Activists in India and Ukraine used their bodies. In Kashmir, they used their boats. In Dhaka, three motherly-looking women held three footballs to spell out the message.

From Kinshasha to Addis Ababa, Antarctica to the Philippines, Vermont to Dhaka, Micronesia to the Maldives, the message formed around the world on Saturday was the number 350 — a number the activists wanted to engrave in the minds of world governments about global warming as nations prepare to convene in Copenhagen in December on the issue.

The number 350 represents the goal by some climate scientists for reducing the amount of carbon dioxide in the air: from the current level of 387 parts per million to 350.

Activists organized under the name “350.org” say that if the gas concentration exceeds that amount for too long, global warming will cause sea levels to rise, and drought and famine to plague the Earth.

World governments are to meet in December in Denmark to map out the next steps to control carbon emissions after the Kyoto Protocol expires in 2012. But the world’s two largest emitters — the US and China — are dragging their feet about a new agreement.

On Saturday, US media reported that U.S. President Barack Obama is not likely to attend the climate conference, as had been earlier reported.

Mr. Obama is “leaning toward not going,” a senior administration official told Fox News. A major reason is that the climate conference is not a “head of state” event.

The Washington insider publication The Hill said Mr. Obama will not attend because the conference conflicts with Obama’s Nobel Peace Prize acceptance speech in Olso. Senior White House officials told the The Hill that Obama could use that speech to speak about the subject.

Organizers of Saturday’s climate actions said that more than 4,000 events were planned in 170 countries.

The 350.org protestors — gathered under the International Day of Climate Action — included Indian students at Marina beach, Chennai, who built a human pyramid holding signs with “350” written on them.

In Kiev, Ukrainian activists formed a giant 350 figure during an ecological rally, the European Press Photo Agency (epa) reported.

In Kashmir, owners of traditional Kashmiri boats formed the number 350 on Dal Lake, near Srinagar, the summer capital of Indian Kashmir.

Photos on the action’s website shows climbers holding a sign atop Mount Kilimanjaro; underwater divers in Australia’s Great Barrier Reef and in the Maldives; red-clad climbers on a granite rock face in the U.S. state of Vermont; and climbers on Cape Town’s Table Mountain dangling giant banners.

In Veracruz, Mexico, activists danced a ritual of the Totonacas against the backdrop of ancient ruins.

Photos from Mongolia showed three men on horseback. In China’s Inner Mongolia, activists clad in blue uniforms spelled their message against an arid landscape.

In Cairo, activists gathered at the pyramids. In Venice, Italy, banners were hung from the Rialto Bridge. Australian women put on their bathing suits, jumped in the water and displayed “350” signs on their heads.

The 13th World Forestry Congress ended on Friday in Buenos Aires with a call for “urgent action” to protect forests, saying trees are the most important tool to sequester carbon dioxide. They urged forests to play a key role in Copenhagen.

Mr. Obama said on Friday he was confident that the US Congress can pass a legislation aimed at curbing greenhouse-gas emissions, but would not say whether this can be done before December’s critical summit in Copenhagen.

Some prominent Republicans have voiced support for a cap-and-trade bill which is effectively designed to put a price on carbon emissions, the chief greenhouse gas blamed for global warming.

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