See more Harvey aftermath photos and coverage

Nature’s brutal fist has fallen hard on the city of Houston and other communities in southeastern Texas. Its marks can be seen in the houses flooded by the torrential waters of hurricane Harvey, in the streets that have turned into racing rivers, and in the stunned, fearful eyes of the tens of thousands of people who have fled their homes.

But another force has played a role in the devastation where at least 31 people have died during the heaviest tropical rainfalls in U.S. history. It is the hand of humankind.

Many scientists agree that conditions associated with climate change have made this tropical storm more extreme and damaging than it otherwise would have been. Of course, it is both misleading and incorrect to say climate change caused this extreme weather event. Coastal regions of Texas have always been vulnerable to hurricanes and flooding. Houston’s rapid growth in recent years has seen more people living in areas particularly at risk when heavy rains fall.

But climate change has most likely played a significant role in the catastrophe, according to a statement from the United Nations’ World Meteorological Organization on Tuesday. “Climate change means that when we do have an event like Harvey, the rainfall amounts are likely to be higher than they would have been otherwise,” said Clare Nullis, the organization’s spokesperson. There is broad scientific agreement that more heat is being trapped in the Earth’s atmosphere due to greenhouse gases caused by human activity.

A hotter planet — and ours has definitely become hotter in recent years — is melting the polar ice caps. Sea levels have risen more than eight inches (20 centimetres) in the past century, which means storm surges sweep over larger, unprotected coastal areas. Warmer seas mean more evaporation. A warmer atmosphere holds more moisture. Theoretically, these factors mean heavier rainfalls than normal in tropical storms.

On the soggy, saturated ground of southeastern Texas, the theory seems to have been proven. Some areas received in excess of 50 inches of rain — more than a metre — in just three days. So, while Harvey is a natural event, it is also in many ways an unnatural one.

For those who have ignored the reality that the Earth’s climate is being changed by humans, Harvey should be a wake-up call. For those who believe in climate change but have been bogged down in debating what should be done and by whom, it should show what the future will be like. Sadly, the warnings of scientists and evidence from hurricane Harvey have not convinced Donald Trump that climate change is real and demands a presidential response.

Hurricane Harvey’s victims deserve compassion and help, and it will come. But the people of this planet deserve even more.