President Barack Obama and UN Secretary General Ban Ki-Moon held a meeting Tuesday at the White House where they discussed climate change and humanitarian crises in the Middle East.   

Obama said the main topic of discussion with Ban was about the "urgency of a world response to the threat of climate change", adding that the U.S. and UN could be the leaders in addressing the "critical issue that faces humankind going forward".

Through power plant rules and ongoing renewable energies work, the issue could be taken a step further at the upcoming UN Climate Change Conference in Paris at the end of  the year, Obama said.    

"The world has to step up in a concerted way on behalf of our children and future generations," Obama said.  

Ban praised Obama for his "visionary and forward leadership announcement", regarding his plan to cut greenhouse gas emissions by U.S. power plants by nearly a third within 15 years.

The Clean Power Plan, Ban said, shows the world that the U.S. was able to change the world "in addressing a climate phenomenon".

Shifting to the ongoing humanitarian crisis in Syria, Obama emphasized the need to stop the killing and reach a realistic political process to transition to a government that is "reflective of all the people of Syria".

Ban and Obama also discussed the conflict in Yemen where forces loyal to Yemen's exiled President Abd Rabbuh Mansur Hadi are fighting Shia Houthi militia.

The fighting has forced some refuges into “organizations like Daesh", according to Obama.

"Eighty percent of the population, to be exact, more than 21 million people, are in need of urgent humanitarian assistance," Ban said.  

In South Sudan, Obama said he wants to hold fast to an Aug. 17 deadline for an agreement between the warring sides.