A nation divided
In the decade leading up to the controversial loss to George W. Bush for President, I lived in a community of friends, classmates, and neighbors who were vehemently critical of Al Gore and his political career. Admittedly, the attitude rubbed off on me, since I was fairly indifferent to American politics at the time, and these were people I generally respected. As a result, I probably never gave the former Vice President a fair hearing. “Al Gore endorsed this? Hmm, it must be bad for America.”
At the risk of exposing my age, I will share with you that I was just barely ineligible to vote for or against Al Gore. But I distinctly remember how many classmates were overjoyed to have turned 18 already, so they could tell their least favorite candidate where to stick it. From this experience, I gained two valuable impressions still relevant today. First, I had not thought critically enough about politics to cast a meaningful vote. Since I had close friends in both camps, it wouldn’t suffice to jump on a partisan bandwagon based on whom I liked better or who shared my religious views, which subconsciously I had begun to do. Secondly, without realizing it, I was immersed in the “us vs. them” mentality that continues to fuel political rhetoric. It was inconceivable to me that one could support multiple political parties or candidates, depending on how they addressed a particular issue.
In the end, the court sided against Al Gore; I’ve never had to decide if I should grant him my vote for a political office. Only four years later, however, I would revisit the emotions behind that political dichotomy when An Inconvenient Truth burst onto the scene. Admittedly, my gut reaction was “Al Gore endorsed this. How can it be right?” It took some time for those ‘valuable impressions’ to regain control and allow the scientist in me to think through the issue.
The Politicization of Science
I have prefaced my comments this way, because I am not eager to defend every position held by Al Gore. And that’s the point. What motivates me to write today—what really irks me—is the manner in which politics have driven the way we examine scientific claims. Scientists and research groups are not candidates running for office. They do not lose their funding or positions when their views are proven wrong. Instead, they gain an opportunity to move science forward. In the process, new research ideas, access to grant proposals, and the chance to improve one’s reputation all arise. Regardless, the widespread misconceptions over what motivates researchers have led us to conflate the two professions.
Especially when a politician joins the effort to educate the public about a pertinent, albeit ‘inconvenient’, scientific matter.
Now, I greatly admire that Al Gore has brought the issue of climate change to the forefront of critical discussion among the global public. He had a voice much louder than scientists conducting the very research that will impact how our world looks in the coming century. But in response, the public has been rather hasty to associate the science behind climate change with the politics of Al Gore—vocally or not. There is no better evidence for this than the abundant criticism directed personally at Gore, rather than the actual scientists for whom he means to speak.
Al Gore, sea ice, and failed hypotheses
During his Nobel prize acceptance speech and in a few presentations, Al Gore famously discussed the climate models that project how rapidly Arctic sea ice could disappear in response to global warming. Therein, he noted that the Arctic might be ice-free in as little as 5-7 years, according to one climate model that deviated strongly from most others. In other words, the vast majority of climatologists (summarized by the IPCC) projected that Arctic sea ice would not disappear for decades, if ever. But in light of the fact that ice was fading faster than previous model projections, one research group considered how we may have underestimated certain climate feedbacks.
If the new model turned out to be correct, or at least more correct than others, then we should expect ice-free conditions much sooner. This possibility has significant implications for the rate of future warming and weather patterns. Sea ice reflects more solar energy than the open ocean, so the rate of northern hemispheric warming would increase in response. Counterintuitively, ice-free summers also result in extreme winter weather (as witnessed this year) for much of the northern hemisphere, due to the way open ocean can affect atmospheric pressure patterns.
It has now been at least 5 years since Al Gore cited this model, as any Google search for “Al Gore sea ice prediction” will immediately tell you. So was the model correct? Well, yes, essentially it was. The volume of sea ice (for September) has continued to fall to nearly 25% of its value at the beginning of satellite measurements, with no sign of recovery. Much of what remains is very thin, seasonal ice, rather than the multi-year ice that previously dominated. According to these models, the criteria for an “ice-free Arctic” is not zero ice whatsoever, but consistently less than ~1 million km2 (80% areal loss; IPCC, 2013, p. 995). But that hasn’t stopped a flood of overreaction to Al Gore’s statement: “It’s been 5 years. There’s still some ice remaining. Al Gore was wrong!”
Was Al Gore “spectacularly wrong” about sea ice?
A couple weeks ago, young-Earth creationist blogger Jay Wile added to the conversation with his own thoughts:
Obviously, Mr. Gore’s favored prediction is clearly wrong… The amount of ice in the Arctic [for September 2014] is below average, but it is clearly not zero. Also, there is significantly more ice in the Arctic than there was two years ago.
Dr. Wile is technically correct in that Arctic sea ice has not disappeared completely and was slightly lower in 2012. In light of this, we might concede that Al Gore does have a tendency to emphasize more ‘alarming’ possibilities for a warming world than is scientifically justified. Given that he is foremost a politician that wants to effect international action, this tendency is at least understandable. But Dr. Wile somewhat misses the point of Gore’s warnings back in 2007–2008, which was to say “Hey, this may not take decades, plural, and that’s a little unsettling.” Since that time, Arctic sea ice continued to disappear at a rate far higher than projected by the majority of climate models. So as far as we can tell, the reality lies in favor of Gore’s so-called alarmism on this point. Regarding the fact that Arctic sea ice is undeniably shrinking, though, Dr. Wile continues:
So we clearly have a losing trend when it comes to Arctic sea ice. However, it isn’t the trend of Vice President Gore’s favored prediction. That trend would have reached zero by now.
Two points need to be made. First of all—and Dr. Wile seems to acknowledge this—Al Gore didn’t predict anything, because he is not a research scientist. As is evident from every full citation of Al Gore’s discussion on Arctic sea ice, the former Vice President has only informed us what various studies suggest about the future impact of global warming. It really is inconsequential, therefore, which of these studies Gore may have ‘favored’ back in 2007–2008. He wasn’t betting on a horse race, but was trying to understand and communicate the scientific literature to the best of his ability. It’s worth noting that in this regard, he is miles ahead of most of his political colleagues.
Secondly, there is a key difference between scientific predictions and model projections. If I tell you that a train leaving Chicago at 100 km/hour will reach its destination 1,000 km away in exactly 10 hours, that’s a scientific prediction. Nobody can predict, however, when exactly Arctic sea ice might disappear, because there are far too many variables involved. Earth’s climate and weather systems are too chaotic and internally dynamic to represent with a simple set of equations, hence even the most advanced climate models can only make projections. A projection necessarily depends on a host of assumptions about the behavior of unpredictable elements, and so it is always accompanied by caveats and error bars. The fact that minimal sea-ice volume did not reach zero in 2014 does not mean the climate model was wrong, and it certainly doesn’t imply that climate science is in peril. Dr. Wile disagrees:
Can’t we see this [downward trend] as evidence for global warming? I don’t think so. Why? Because if we look at the other side of the globe, we see the opposite… While Arctic ice is below average, Antarctic ice is way above average… So whatever is going on with sea ice, it is certainly not global. While the Northern Hemisphere is clearly losing sea ice, the Southern Hemisphere is clearly gaining sea ice. If you want to claim that the loss of sea ice in the Arctic is due to human-caused global warming (as Vice President Gore and many, many others do), what is to blame for the rise in Antarctic sea ice? Global cooling?
In this paragraph, Dr. Wile effectively reminds us that he is not a climatologist of any sort, or at least that we need to be cautious in how we communicate climate science. The concept of global warming does not imply that every region on Earth will see comparable warming trends; neither does it preclude that some regions might see a cooling trend. What Dr. Wile fails to mention is that no climate model has projected a similarly rapid, near-term decline in Antarctic sea ice; some quite the opposite (see also Bintanja et al., 2013). The IPCC report (2013, p. 996) summarizes thusly:
There is low confidence in Antarctic sea ice model projections that show near-term decreases of sea ice cover because of the wide range of model responses and the inability of almost all of the models to reproduce the mean seasonal cycle, interannual variability and overall increase of the Antarctic sea ice areal coverage observed during the satellite era.
Why such a contrast to the Arctic situation? First of all, Antarctica is really really cold, due to the fact that the south pole is underlain by a giant continent—not a circulating ocean that gets warmer every year. Extensive continental ice sheets have a tendency to generate stable, descending air masses over their core. In other words, extremely cold air constantly circulates from the south pole to the Antarctic coastline, which effectively blocks most warm currents that might otherwise enhance melting of sea ice. I alluded briefly to this phenomenon in a recent post on ice ages, because it explains helps to explain why Antarctica is relatively dry compared to its northern counterpart. The Atlantic Gulf Stream regularly brings warm ocean currents deep into the Arctic, which exacerbates the melting of sea ice. Antarctic sea ice shouldn’t respond similarly to global warming, however, because its temperature is buffered by a massive, ice-covered continent.
So what about Dr. Wile’s statement that while the Arctic is obviously warming, Antarctic sea ice continues to grow? This trend is documented in the graphic above, which he shared in his post. But note the difference in scale: while Arctic sea ice extent has depleted by more than 30% (or 60% by volume), equal to nearly 5 million km2 lost, Antarctic sea ice extent has increased by only 5%, or less than 1 million km2. Does Dr. Wile really believe that these trends balance out, somehow justifying his rejection of global warming?
While the growth in Antarctic sea ice is not completely understood, it is certainly not surprising. Over the last ~120,000 years, the northern and southern poles have frequently been out of phase, due to the large-scale oceanic currents and atmospheric teleconnections that move heat from one side of the globe to the other. Besides, whatever the behavior of Antarctic sea ice in recent decades, we are fairly confident that continental ice has already begun to destabilize—i.e. the Antarctic is warming. More importantly, the global average temperature continues to rise, primarily due to greenhouse gas emissions, for which we are mainly responsible. But if nitpicking at so-called failed predictions helps one rationalize the dismissal of this evidence, then I suppose there is little I can say, because the debate is no longer rooted in science.
Update: For a concise and clarifying overview of Antarctic sea ice trends, see this article.