Strong winds disperse air pollution. When the wind speed near the earth surface declines, it would be more difficult to eliminate haze and bring about more hazy days. According to the latest forecast by ProfJian Ma at the SHOU, this is not going to be a common phenomenon around the globe, and people do not have to worry too much about the increase of hazy days resulted from climate change.
One of the expected consequences of the rising concentration of greenhouse gases in the atmosphere is the increased static stability of the atmosphere, which weakens tropical troposphere circulation. The global climate models simulate this effect.Thus,onespeculates the reduction ofthe surface wind speed, which seems to be easily acceptable for many people. However, according to actual satellite data, the surface wind speed observed on large scales has not been weakened.
As pointed out by Jian Ma, “Climate forecast seems to be different from data observation, and this has been a controversial debate for more than a decade, asa confusion for the scientific world. Why is there such difference, and what is the essence of the problem? We believe that it’s very important to reconcile different opinions, and have made great efforts in this respect.”
To solve this problem, Ma Jian collaborated with his colleagues in both China and the U.S. to conduct a numerical simulation research on surface wind speed, and suggested a new forecast, that is, the spatially averagedland/ocean surface wind speed basically maintains a constant trend in global warming, which is consistent with satellite measurements and suggests that the above-mentioned speculation is groundless. To exclude the relationship between the weak change in surface wind and the “hiatus” of global warming started in the mid-1990s, Ma Jian led his team to analyze both the forecasts by 19 global climate models (CMIP5) concentrated and the data from wave height-corrected Wave and Anemometer-Based Sea Surface Wind (WASWind) during 1970-1995. They also illustrated the upcoming changes in the future century.
According to Ma’s team, even when troposphere circulation is weakened, the combination of various dynamic processes will prevent the global- and tropical-mean surface wind speed from experiencing substantial changes: In the large-scale tropics, the changes in sea surface temperature will enhance the surface winds of many regions, offset the trend of weakening Walker circulation and avoid significant changes in spatial-mean wind speed; in high-latitude regions, the surface wind shifts towards polar regions with synoptic eddy-driven mid-latitude westerlies, without experiencing much change in speed. Thus, speaking from the perspective of wind force, global warming does not increase the occurrence rate of haze.
This result has recently been published on SCI journal Environmental Research Letters, a high-level environmental research journal with an impact factor of 4.134. After being published, the paper has drawn wide attention, and has been covered by Environment Research Web (http://environmentalresearchweb.org/) with a feature article.
High-concentration greenhouse gases have resulted in global warming and adversely influenced human’s work and life in many aspects; however, in terms of surface wind force, various acting mechanisms seem to offset each other to some extent, giving rise to a relatively weak negative influence on the environment. As a result, the surface wind speed has gone through only insignificant changes, which not only does not increase the occurrence rate of haze, but also sustains the potential wind energy,as a clean energy source for wind power generation without the threat of climate change. Of course, these are the average results on large scales.When it comes to a specific country or city, these changes will have much diversity and need specific analyses.
Jian Ma, Ph.D. in Meteorology of the University of Hawaii and Professor of the College of Marine Science of SHOU, is mainly engaged in research on air-sea interaction and climate change. Hewas appointed as Chair Professorship of Shanghai Universities --Eastern Scholarsince September 2015, andcurrently serves as Editor(Ocean Sciences) of Geoscience Letters, the official journal of the Asia-Oceania Geosciences Society (AOGS).