David A. Andelman, a contributor to CNN and columnist for USA Today, is the author of " A Shattered Peace: Versailles 1919 and the Price We Pay Today ." He formerly served as a foreign correspondent for The New York Times and Paris correspondent for CBS News. Follow him on Twitter @DavidAndelman . The views expressed in this commentary are his.

(CNN) On December 12, French President Emmanuel Macron is gathering in Paris all the world's leaders who concluded the COP21 climate agreement two years ago, when the world unanimously agreed for the first time that it was necessary to slash greenhouse gas emissions and restrain global warming if human life were to survive on Earth.

Leaders of virtually every country who signed this pact are expected to return to Paris in December -- except Donald Trump. His absence is particularly alarming as America becomes the target of two of history's most vicious back-to-back hurricanes , and two more on deck behind them, and becomes one of the world's biggest and most immediate victims of climate change. And then there are the wildfires burning across the far West, their smoke headed east as well -- more than 100 at last count, consuming more than 2 million acres and hundreds of homes -- attributed to tinder-dry lands and record high temperatures.

He should rethink his approach to climate change and go to the December meeting, if for nothing else, to make America great again.

The United States is getting a front-row seat this summer to what a warming Earth promises for the future of humanity — and sadly it's just a mild foretaste. In March, Kerry Emanuel, MIT's eminent professor of meteorology and co-director of the Lorenz Center, concluded in a remarkable paper for the American Meteorological Society that "Climate change potentially affects the frequency, intensity, and tracks of tropical cyclones."

And, as a member of the World Meteorological Organization's expert team, Emanuel signed a statement on September 1 that observed, "Hurricanes in a warmer climate are likely to become more intense, and that it is more likely than not that the frequency of Category 4 hurricanes like Harvey will increase over the 21st century." And sure enough, a week later, along came Irma.

If there were any doubt about the impact of climate change on the frequency and intensity of what scientists generally call "cyclones" — known in Asia as typhoons and in the North Atlantic and Gulf of Mexico as hurricanes — that doubt is easily resolved by simply looking at some of their detailed research, using real-life hurricanes and vastly complex computer modeling. As Emanuel points out in his paper, the data seems to suggest "we would expect a significant increase in extremes of storm intensification, including those that happen just before landfall."

But there's still more. In the case of many hurricanes, such as Harvey, the principal damage is from water rather than the brute force winds of Irma. Harvey, in the course of its repeated passes through the Gulf of Mexico, drew new sources of water from the warming seas of the Gulf, dumping each load over southeast Texas and southwest Louisiana.

As the WMO statement points out "the tropical atmosphere generally hold[s] more water vapor due to climate warming (about 7% more water vapor per degree Celsius sea surface temperature increase)." As the science appears to suggest, a 10 degree rise in the water's temperature could be expected to add 70% to what was available for Harvey to dump on Houston.

This phenomenon of more intense hurricanes, accompanied by more powerful and damaging rainfall, is hardly confined to North America. Last month Typhoon Hato caused more than $1 billion in damage, including severe flooding and multiple deaths.

Johnny Chan, who also signed the WMO statement, is the director of Guy Carpenter Asia Pacific Climate Impact Centre at the School of Energy and Environment, City University of Hong Kong. He pointed out that "global warming is going to produce more heavy rain, simply because with global warming you have more evaporation getting into the atmosphere; so there is more moisture in the atmosphere. With more moisture in the atmosphere, the rains will be heavier."

It was, therefore, hardly surprising that the climate scientists who helped draft the COP21 document in late 2015, alongside diplomats and politicians from 175 countries, were intent on doing everything within their power to limit the warming of the Earth's atmosphere — and by direct extension, the warming of the waters that hurricanes pass over.

President Trump's withdrawal of the United States from the COP21 agreement was a global wake-up call -- which will undoubtedly intensify as links become even clearer between global warming and the catastrophes of Hurricanes Harvey and Irma -- to every nation and a host of localities. Of particular concern, however, is efforts by the Trump administration, particularly the Environmental Protection Agency , to undermine the clear conclusions of atmospheric scientists monitoring greenhouse gas emissions and any future research that could confirm any conclusions already reached. Such efforts could have an equally serious effect on our ability to forecast and track the patterns of future storms.

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So, it was not merely a fit of political pique that led President Macron, in a live broadcast from the Elysee Palace last June, to invite American climate scientists to France where they would find a welcome refuge to pursue their research, with the goal, in a clear swipe at President Trump, to "make our planet great again."

French officials, who may see themselves privately as the godfathers of the COP21 process, are anxious for the December conference to begin to move the accord from a simple pledge by each of the signatories to a binding agreement in the form of a treaty , the most sweeping ever concluded.

There could be no greater tribute to those who lost their lives, homes or property in Harvey and Irma, than for Trump to join Macron in this crusade and accept the fact that climate change is a dangerous and real phenomenon.