Yale Environment Review

Yale Environment Review (YER) is a student-run review that provides weekly updates on environmental research findings.

You can’t dodge the impacts of climate change

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Hu, Z., Li, Q., Chen, X. et al. Theoretical and Applied Climatology (2016) 126: 519.  DOI: 10.1007/s00704-015-1568-x

Tuesday, May 9, 2017

New research shows that climate change has profoundly altered another region. The victim this time is a mountainous region in northwestern China.

Climate change disrupts the planet’s hydrological cycle, altering the way water moves through and between atmosphere, soil, rivers, and oceans. It has altered the pattern of rainfall — the intensity and frequency of precipitation —  on a regional scale. And it’s going to keep on changing. A recent study indicates that in high areas of China, temperature increased between 1958 and 2012, lengthening the warm seasons. The study also identifies changes in the distribution of rainfall throughout the year, indicating wetter winters and drier springs. All these trends are expected to continue.
For the study, a group of researchers led by Xi Chen at the Xinjiang Institute of Ecology and Geography used free-access historical climate data from a Chinese meteorological center to evaluate the changes in precipitation and temperature. Specifically, they studied daily records of precipitation and extreme temperatures in the Bayanbuluk grasslands, located in the northwestern part of China. during the 54-year period. They verified the soundness of the data set and applied statistical analyses to determine changes in the frequency and intensity of the changes in the climate. In addition, they analyze the correlation between temperature and precipitation with vegetation over the time period.
These grasslands are located in high-latitude alpines, with elevations between 1,400 and 4,500 meters, and have little rain per year. The results show that the annual minimum temperature has increased by 0.67 Celsius degrees. This value is more than 10 times higher than the global temperature increase in the 20th century. Also, the maximum daily temperature per year has increased but to a lesser degree. Thus, the difference between the daily high and low temperatures has decreased while the average is rising. This means that days are getting warmer in the region. Seasonally, winter is the period that suffers the strongest warming effect. The number of cold nights and days has dropped. As a result, the growing season of crops is getting longer.
As for rainfall, even though the Bayanbuluk grasslands are getting only slightly wetter annually, the distribution of rainfall throughout the year has changed. In spring, rainfall decreases from year to year while it increases in the other three seasons, especially in the summer. These findings in temperature and precipitation matched the findings from past literature. 
The authors identified that warmer days and a wetter climate encourage vegetation growth between 1950 and 2010, favoring livestock production but at the same time increasing the magnitude of floods. Furthermore, the researchers suggest that the wet-warming effect in this region will continue to increase, possibly leading to a degradation of the ecosystem in the future.
This study is another example that demonstrates how days are getting warmer and precipitation is increasing even in elevated arid areas such as the Bayanbuluk grasslands. The results serve as a reference to and warning against how climate change is transforming elevated areas.