A new study threw gas into the flames of climate change debates. Three economists from Stanford University and the University of California (UC) in Berkeley looked into the World Bank data covering 166 countries from years 1960 to 2010.

The researchers tracked the relationship between temperature change and productivity levels. The trio identified the best average yearly temperature that matches top productivity levels: 13 degrees Celsius. This is the temperature of San Francisco's bay area. They found that the world's largest economies share an average temperature of 13 degrees Celsius, which could be the best temperature where people are effective in 'producing stuff'.

But no thanks to climate change, all that could change. The rise or fall of average temperature in a country directly affects gross domestic product (GDP) growth. For instance, if the average temperature in the United States rises by 4 degrees Celsius, that could lead to the loss of 1 percent point of GDP growth. The numbers could be small now, but an annual 4 degree Celsius increase could lead to accumulating productivity loss by the year 2100.

The researchers found that if the climate change persists, it could make the world poorer by 23 percent towards the century's end. In general, 77 percent of countries worldwide will experience per capita income decrease.

"People have long been worried that the effects on people in poor countries would be really negative and we confirmed that. One of the main findings is that rich countries are not isolated. Climate change could reshape the global economy. Rich companies are part of the story and could be impacted in important ways," said study co-author Marshall Burke, Stanford University's department of earth system science assistant professor.

The economists listed possible factors that could contribute to the climate change-driven economy change:

• Human health worsens along with rising temperatures. More deaths caused by diseases like malaria and dengue in emerging nations.

• Human conflicts are more prevalent in higher temperatures. Social conflicts affect economic activities.

• Productivity drops as temperature rises.

• People tend to commit more mistakes in hotter temperatures.

The researchers projected that countries like Canada, Russia, and countries in northern and central Europe would have an increase in productivity due to the warming weather. However, the length of such productivity cannot be verified if climate change continues to take its toll. Emerging countries in the tropics and subtropics would be hit the heaviest as global warming rages on. This slow but consistent phenomenon could lead to the more distinct divide of rich and poor nations.

The researchers published their findings in the Nature journal on Oct. 21.