Climate change will cause a shift in Earth's tropical rain belt — threatening water and food supply for billions, study says

By 2100, billions of people are at risk of facing more flooding, higher temperatures and less food and water. A new study published in "Nature Climate Change" found that the climate change will cause the Earth's tropical rain belt to unevenly shift in areas that cover almost two-thirds of the world, potentially threatening environmental safety and food security for billions of people. 

The tropical rain belt, otherwise known as the Intertropical Convergence Zone, or ITCZ, is a narrow area that circles the Earth near the equator where trade winds from the Northern and Southern hemispheres meet. Areas along the equator are among the warmest on Earth, and this, paired with the winds, creates significant humidity and precipitation. 

"Our work shows that climate change will cause the position of Earth's tropical rain belt to move in opposite directions in two longitudinal sectors that cover almost two thirds of the globe," lead author Antonios Mamalakis said in a statement, "a process that will have cascading effects on water availability and food production around the world." 

Mamalakis and other researchers came to this conclusion by analyzing computer simulations from 27 climate models. Specifically, they looked at how the rain belt would respond if greenhouse gas emissions continue to rise through the end of the current century. 

In a video posted on YouTube, Mamalakis explained the belt will likely shift between 2075 and 2100. 

Over eastern Africa and the Indian Ocean, evidence shows that the ITCZ will shift north. This will likely result in "increased drought stress over Madagascar and intensified flooding over southern India," Mamalakis said.

Madagascar is already seeing the devastating impacts of continuous drought. Half of the region's population has been impacted by several years of drought, according to the United Nations, and many families have been forced to live off of eating insects. The area has the 10th highest rate of stunting in the world, with almost half of Madagascar's children under five years old suffering from chronic malnutrition. 

But while this is happening, the ITCZ will also shift to the south over the eastern Pacific and Atlantic Oceans, Mamalakis explained, which will likely lead to increased drought stress over Central America.  

Greenhouse gas emissions play a significant role in climate change, as it traps heat radiating from the sun. 

Fellow researcher James Randerson said the effects of this will be felt "faster" in certain areas, including Asia. 

"In Asia, projected reductions in aerosol emissions, glacier melting in the Himalayas and loss of snow cover in northern areas brought on by climate change will cause the atmosphere to heat up faster than in other regions," Randerson said. "We know that the rain belt shifts toward this heating, and that its northward movement in the Eastern Hemisphere is consistent with these expected impacts of climate change."

The researchers have said that with this information, the next step is to figure out more specifically how these changes will impact natural disasters, infrastructure and ecosystems, and what changes need to be made to policy and management.