That it could lead to more floods.
As far as I understand it, the idea is that climate change/global warming will lead to more incidents of extreme weather in many regions of the world. One of the ways this will display itself is a greater number of river flooding/burst river banks in these areas it could also lead to more intense and/or more frequent heatwaves and drought in some areas.
In the UK, for example, it is predicted that while there will not necessarily be more rain, it will be more concentrated and we will have more occasions of very high levels of rain fall in just a few days, so there will be many more incidents of floods.