Benny Peiser & Matt Ridley: Your Complete Guide To The Paris Climate Summit

At the Paris conference, expect an agreement that is sufficiently vague and noncommittal for all countries to claim victory.

In February President Obama said, a little carelessly, that climate change is a greater threat than terrorism. Next week he will be in Paris, a city terrorized yet again by mass murderers, for a summit with other world leaders on climate change, not terrorism. What precisely makes these world leaders so convinced that climate change is a more urgent and massive threat than the incessant rampages of Islamist violence?

It cannot be what is happening to world temperatures, because they have gone up only very slowly, less than half as fast as the scientific consensus predicted in 1990 when the global-warming scare began in earnest. Even with this year’s El Niño-boosted warmth threatening to break records, the world is barely half a degree Celsius (0.9 degrees Fahrenheit) warmer than it was about 35 years ago. Also, it is increasingly clear that the planet was significantly warmer than today several times during the past 10,000 years.

Nor can it be the consequences of this recent slight temperature increase that worries world leaders. On a global scale, as scientists keep confirming, there has been no increase in frequency or intensity of storms, floods or droughts, while deaths attributed to such natural disasters have never been fewer, thanks to modern technology and infrastructure. Arctic sea ice has recently melted more in summer than it used to in the 1980s, but Antarctic sea ice has increased, and Antarctica is gaining land-based ice, according to a new study by NASA scientists published in the Journal of Glaciology. Sea level continues its centuries-long slow rise—about a foot a century—with no sign of recent acceleration.

Perhaps it is the predictions that worry the world leaders. Here, we are often told by journalists that the science is “settled” and there is no debate. But scientists disagree: They say there is great uncertainty, and they reflected this uncertainty in their fifth and latest assessment for the United Nations Intergovernmental Panel on Climate Change (IPCC). It projects that temperatures are likely to be anything from 1.5 to 4.5 degrees Celsius (2.7 to 8.1 degrees Fahrenheit) warmer by the latter part of the century—that is, anything from mildly beneficial to significantly harmful.

As for the impact of that future warming, a new study by a leading climate economist, Richard Tol of the University of Sussex, concludes that warming may well bring gains, because carbon dioxide causes crops and wild ecosystems to grow greener and more drought-resistant. In the long run, the negatives may outweigh these benefits, says Mr. Tol, but “the impact of climate change does not significantly deviate from zero until 3.5°C warming.”

The next 10-15 years will show whether the global-warming slowdown continues or whether a strong warming trend terminates the current pause for good. The Paris summit is likely to agree to a review process that reassesses global temperatures and carbon-dioxide emissions every five years. If the climate is less sensitive to carbon-dioxide emissions than climate models assume, the new accord should allow for the possibility of carbon-dioxide pledges to be relaxed in line with empirical observations and better scientific understanding.

Concerned about the loss of industrial competitiveness, the Obama administration is demanding an international transparency-and-review mechanism that can verify whether voluntary pledges are met by all countries. Developing countries, however, oppose any outside body reviewing their energy and industrial activities and carbon-dioxide emissions on the grounds that such efforts would violate their sovereignty.

This article was first published in the Wall Street journal.