If you want to be happy, move to a cold European country. That seems to be the message sent out by the 2016 World Happiness Report. Denmark overtook Switzerland as the world's happiest place, according to a report prepared by the Sustainable Development Solutions Network (SDSN) and the Earth Institute at Columbia University. The United States was ranked at 13, Germany at 16, the United Kingdom at 23, France at 32, and Italy at 50.

Eight sub-Saharan African countries were among the 10 least happy places on earth, along with Syria and Afghanistan.

Aiming to "survey the scientific underpinnings of measuring and understanding subjective well-being," the report, now in its fourth edition, ranks 157 countries by happiness levels using factors such as per capita gross domestic product (GDP) and healthy years of life expectancy. It also rates "having someone to count on in times of trouble" and freedom from corruption in government and business.

While the differences between countries where people are happy and those where they are not could be scientifically measured, "we can understand why and do something about it," according to Professor Jeffrey Sachs, head of the SDSN and special advisor to UN Secretary General Ban Ki-moon.

The 2016 survey showed that three countries in particular, Ireland, Iceland and Japan – ranked 19, 3 and 53 respectively – were able to maintain their happiness levels despite external shocks such as the post-2007 economic crisis and the 2011 earthquake because of social support and solidarity.

Sachs issued a warning for the US: "There is a very strong message for my country, the United States, which is very rich, has gotten a lot richer over the last 50 years, but has gotten no happier. The message for the United States is clear. For a society that just chases money, we are chasing the wrong things. Our social fabric is deteriorating, social trust is deteriorating, faith in government is deteriorating," he said.