But perhaps the withdrawal can serve as a reality check that will motivate folks on both sides of the political spectrum to deal with increasing greenhouse gases in a more effective way.
The Paris Accord: Mainly Symbolic
First, the reality check. Some politicians, the media, and others have claimed that the loss of the Paris Accord is nearly the end of the world. In truth, the Paris Accord was a voluntary agreement, with little teeth, and inadequate to do the heavy lifting that is necessary to deal with increasing greenhouse gases. The voluntary national reductions would have only a minor impact on rising temperature, perhaps reducing the warming by a few degrees fifty years from now. Don't believe me? Those were the conclusions of Dr. James Hansen, well know climate scientist and advocate of strong action; a number of major climate scientists concurred with him.
The value of the Paris Accord was mainly symbolic: a statement by nearly all nations in the world that anthropogenic (human-caused) global warming was a problem that needed to be dealt with (sometime). That in itself is useful. But to seriously stop global warming from exceeding 2C by the end of the century requires draconian (huge) declines in greenhouse gas emissions this decade (like 80-90% reductions) and no nation is willing to do this.
Thus, there was no need for the U.S. to drop out of the Paris Accord, we simply could have changed our national plan. But Trump dropped out to make his political base happy. A symbolic rejection of a symbolic agreement.
The Reality of Human-Forced Climate Change
Greenhouse gases are increasing rapidly now, driven by population growth, improving living standards, and particularly by the large increase of coal burning in China. Reality is that we are doing a major experiment with the climate system of the planet. Major warming is inevitable.
There is, of course, uncertaintiy of how much CO2 humans will emit during the century. And there are major issues with the main tools folks like me use to simulate future climates: Global Climate Models (GCMs). These atmosphere/ocean models are wonders and can realistically simulate many aspects of the current earth's climate. But they have well known flaws as well.
Many do not get details of the earth's cloud field correct. Others produce a double ITCZ (the Intertropical Convergence Zone), an important east-west band of clouds/convection in the tropics. Most do a poor job in simulating convection (e.g., thunderstorms) and fail to correctly simulate important features like the MJO (Madden-Julian oscillation). Most underestimate interdecadal (natural) variability and many appear to be overly sensitive to greenhouse gases (producing more warming than they should). And none of them have sufficient resolution to get local climate impacts correct.
Importantly, the global models have problems simulating the current climate until they are tuned, adjustments made in key parameters to optimize their duplication of current conditions. What are the implications of such tuning for a different climate? We do not know.
And then there is natural variability, variations in the climate that are inherent in the climate system. There are still major deficiencies in our knowledge of what drives such variability and how it will change as the earth warms.
The lack of communication of these uncertainties has unnecessarily left the climate community open to attack by skeptics, who note the lack of prediction of the recent "pause" in global warming, which was probably due to natural variability.
But even with their deficiencies, global climate models are useful tools for getting broad trends (the earth will warm, the arctic warms more rapidly than other locations, sea level will rise), but quantitative forecasts must be considered highly uncertain.
Time for More Effective Measures
In some ways, the Paris Agreement was problematic: it gave folks the impression that mankind was dealing with global warming, while we were really kicking the can down the road. Perhaps with the knowledge that the emperor has no clothes, mankind (and the U.S.) can get more serious about the issue. And both sides of the U.S. political spectrum will have to change their approaches if we are to have any hope of dealing with the problem.
1. Stop fixating on Donald Trump
The environmental community and the "left" are fixated on Donald Trump, an individual who historically has never had a real interest in climate change. The guy wants attention and does anything to get it. Stop giving him what he wants. Ignore his silly tweets. Do what he will hate the most: make him irrelevant. Work around him.
2. Depoliticize Climate Change
Both the left and the right have used global warming as political tools and as litmus tests of "right thinking." Both sides need to stop doing this. It wasn't long ago (2008) that Senator McCain, the Republican presidential candidate, talked about the need to deal with global warming. More recently the Republican party made skepticism about global warming an official tenet of their belief system. Democrats and "progressives" have taken a similar tack, making global warming action a central principle of their belief system. And they have made the serious mistake of connecting climate change to their political goals (such as equity, racism, labor practices) and have participated in exaggerating current climate impacts in order to push folks to "do the right thing."
It turns out the folks of all walks of life believe that global warming is a threat. To demonstrate this, here is a graphic of the % of adults that believe global warming will hurt future generations (produced by the wonderful Yale Climate Communications group). A majority in every state.
Greenhouse warming is too serious an issue to be a political football of either side. Effective national efforts on climate change is best done in a bipartisan way. Democrats need to work with moderate Republicans, who are not the enemies many of the left claim. Consider: many Republicans support climate research and research on renewable energy technologies. A group of moderate Republican leaders have supported a national, revenue-neutal carbon tax.
3. The Solutions will be Based on Technology, Not Sacrifice
One thing is abundantly clear: most people are not willing to make real sacrifices to deal with global warming, even those with the most knowledge of the threat. A study by the Energy Research Institute of the University of Chicago found that 43% of Americans were unwilling to pay an additional $1 per month in their electricity bill to combat climate change, and a large majority were unwilling to pay $10 per month. I have found that many of those with the most knowledge of global warming (climate scientists) have the largest carbon footprints. Same with many of the most vocal politicians and advocates (like Al Gore). How many of you are willing to give up flying for vacations and visiting families? One international roundtrip flight emits enough carbon emission per passenger to equal daily work commutes for a year. No nation is willing to make draconian changes in their economy necessary to address the problem,if such changes will be costly or reduce the quality of life. This is reality, one that some folks (such as Charles Mudede of the Seattle newspaper, the Stranger) are not willing to accept.
So, as Bill Gates and others have stated, the solution to the global warming problem will have to be based on improved technologies that will allow people to live high-quality lives with minimal sacrifice or cost. To use energy without emitting greenhouse gases. And there is reason for optimism. The costs of renewable energy has plummeted, with wind and solar now economically viable without government credits. Energy storage technologies are advancing rapidly and long-range high-voltage direct current interconnects will allow long-distance buffering of load and generation. Adaptive energy usage by smart appliances could play a major role in balancing load and there is no reason why electric cars (perhaps with gas backup generators) could not become the standard around the nation.
After Fukashima, nuclear energy was rejected by many, but new-technology nuclear generation should play an important role in the future energy mix until renewables can take over. Eventually, fusion power will be available, but we can not depend on that.
4. Research on climate change and energy technologies
One thing is clear: all sides of the political spectrum are willing to support research on climate change and new energy technologies. There is a huge amount of work needed to improve global climate models, including their physical descriptions of key phenomena such as sea ice, convection, and low clouds. Regional climate modeling needs to be perfected to provide insights into regional climate change (such as our project at the UW). And we have to run our models many times using an ensemble approach, to produce probabilistic climate projections.
And research must continue on energy storage, transmission, and generation, supported by both the Federal government, states, foundations, and private sector entities, such as the Gates effort.
5. Resilience and Adaptation
There is no way to prevent substantial warming because the atmosphere/oceans have not caught up with current greenhouse gas concentrations. And there is no reason to expect that mankind will turn the greenhouse gas juggernaut around quickly. So we need to work on preparing our infrastructure and population for global warming. Humans are adaptable and changes will be relatively slow, so preparation and adaptation should be generally possible. Current research suggests there are no "tipping points" or climate cliffs with abrupt changes. And because our models are probably oversensitive to greenhouse gases, we probably have more time to make necessary changes.
For some, talking about resilience/adaptation is rejected because they only want to consider mitigation (reducing greenhouse gas emission). But such sentiments are not realistic--we need to prepare. For example, in Washington State the snowpack will decline by the end of the century, while total precipitation will probably increase modestly. Thus, eastern WA agriculture must use water more efficiently and additional reservoir capacity will be needed to store winter precipitation and run-off. It also means moving population away from rivers, which will undoubtedly have higher flood peaks during storm season.
6. National Coalitions of State and Groups
If the Federal government is going to be missing in action during the next few years, there is no reason that concerned states, such as WA, CA, OR, and NY can't work together to develop technologies, do research, and begin adaptation. They will be joined by others (cities, foundations) and I suspect even some Republican/battleground states will become involved (such as Florida and perhaps Texas). Already one such group is being formed: the Climate Alliance. The train will leave with or without Trump and friends.
In summary, perhaps Trump's rejection of the Paris Accords could end up being a good thing if both sides of the political spectrum put ideology aside, secure a realistic appraisal of the problem, and move forward with both mitigation and adaptation.