• The leaders of China and Russia said they won't be at this week's COP26 climate-change summit.
• Their absence may make it harder for others to secure big commitments to reducing emissions.
• China emits around 28% of the world's CO2 emissions, while Russia emits around 5%.

China's Xi Jinping and Russia's Vladimir Putin are set to snub this week's COP26 summit on climate change in Glasgow.

Their absence is especially significant given their nations' contributions to global emissions, with China producing an estimated 28% and Russia 5% of global CO2 output.

The Kremlin confirmed last week that Putin would not travel to Scotland for the summit, while China is said to be planning to send its special envoy on climate change instead.

The Times newspaper reported last week that Johnson had been told that Xi would not attend in person.

Other world leaders at the summit may find it harder to strike a historic agreement on climate change without Xi and Putin around.

UK Prime Minister Boris Johnson, who is hosting the summit, is seeking support from other world leaders to commit to a radical plan tackling climate change.

Xi has not left China since the beginning of the coronavirus pandemic, Reuters reported, choosing instead to attend summits by video-link. 

Putin's spokesman Dmitry Peskov said that Putin would "unfortunately" not fly to Glasgow but said that climate change was "one of our foreign policy's most important priorities," AFP reported.

China emits nearly 28% of the world's global carbon dioxide emissions, according to Our World in Data, more than any other country. The figure grew rapidly as the country's expanding economy industrialized.

Russia emits around 5% of the world's carbon dioxide emissions, according to Our World in Data — the fourth highest in the world behind China, the US, and India.

US President Joe Biden and India's Prime Minister Narendra Modi are planning to attend the summit, as well as at least a dozen other national leaders.