All nations will suffer the effects of a warmer world, but it is the world's poorest countries that will be hit hardest by food shortages, rising sea levels, cyclones and drought, the World Bank said in a report on climate change.

Under new World Bank President Jim Yong Kim, the global development lender has launched a more aggressive stance to integrate climate change into development.

"We will never end poverty if we don't tackle climate change. It is one of the single biggest challenges to social justice today," Kim told reporters on a conference call on Friday.

The report, called "Turn Down the Heat," highlights the devastating impact of a world hotter by 4 degrees Celsius (7.2 Fahrenheit) by the end of the century, a likely scenario under current policies, according to the report.

Climate change is already having an effect: Arctic sea ice reached a record minimum in September, and extreme heat waves and drought in the last decade have hit places like the United States and Russia more often than would be expected from historical records, the report said.

Such extreme weather is likely to become the "new normal" if the temperature rises by 4 degrees, according to the World Bank report. This is likely to happen if not all countries comply with pledges they have made to reduce greenhouse gas emissions. Even assuming full compliance, the world will warm by more than 3 degrees by 2100.

In this hotter climate, the level of the sea would rise by up to 3 feet, flooding cities in places like Vietnam and Bangladesh. Water scarcity and falling crop yields would exacerbate hunger and poverty.

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