Just how much is 17 trillion gallons of water, anyway?

Can you visualize 26 million Olympic swimming pools? Actually, you can.

That’s the amount of rain dumped on Houston and southern Texas these past few days by Hurricane Harvey, the “weather event” that triggered catastrophic flooding and continues to wreak havoc on one the U.S.’s fourth-largest city in terms of population (6.5 million people, according to the U.S. Census Bureau's July 1, 2010 estimate).

The existential media question — what’s the difference between a meteorologist and a climatologist? — is mirrored in big-picture terms with Hurricane Harvey and its aftermath.

It’s no longer a question of weather vs. climate, or even nature vs. engineering, but rather the status quo vs. the future of the planet.

 ©U.S. National Oceanic and Atmospheric Administration (NOAA)

©U.S. National Oceanic and Atmospheric Administration (NOAA)

The political winds are shifting in Washington, DC and other national capitals, as it becomes more apparent — to those who follow science and pay attention to the news — that rising man-made emissions are pushing the global climate deeper into uncharted territory.

As widespread as the flooding in the Gulf of Mexico is, it pales in comparison to what is going on in India, Nepal and Bangladesh, where overnight accounts from BBC World estimate that nearly half of Bangladesh — the entire country,  not just regional pockets — is underwater, due to unseasonably heavy monsoon rains.

 ©Google Images

©Google Images

Coupled with deadly mudslides in Sierra Leone last week and last month’s overflow of a key tributary to China’s Yangtze River, climate scientists warn that weather extremes are likely to be the norm in the near future, not the exception. As The Guardian global environment editor Jonathan Watts noted in an article earlier this week, we are now living in an era of unwelcome records.

The science is in. Since the advent of climate records, each of the past three years have registered steadily rising records for high temperatures. The amount of carbon dioxide in the air is the highest it’s been in four million years. We know this from geological carbon readings. This isn’t fake science, in other words, just as Hurricane Harvey and its devastating after-effects aren’t fake news.

 ©ABC News

©ABC News

Climatologists note that high amounts of carbon dioxide do not cause storms, per se, but they do make storms more volatile and violent — and more destructive.

Again, science is the key. As seas warm, sea water evaporates faster. Warming air holds more water vapour than cold air. For every increase in air temperature of just half-a-degree Celsius, atmospheric water content increases by three percent, give or take. The skies fill more quickly, and hold more water. Scientists call the Clausius-Clapeyron effect. The plain truth is that the surface temperature of the Gulf of Mexico is more than a degree higher than it was just 30 years ago.

Climatologists estimate that sea levels have risen more than 20 centimetres in 100 years of man-made global warming. Melting glaciers and the calving of massive ice shelves off Antarctica expand the volume of seawater.

 ©Guardian/Reuters

©Guardian/Reuters

The result is not worldwide floods or worldwide droughts so much as it is climatic extremes in regions already prone to flood and drought.

Friederike Otto, deputy director of Oxford University’s Environmental Change Institute, told The Guardian that the world can expect to see extreme rainfall amounts and record-setting temperatures “for the foreseeable future.”

Effects will vary from country to country. Bangladesh, for example, is particularly susceptible to ocean flooding, as are large swaths of the southern coastal U.S., because the topography is essentially flat and only slightly above sea level.

Recent storms have shown a tendency to stall, rather than blow through. One reason why Hurricane Harveyhas taken so long to clear Texas and Louisiana’s Gulf coast is that a massive high-pressure ridge over the northwest U.S. and southeastern Canada has blocked the storm from moving on its traditionally north-northeasterly track, if only temporarily. The longer Harvey lingers over flat lowland areas of coastal Texas and Louisiana, the more rain it will dump — and the worse the flooding will get.

 ©CNET

©CNET

Climate researchers have cited dramatic warming in the Arctic as one reason why high-pressure ridges keep building over British Columbia and Washington State in the summer months, and why it takes weeks rather than days for those pressure ridges to break down and allow the jet-stream to resume its normal track along the U.S.-Canadian border.

Hurricane Harvey is not a local story, in other words, or even regional, but rather international. That’s why climate change is a global concern, and not just a one-time local news hit on the nightly news.

One thing is becoming abundantly clear — and not just because of Harvey. This is no time to play politics with climate change. It’s basic science.