Climate change caused by global warming is contributing to the deaths of nearly 400,000 people a year and reducing the world’s gross domestic product by 1.6 percent annually, amounting to about $1.2 trillion, a new study says.

If unchecked, rapidly escalating temperature and carbon-related pollution may cut global GDP by 3.2 percent a year by 2030 and claim the lives of more than 100 million people, according to a 331-page study carried out by the DARA group, a non-governmental organization based in Europe, and the Climate Vulnerable Forum. It was written by more than 50 scientists, economists and policy experts, and commissioned by 20 governments.

Temperatures have already risen by about 0.8 degrees Celsius above pre-industrial times. Lower-income countries are the most vulnerable as they face increased risk of drought, water shortages, crop failure, poverty and disease. On average, they could see an 11 percent loss in GDP by 2030 due to climate change, DARA said.

“One-degree Celsius rise in temperature is associated with 10 percent productivity loss in farming,” Bangladesh's Prime Minister Sheikh Hasina said in response to the report. “For us, it means losing about four million metric tons of food grain, amounting to about $2.5 billion. That is about 2 percent of our GDP.”

“Adding up the damages to property and other losses, we are faced with a total loss of about 3 percent to 4 percent of GDP,” Hasina said. “Without these losses, we could have easily secured much higher growth.”

While poorer countries face the steepest economic damage in terms of GDP losses, big countries will not be spared.

"In less than 20 years, China will incur the greatest share of all losses at over $1.2 trillion. The U.S. economy will be held back by more 2 percent of GDP; India, over 5 percent of its GDP," the report said.

The largest economic stress impacts by 2030 due to climate change are projected to be in Central Asia and Russia, and in Eastern Europe, the Pacific, and large parts of Africa, according to the report.

Significant impacts of sometimes 1 percent or more of GDP were reported in regions already plagued by the effects of water scarcity and challenging agricultural markets.

And North Africa, regions of Sub-Saharan African, Pacific island states, and Southeast Asia also bear significant burdens of around 0.5 percent of GDP.

The full report is available here.