By my count, there are four leading scientific explanations for the short-term slowdown overlaying the long-term rate of global surface warming. They are:
Enhanced heat uptake by the world’s oceans, especially over the Pacific due to enhanced easterly winds
Sustained small to medium-sized equatorial volcanic activity
Slightly reduced solar irradiance
Natural variability, including the Interdecadal Pacific Oscillation
One interesting aspect to these explanations’ presence is most researchers believe their explanation is the leading one. It is a symptom of the state of climate science: specialization proliferation leads to poor cross-disciplinary communication. Someone might have this within their purview, but I am currently unaware whether anyone is apportioning relative causality of these explanations together. Attribution is challenging, of course, but such an effort seems worthwhile to me.
Some recent science updates on these explanations:
The US-China climate deal announced in December 2014 generated big news. It was yet another diplomatic success for the Obama administration and John Kerry’s State Department. Nothing I say below takes away from that success. In terms of climate action success, the deal ranks pretty low to me. I’ll quickly summarize what I understand of the deal and then share why I think it isn’t a significant climate deal.
China, the world’s biggest emitter of greenhouse gases, pledged in the far-reaching agreement to cap its rapidly growing carbon emissions by 2030, or earlier if possible. It also set an ambitious goal of increasing the share of non-fossil fuels to 20 percent of its energy mix by 2030.
Obama announced a target to cut U.S. emissions 26 to 28 percent below 2005 levels by 2025 – eight years after he leaves office — the first time the president has set a goal beyond the existing 17 percent target by 2020.
The bolded portions highlight the agreement’s big news. China agreed to a carbon emissions cap and the U.S. pushed its emissions reduction target out 5 years and increased the target by ~11% below 2005 levels.
Those are good goals. Are they sufficient goals? It depends on what you consider sufficient. I consider goals that will actually achieve the stated climate target of <2C warming by 2100 as sufficient. These goals won’t achieve that target. But then, as I’ve written for some time now, I don’t think we can set goals that achieve the <2C by 2100 target. There are technical and political hurdles that we chose not to surmount during the past 30+ years. Why won’t this agreement achieve that target? Let’s take a quick look from the same International Business Times article:
China completes a new coal plant every eight to 10 days, and while its economic growth has slowed, it is still expanding at a brisk rate exceeding 7 percent.
The scale of construction for China to meet its goals is huge even by Chinese standards. It must add 800 to 1,000 gigawatts of nuclear, wind, solar and other zero-emission generation capacity by 2030 — more than all the coal-fired power plants that exist in China today and close to the total electricity generation capacity in the United States.
And to meet its target, the United States will need to double the pace of carbon pollution reduction from 1.2 percent per year on average from 2005 to 2020 to 2.3 to 2.8 percent per year between 2020 and 2025.
Who out there truly believes that China can deploy 800 GW of zero-emission generation capacity in less than 15 years? Remember before you answer in the affirmative that China’s deployment of coal-fired plants exceeded anything in history and that coal remains an extremely cheap energy resource. All the other technologies currently cost more in terms of deployment. What incentives does China, as a developing nation, have to spend more money for intermittent power sources? They’re more interested in growing their economy, as the U.S. is. Speaking of the U.S. – I emphasized part of that quote quite purposefully to highlight the scale of the issue. China must, in 15 years, deploy as much generation infrastructure as exists in the entire U.S. today. Our infrastructure took decades and decades to build out. China needs to do the same thing, with more expensive infrastructure, in 15 short years!? I will be among the first to congratulate China if they accomplish this daunting task and I don’t think China should shy away from working towards it. I just don’t think they have a realistic chance of actually accomplishing it.
What about the U.S.? We need to more than double the decarbonization rate of our economy to achieve our emissions goals. Remember that most of the decarbonization achieved since 2005 was due first to the Great Recession and second to the natural gas boom. The Great Recession is finally behind us, though effects linger. The natural gas boom? It’s currently experiencing strong headwinds as OPEC pushes the cost of oil down to the $50 range from the $100-110 range last year. It’s economically unfeasible to frack for natural gas with $50 per barrel of oil. While the natural gas industry won’t collapse (at least I hope it doesn’t), it won’t support additional decarbonization for the foreseeable future either.
I believe we are well on our way toward 3-4C warming by 2100 and must plan and act accordingly. This deal, while diplomatically ambitious, is not climate ambitious enough to drive us away from those thresholds.
Welcome back to me. I took a break due to heavy class load and studying for qualifying exams. I’m looking forward to a good 2015. I tagged plenty of material while I was short on writing time, so stay tuned for lots of climate and energy science and policy discussions.
I remember all too many climate scientists tripping over one another in their mad rush to a microphone to declare that the Arctic would be ice-free in just a few short years – a claim I thought was silly and dangerous.
Why silly? Because these same scientists, preaching objectivism and claiming science has an impenetrable hold on truth over all other comers, no more understood the cryosphere then than they do now. This most result lays bare that type of truth: we don’t know enough about the cryosphere system to accurately or precisely project conditions in the near to medium future. While it is very likely that summer Arctic sea ice will be missing at some point in the future, the timing of that event is very much in question. I think it will be sooner than the IPCC AR4 model projections (see quoted statement below), which read: “In some projections, arctic late-summer sea ice disappears almost entirely by the latter part of the 21st century.” Papers written prior to the 2014 AR5 report projected ice-free conditions between 2037 and 2050. But there is still 35 years in the meantime. What will Arctic sea ice be like during those 35 years? Like good scientists, we should collect data as well as run and test models during that time to more fully understand the system. But good scientists do not claim knowledge they do not have.
The 2007 IPCC report made clear the level of uncertainty that exists:
A systematic analysis of future projections for the Arctic Ocean circulation is still lacking. Coarse resolution in global models prevents the proper representation of local processes that are of global importance (such as the convection in the Greenland Sea that affects the deep waters in the Arctic Ocean and the intermediate waters that form overflow waters).
Which leads to the dangerous part of scientists’ misguided efforts to “educate” the public at every turn, a strategy motivated by perceived successes by fossil fuel corporations and their backers. Moreover, the perceived extreme position of those corporations elicited a corresponding response from scientist-activists. One problem with this is the potential to appear foolish to the very people scientists are trying to convince of real climate risks when dire projections end up wrong. Scientists historically and currently enjoy wide-spread and deep respect by the public. I can’t believe that will continue if, for instance, grandiose claims of significant events end up wrong. How often do you and your friends make fun of the local weatherman after a busted forecast? I think scientists should instead tap into that deep reservoir of trust and leverage it intelligently. If the best science indicates an ice-free Arctic by 2035-2050, then say that. If conditions change radically, there will of course be a ready explanation that the public will gladly receive.
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