55 Music Concourse Dr.
Golden Gate Park
San Francisco CA
Regular Hours:


9:30 am – 5:00 pm


11:00 am – 5:00 pm
Members' Hours:


8:30 – 9:30 am


10:00 – 11:00 am

The Academy will be closed on Thanksgiving and Christmas Day.

Planetarium will be closed Sep. 22, 23, 24

Climate Change 

March 18, 2011

Thoughts on Sendai


The earthquake that struck the Sendai region off the coast of Japan one week ago is one of the largest that we have ever measured; 9.0 on the moment magnitude scale. I’ve received many questions about this event, and have heard a lot of misinformation both in the media and on the internet. I’m therefore going to use a little space on my climate change blog to talk about this event, and also discuss its relevance to climate change. First, however, I want to pay my respects to all the victims, their families and friends, the rescue workers, and the people of Japan in general. This was a terrible disaster, the consequences of which will continue to be felt for sometime.

Now here are some facts:

1. The Sendai quake resulted from movement along a subduction zone, in a region where the oceanic Pacific plate meets the North American and Eurasian continental plates. Ocean plates of the Earth’s surface are composed primarily of basalt, and being denser than continental plates, will be subducted below the continental plates to be recycled in the Earth’s mantle layer. While it may be easy to visualize plate movements (plate tectonics) as dynamic and fluid, this is true only on very large spatial scales and on very long time scales. On the human time scale, these are immense masses of rock grinding against each other, and it is not at all smooth or fluid. The moment by moment movement is jittery, sticky and frictional. Stress built up in that region, and the plates finally started to slip last week, peaking at the 9.0 quake on March 11. Aftershocks continue to be felt. Note that an aftershock is not necessarily weaker than the initial quake; it simply follows as a result of the same release of stress. The 9.0 was, in fact, itself probably an aftershock of a 7.5 the day before.

2. It is unlikely that an earthquake of that magnitude will strike California, even along the dreaded San Andreas Fault. The San Andreas is a different type of fault, or crack in the Earth’s surface. Here, two plates are sliding past each other, and the fault itself is much shallower than the subduction zone off Japan. If and when the Big One occurs in northern or southern California, it is likely to be in the neighbourhood of 8.0.

3. 9.0, 8.0, both measured on the moment magnitude scale, NOT the Richter scale. The Richter scale is an older measure of Earth movement based on particular instrument measures. While apparently embedded in the media’s vocabulary, it is not a very useful scale at magnitudes beyond around 6.5. Therefore, a new scale, the moment magnitude scale, was formulated many years ago and it is based on the amount of energy released during an Earth movement. That energy is released mostly in the form of rock deformation, heat, and mechanical waves that travel through the Earth’s surface away from the source. We can measure the latter, and through careful calculations arrive at a measure of the total energy. For comparison, and for those of you who may remember it, the 1989 Loma Prieta quake that struck the San Francisco Bay area, magnitude 6.9, was about 1,000 times less energetic than the Sendai quake! The San Andreas Big One, at 8.0, would be about 32 times less powerful than Sendai, but about 45 times more powerful than Loma Prieta. These are powerful events!

4. A quake similar to the Sendai event is more likely to be generated by the Cascadia subduction zone that lies off the coasts of Oregon, Washington and British Columbia.

5. The Sendai quake generated a devastating tsunami that wreaked more havoc than the quake itself. Tsunamis are generated whenever large amounts of water are displaced, usually the result of large movements of the sea floor, as in Sendai, landslides, volcanism, or some combination of these. The Sendai tsunami was particularly deadly because of the proximity of the source to the coast, the rapid shallowing of the sea floor in that area, and the density of the human population. Like ripples in a pond, tsunamis radiate away from their sources at high speed, but are really perceptible only as they enter shallow water. The Sendai tsunami eventually caused damage in areas as far away as Hawaii, northern California, and the Galapagos Islands. This is not the first major tsunami to strike the region; a similar event struck in July, 869 C.E.

6. As I write, the U.S. Congress is considering a bill that would include a $900 million cut to the National Oceanographic and Atmospheric Administration, which administers the United States tsunami warning system. Implementation of the cut is up to NOAA’s top administrators, so write to them now and save your favourite system! Or, if you like surprises, select from among tsunami, hurricane, etc.

7. The tragedy at Sendai continues because of damage to the Fukushima Da’ichi nuclear power plant. Most of the critical damage is exacerbated by or results from failure of coolant pumping systems, and those systems in turn failed primarily because their supplemental fuel storages were swept away by the tsunami. Under current conditions, the amount of radiation that most people, anywhere, will receive from the plant is far less than what you would receive from daily exposure to natural sources in your environment, a trip to the dentist, or a CT scan.

Is any of this relevant to the climate change problem? Yes, for at least two reasons. First, coastal living is not without hazard. Flooding, storms, storm surges, sea level rise and tsunamis are among those hazards. All but the last of these are becoming more problematic as a consequence of global warming. The coasts of Japan are, like many other coastlines around the world; highly productive, economically important, and densely populated. The consequences of global warming are already being played out daily in places such as Bangladesh, Indonesia, and many low-lying oceanic islands.

Second, nuclear energy. I am firmly on the fence with this one. On the one hand, producing energy by nuclear fission generates heaps of highly radioactive wastes and, as current events bear witness, is an inherently risky business. But splitting an atom is very energetic, and produces no greenhouse gases. I am skeptical of solutions based solely on clean, renewable energy sources such as solar and wind energy, and here’s why. Those processes are far less energetic, given current technologies, than is nuclear and the burning of fossil fuels. Given the rate of ongoing global population growth, and our ever-increasing energy consumption, clean technologies simply cannot succeed. They cannot, that is, unless we also greatly increase the efficiency of our energy-consuming activities, and conserve, conserve, conserve. The time has come to make do with less. Until we do, our future will continue to depend on technologically archaic, dirty and dangerous energy production. And, if you wonder why energy-producing technology lags decades to more than a century behind health, communication, transportation and other technologies: money. When we demand better, and we are willing to pay for it, change will follow.

Filed under: Climate Change — Peter @ 3:26 pm

January 13, 2011

Climate change to go on for at least “1,000 years”

Ris­ing car­bon di­ox­ide lev­els in the Earth’s at­mos­phere will cause un­stop­pa­ble changes to the cli­mate for at least the next 1,000 years, a new study sug­gests…” (read more).

A very interesting study which asks the question, “What if we ceased putting any more carbon dioxide from fossil fuels into the atmosphere, what would be the consequences a millenium into the future?” This is the sort of thing that one can do with models, explore areas of parameter space that we are unlikely to experience, or to sample in any reasonable timeframe. The results of this particular exercise are not encouraging. There is some recovery from the effects of warming in the Northern Hemisphere, but general catastrophe in the Southern Hemisphere as the Antarctic ice sheet collapses. Definitely not encouraging, since the scenario is run under unrealistically optimistic conditions.

Filed under: Climate Change — Peter @ 7:51 pm

December 22, 2010

Ecosystem Impact of the Deepwater Horizon Disaster

Oil spill magnitudesEcosystem Impact of the Deepwater Horizon Disaster.

A Pritzker Lecture in November, 2010 at the California Academy of Sciences.

Filed under: Climate Change — Peter @ 9:10 pm

November 21, 2010

53% – Majority of Republicans No Longer See Evidence of Global Warming


A 53%-majority of Republicans say there is no solid evidence the earth is warming. Among Tea Party Republicans, fully 70% say there is no evidence.” (…read more).

Interesting. Why? Has the evidence disappeared? Did someone solve the problems and forgot to tell the rest of us? One more time: Science is not about belief or disbelief. Nature does not hold opinions; it simply is. One more time: The planet doesn’t give a fig what we believe or disbelieve.

If you find yourself in the minority, yet vocal and influential category of deniers, I welcome you to comment here. Tell me why, the basis for your disbelief, and any questions that you have. Dialogue is sorely needed, as is understanding.

Thanks C.D. for the link.

Filed under: Climate Change — Peter @ 9:38 am

October 29, 2010

Thinking about public transportation?

For those of us fortunate enough to have efficient public transportation available, the question often arises as to the environmental effectiveness of the options. That is usually a very complicated question, with complicated answers, but I was very pleasantly surprised to discover this: The BART Carbon Calculator. BART stands for Bay Area Rapid Transit, and is the regional commuter rail system for the San Francisco Bay area. On peak days, BART transports close to the equivalent of all daily domestic flights in the United States! So, while planning a trip to the Oakland Airport this morning (to attend the Annual Conference of the Geological Society of America), I was surprised by this little calculator that popped up to inform me of the environmental impact of my decision and route.

Now, not all transit systems are equivalent. Too many of them rely on high-emissions, even environmentally hazardous, vehicles. But at the very least, they are no worse than a passenger vehicle, and they are always better than passenger traffic because of the volume of passengers in a single vehicle. So check out your local transit system and see if they’re already impressing you with a similar calculator. If they’re not, then encourage them to do so! It’s good for the public, it’s good for business, and it’s good for the environment.

Filed under: Climate Change — Peter @ 9:09 am

September 22, 2010

BBC News – Arctic claims summit gets under way in Moscow

BBC News – Arctic claims summit gets under way in Moscow.

Never mind the primary reason for this territorial fight, the fact that human-driven global warming is largely responsible for this sudden bonanza. Any and all mineral exploitation of the Arctic should be made contingent upon some proceeds from the new Gold Rush being diverted to mitigation of the effects of carbon dioxide emissions. All the countries involved are big talkers when it comes to talk regarding climate change. It’s time to put your money where your mouth is.

Filed under: Climate Change — Peter @ 5:49 am

September 15, 2010

BBC News – ‘Rapid’ 2010 melt for Arctic ice – but no record

BBC News – ‘Rapid’ 2010 melt for Arctic ice – but no record.

Filed under: Climate Change — Peter @ 8:25 pm

August 6, 2010

BBC News – Huge ice sheet breaks from Greenland glacier

via BBC News – Huge ice sheet breaks from Greenland glacier.

Filed under: Climate Change — Peter @ 8:47 pm

July 21, 2010

Oysters and the Ecosystem | Radio Times | WHYY

While some people may see oysters as only a delicious delicacy, researchers are using them to understand the long term environmental impact of the Gulf oil spill. Oyster shells turn out to hold important clues about past ecological disasters. This hour, the importance of oysters – more than just good eating, these mollusks play a key role in the ecosystem. Guests PETER ROOPNARINE, a curator at the California Academy of Natural Science and PAUL CALLOMON, a collections manager at the Academy of Natural Science, tell us about reading oyster shells and the threats oysters face from pollution, climate change, acidification, overharvesting, and invasive species.

Filed under: Climate Change — Peter @ 8:37 am

July 19, 2010

Stephen Schneider, 1945-2010

The First Okazaki Biology Conference: The Biology of Extinction

The First Okazaki Biology Conference: "The Biology of Extinction"

It was with great sadness that I learned this evening of the passing of Dr. Stephen Schneider, Nobel Laureate, IPCC author, Stanford University professor, and much more. Many of you will no doubt read biographical pieces over the next few days, so I won’t do that here. I just wish to say something personal on this blog. I met Stephen several years ago at a week-long conference on extinction, held in Okazaki, Japan. Sitting with about 70 other scientists in a room, for 5 days, discussion extinction, is an enlightening if not depression experience. Stephen was one of the closing speakers of the week, and of course spoke on the topic of climate change. After I returned from that meeting, I re-focused much of my work, in fact I changed it. Previously I studied extinction mostly from a paleontological and mostly academic viewpoint. I now take it as a personal responsibility, and as an applied science. Stephen Schneider had that influence on me.

Stephen was by all accounts a great scientist, a gifted communicator, and a seemingly tireless worker for what he believed in. He once flew an overnight flight from London, where he was attending UN meetings, to give a lecture to teachers in the Academy’s Bioforum series. I never knew him well enough to say this to him, but he was a great influence on me in the short time that I knew him. We could all honour him by ensuring that his work and efforts to address climate change bear fruit.

Filed under: Climate Change — Peter @ 9:46 pm
« Previous PageNext Page »

Academy Blogroll