下面是完整代码:
```python
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
# Add the time-series for "relative_temp" to the plot
ax.plot(climate_change.index, climate_change["relative_temp"])
# Set the x-axis label
ax.set_xlabel("Time")
# Set the y-axis label
ax.set_ylabel("Relative temperature (Celsius)")
# Show the figure
plt.show()
```