MONRE has issued a set of scenarios for expected climate change events as a first step in ‘mainstreaming’ climate change assumptions into long-range Government planning.
This MONRE map shows the impact of a 75 cm rise in average sea levels on the Mekong Delta region. The bright red zones will only be inundated in the event of a storm surge; the darker areas will be – all else being equal – permanently under water.
The scenario-building work by the Ministry of Natural Resources and Environment (MONRE) relies on extensive historical data and the best current estimates by the Vietnamese and international scientific community. Minister Pham Khoi Nguyen said MONRE will continue to update the scenarios, especially on sea rise level, so that ministries, sectors and provinces can take specific actions to limit negative impacts of climate change.
Deputy Prime Minister Hoang Trung Hai has authorized the scenarios’ distribution extensively throughout the Vietnamese administration.
Nguyen told reporters that in the last 50 years, Vietnam’s average temperature increased by 0.5-0.7oC while the sea level rose by 20cm. Both trends have intensified the impact of storms and floods.
What do the scenarios say?
Vietnam, with large populations concentrated in low-lying delta regions, is recognized as one of the nations most vulnerable to climate change – an unsettling fact that has energized government experts and planners.
According to the MONRE scenarios, 90 years from now Vietnam’s average temperature will be 2.3 degrees Celsius above the average level of the 1980-1999 period. It is forecast that the temperature rise will be greatest in Vietnam’s northern half, roughly 2.8 degrees C. Overall, winter temperatures will rise more rapidly than summer temperatures.
The scenarios also show greater total rainfall, wetter wet seasons and drier dry seasons, especially in the southern region.
The tendency is predicted to be more pronounced in the north.
Regarding sea levels, the MONRE experts predict the average level of Vietnam’s seas will rise 28-33 cm by the middle of the 21st century and 65-100 cm by the end of the 21st century as compared with the 1980-1999 period.
Local authorities to define losses caused by climate change
The head of the National Institute for Hydrometeorology and Environmental Sciences, Tran Thuc, told reporters that these scenarios only take into account average parameters, because although there is no question climate change is occurring at an accelerated rate, there’s considerable uncertainty about its likely extent. The current scenarios don’t provide detailed judgments about losses caused that are likely to be experienced by regions and cities that are highly vulnerable to climate change, like the Mekong Delta and HCM City.
The scenarios only tell when the sea level rises by 65 or 75 centimeters, how many square kilometers of land in HCM City or the Mekong Delta will be flooded. According to Thuc, local governments can use the data to understand more clearly the likely local impacts. He said the MONRE will provide local authorities with detailed maps of areas that will be flooded at different sea rise levels. MONRE will assist the most vulnerable locations to estimate specific losses caused by climate change and work out responses that mitigate or adapt to its impact.
The experts who developed the scenarios discovered noteworthy points in weather and the sea level:
Â· The annual average temperature of the last four decades (1961-2000) was higher than the annual average level of the three decades ago (1931-1960).
Â· In Hanoi, Da Nang and HCM City, the annual average temperature during the 1991-2000 period was higher than that of the 1931-1940 decade, + 0.8oC for Hanoi, + 0.4oC for Da Nang and + 0.6oC or HCM City. The trend has continued into the first decade of the 21st century: in 2007, the average annual temperature of the three above cities was 0.4-0.5oC above the average of the 1991-2000 decade.
Â· There have been fewer but sharper cold spells in the past two decades, for example the prolonged cold snap recorded in the North in January and February 2008.
Â· Tropical storms impacting Vietnam have grown stronger and they have tended to move southwards. The storm season also ended later, with many storms having abnormal tracks.
Scenarios for sea level rise, all else being equal:
1/ HCM City: If the average sea level rises by 65cm, 128 square kilometers of land (6 percent of the total area) will be submerged. The flooded area will increase to 204 square kilometers (10 percent) if the sea level rises by 75cm and 473 square kilometers (23 percent) in the event of a one meter rise.
2/ The Mekong Delta: If the sea level is up by 65 cm, up to 5133 square kilometers of land (12.8 percent) will be submerged; at +75 cm, 7580 square kilometers (19 percent). A one-meter rise in the average sea level will inundate 15,116 square kilometers, 37.8 percent of the Delta’s current land area.
Under the various scenarios, a considerably larger area would be subject to periodic flooding as a result of storm surges.