Billions of people could be at risk from droughts, as global warming threatens to shrink a tropical belt providing critical summer rain, warns a new study.
Researchers say droughts in Central America result from the contracting of the Intertropical Convergence Zone (ITCZ), a critical rainfall belt near the equator.
An international team of scientists looked at previous rainfall patterns within the ITCZ, including Belize in Central America, which is currently experiencing drought.
The ITCZ expands in a cooler climate, but contracts or shrinks as temperatures increase.
As a result, Central American nations could experience drier conditions, leading to crop failure and possible famine.
The team warns that this is already leading to social unrest and mass migration from affected regions, including Central America and sub-Saharan Africa.
NASA image shows the Intertropical Convergence Zone as a layer of precipitation close to the equator where north and south winds meet
The ITCZ is the world's most important rainfall belt affecting the livelihood of billions of people worldwide.
It is a low-pressure belt where winds from the north and southern hemispheres meet.
Water vapour condenses as air rises and cools in the ITCZ, forming clouds and falling as rain.
From satellite images, the ITCZ is seen as a band of clouds that generally circle close to the equator around the globe.
Globally, seasonal shifts in the location of the ITCZ across the equator dictate the initiation and duration of the tropical rainy season.
‘In the last five years there have been mass migrations of people in Guatemala and Honduras – partially driven by political instability, but also driven by drought-related conditions and changes in seasonality,’ said co-author of the study Keith Prufer, Professor of Anthropology at the University of New Mexico.
‘This is creating enormous problems for agricultural production and feeding a growing population.
‘There is growing evidence that these changes are a direct consequence of climate change.’
The research team reconstructed 1,600