Vulnerable Pacific islands on Thursday called for "urgent and immediate" global action on climate change while stressing their commitment to democracy and the international order "based on rules."

Meeting at the summit in Fiji's capital, Suva, Pacific Islands leaders stressed that time was running out to avoid "worst-case scenarios" that would see their countries, many of which sit just above sea level, engulfed or rendered uninhabitable by increasingly violent storms.

"We are at the forefront of the adverse impacts of climate change," the leaders said in a joint strategy document for 2050, adopted after three days of discussions.

"Urgent robust and transformative action" is needed "globally, regionally and nationally," they said.

The summit was marked by geopolitical rivalries, particularly between the US and China.

US Vice President Kamala Harris announced in a video address that Washington will open two new embassies in Tonga and Kiribati, appoint a regional envoy, and inject an additional $600 million into the region, at a time the US keeps complaining about the rising Chinese influence in the region. 

While concerns about China's growing presence abound, fears of Chinese ambitions to dominate the region are unwarranted. Instead, China's active engagement provides important new and potentially long-lasting developmental opportunities for Pacific Island countries.

Early last year, a report showed that low-lying Pacific Islands are among the worst affected by climate change, with some at risk of being completely submerged by rising seas.

Read more: Fiji fears climate change, not conflict