THE PAST FORTY years were supposed to be different.

In the years after World War II, battle-scarred countries vowed never again to witness such large-scale crises as were seen in the first half of the 20th century. There was a concerted effort by many developed countries to prevent any man-made disasters, and to put in place new ways to deal with natural disasters.

The crises which have struck around the world in the past four decades have been devastating. From the earthquake in Haiti in 2010 to the genocide in Rwanada in 1994, the world has witnessed atrocities on a scale never previously imagined. What has changed, however, is how the world responds.

These photos show some of the most striking images from some of the the worst disasters. Some reader discretion is advised.

1. Famine in North Korea

The notoriously secretive communist country has never been open about just how badly it was affected by the famine which hit during the late 1990s, but the World Food Programme has estimated that up to two million North Koreans died and six million needed food aid when unexpectedly bad weather caused severe damage to food stocks.

This photograph showing severely malnourished children in an orphanage was taken by Trócaire director Justin Kilcullen during a visit to North Korea and was one of the first images to emerge from the country documenting the extent of the famine.

2. Earthquake in Haiti

The earthquake which struck the Caribbean nation of Haiti in January 2010 was devastating: more than 250,000 people were killed and 1.2 million people – almost one-eighth of the population – were left homeless. This photograph shows an injured woman shortly after the earthquake hit. (AP Photo/Santiago Lyon)

3. Genocide in Rwanda

In the space of 100 days between April and June 1994, an estimated 800,000 Rwandans - the majority of them Tutsis - were killed in a brutal, bitter mass slaughter, the largest genocide in Africa in modern times.  Rwanda had long battled with ethnic tension but the world was shocked by the graphic  images which showed the extent of the violence.

Despite this, western countries did not intervene to stop the slaughter - even when it became clear what was happening - leading to much criticism of their overly cautious approach. Instead, the role fell to humanitarian and aid organisations. This photograph shows Tutsi victims being buried in a mass grave in Rwanda. (AP Photo/Jorge Cruz)

4. El Salvador

The assassination of Archbishop Oscar Romero as he celebrated mass in El Savador in 1980 was the trigger for a bloody civil war which lasted 12 years and claimed the lives of an estimated 75,000 people. The war was brutal: Irish aid agency Trocáire has described it as one of the most dangerous emergency relief programmes in its history as it battled to help the people of the country.

This photograph shows a nun kissing the forehead of the assassinated Archbishop at the hospital he was brought to after he was shot. (AP Photo/Eduardo Vazquez Becker)

5. Asian tsunami

The disastrous earthquake and tsunami which hit 13 countries in Asia on 26 December 2004 was the world's largest since the 1960s and released as much energy as 23,000 Hiroshima-sized atomic bombs. At least 226,000 people were killed, including 166,000 in Indonesia, and more than half a million were injured. Millions more lost their homes or their belongings.

This photograph shows the scale of the devastation left in the commercial area of Banda Aceh in northwest Indonesia five days after the tsunami ravaged the city. (Photo: Bullit Marquez/AP)

6. Cambodia

In the course of four years in the late 1970s, the ruling Khmer Rouge party in Cambodia was responsible for one of the worst mass killings of the 20th century. Estimates suggest anywhere between one million and 2.5 million died from execution, starvation and disease under the communist regime.

This photo shows a soldier of the Khmer Rouge waving his gun and ordering shop owners to abandon their properties in Phnom Penh in April 1975 as the capital fell to the communist forces. (AP Photo/Christoph Froehder)

7. Sudan

There were hopes that splitting Sudan into two independent countries in 2011 would help ease tensions after the civil war which lasted two decades. However the conflict - which has led to the deaths of an estimated 1.5 million people - continues to take its toll, exacerbated by food shortages and humanitarian crises. Few aid agencies are able to get through to deliver help.

This photograph shows an ill child at a clinic in Sudan. (Photo: Julien Behal/PA Wire)

8. Somalia

In 1992, Somalia was in chaos. The country was in the middle of a famine and a brutal civil war, which made the distribution of aid even more difficult. The State had collapsed and rival militias were vying for control of the country.The UN has estimated that around 300,000 people - many of them children - died, while some 2 million people were forced out of their home areas by the violence .

This photo shows a man clinging to a wheelbarrow outside a feeding centre in the Somalian city of Baidoa in November 1992. It is not known whether the man survived. (AP Photo/David Brauchli)

9. Chile

This photograph from 11 September 1973 shows soldiers and firefighters carrying the body of Chile's president Salvador Allende from the destroyed presidential palace in Santiago, after a US-backed coup by the military overthrew Allende's democratically elected government. Allende took his own life.

Thousands of people were killed or 'disappeared' during the regime led by General Augusto Pinochet until 1988, while tens of thousands were held as political prisoners and tortured. Religious organisations and NGOs repeatedly sought help from foreign aid agencies over the human rights abuses which took place in the country over fifteen years. (AP Photo)

• Trocáire's Lentin campaign runs until this Sunday 31 Easter. To find out more visit trocaire.org/lent or call 1050 408 408.
• The agency is thanking Irish people for four decades of life-changing support, which has helped people across the developing world overcome poverty, injustice and human rights abuses.

Read: Here's how Ireland distributed €159 million among nine countries last year >

In pics: 40 years of the Trócaire Lenten box >