If the study is correct, tourism could decline while food prices increase.
The report was presented Wednesday at a UN conference in Doha, Qatar.
"Climate change is a reality for the people of the Arab countries," said Inger Andersen, Vice President of the World Bank's Middle East and North Africa.
"Everyone will be affected, but particularly the poor, who are the least able to adapt ... the time to act is now, at both regional and national levels."
A lack of water, which is already a critical problem in the region, could increase, according to the report.
Temperatures can already reach 50°C in the summer in the Middle East and north Africa -- and those temperatures may rise in the years to come.
Available water supplies are expected to decline by 10 percent by 2050, while the demand for water is projected to increase 60 percent by 2045.
The report urges the countries named in the report to improve their infrastructure for future changes, including improvements to drainage systems.
"Reducing vulnerability to climate change will require concerted action at several levels," said Rachel Kyte, Vice-President of the World Bank's sustainable development.
"The political will is essential to make climate change a national and regional priority."
According to the report, the effects of climate change can already be seen in many parts of the Middle East and north Africa.
Over the past 30 years, weather-related disasters have affected 50 million people in the Arab world, with a direct cost of U.S. $12 billion.
The report cites the Nile flood of 2006 - which was responsible for 600 deaths - as well as record drought in the Jordan River basin, which lasted five years, ending in 2008.
Of the 19 record temperatures recorded in 2010, nearly a quarter were in the Arab world.
In 2010, an intense cyclone formed by the Arabian Sea, with winds of 230 km per hour.
The storm left 44 dead and caused damages estimated at U.S. $700 million in Oman.