Viewpoint
Robert Kopp, a professor at the Dept of Earth & Planetary Sciences, Rutgers University, and Director of the university’s Coastal Climate Risk & Resilience Initiative, presents his view of the US’s proposed withdrawal from the Paris Climate Agreement

Even before the Paris Agreement was signed in December 2015, market forces and policy measures were starting to tilt the world toward a lower-carbon future. US carbon dioxide emissions peaked in 2007, and Chinese emissions may have peaked in 2014. Solar energy, wind and energy storage are expanding rapidly.
Yet as a climate scientist and a climate policy scholar, I know market forces and current policies are far from adequate to limit the rise in global temperatures, as envisioned in the Paris Agreement.
And so the Trump administration’s decision to withdraw from the Paris Agreement could have a range of consequences for the United States and for humanity. But how broad will these impacts be?
Part of the uncertainty stems from how the climate system will respond to humanity’s greenhouse gas emissions. If we are lucky, the climate will be less sensitive than scientists think is most likely; if we are unlucky, it will be more sensitive. But most of the uncertainty arises from how the 194 other signatories of the Paris Agreement and the global economy will respond to Trump’s decision.

The optimist’s case
The Paris Agreement’s long-term goal is to limit global warming to 1.5 to 2.0 deg C above preindustrial temperatures, or about 0.5 to 1.0 deg C above the current global average temperature.
Current policies in the US, even without the power plant regulations proposed by the Obama administration, are adequate to reduce greenhouse gas emissions to about 16 percent below 2005 levels by 2020. But significant new policies at the federal and state level are necessary to meet the US commitment under the Paris Agreement to lower its emissions to 26 percent to 28 percent below 2005 levels by 2025. Largely independent of Trump’s decision to withdraw from the Paris Agreement, his obstruction of federal policy to cut greenhouse gas emissions means these targets are not likely to be met.
Meanwhile, however, China and Europe appear to be ready to take up the mantle of climate leadership that the US is abdicating. And so if the US departure from the Paris Agreement does not disrupt international progress, then Trump’s move may prove largely symbolic. (Indeed, under the terms of the Paris Agreement, the departure will not take effect until November 4, 2020 – a day after the next presidential election.) Nonetheless, US industry may suffer and the US’s reputation as a reliable diplomatic partner certainly will.
But the planet will not notice much. Over the five years between 2020 and 2025, the U.S. will emit a total of about 2.5 billion more tons of carbon dioxide-equivalent greenhouse gases than it would if it got on a path to meet its 2025 goal. That’s about the same as a 6 percent increase in one year’s worth of global carbon dioxide emissions.
Until recently, the federal government used an estimate of the social cost of carbon dioxide – one way to calculate the damage caused by climate change – of about US$40/ton. Based on that estimate, the additional emissions caused by the US failing to meet its Paris commitment would cause about $100 billion of damage to the global economy – not an insignificant number, but small in comparison to the size of the global economy. If state governments in California and elsewhere pick up some of the slack left by federal abdication, as some governors are pledging they will, the damage will be less.
If, after Trump, the US rejoins a healthy global climate regime and shifts with a few years’ delay on to an emissions trajectory consistent with Paris’ long-term goals, then the climate will not be much harmed by any transient US lethargy. The main damage will have been to US leadership, in the clean energy industry and in the world at large.
The pessimist’s case
However, the Paris Agreement would not have happened without US leadership. Perhaps, despite the efforts of China and Europe, it will fall apart without the US.
President Trump has talked often about reopening coal mines. This is unlikely to happen without significant subsidies – coal is in general no longer competitive as an electricity source with natural gas or, increasingly, solar or wind energy.
But if Trump’s vision of a “canceled” Paris Agreement and booming coal economy were to be realised, an analysis my colleagues and I did shows that the costs to the US could be severe. As I wrote in August:
By the middle of the century, climate models indicate that global mean temperature would likely be about 0.5-1.6 deg F warmer than today under the Paris Path, but 1.6-3.1 deg F warmer under the Trump Trajectory. The models also show that, by the last two decades of this century, temperatures would have stabilized under the Paris Path, while the Trump Trajectory would likely be about 4.4-8.5 degF warmer.
Sea-level projections by the Intergovernmental Panel on Climate Change (IPCC), by our research group and by others indicate that global average sea level at the end of the century would likely be about 1-2.5 feet higher under the Paris path than in 2000.
Emerging science about the instability of the Antarctic ice sheet suggests it might be around three to six feet higher – or even more – under the Trump trajectory. And, due to the slow response of the ocean and ice sheets to changes in temperatures, the Trump trajectory would lock in many more feet of sea-level rise over the coming centuries – quite possibly more than 30 feet.
Quantitative risk analyses show that warming would impose costs on human health, on agriculture and on the energy system. It would increase the risk of civil conflict globally. And rising seas would reshape coastlines around the U.S. and around the world.
The ultra-pessimist’s case
The pessimist’s case assumes that future catastrophes will come from the climate and its effects. The ultra-pessimist looks elsewhere.
The Paris Agreement is a milestone agreement within a cooperative system of global governance in which organizations like NATO, the United Nations and the European Union play key roles – a system which some of President Trump’s key advisers seek to undermine.
If isolationist policies, including pulling out of the Paris Agreement and weakening the Western alliance, lead to a global trade war and thence to an economic depression, the shutdown of significant chunks of the economy could lead to a larger reduction in greenhouse gas emissions than any careful, deliberate decarbonisation policy.
The US saw a small version of this between 2007 and 2009, when the economic downturn was the primary driver of a 10 percent drop in US emissions. Most economic models, including those used to produce projections of future greenhouse gas emissions, are not capable of modeling abrupt changes such as these.
Ironically, Trump’s decision to withdrawal from global governance, including the Paris Agreement, would in this scenario lower emissions. But global depression is one of the most harmful ways possible to do that – one that would inflict great hardship on the American workers Trump purports to help.
This article was originally published on The Conversation. Read the original article.
At least this is presented as a “Viewpoint”. Those of us who disagree with the AGW advocates are well aware of the fallacies in the arguments above: most specifically,
1. CO2 warms the world, the evidence is very weak on this driving factor. The IPCC reports calculate a radiative forcing factor by committee rather than real science. This value of about 7 W/m2 is used to produce forecasts that can never be checked or demonstrated to occur.
2. The 2 deg K rise is an artefact devised to create fear. The world has survived many warmer periods than the present without difficulties. It cannot survive cooling so well.
3. The climate accord was purely to transfer wealth from the west to the developing world, a good objective but flawed in reasoning as western growth generates world growth, so stagnation caused by energy price rises will not benefit the world.
As you will notice I do not agree with the viewpoint, however good discussion and debate are always a good thing. Until the Trump appeared, we “deniers” were denied platforms in the popular meja.
Jack, I agree with your post….but, you say ” The world has survived many warmer periods than the present without difficulties. It cannot survive cooling so well.”
The world can/has survived heating & cooling very well in the past ;
….It is modern man that wont survive cooling so well.
I still look forward to the +3C that our ancestors enjoyed in the Roman Warm Period.
It’s difficult to participate in good discussion and debate when projections for humanities well being are all based on computer predictions.
Everyone is bashing President Trump for withdrawing from the Paris Agreement. First of all, the withdrawal doesn’t mean the US is throwing all set goals off the table. It doesn’t mean the U.S. doesn’t care. The one aspect of this withdrawal that only a couple of educated writers have mentioned is the financial one. This agreement translate into huge amounts of financial resources for all the countries that signed on. I would like to see a spreadsheet of what each country has contributed financially to this effort. I believe from the data I have seen, that the U.S. has spent the lion’s share of the financial burden required to meet the goals of the Agreement, while other large viable countries such as China and Russia have done little financially. Perhaps the U.S is a little tired of opening our check book to cover the financial burdens while other very capable countries are not. The same can be said about the UN. Look at how many countries have failed to pay their dues, and yet these countries are the 1st ones to point their fingers at the U.S. I know many will disagree with me and that’s fine! I am just asking for everyone to look at the entire larger picture. there is more to this than just climate control.
Respectfully submitted by Rex Willoughby-
The Paris Agreement needs to be reviewed and probably thoroughly overhauled.
Has anyone read through the individual country statements setting out how much they will reduce their emissions by.
Some of these documents are preposterous.
They should be categorised in groups according to what is possible with probabilities of success – then we will have a better idea of whether the global emission goals can be met or not.
At the moment I am highly sceptical as to whether this process is credible.
I agree entirely with Andrew Cox about the INDCs that are being touted as a great success being a disgraceful con on the western world.
I rarely support USA foreign policies, seeing the shambles that their regime-change approach has caused. However, Trump’s speech about the Paris accord is well worth reading and gives an accurate explanation of the position (doubt that he wrote any of it!). The idea that the West pays India and China to burn more coal (and of course take over our industry) is beyond stupid, only an Obama would have signed up to it!
Thank you Robert and The Engineer for publishing the article. What matters is what those of us, in the fact-based reality, do, individually and collectively, to bend the current anthropogenic climate change trend and achieve, or rather surpass the Paris agreement targets, and sooner, by 2030.
Coal is dead anyway, but for the “alternative facts” or covfefed crowd. Oil and rest of fossils will follow, stop using them, is that simple.
https://www.bloomberg.com/news/articles/2017-06-15/solar-power-will-kill-coal-sooner-than-you-think
Here is the rational response in the US:
https://medium.com/@ClimateMayors/climate-mayors-commit-to-adopt-honor-and-uphold-paris-climate-agreement-goals-ba566e260097
https://phys.org/news/2017-06-cities-states-defy-trump-embrace.html
Can I suggest that Silvia examines the recently published BP Energy Outlook to get some real facts about energy. Coal production in the world has increased by 2.5% / year over the last 20 years and remains the world’s dominant energy source: some death!
It is mainly the UK who have self-destroyed on the altar of carbon reduction: Germany burns about the same as 20 years ago. The USA is the other big reducer of coal usage and that has followed massive gas fracking successes.
I already read it and it shows that coal is in terminal decline. It will stay in the ground, where it belongs. World coal production had the biggest drop on record in 2016, following 2 years of decline. No surprise as the global coal consumption peaked in 2014.
Direct quote: “The fortunes of coal appear to have taken a decisive break from the past,” BP’s Chief Economist Spencer Dale said at a briefing in London on Tuesday. The most important outcome of this “is carbon emissions, which saw little or no growth for a third consecutive year.”
https://www.bloomberg.com/news/articles/2017-06-13/coal-s-era-starts-to-wane-as-world-shifts-to-cleaner-energy
It’s all good news for a livable planet, which humans, the only animals capable of rational thought, the only animals that use disproportionate resources for survival, have a duty to sustain.