All combined, the natural disasters that the world saw in 2011 have amounted to a whopping economic cost of $US380 billion, according to a new report issued by the United Nations on Monday.

From the Queensland floods that hampered Australia's mining productions to the epic Japanese earthquake that virtually halted Japan's economic activities in March 2011, the UN report said that the disasters that mankind experienced last year proved as the costliest ever.

Prior to Japan's disaster woes, which also spawned tsunami waves that obliterated communities and killed thousands, a powerful tremor also struck New Zealand then by mid-year, a large tract of Thailand was engulfed in flood waters, bringing the country's manufacturing to a prolonged standstill.

And before the year ended, flash floods and a quake hit the Philippines, bringing with them considerable deaths and sufferings in the immediate aftermath.

According to Margareta Wahlstrom, who handles the UN Secretary-General's disaster risk reduction department, what happened in 2011 had exceeded the economic costs spawned by Hurricane Katrina, which ravaged the southern United States in 2005.

Wahlstrom noted too that the Japan's series of disasters last year clearly emerged as the most disturbing event in 2011, both socially and economically.

The magnitude-9 quake that shook Japan generated gigantic tsunami waves that delivered most of the damages that the country had sustained, which for a time threatened the rest of the world too when inundating waters knocked out the generators that powered the coolers of the nuclear reactors in the Fukushima power plants.

The UN report said that what happened in Fukushima almost replicated the fear that gripped the world when radiation escaped into the atmosphere during the Chernobyl nuclear accident in the mid-1980s.

Inevitably Japan found the solution to avert a near-nuclear disaster but the country's economy, already reeling from a previous recession, absorbed the damages most, with the Japanese government overwhelmed by production stoppages and rebuilding efforts.

Considering the natural forces that were unleashed during those disturbances, the UN report also noted that human toll of the numerous disasters had decreased considerably as countries appeared better equipped to minimise deaths and injuries.

Still, Wahlstrom said that "50 percent of the world's population is exposed to disaster risks because they live in the highly vulnerable areas," with Japan being singled out by the UN report as having the highest economic exposure and the second-highest population exposure to potential disasters.

"The economics of disasters is becoming a major threat to a number of countries ... and the main message is that this is an increasing, very rapidly increasing trend with increasing economic losses," Wahlstrom was reported by the Associated Press (AP) as saying in the UN report.

She added that natural disaster have become more deadly because of climate change, which the UN blamed to the abuse of natural resources and destruction of the environment.

Consequently, governments need to mull over sweeping measures that would better prepare them on the projected challenges of the decades ahead, mostly confined on the economic impacts of climate change and natural disasters.

The UN report also warned that as the global population further explodes, more resources will be required to sustain man's existence while taking into consideration that the planet now faces dwindling natural resources.

Over the next 40 years, the world must strive to generate more food, energy and water in order to ensure that man can still live decently, the UN report said.