The World Bank Group says it is doubling funding for poor countries preparing for climate change to $200 billion over five years.

The Washington-based organisation said on Monday that about half would come from the World Bank itself, while the rest would be sourced from other institutions within the group and private capital.

The bank said some $50 billion will be earmarked for climate adaptation, a recognition that some adverse effects of global warming can't be avoided anymore but require a change in practice.

This includes building homes that can withstand more extreme weather and finding new sources of freshwater as rising seas contaminate existing supplies.

The announcement comes as leaders are meeting in Poland for UN talks on tackling global warming.

Dozens of environmentalists have picketed the site of a former coal mine in Poland that is located near to where a global climate summit is being held.

Polish group Action Democracy said on Sunday that its supporters were protesting Poland's continued reliance on coal, a particularly dirty fossil fuel.

The summit taking place on December 2-14 in Katowice is intended to build on the 2015 Paris climate accord, which set a goal of limiting global warming to well below 2 degrees Celsius by the end of the century.

Host country Poland still gets most of its electricity from burning coal. The government's current plans put it far off course from achieving climate neutrality by 2050, a goal scientists say must be reached to prevent catastrophic climate change.

A protester in Brussels on Sunday. AP

At least 65,000 people marched on the European Union's headquarters in Belgium to show support for the bloc's proposed curbs on climate change.

Braving rain and wind, demonstrators thronged the main road in central Brussels where the EU headquarters are located. Police said the peaceful march, held as a global climate conference got underway in Poland on Sunday, was the biggest climate demonstration in Belgium's history.

The EU has proposed cutting greenhouse gas emissions from member countries to net zero by 2050. Scientists say that target needs to be adopted worldwide to avoid catastrophic global warming.

The EU has traditionally been among the most ambitious climate advocates.