kenya also contributes troops to an African Union peacekeeping force in Somalia, where al Qaeda-linked insurgents are battling the government. The mandate of the AU force is up for renewal next month and the United States is a key donor.

Blinken will also meet civil society representatives, considered an important bulwark of Kenyan democracy ahead of next year's national election. Polls can sometimes turn violent and Kenya, East Africa's wealthiest and most stable nation, is headquarters to many multinationals.