The Global Climate Risk Index, published by the German environmental think tank Germanwatch, ranked Vietnam sixth among countries hit hardest by extreme weather events in that period, with its Climate Risk Index (CRI) at 29.83.

Puerto Rico, Myanmar, Haiti, the Philippines and Pakistan are adjudged the worst affected nations with the lowest CRI scores.

The other four that make the top 10 are Bangladesh, Thailand, Nepal and Dominica, according to the survey results announced at the ongoing 2019 United Nations Framework Convention on Climate Change in Madrid, Spain.

The index for the 1999–2018 period is based on average values over a 20-year period, and the countries featured in the top 10 can be divided into two groups: those that have a high ranking due to exceptional catastrophes and those that are continuously affected by extreme events.

Vietnam suffered 226 extreme events in 1999-2018 with a death toll of 285 and losses of more than $2 billion per year.

Germanwatch uses data from the NatCatSERVICE database of the Munich Reinsurance Company, a reinsurance company based in Munich, Germany, as well as the socioeconomic data from the International Monetary Fund (IMF) to compile the CRI index.

The independent non-governmental organization that has been advocating for global equity and the preservation of livelihoods since 1991, has presented the index at the annual U.N. climate meet since 2006.

Even though the evaluation of the rising damages and fatalities do not allow for simple conclusions on the influence of climate change on these events, it shows the increase of heavy disasters and does give a good impression of how states and territories are affected, Germanwatch says.

Last year alone, Japan, the Philippines and Germany were the most affected countries followed by Madagascar, India and Sri Lanka, with Japan and Germany hit hardest by heat waves and drought.

"The Climate Risk Index shows that climate change has disastrous impacts especially for poor countries, but also causes increasingly severe damage in industrialized countries like Japan and Germany," said David Eckstein, policy advisor at Germanwatch.

"Countries like Haiti, Philippines and Pakistan are repeatedly hit by extreme weather events and have no time to fully recover. This underlines the importance of reliable financial support mechanisms for poor countries like these, not only in climate change adaptation, but also for dealing with climate-induced loss and damage."

Germanwatch said heat waves were a major cause of damage in 2018.

Of the 10 most affected countries last year, Germany, Japan and India suffered from extended periods of heat. Recent science has confirmed the long established link between climate change and the frequency and severity of extreme heat. In Europe, for example, extreme heat spells are now up to 100 times more likely than a century ago. Furthermore, due to a lack of data, impacts of heatwaves on the African continent may be under-represented, the U.N. meet heard.