Hurricane Harvey (Figure. 1) was the first major (Saffir-Simpson scale 3) hurricane to make landfall in the United States since Wilma in 2005. In a four-day period, many areas received more than 40 inches (1,000mm) of rain as the system meandered over eastern Texas and adjacent waters, casing catastrophic flooding.

Figure. 1: Hurricane Harvey near the coast of Texas at peak intensity late on August 25,2017 (image captured by NOAA’s GOES-16 satellite)

Climate change made things worse?There are certain climate change-related factors that we can say worsened the flooding. Coastal subsidence caused by human disturbance such as oil drilling, a factor which affects the Sea level rise. The sea level is more than 15cm over the past few decades. So that means the storm surge was half a foot higher than it would have been just decades ago, meaning far more flooding and destruction. (Mann, 2017)

Figure 2.: Residential neighborhoods near the Interstate 10 sit in floodwater in the wake of Hurricane Harvey in Houston Aug 29,2017 (abc NEWS, 2017)

Moreover, sea surface temperatures in the region have risen about 0.5 ^oC over the past few decades from roughly 30 ^oC to 30.5 ^oC which contributed to warmer sea surface temperatures. Sea surface temperatures in the area where Harvey intensified were 0.5 – 1 ^oC warmer than current – day average temperatures, which translates to 1 – 1.5 ^oC warmer than average temperatures a few decades ago. The moisture in the atmosphere increased by 3-5 % (Mann, 2017).

The large amount of moisture creates the potential for much greater rainfalls and greater flooding. So, the combination of coastal flooding and heavy rainfall is responsible for this devastating flooding. Harvey was almost certainly more intense than it would have been in absence of human- caused warming, which means stronger winds, more wind damage, and a larger storm surge. (Mann, 2017)

Generally, the climate of Houston brings very heavy rainfall, which together with tidal flood events means that there have been repeated floods in the city ever since its founding in 1836 (Gabbatt, 2017).

Figure 3.: A family evacuate their home after flooding from Hurricane Harvey, Houston, Texas, 27 August (Joe Readie/ Getty Images)

Also, the rapid uncontrolled urban development in Houston is a factor that increasing the flooding. The wetlands have been replaced by hard surfaces and the rainwater cannot pass through the aquifer, which results in overwhelming the drainage capacity of the rivers and channels.

In conclusion, while we cannot say climate change ‘’caused’’ Hurricane Harvey, we can say that it exacerbated several characteristics of the storm in a way that greatly increased the risk of damage and loss of life.

So, what are you thinking Climate change made Hurricane Harvey deadlier?

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