Hurricane Harvey is worse due to human activity and global warming

Hurricane Harvey and the resultant flooding in Houston are worse than they would have been without global warming, and other human interventions.

There are at least 7 factors that interact with this catastrophe.
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1. Sea surface temperatures are higher than in the past. This increases the power and water content of the hurricane
2. Deep sea temperatures are higher also. Hurricanes pull up water from the deeper layers of the sea. Normally these will cool the situation. Now these deeper layers are warmer
3. Air temperatures are higher, allowing the storm to carry more water
4. Changes to the subtropical jet stream may be decapitating forming hurricanes, and so holding back a tendency for warmer sea surfaces to create more hurricanes; at the same time these changes may be contributing to blocking weather patterns. This is a very important factor in the case of Harvey, who has stalled over and around Houston instead of moving on, resulting in far worse flooding
5. Sea level rise has created higher water tables, slowing runoff, and also contributed to the storm surge that is part of the flooding
6. Development of roads and houses in the area has reduced the ability of the soil to absorb rainfall
7. The land around Houston has been subsiding due to extraction of water and oil

All of these factors work together. Climate is a system, not a simple, single cause and effect event.

Note that Houston is not the only place to be suffering extreme weather. India, Nepal and Bangladesh are having major floods.