The People's Liberation Army's Air Force Air Demonstration Team, China's best-known aerobatic team, performs at Langkawi International Maritime and Aerospace Exhibition in Langkawi, Malaysia, on Thursday

Vincent Thian/AP

The People’s Liberation Army’s Air Force Air Demonstration Team, China’s best-known aerobatic team, performs at Langkawi International Maritime and Aerospace Exhibition in Langkawi, Malaysia, on Thursday

A father and son on a makeshift boat made from styrofoam paddle through a garbage filled river as they collect plastic bottles that they can sell in junkshops in Manila on March 19, 2015. They earn three US dollars a day. The Philippines will be observing World Water day on March 22, a global event that focuses on finding access to clean and safe water

Noel Celis/AFP

A father and son on a makeshift boat made from styrofoam paddle through a garbage filled river as they collect plastic bottles that they can sell in junkshops in Manila on Thursday

Police officers are seen on the pavement outside parliament in Tunis...Police officers are seen on the pavement outside parliament in Tunis March 18, 2015. Gunmen attacked Tunisia's national museum near its parliament on Wednesday, killing at least seven tourists and taking others hostage inside the building, the government said

Zoubeir Souissi/Reuters

Police officers are seen on the pavement outside parliament in Tunis. Gunmen attacked Tunisia’s national museum near its parliament on Wednesday, killing at least seven tourists and taking others hostage inside the building

Israeli Prime Minister Benjamin Netanyahu waves to supporters at the party headquarters in Tel Aviv March 18, 2015. Netanyahu claimed victory in Israel's election after exit polls showed he had erased his center-left rivals' lead with a hard rightward shift in which he abandoned a commitment to negotiate a Palestinian state

Amir Cohen/Reuters

Israeli Prime Minister Benjamin Netanyahu waves to supporters at the party headquarters in Tel Aviv on Wednesday. Netanyahu claimed victory in Israel’s election after exit polls showed he had erased his center-left rivals’ lead with a hard rightward shift in which he abandoned a commitment to negotiate a Palestinian state

Wheelchair-bound Palestinian student teacher Ahmed al-Sawaferi, 25, who said that he lost his both legs and his left arm in an Israeli air strike in 2008, gives a class at an elementary school in Gaza City...Wheelchair-bound Palestinian student teacher Ahmed al-Sawaferi, 25, who said that he lost his both legs and his left arm in an Israeli air strike in 2008, gives a class at an elementary school in Gaza City March 18, 2015. Al-Sawaferi, a father for two children, is due to hold a B.A in Islamic studies after finishing his last university semester in June this year

Suhaib Salem/Reuters

Wheelchair-bound Palestinian student teacher Ahmed al-Sawaferi, 25, who said that he lost his both legs and his left arm in an Israeli air strike in 2008, gives a class at an elementary school in Gaza City on Wednesday. Al-Sawaferi, a father for two children, is due to hold a B.A in Islamic studies after finishing his last university semester in June this year

A Palestinian protester returns a tear gas canister fired by Israeli troops during a protest against what Palestinians say is land confiscation by Israel for Jewish settlements, near the West Bank town of Abu Dis near Jerusalem March 17, 2015.

Mohamad Torokman/Reuters

A Palestinian protester returns a tear gas canister fired by Israeli troops during a protest against what Palestinians say is land confiscation by Israel for Jewish settlements, near the West Bank town of Abu Dis near Jerusalem on Tuesday

Helpers in boats lead swans from their wintering grounds back to the Aussenalster river in Hamburg, northern Germany, on March 17, 2015. Around 120 swans were moved from their ice-free winter home back to the city center

Daniel Bockwoldt/DPA/AFP

Helpers in boats lead swans from their wintering grounds back to the Alster river in Hamburg, northern Germany. Around 120 swans were moved from their ice-free winter home back to the city centre

The 'Frecce Tricolori' Italian Air Force acrobatic squad fly over Rome, Tuesday, March 17, 2015 to mark the 154th anniversary of the Italian Unification in 1861

Gregorio Borgia/AP

The ‘Frecce Tricolori’ Italian Air Force acrobatic squad flies over Rome on Tuesday to mark the 154th anniversary of the Italian Unification in 1861

Ultra orthodox Jewish rabbi Gershon Edelstein prepares to vote in Bnei Brak, Israel, Tuesday, March 17, 2015.  Israelis are voting in early parliament elections following a campaign focused on economic issues such as the high cost of living, rather than fears of a nuclear Iran or the Israeli-Arab conflict.

Oded Balilty/AP

Ultra orthodox Jewish rabbi Gershon Edelstein prepares to vote in Bnei Brak, Israel, in an unexpectedly close general election

Boys play as cows graze through garbage at the Deonar landfill site in Mumbai, India. Mumbai is running out of space for its waste, and Deonar, Asia's oldest and largest dumpsite, is bursting. Each day, more than 500 trucks line up along a two-lane dirt road in an eastern suburb, waiting to add to a mountain of refuse tall enough to submerge the White House twice over

Dhiraj Singh/Bloomberg

Boys play as cows graze through garbage at the Deonar landfill site in Mumbai, India. Mumbai is running out of space for its waste, and Deonar, Asia’s oldest and largest dumpsite, is bursting

People bring flowers to the eternal flame on the memorial of the heroic defense of Sevastopol (1941-1942) as Crimeans celebrate the first anniversary of the referendum on Monday in Sevastopol, Crimea . Today marks the first anniversary of the referendum which resulted in the annexation of the territory by Russia

Alexander Aksakov/Getty Images

People bring flowers to the eternal flame on the memorial of the heroic defense of Sevastopol (1941-1942) as Crimeans celebrate the first anniversary of the referendum on Monday in Sevastopol, Crimea . Today marks the first anniversary of the referendum which resulted in the annexation of the territory by Russia

Visitors and participants visit the Temple by renowned Burning Man artist David Best on March 16, 2015 in Londonderry, Northern Ireland. Members of the public will be able to use the Temple as a space for contemplation and remembrance, and to leave mementos, messages and photographs in its interior. Following this period, Temple and its contents will be ceremonially torched in a ceremony at dusk on Saturday March 21st

Charles McQuillan/Getty Image

Members of the public visit art project ‘The Temple’ in Londonderry, Northern Ireland. David Best’s installation hosts space for contemplation and remembrance, and people are encouraged to leave mementos, messages and photographs inside until Saturday, when ‘Temple’ and its contents will be ceremonially torched at dusk.

Mayor of London Boris Johnson plants flowers at the Royal Botanical Gardens where he joined Kew apprentices, diploma students, and Kew horticulturist Carlos Magdalena to plant young Victoria Amazonica Waterlilies, a colourful hybrid of waterlilies and lotus plants, in the Princess of Wales Conservatory at Kew Gardens

Stefan Rousseau/PA

Mayor of London Boris Johnson plants flowers at the Royal Botanical Gardens where he joined Kew apprentices, diploma students, and Kew horticulturist Carlos Magdalena to plant young Victoria Amazonica Waterlilies, a colourful hybrid of waterlilies and lotus plants, in the Princess of Wales Conservatory

A man stands between two trolleys loaded with bags containing his clothes and personal belongings outside the entrance of Fiumicino international airport in Rome...A man stands between two trolleys loaded with bags containing his clothes and personal belongings outside the entrance of Fiumicino international airport in Rome March 16, 2015.

Alessandro Bianchi/Reuters

A man stands between two trolleys loaded with bags containing his clothes and personal belongings outside the entrance of Fiumicino airport in Rome

People do morning exercises on a polluted day in Jiaozuo, Henan province, March 16, 2015. China cannot relent on efforts to tackle pollution, though a rapid turnaround should not be expected, the environment minister told a news conference early this month during China's annual parliamentary meeting.

China Daily/Reuters

People perform morning exercises on a polluted day in Jiaozuo, Henan province, China on Monday.

An Afghan health worker administers polio vaccine drops to a child on the second day of a vaccination campaign in Kabul on March 16, 2015. Nearly nine million children throughout Afghanistan will be immunized during a three-day national polio immunization drive launched on March 15.The immunization campaign comes shortly after Afghanistan reported its first case of polio virus for 2015, in Helmand, in the Southern Region. Afghanistan and Pakistan are the only two countries in the world to have reported cases of the crippling polio virus in the past eight months and it is increasingly likely that these are the last two countries on Earth with active polio transmission

Shah Marai/AFP

A health worker gives polio vaccine drops to a child on the second day of a national campaign in Afghanistan on Monday. Nearly nine million children in the country are being immunised during the three-day programme.

Supporters of Ahmed Ali Abdullah Saleh, the son of Yemen's former President Ali Abdullah Saleh, dance as they demonstrate to demand for a presidential election to be held and for him to run for presidency in Sanaa...Supporters of Ahmed Ali Abdullah Saleh, the son of Yemen's former President Ali Abdullah Saleh, dance as they demonstrate to demand for a presidential election to be held and for him to run for presidency in Sanaa March 13, 2015.

Khaled Abdullah/Reuters

Supporters of Ahmed Ali Abdullah Saleh, the son of Yemen’s former President Ali Abdullah Saleh, dance as they demonstrate to demand for a presidential election to be held and for him to run for presidency in Sanaa on Friday

A Royal Air Force Chinook flies over London during a Service of Commemoration for troops who were stationed in Afghanistan on March 13, 2015 in London, England. Royals including the Queen and the Duke and Duchess of Cambridge were joined by veterans and families at St Paul's Cathedral for a service commemorating the end of British involvement in the Afghanistan war.

Carl Court/Getty Images

A Royal Air Force Chinook flies over London during a Service of Commemoration for troops who were stationed in Afghanistan on Friday in London, England

A woman cries as she walks past destroyed houses in the town of Debaltseve, north-east from Donetsk, March 13, 2015.

Marko Djurica/Reuters

A woman cries as she walks past destroyed houses in the town of Debaltseve, north-east from Donetsk on Friday

Palestinian children play amidst debris of houses that were destroyed during the 50-day war between Israel and Hamas militants in the summer of 2014, in the Gaza Strip town of Beit Hanun on Friday.

Mohammed Abed/AFP

Palestinian children play amid debris of houses that were destroyed during the 50-day war between Israel and Hamas militants last summer, in the Gaza Strip town of Beit Hanun on Friday