In recent years, the frequent occurrence of winter sandstorms in northern China shows that there are serious phenomena in the land in northern China: (a) soil erosion B. desertification C. climate.

Due to the scarcity of vegetation in the north and northwest of China, sandy soil, frequent cold wave and windward weather, sandstorm weather is prone to occur in dry spring. Sandstorm weather has a serious impact on local industrial and agricultural production and people's daily life. In recent decades, due to the serious desertification of land in northwest and north China, sandstorm weather has an increasing trend.

Therefore, choose: B.