For all its costs, the Paris treaty will have almost no effect on global warming, and by depleting global income it will make it harder for countries to adapt and innovate in response to whatever changes occur

See The Case for Pulling the U.S. Out of the Paris Climate Accord by Ross McKitrick of Cato.

"EPA Secretary Scott Pruitt has argued that the Paris Agreement on Climate Change is a bad deal for the U.S. because it doesn’t bind China and India. But that implies it could be fixed by imposing the same ruinous terms on developing countries—which would in fact just spread the damage. The real reason for pulling of the Paris Accord is that it is a futile gesture based on empty and dishonest premises.

The first thing to note is that the same computer models that say global warming is a problem also say that Paris will not fix it. If one were to graph the standard warming projections over the next century with and without Paris, the two lines overlap almost exactly. Whatever greenhouse gas (GHG) concentration we would have reached in the year 2100 without Paris, we will reach it shortly thereafter with. For all its costs, the Paris treaty will have almost no effect on global warming, and by depleting global income it will make it harder for countries to adapt and innovate in response to whatever changes occur. Thus not only does Paris not solve the problem, it arguably makes it worse.
This, by the way, was equally true of the earlier Kyoto Protocol: all cost and no benefit. Under current technology and economic realities we have only two options: do nothing and adapt to whatever changes the climate will undergo over the next century, or take a lot of costly and futile actions today and adapt to whatever changes the climate will undergo over the next century. There has never been a third option involving costly actions today that stop the climate from changing.

Paris binds countries to meet their self-imposed Nationally Determined Contributions, or NDCs. The Obama Administration submitted an NDC that committed the U.S. to a twenty six percent reduction in GHG emissions below 2005 levels by 2025 through specific regulatory measures, all of which were enacted by Executive Order rather than by passing laws in Congress. It amounts to an attempt by one Administration to bind all future Administrations despite lacking legislative warrant. If the U.S. NDC was supposed to be legally binding then it should have gone through Congress. And now that some of those measures have been repealed by the current Administration, it is dishonest to keep the existing NDC as part of the Paris Agreement.

Paris embeds an inconsistency between calling for the use of the “best available science” while also prejudging what that science is allowed to say. The Accord’s preamble calls climate change an “urgent threat” even though mainstream climate science and economics does not imply this, instead placing global warming rather low on the list of problems confronting the world. The Agreement enshrines the ill-defined and arbitrary target of holding “the” global average temperature to 2^oC above pre-industrial levels while completely ignoring the critical question of how it should be measured. Nor does it say how much of the warming is natural and should not be counted against the 2^oC limit. This omission alone makes the overall target absurd, since it could bind the world to taking actions to prevent the sun from shining brighter.

The Paris Agreement also veers into absurdity by its political and ideological language, requiring countries to address extraneous themes like gender equity, biodiversity, poverty eradication, migrants, disabled persons, a “just transition of the workforce,” “creation of decent work,” and so on. Having larded the treaty with social justice slogans, its authors cannot be surprised if they become points of contention. It is not surprising that conservative governments will dislike these items, and if the authors respond that they can simply be ignored, then they should not have been in the treaty to begin with.

Finally, a proponent might acknowledge all these problems yet still defend Paris as a “good first step” in the expectation that later steps will yield big benefits.  But this is flawed reasoning. In any well-structured policy transition the first step yields the highest benefits at the lowest cost—the so-called low hanging fruit. Subsequent steps cost more and yield less, until the point is reached where costs exceed benefits and the process stops. Paris, like Kyoto, cost too much to implement while yielding unmeasurably small benefits. Subsequent steps will only be worse. It is a bad first step on a road to nowhere.

Pulling out of the Paris treaty would send a signal that the U.S. will not bind itself to bad deals based on hype and empty slogans. If this is the best global climate diplomacy could come up with then it is time to pursue other options."