Climate change is impacting the Caribbean, with millions facing increasing food insecurity and decreasing freshwater availability as droughts become more likely across the region, according to new Cornell research in Geophysical Research Letters.
“Climate change – where mean temperatures rise – has already affected drought risk in the Caribbean.
Since 1950, the Caribbean region has seen a drying trend and scattered multiyear droughts.
But the recent Pan-Caribbean drought in 2013-16 was unusually severe and placed 2 million people in danger of food insecurity.
In Haiti, for example, over half the crops were lost in 2015 due to drought, which pushed about 1 million people into food insecurity, while an additional 1 million people suffered food shortages throughout the region, according to the United Nations Office for the Coordination of Human Affairs.
Examining climatological data from the 2013-16 Pan-Caribbean drought, anthropogenic warming accounted for a 15 to 17 percent boost of the drought’s severity, Herrera said.
Climate model simulations indicate the most significant decrease in precipitation in the Caribbean might occur May through August – the rainy season.
A failed rainy season in spring and summer, added to a normal dry season in the late fall and winter, prolongs a drought.
Park Williams, Lamont Doherty Earth Observatory, Columbia University.
The research was supported by the National Center for Atmospheric Research, the National Science Foundation and NASA.

Paper: ‘Glacierized Headwater Streams as Aquifer Recharge Corridors, Subarctic Alaska’.
Arctic river discharge has increased in recent decades although sources and mechanisms remain debated.
Here we link glacier runoff to aquifer recharge via a losing headwater stream in subarctic Interior Alaska.
Our findings suggest a linkage between glacier wastage, aquifer recharge along the headwater stream corridor, and lowland winter discharge.
Observations of increased river discharge in summer and winter span the scientific community and Arctic residents.
High-latitude mountain glaciers represent an overlooked source to subarctic river discharge and aquifer recharge.
Our results suggest a linkage between glacier melt, headwater discharge, aquifer recharge, and lowland winter streamflow that may be hydrologically important also in other semiarid glacierized regions within and outside the subarctic.
Our measurements show that an Interior Alaska headwater stream lost significant amounts of its annual water (46%) to the underlying aquifer, while glacier runoff represents a significant share (>15%) of annual discharge under both low (3%) and high (60%) glacier coverage.
The glacier mass loss has likely served as the dominant supply to the Tanana River’s long-term increase in annual and winter discharge considering no commensurate increase in Interior Alaska precipitation.
We conclude that the role of mountain glaciers on subarctic watershed hydrology and permafrost deserves increased attention, especially considering the well-documented decline in ice cover and increased winter river discharges.

The western-most region of the continental United States set records for low snowpack levels in 2015 and scientists, through a new study, point the finger at high temperatures, not the low precipitation characteristic of past “snow drought” years. The study suggests greenhouse gases were a major contributor to the high temperatures, which doesn’t bode well for the future, according to authors of a new study published in the journal Geophysical Research Letters. In 2015, more than 80 percent of the snow measurement sites in the region — comprised of California, Oregon, Washington, western Nevada and western Idaho — experienced record low snowpack levels that were a result of much warmer-than-average temperatures. Most of the previous records were set in 1977, when there just wasn’t enough moisture to generate snow, according to Philip Mote, director of the Oregon Climate Change Research Institute at Oregon State University and lead author on the study. “The 2015 snowpack season was an extreme year,” Mote said. “But because of the increasing influence of greenhouse gases, years like this may become commonplace over the next few decades.” Impacts of the snow drought in California, Oregon and Washington led the governors of those states to order reductions in water use and saw many ski areas, particularly those in lower elevations, struggle. California has been in a drought since 2011 and this multi-year period of low precipitation, by some measures, is the state’s most severe in 500…

‘Traveling’ droughts bring new possibilities for prediction.
A small subset of the most intense droughts move across continents in predictable patterns, according a new study published in the journal Geophysical Research Letters by researchers in Austria and the United States.
The study could help improve projections of future drought, allowing for more effective planning.
These traveling droughts also tend to be the largest and most severe ones, with the highest potential for damage to the agriculture, energy, water, and humanitarian aid sectors.
"Most people think of a drought as a local or regional problem, but some intense droughts actually migrate, like a slow-motion hurricane on a timescale of months to years instead of days to weeks," says Julio Herrera-Estrada, a graduate student in civil and environmental engineering at Princeton, who led the study.
The researchers analyzed drought data from 1979 to 2009, identifying 1,420 droughts worldwide.
They found hotspots on each continent where a number of droughts had followed similar tracks.
What causes some droughts to travel remains unclear, but the data suggest that feedback between precipitation and evaporation in the atmosphere and land may play a role.
"This study also suggests that there might be specific tipping points in how large and how intense a drought is, beyond which it will carry on growing and intensifying," said Justin Sheffield, a professor of hydrology and remote sensing at the University of Southampton.
Sheffield was Herrera-Estrada’s advisor while serving as research scholar at Princeton.

Study: Droughts Can Travel Like a Slow-Moving Hurricane.
Depending on the continent, some droughts move 800 to 1,900 miles from what researchers are calling hotspots.
From that data, the researchers located as many as four hotspots from each continent.
In North America, on average it takes 16 months for a drought to migrate 500 miles.
In North America, hotspots do not seem to favor a particular region of the continent, but droughts do typically move toward the north from the southwestern United States.
Movement of the droughts is erratic on most continents, except in Australia where drought tends to travel toward the north.
Since there is less water to evaporate from a drought-stricken area, there is less water available to fall out as rain or snow downwind.
In the first scenario, a ridge or dome of high pressure may move slightly from region to region over time while creating dry conditions underneath it.
In the second scenario, the weather patterns that result from El Niño often breed areas of drier conditions in some parts of the globe.
In the United States, the Ohio Valley is often a location where drier than average conditions set up.