A man and a boy collect recyclable waste at a rubbish dump outside Yemen's Red Sea port city of Houdieda January 19, 2016. REUTERS/Abduljabbar Zeyad 

A cart driver trots his horse down a country road outside Peshawar, Pakistan January 19, 2016. REUTERS/Khuram Parvez 

A coffee picker carries sacks of coffee cherries at a plantation in the Nogales farm in Jinotega, Nicaragua January 7, 2016. Soaring temperatures in Central America due to climate change are forcing farmers to pull up coffee trees and replace them with cocoa, spurring a revival in the cultivation of a crop once so essential to the region's economy. Picture taken January 7, 2016.REUTERS/Oswaldo Rivas

Coffee pickers carry sacks of coffee cherries at a plantation in the Nogales farm in Jinotega, Nicaragua January 7, 2016. Soaring temperatures in Central America due to climate change are forcing farmers to pull up coffee trees and replace them with cocoa, spurring a revival in the cultivation of a crop once so essential to the region's economy. Picture taken January 7, 2016. REUTERS/Oswaldo Rivas

A coffee picker carries sacks of coffee cherries at a plantation in the Nogales farm in Jinotega, Nicaragua January 7, 2016. Soaring temperatures in Central America due to climate change are forcing farmers to pull up coffee trees and replace them with cocoa, spurring a revival in the cultivation of a crop once so essential to the region's economy.Picture taken January 7, 2016.REUTERS/Oswaldo Rivas

A coffee picker carries sacks of coffee cherries at a plantation in the Nogales farm in Jinotega,Nicaragua January 7, 2016. Soaring temperatures in Central America due to climate change are forcing farmers to pull up coffee trees and replace them with cocoa, spurring a revival in the cultivation of a crop once so essential to the region's economy. Picture taken January 7, 2016. REUTERS/Oswaldo Rivas

A worker plays a trumpet at the Nogales farm in Jinotega, Nicaragua January 7, 2016. Soaring temperatures in Central America due to climate change are forcing farmers to pull up coffee trees and replace them with cocoa, spurring a revival in the cultivation of a crop once so essential to the region's economy. Picture taken January 7, 2016. REUTERS/Oswaldo Rivas

Workers carry sacks of coffee beans at a warehouse at the Nogales farm in Jinotega, Nicaragua January 7, 2016. Soaring temperatures in Central America due to climate change are forcing farmers to pull up coffee trees and replace them with cocoa, spurring a revival in the cultivation of a crop once so essential to the region's economy. Picture taken January 7, 2016. REUTERS/Oswaldo Rivas TPX IMAGES OF THE DAY

A worker carries a sack of coffee beans at a warehouse at the Nogales farm in Jinotega, Nicaragua January 7, 2016. Soaring temperatures in Central America due to climate change are forcing farmers to pull up coffee trees and replace them with cocoa, spurring a revival in the cultivation of a crop once so essential to the region's economy. Picture taken January 7, 2016. REUTERS/Oswaldo Rivas

A boy collects fodder for cattle between trees in an orchard in Charsadda near Peshawar, Pakistan January 13, 2016. REUTERS/Fayaz Aziz 

Residents fill sandbags to protect their homes after an El Nino-strengthened storm brought rain to Los Angeles, California, United States, January 6, 2016. REUTERS/Lucy Nicholson 

Residents fill sandbags to protect their homes after an El Nino-strengthened storm brought rain to Los Angeles, California, United States, January 6, 2016. REUTERS/Lucy Nicholson 

A woman participates in a sack race at a shopping center in Paris on the first day of the winter sales in France, January 6, 2016. REUTERS/Benoit Tessier 

People participate in a sack race at a shopping center in Paris on the first day of the winter sales in France, January 6, 2016. REUTERS/Benoit Tessier 

People participate in a sack race at a shopping center in Paris on the first day of the winter sales in France, January 6, 2016. REUTERS/Benoit Tessier 

A boy collects dry leaves to be used for cooking fuel and heating during winter at a field in Charsadda near Peshawar, Pakistan, December 22, 2015. REUTERS/Fayaz Aziz 

A worker fills a 1-tonne super sack with coffee beans for export at a coffee warehouse in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

A worker transports 1-tonne super sacks with coffee beans for export at a coffee warehouse in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

A worker transports 1-tonne super sacks with coffee beans for export at a coffee warehouse in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

A worker transports 1-tonne super sacks with coffee beans for export at a coffee warehouse in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

A worker loads a 60-kg jute bag of coffee beans for export onto a belt at a coffee warehouse in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

A worker loads a 60-kg jute bag of coffee beans for export onto a belt at a coffee warehouse in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

Workers unload 60-kg jute bags of coffee beans for export in a coffee warehouse in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

Workers unload 60-kg jute bags of coffee beans for export in a coffee warehouse in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

Workers load 60-kg jute bags of coffee beans for export into a container in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

Workers load 60-kg jute bags of coffee beans for export into a container in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

Workers load 60-kg jute bags of coffee beans for export into a container in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

Workers load 60-kg jute bags of coffee beans for export into a container in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

Workers load 60-kg jute bags of coffee beans for export onto a container in Santos, Brazil, December 10, 2015. By introducing massive plastic sacks to replace the 60-kg (132-lb) jute bags that have dominated coffee shipments for more than two centuries, firms are saving millions of dollars a year, in a move so successful it is expected to reshape the global industry. Until a few years ago, the world's biggest coffee producer dispatched nearly all its exports in jute bags. Next year will see Brazil export more than half its green coffee in 1-tonne polypropylene 'super sacks' or 21.6-tonne polyethylene liners. Picture taken December 10, 2015. REUTERS/Paulo Whitaker 

A shop owner poses for a photograph at the Mercato market in Addis Ababa December 16, 2015. Addis Ababa's 'Mercato' - Italian for 'market' - is reputedly the biggest open-air market in Africa, lying in the west of the capital. Supermarkets have sprouted across the city as the metropolis has expanded with Ethiopia's booming economy, but Mercato remains a popular destination for shoppers seeking clothing, electronics and a huge range of other items. It has been around for as long as the city, which was founded at the end of the 19th century, but it took its current form, and its name, from the Italians who invaded Ethiopia in 1935. The Italian occupation ended in 1941. Picture taken December 16, 2015. REUTERS/Tiksa Negeri

Labourers unload sacks of rice from a handcart at a wholesale market in Kolkata, India, December 14, 2015. India's wholesale prices fell for a 13th straight month in November, but a sharp pickup in food prices and a pending wage hike for millions of government employees are likely to keep policymakers worried about potential inflationary risks. REUTERS/Rupak De Chowdhuri 

Labourers load sacks of flour and rice onto a supply truck at a wholesale market in Kolkata, India, December 14, 2015. India's wholesale prices fell for a 13th straight month in November, but a sharp pickup in food prices and a pending wage hike for millions of government employees are likely to keep policymakers worried about potential inflationary risks. REUTERS/Rupak De Chowdhuri 

A squirrel stretches out on a heap of sacks filled with paddy at a grain market in Chandigarh, India, December 2, 2015. REUTERS/Ajay Verma TPX IMAGES OF THE DAY

A woman who sells recyclable waste walks though Times Square with bags of full of bottles and cans in the Manhattan borough of New York November 25, 2015. REUTERS/Carlo Allegri 

People help lift a horse who slipped pulling a cart, overloaded with sacks of onions, on outskirts of Peshawar, Pakistan November 25, 2015. REUTERS/Fayaz Aziz 

A member of al-Qaeda's Nusra Front stands in front of piled sandbags as other members sit in a trench near the two Shi'ite Muslim towns of al-Foua and Kefraya in northwestern Syria, September 22, 2015. REUTERS/Khalil Ashawi 

Roy Ruffin opens sacks of samples from cotton bales at the USDA cotton classing lab in Memphis, Tennessee October 24, 2015. The USDA classes nearly all of the cotton produced in the United States. Fields along the Mississippi River Delta once gleamed white in the autumn with acre upon acre of cotton ready to be picked. This year U.S. farmers planted the fewest acres of cotton since 1983, according to U.S. Department of Agriculture data. REUTERS/Brian Snyder PICTURE 18 OF 28 FOR WIDER IMAGE STORY "THE LEGACY OF 'KING COTTON' IN THE AMERICAN SOUTH" SEARCH "KING COTTON" FOR ALL IMAGES 

A man carries a sack of onions at the market after the curfew is lifted in Birgunj, Nepal November 5, 2015. Nepal has faced an acute fuel crisis for more than a month since protesters in the lowland south, angered that a new constitution fails to reflect their interests, prevented supply trucks from entering from India. Many in Nepal see India's hand in the protests although it denies any role. REUTERS/Navesh Chitrakar 

A woman pushes a bicycle with a sack on the back of it in central Pyongyang October 9, 2015. Picture taken October 9, 2015. To match Insight NORTHKOREA-CHANGE/ REUTERS/Damir Sagolj 

A man waits to receive food provided by the United Nations' World Food Programme (WFP) during a visit by a European Union delegation, at an Internally Displaced Persons (IDP) camp in Azaza, east of Ad Damazin, capital of Blue Nile state, Sudan October 21, 2015. The camp houses people displaced by war between Sudan People's Liberation Movement-North (SPLM-N) rebels and the Sudanese government. REUTERS/Mohamed Nureldin Abdallah TPX IMAGES OF THE DAY

A food vendor carries a sack containing food item as he evacuated due toTyphoon Koppu in Manila, October 18, 2015. Powerful Typhoon Koppu ploughed into the northeastern Philippines before dawn on Sunday destroying homes and displacing 10,000 people and whipping up coastal surges four meters (12 feet) high, disaster agency officials said. There were no reports of casualties after the category four typhoon, with central destructive winds of 175 kph (109 mph), made landfall around 1 a.m. (1700 GMT) near the town of Casiguran in Aurora province. REUTERS/Erik De Castro 

People rest next to stacked sacks of onions at a wholesale vegetable market in New Delhi, India, October 14, 2015. India's wholesale prices fell for an 11th straight month in September, plunging an annual 4.54 percent primarily on the back of tumbling oil prices, government data showed on Wednesday. REUTERS/Anindito Mukherjee 

A child drinks water near the monthly food ration at a distribution center in rural Mupinga area in Chiredzi, Zimbabwe, October 6, 2015. Tens of millions of people across sub-Saharan Africa are going hungry due to erratic weather and the situation is set to worsen as the El Nino weather pattern reaches its peak, the Red Cross said on Monday as it launched funding appeals for six countries, including Zimbabwe. REUTERS/Philimon Bulawayo 

An elderly woman arrives to collect her monthly food ration at a distribution center in rural Mupinga area in Chiredzi, Zimbabwe, October 6, 2015. Tens of millions of people across sub-Saharan Africa are going hungry due to erratic weather and the situation is set to worsen as the El Nino weather pattern reaches its peak, the Red Cross said on Monday as it launched funding appeals for six countries, including Zimbabwe. REUTERS/Philimon Bulawayo 

Women arrive to collect their monthly food rations sourced by World Food Programme (WFP), in the rural areas of Mupinga, Chiredzi, Zimbabwe, October 6, 2015. Tens of millions of people across sub-Saharan Africa are going hungry due to erratic weather and the situation is set to worsen as the El Nino weather pattern reaches its peak, the Red Cross said on Monday as it launched funding appeals for six countries, including Zimbabwe. REUTERS/Philimon Bulawayo TPX IMAGES OF THE DAY

Zimbabwean women collect their monthly food ration from a distribution center in rural Mupinga area in Chiredzi, Zimbabwe, October 6, 2015. Tens of millions of people across sub-Saharan Africa are going hungry due to erratic weather and the situation is set to worsen as the El Nino weather pattern reaches its peak, the Red Cross said on Monday as it launched funding appeals for six countries, including Zimbabwe. REUTERS/Philimon Bulawayo 

A Zimbabwean woman collects her monthly food ration from a distribution center in rural Mupinga area in Chiredzi, Zimbabwe, October 6, 2015. Tens of millions of people across sub-Saharan Africa are going hungry due to erratic weather and the situation is set to worsen as the El Nino weather pattern reaches its peak, the Red Cross said on Monday as it launched funding appeals for six countries, including Zimbabwe. REUTERS/Philimon Bulawayo 

Farmers from Burkina Faso weigh sacks of cocoa in a village built inside the protected Gouin-Debe forest in Blolequin department, western Ivory Coast August 17, 2015. Picture taken August 17, 2015. To match Insight IVORYCOAST-COCOA/ENVIRONMENT REUTERS/Luc Gnago 

A sachet with the GrabTaxi logo is seen in a car in Hanoi, Vietnam September 9, 2015. A young, tech-savvy population short on cars but big on smartphones is driving double-digit growth for ride-hailing apps Uber and GrabTaxi in Vietnam, and inspiring some executives to dream of replacing private car ownership altogether. Ride-sharing apps have taken off among Vietnam's rapidly expanding middle class as they provide four-wheeled comfort in a country better known for chaotic swarms of scooters and Southeast Asia's most expensive taxi fares. Picture taken September 9, 2015. REUTERS/Kham 

Migrants sleep in sleeping bags near the main bus station in Istanbul, Turkey, September 18, 2015. Hundreds of Syrians and other migrants thronged a small park in central Istanbul on Wednesday, hoping for a last chance to reach Europe before poor weather makes their favoured route from Turkey to Greece too dangerous to undertake. REUTERS/Huseyin Aldemir 

A migrant rests in a sleeping bag in a makeshift camp at a collection point in the village of Roszke, Hungary, September 7, 2015. Picture taken on September 7, 2015. REUTERS/Marko Djurica

A combination of pictures shows a migrant resting in a sleeping bag (top) taken on September 7, 2015 and garbage on the ground on September 17, 2015 at the same place in a makeshift camp at a collection point in the village of Roszke, Hungary. REUTERS/Marko Djurica/Dado Ruvic 

A worker carry sack of fruit as walks during haze shrouded in Jambi, on the Indonesian island of Sumatra, September 17, 2015. A worsening haze across northern Indonesia, neighbouring Singapore and parts of Malaysia on Tuesday forced some schools to close and airlines to delay flights, while Indonesia ordered a crackdown against lighting fires to clear forested land.REUTERS/Beawiharta 

A labourer moves sacks of cement from one truck to another bound for Afghanistan at a transit depot in Peshawar, Pakistan September 16, 2015. Pakistan and Afghanistan have shelved a raft of agreements that promised to more than triple cross-border trade, officials said, as economic ties seen as key to regional stability fall victim to rivalry and suspicion. REUTERS/Fayaz Aziz 

A labourer moves sacks of onions to a truck bound for Afghanistan at a transit depot in Peshawar, Pakistan September 15, 2015. Pakistan and Afghanistan have shelved a raft of agreements that promised to more than triple cross-border trade, officials said, as economic ties seen as key to regional stability fall victim to rivalry and suspicion. Picture taken September 15, 2015. REUTERS/Fayaz Aziz 

A boy waits for customers while sitting near his livestock for sale at a cattle market on the outskirts of Islamabad, Pakistan, September 15, 2015. Muslims across the world are preparing to celebrate the annual festival of Eid al-Adha or the Festival of Sacrifice, which marks the end of the annual hajj pilgrimage, by slaughtering goats, sheep, cows and camels in commemoration of the Prophet Abraham's readiness to sacrifice his son to show obedience to Allah. REUTERS/Faisal Mahmood

An employee of a local farm has a meal while sitting on sacks of potatoes for sale at a street market on an embankment of the Yenisei River in the Siberian town of Divnogorsk near Krasnoyarsk, Russia, September 10, 2015. REUTERS/Ilya Naymushin 

An employee of a local farm loads sacks of potatoes on a customer's trailer at a street market on an embankment of the Yenisei River in the Siberian town of Divnogorsk near Krasnoyarsk, Russia, September 10, 2015. REUTERS/Ilya Naymushin 

Customers buy potatoes from a local farm at a street market on an embankment of the Yenisei River in the Siberian town of Divnogorsk near Krasnoyarsk, Russia, September 10, 2015. REUTERS/Ilya Naymushin 

Employees of a local farm weigh sacks of potatoes at a street market on an embankment of the Yenisei River in the Siberian town of Divnogorsk near Krasnoyarsk, Russia, September 10, 2015. REUTERS/Ilya Naymushin