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China's 'Green Great Wall' Has Created an Unexpected Environmental Mess
August 31, 2018
A massive tree-planting campaign the country embarked on years ago to help clean up the environment now looks like it is increasing pollution.
A coniferous forest shrouded in fog.
There is a sarcastic saying that “no good deed goes unpunished”. In the case of China’s national tree-planting campaign begun to help save the environment, a new research study appears to be proving the truth of that saying, as it now says the country’s ‘Green Great Wall’ planting campaign is trapping pollution across the country.
This is the conclusion of a new research study published this month in the journal Atmospheric Chemistry and Physics. The work was jointly conducted by scientists at the Institute of Earth Environment at the Chinese Academy of Sciences in Xian, the Joint Centre for Global Change Studies in Beijing, and the National Center for Atmospheric Research in Boulder, Colorado.
The Chinese forestation program, the largest ever conducted by any country in the world, was created to help with soil and water conservation in the country. It has been wildly successful in that, with forest coverage having increased from 8.6 percent in 1949 to 21.17 percent as of 2017. The total size of the man-made forest is now 69.3 million hectares. That is a region larger than the entire country of France.
In addition to controlling soil and water loss, some studies have calculated out that the trees have the potential to remove ozone, nitric oxides, sulphur dioxide and PM2.5 particulates – pollution components common in motorcycle exhaust, for example. The concept was that their leaves could operate as a sort of living air filter.
While it is hard to think of planting carbon-dioxide absorbing trees as a negative, one hint at how environmental issues may not have been fully thought through in the planning is that some are now on land like desert, steppe and high mountain areas. Those regions are ones where trees would not have grown naturally and their presence there could conceivably cause problems.
A second and more serious problem is that wind which normally would have blown through open plains with just groundcover is now stopped by the trees. That prevents much of the natural smog dispersal those winds create.
Overall, the scientists involved in the study have raised major concerns about the forestation that need to be addressed. Using satellite data on the spread of the artificial forests, the researchers looked into the rate of pollution growth locally to see if there was any correlation. What they found was that as much as 6 percent of the air pollution increase in all of northern China’s 218,000 square kilometers was likely caused by the presence of the man-made plantings. Far from acting as a living air filter, the wall of trees is walling in the smog.
In a specific example, the researchers looked into a major smog incident which occurred in Beijing in January 2014. In that case it appears the newly-planted trees blocked an estimated 15 percent of the highly-toxic PM2.5 fine particulates (less than 2.5 microns in size). That drove the PM 2.5 level to 350 micrograms per cubic meter of air during peak times then. That is 14 times what the World Health Organization calls safe.
These scientific findings, while new, were already understood at a gut level by many of the Chinese people. There is already a saying in the country that where there are more trees there will now be more smog.
Despite these findings, China’s government plans to continue its aggressive planting campaign. This year alone it intends to plant another 84,000 square kilometers of new forests. 60,000 soldiers from the People’s Liberation Army having been pressed into service for the campaign, much of which is focused on lands north of Beijing. The total plantings this year are equivalent in coverage to a land mass the size of Ireland.
The researchers are under pressure to keep quiet about the results, now that they have been published. One of the researchers in the study – whose name is being kept confidential for obvious reasons – said that, “We are not allowed to speak to media (about the paper) without authorization. I don’t think we will get a nod from the top.”
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