Incredibly, we are entering negotiations on the most important issue humanity has ever faced, knowing that the terms we collectively propose will not prevent the catastrophe we're trying to prevent.
The negotiations in question - the 21st Conference of Parties, or COP21 in UN parlance, are adopting the 2-degree Celsius limit on warming agreed to in Copenhagen, even though that figure has been controversial for many in the scientific community. Worse, the pre-agreements leading GHG emitting countries are bringing to the table a guarantee that we will blow even by that shaky limit.
It's as if we set out to negotiate a nuclear arms agreement that could only guarantee a slightly smaller nuclear war. Literally, the amount of energy we're trapping with greenhouse gasses is equivalent to setting off 400,000 Hiroshima-sized nuclear bombs per day, each day, 365 days per year.
What is the "Safe Limit" to Warming?
The short answer is, how much risk are you willing to tolerate?
In many ways, we've already passed a "safe limit" with the .85 C temperature increase our GHG emissions have caused to date. We're experiencing irreversible sea-level increases that will last thousands of years from the complete meltdown of Greenland and large parts of Antarctica. We also see mass extinctions, widespread desertification, record-setting droughts, and near-epochal forest fires across the globe. This, in turn, has triggered climate refugees, and they are becoming a major threat - perhaps the major threat - to our national security.
We'll examine the kinds of risks we're playing within a moment, but let's clear up a few things before we do.
Mitigating Global Warming Is Not About Jobs, the Economy, or Lack of Clean Technology
Contrary to what you hear from the Republican clown car, fossil fuel interests, and antediluvian neoclassical economists, this is not an economic or jobs issue. Tackling climate change is affordable and will have an enormous positive payback in the longer term. Clean energy investments create more jobs than investments in fossil fuels, so on net, they actually increase the number and quality of jobs in our economy.
Second, this is not about physics or technology. We have the technologies to cut GHG emissions to net zero; they're affordable, and we've had them for close to a decade now.
This is about a complete lack of political will. Because politicians are either owned by fossil fuel interests or lack the courage to discuss hard or complex topics, we are being exposed to enormous risks to our health and the health of the planet.
So, What Kind of Risks Are We Incurring?
One layer of risk comes from choosing 2C as an appropriate limit. It's too high. The title of Hansen et. al. recent paper says it all:
"Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 *C global warming is highly dangerous."
There is a discrepancy between the geologic record's account of how damaging a 2 C rise was and the predictions of our models. Take sea levels, for example. As Hansen and others have noted, sea levels rose by 5 to 9 meters when the temperature was about 1 C warmer than today. And the seas rose considerably faster than our models forecast—as much as several meters in 50 years.
The way we operationalize the 2 C limit has risk built into it
The world settled on the 2 C limit at COP 15 in Copenhagen in 2009. To operationalize it, the IPCC developed a carbon budget in their Fifth Assessment Report, released in 2013 and recently updated. If you look at the budget for tons of carbon dioxide (not tons of carbon), by the end of this year, we can only emit about 800 billion more tons to have a "likely" chance of staying below 2C of warming. "Likely" means a 66% probability or, to make that concrete, that's like putting two bullets in the chamber of a six-gun, putting it to our temples, and taking our chances. The situation worsens if you throw in other GHGs, such as methane. According to an analysis by The Carbon Brief, we only have 20.9 years without significant reductions until we blow by even this risky limit.
To understand just how crazy this is, it might help to conduct a little thought experiment.
Imagine approaching a broad river and seeing two tollbooths, each serving a separate bridge. The one on the left -- which requires you to change lanes and make some other maneuvers - leads to a bridge with a huge margin of safety. It's been designed to handle stresses well beyond anything that could be anticipated. The one on the right allows you to continue on without pausing or maneuvering, but it leads to a bridge that has only a 66% chance of not collapsing. And just to see how completely crazy we are, imagine the price is about the same for either bridge.
Now consider this: We've chosen the second bridge.
Black Swans, positive feedback, and un-modeled disasters
Yet another layer of risk comes from the fact that we are assuming no surprises while ignoring known feedback. Just 3 of these feedbacks could, by themselves, increase the global temperature by nearly 2.5C.
The first results from decreases in sulfur aerosols from phytoplankton as the seas become more acidic and these critters die off. Sulfur aerosols are known to moderate solar gain and mitigate global warming. However, this could increase warming by close to 1F by 2100.
Extreme weather events could add another 1.5 F since they affect the Earth's ability to sequester human emissions and, in some cases, directly increase those emissions. Add these to the 2 F expected from methane releases—a conservative number if one compares the results of similar events in the geologic record—and these 3 feedbacks alone could add just under 4.5 F, or 2.5 C, to our worst-case projections for 2100.
Finally, with limited or no margin of safety, we leave the world vulnerable to what Nassim Taleb called Black Swans - unexpected and unanticipated events that create non-linear responses that overwhelm forecasts and predictions. Most of the profound events in human history have been shaped in whole or part by Black Swan events, and the more complex a system is, the more likely a Black Swan could emerge. The European "discovery" of the Americas, The Great Depression, the rise of Hitler, and the fall of the Soviet Union are among Black Swans that changed the course of history. No one called them. No one predicted them.
In a system as complex as our climate, the advent of a Black Swan is possible, and with no margin of safety, it could be devastating.
The Paris COP can be a start, but it is nothing more than that, and we have to acknowledge that beforehand.
One of the most dangerous scenarios I can imagine is for the world's countries to agree to their woefully inadequate self-determined emission reduction goals and then walk away with the illusion of victory. It would only be that much harder to achieve meaningful reductions in the future, and time is ebbing away.
About the only good outcome from COP 21 I can foresee is an admission that 2C is too high, and a commitment to build the same margin of safety we give to a bridge, into the preservation of our Planet.
But don't count on it.
