The latest cyclical warming of Pacific Ocean waters, first observed centuries ago and formally tracked since 1950, began earlier this year and has already been felt across Asia, Africa and Latin America.
Weather experts predict this El Nino will continue into the spring of 2016 and could wreak havoc, because climate change is likely to exacerbate the intensity of storms and flooding in some places and of severe drought and water shortages in others. El Nino's impacts are global, with heavy rain and severe flooding expected in South America and scorching weather and drought conditions likely in the Horn of Africa region.
The risk is especially great for East Asia-Pacific countries that are highly vulnerable to altered weather patterns because of climate change. This year will likely be the hottest ever recorded, increasing the El Nino effect caused by weakened trade winds that fail to push warmer Pacific Ocean waters to the west.
We know what the potential effects might be. In 1997 and 1998, the strongest El Nino on record led to the deaths of 23,000 people from natural disasters, increased poverty rates by 15 percent in some countries and cost governments up to $45 billion owing to severe storms, droughts and other effects.
Such a global challenge calls for a global response - with coordinated efforts by governments, international institutions such as the World Bank, relief agencies and communities - to minimize the death and destruction from natural catastrophes while building more resilient societies.
The good news is that we have learned from the past how to better predict, prepare and respond. We now know that disaster risk management and early warning systems can provide forecasts and data that reduce death tolls and economic losses from severe weather.
These achievements show that building resilient and adaptable societies is the most effective strategy to meet challenges such as El Nino. But instead of limiting our approach to the specific challenge of El Nino, we should continue to support investments in sustainable growth and building resilience to the changing climate.
In its recent East Asia-Pacific Economic Update, the World Bank Group warned that failing to anticipate El Nino's impacts could have serious economic development repercussions for the region. Food shortages, wildfires and depleted water resources are likely in some areas, and torrential rains in other areas can cause flooding and human migration.
An El Nino typically leads to higher demand for polluting energy sources like coal and crude oil, because hydropower generation declines due to high heat and drought. Drought and flood can also spark outbreaks of diseases from contaminated water and reduced hygiene as well as mosquito-borne viruses like dengue.
In the Philippines, the government predicts 80 percent of the country will likely experience drought by February 2016, while farmers in parts of Vietnam, Laos and Cambodia are already leaving fields and rice paddies unplanted due to excessively dry and hot conditions.
In China's Liaoning province, the lowest rainfall levels since 1951 left more than 230,000 people short of drinking water in July. This summer, Myanmar experienced severe flooding and landslides that displaced more than 1.6 million people.
Pacific islanders also face water shortages, because lack of rainfall threatens freshwater sources in societies mostly dependent on agriculture. Water shortage can have serious health implications, with increased risk of disease outbreak.
Now, as we get ready to confront an El Nino that could be one of the strongest on record, it's time for us to mobilize a unified response to protect the development gains of recent decades for people in East Asia Pacific.
The author, Axel Van Trotsenburg, is the World Bank vice-president for East Asia and Pacific.
