Unlike many other base metals, the copper has been growing since the end of January. However, the copper prices might be only zigzaging around the 4-year downtrend.
The prospects of rising interest rates in the US and more stimulus in China are said to be among the main reasons for this bullishness. However, despite the stimulus, China's GDP growth in Q1 2015 was the slowest in six years. There is also no deficit of this metal on the market. That is why it is unlikely for the copper to grow indefinitely in the future.