September 30, 2013
September 30, 2013
I’ll be flying today, so posting sporadically.
I’m going to the Earth 101 event in Reykjavik, a collaboration between the University of Iceland and the Reykjavik International Film Festival, focused on communicating climate change thru film and video. Mike Mann and Stefan Rahmstorf, as well as a host of amazingly accomplished other folk. I’m very lucky to have made the cut.
I’ll be presenting in a couple of formal venues, hope there will be some time to get together in smaller groups to get to know some of these folks. In addition, I’ll be sharing living quarters with Phil Coates, an internationally renowned Arctic photographer/filmmaker, from whom I’ve already learned a lot long distance. We hope to take a few days after the conference to get out in the boondocks and look around, as well.
September 30, 2013
In Copenhagen, where I was briefly in June, you notice a few things.
a. How much quieter the city center is
b. How many people are riding bicycles, not for pleasure (only), but to actually get somewhere
c. How many more very slender and healthy looking middle age and older people you see
The video above does a very nice job of picking out glaring (to European eyes) deficiencies in how bicycle lanes, racks, and other amenities are so far applied in the US. Those nice new bike lanes you may have in your neighborhood? Maybe not as nice as they could be if we were more serious that bicycling is a real alternative way to move, rather than just a sport for kids or athletes.
Progress is being made on this, for sure – but this is one area of our transportation system that could have so many positive effects on our cities and our people, it seems more than a no-brainer to move forward.
September 29, 2013
Jay asks some good questions of Tesla’s lead designer.
September 27, 2013
Here’s a little known news item from an obscure organization that someone obviously is trying to hide by releasing it in a Friday news dump…oh, wait.
A panel of experts appointed by the United Nations, unveiling its latest assessment of climate research, reinforced its earlier conclusions that global warming is real, that it is caused primarily if not exclusively by human emissions, and that it is likely to get substantially worse unless efforts to limit those emissions are rapidly accelerated.
“Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes,” the report said. “It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.”
Going well beyond its four previous analyses of the emissions problem, the Intergovernmental Panel on Climate Change endorsed a “carbon budget” for humanity — an upper limit on the amount of the primary greenhouse gas, carbon dioxide, that can be emitted from industrial activities and forest destruction.
To stand the best chance of keeping the planetary warming below an internationally agreed target of 3.6 degrees Fahrenheit above preindustrial levels and thus avoiding the most dangerous effects of climate change, the panel found, only about 1 trillion tons of carbon can be burned and the resulting gas spewed into the atmosphere.
Just over half that amount has already been emitted since the beginning of the Industrial Revolution, and at current rates of energy consumption, the trillionth ton will be released around 2040, according to calculations by Myles R. Allen, a scientist at the University of Oxford and one of the authors of the new report. More than 3 trillion tons of carbon are still left in the ground as fossil fuels.
However, in the weeks leading up to the publication of the 2013 IPCC report, climate contrarians have been working overtime publishing opinion articles full of myths and misinformation, to mislead and confuse the public about its sobering message. Most of these opinion pieces have focused on the mythical global warming ‘pause’ (more accurately described as a speed bump), which in reality merely refers to a temporary slowing in the warming of air temperatures at the surface of the Earth.
September 27, 2013
What about the converse claim, promoted by critics, that the IPCC has exaggerated the evidence?
Well, if anything, the opposite appears closer to the truth. In many respects, the IPCC has been overly conservative in its assessment of the science. The new report, for example, slightly reduces the lower end of the estimated uncertainty range for a quantity know as the equilibrium climate sensitivity — the amount of warming scientists expect in response to a doubling of carbon dioxide (CO2) concentrations relative to preindustrial levels (concentrations that will be seen mid-century, given business-as-usual emissions).
The IPCC reports a likely range of 1.5 to 4.5 degrees Celsius (roughly 3 to 8 degrees Fahrenheit) for this quantity, the lower end having been dropped from 2.0 degrees C in the fourth IPCC assessment. The lowering is based on one narrow line of evidence: the slowing of surface warming during the past decade.
Yet there are numerous explanations of the slowing of warming (unaccounted for effects of volcanic eruptions and natural variability in the amount of heat buried in the ocean) that do not imply a lower sensitivity of the climate to greenhouse gases. Moreover, other lines of evidence contradict an equilibrium climate sensitivity lower than 2 degrees C. It is incompatible, for example, with paleoclimate evidence from the past ice age, or the conditions that prevailed during the time of the dinosaurs. (See this piece I co-authored earlier this year for the Australian Broadcasting Corp. for a more detailed discussion of the matter.)
The IPCC’s treatment of global sea-level rise is similarly conservative — arguably, overly so. The report gives an upper limit of roughly 1 meter (3 feet) of sea-level rise by the end of the century under business-as-usual carbon emissions. However, there is credible peer-reviewed scientific work, based on so-called “semi-empirical” approaches that predict nearly twice that amount — i.e., nearly 6 feet (2 m) of global sea-level rise this century. These latter approaches are given short thrift in the new IPCC report; instead, the authors of the relevant chapter favor dynamical modeling approaches that have their own potential shortcomings (underestimating, for example, the potential contribution of ice-sheet melting to sea-level rise this century).
September 26, 2013
In anticipation of the new Fifth Assessment of the IPCC (AR5) which will be released tomorrow, there are a number of good backgrounders online. Here are some of the best.
Let me extract the key points and figures. Back in July, scientist Dana Nuccitelli summarized a new study, “Distinctive climate signals in reanalysis of global ocean heat content“:
- Completely contrary to the popular contrarian myth, global warming has accelerated, with more overall global warming in the past 15 years than the prior 15 years. This is because about 90% of overall global warming goes into heating the oceans, and the oceans have been warming dramatically.
- As suspected, much of the ‘missing heat’ Kevin Trenberth previously talked about has been found in the deep oceans. Consistent with the results of Nuccitelli et al. (2012), this study finds that 30% of the ocean warming over the past decade has occurred in the deeper oceans below 700 meters, which they note is unprecedented over at least the past half century.
- Some recent studies have concluded based on the slowed global surface warming over the past decade that the sensitivity of the climate to the increased greenhouse effect is somewhat lower than the IPCC best estimate. Those studies are fundamentally flawed because they do not account for the warming of the deep oceans.
- The slowed surface air warming over the past decade has lulled many people into a false and unwarranted sense of security.
And let’s not forget another key indicator of accelerating warming — the accelerating melting of the great ice sheets as documented in the most comprehensive analysis of satellite altimetry, interferometry, and gravimetry data sets to date:
Okay, so it’s clearly misleading to say the planet has stopped warming. What’s actually going on? It’s pretty nuanced: According to the leaked IPCC draft report, the rate of warming at the planet’s surface (technically, the “global mean surface temperature”) is lower over the last 15 years, kind of like a car easing off the accelerator. The draft states that the rate of surface warming from 1998-2012 was 0.05 degrees Celsius per decade. But over the entire period from 1951 to 2012, it was 0.12 degrees Celsius per decade. (Keep in mind that not every aspect of the climate system necessarily reflects this “slowdown”: Arctic sea ice, for instance, hit a record low in 2007 and then another record low in 2012.)
How significant is the surface temperature slowdown in the context of global warming as a whole? The slowdown is certainly big enough to measure—or else we wouldn’t be discussing it—but not a huge deal in the context of the climate system. That’s because surface temperature itself, while a useful measurement, only captures a small part of what’s actually happening to the planet.