Wednesday, May 23, 2018

Question About Human Vision and Missiles

Consider, say, a missile, 5 meters long and 1 meter in diameter. After it's launched, at what speeds could it be tracked by the human eye? What's the upper limit on that speed? Viz., when does the missile become effectively invisible?

(I know the diameter might not be realistic. I just wanted to make it an easy number.)

This is related to an article I'm working on.


Tuesday, May 22, 2018

James Chadwick Accidentally Went Into Physics

Image result for james chadwick neutron




"...James Chadwick, the discoverer of the neutron, had studied physics only because he was too shy to point out that he had mistakenly waited in the wrong line when matriculating."

From Warped Passages by Lisa Randall

Monday, May 21, 2018

Latest Ocean Heat Content Data

Global warming continues.

The data for ocean heat content for the first quarter of this year came out the other day for the global regions 0-700 meters and 0-2000 meters. They're warmer. Recall that changes in ocean heat content are the best way to detect the planet's energy imbalance -- over 90% of the heat trapped by our greenhouse gases finds it way into the ocean.

After some spreadsheet fun I get the following:


W=watts, J=joules, m=meters; yrs=years; Z=zetta=1021; T=tera=1012.

Note that the 0-700 m record is almost 5 times longer than the 0-2000 m record, so even though it's about 3 times smaller (in volume) it's not too surprising it's absorbed more heat over its record length. 

The uncertainties don't include autocorrelation -- the reality that one quarter isn't independent of the previous quarter, because a warm quarter is more likely to follow a warm quarter etc -- because I'm lazy and because I'm still not quite sure how to include it for the uncertainties of a 2nd-order polynomial fit. (Anyone know? Can you do it quick and dirty by using the effective sample size neff as in equation 9 of this document by Tom Wigley?)

Lots of graphs can be found here.



(In my calculations I've only included the Argo data for the 0-2000 m region, which starts in 2005, shown in red in this last graph.)

Friday, May 11, 2018

Crop Yields Under Global Warming

Up until now I thought that global warming would have a significant impact on crop yields, both in the US and elsewhere.

But I've gathered some numbers, and I'm so sure anymore -- at least for US farmers/farming corps.

My understanding was taken from papers like this one:
“For wheat, maize and barley, there is a clearly negative response of global yields to increased temperatures. Based on these sensitivities and observed climate trends, we estimate that warming since 1981 has resulted in annual combined losses of these three crops representing roughly 40 Mt or $5 billion per year, as of 2002.”
-- “Global scale climate–crop yield relationships and the impacts of recent warming," David B Lobell and Christopher B Field 2007 Environ. Res. Lett. 2 014002 doi:10.1088/1748-9326/2/1/014002
http://iopscience.iop.org/1748-9326/2/1/014002
and this one
“With a 1°C global temperature increase, global wheat yield is projected to decline between 4.1% and 6.4%. Projected relative temperature impacts from different methods were similar for major wheat-producing countries China, India, USA and France, but less so for Russia. Point-based and grid-based simulations, and to some extent the statistical regressions, were consistent in projecting that warmer regions are likely to suffer more yield loss with increasing temperature than cooler regions.”
- B. Liu et al, “Similar estimates of temperature impacts on global wheat yields by three independent methods, Nature Climate Change (2016) doi:10.1038/nclimate3115, http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3115.html 
But -- again, for the US -- these turn out to be quite small numbers, because the market sizes are so big and yields are increasing year-after-year.

So how do crop yields (again, US-only) vary with temperature? Here are some data from the National Climate Assessment (2014), Figure 18.3, p 421


These data are, admittedly, rather scattered and a straight-line trend will have errors. (I don't have the underlying data to calculate those here.) But by eye, I estimate the trends to be, for corn: -0.39 t/ha/°F, and, for soybeans: -0.08 t/ha/°F.

So what are the current yields, and how fast are they increasing? Here is the current yield and trend in corn yields, and the same for soybean yields.

So, plugging in the data, the trend in corn yields = 1.9 bu/acre/yr, and the trend in soybean yields = 0.5 bu/acre/yr. Relative to 2017, these are 1.1%/yr and 1.0%/yr, respectively.

From the same source, 2017 yields are, for corn: 176.6 bu/acre, and for soybeans, 49.1 bu/acre. "bu" is bushels.

I need to know the density of corn and of soybeans: 39.3680 bu/t and 39.7740 bu/t, respectively, from this source.

Translating into metric units: 2017 corn yield = 11.1 t/ha, 2017 soybean yield = 3.1 t/ha.

OK, now we can put things together.

Let's assume the surface warming trend is +0.20°C/decade. That's one degree Celsius in 50 years. (Results for other trends will scale linearly.)

Assuming the current trend in yields continues (iffy?), in 50 years (a long time, granted), yields will have increased by 170% (for corn), and 165% (for soybeans).

But in that time, yields will only decrease due to higher temperature by -6% (corn) and -5% (soybeans).

So agricultural technology will, even if trends continue at only a fraction of their current value, swamp any losses due to global warming.

And it won't take much increase in yields in developing countries for them to cancel out any loses due to higher temperatures, either.

--

Of course, there's no inherent reason to believe that yield increases will continue at their rate of the last 30 years for the next 50 years. Nor will warming stay linear, probably. And we'll need more food to feed ever more people, about 10 B by the middle of this century. And warming won't be limited to just one degree Celsius (we're already at that value anyway).

But I don't anymore see a big problem here. Am I missing something?

Sunday, April 01, 2018

Tuesday, March 27, 2018

Will the Falling Chinese Satellite Hit Someone?

As you probably know, the de-orbiting Chinese space station Tiangong-1 will soon fall to Earth.

This thing is 10.4 meters long and, on launch, weighted 8.5 tonnes.

What are the chances it will hit someone, or something important?

I don't know, and now that I'm reviewing this calculation I feel pretty sure I don't know, but here goes with my original idea.

The satellite will fall between the ± 43° latitude lines. But that's about all that seems known for sure right now.

That area constitutes 348 Mkm2, or 68% of Earth's surface area.

Much of this is ocean, but I don't know exactly how much. I'll assume, for better or worse, that it's the same percentage that the ocean makes up of Earth's total surface area, 70.8%, giving a potential land fall area of 102 Mkm2.

How many people are in this area? I don't know. All I know to do (without a lot of work) is assume it's the same percentage of the world population as is land, which, extrapolating this trend, was 7.46 B in 2017.

(Amazingly, 90% of the world's people live in the Northern hemisphere.)

When might a person be "hit" by a falling satellite? Let's say if it occurs within a 10 m radius of that person. Thus the danger zone around each person is 628 m2, and around all people living in the fall zone is (assuming independence) 3.20 Mkm2.

That's 3.1% of the satellite's potential landing zone. Small, but not tiny.

--

I suspect this number is an overestimate, because

(1) I've overestimated the number of people who live between -43 and +43 degrees latitude, since there's more ocean there than I've assumed, and
(2) I've assumed each person's "target zone" is independent of everyone else's (which is obviously not true in cities.)

Much of Europe and Russia lives above 43° N latitude, and all of Canada does -- and I do too, at 45-epsilon degrees. (I often drive past the a sign in North Salem announcing the 45° line, and based on my home's GPS coordinates I've calculated that I'm about 4.4 km south of this line, or at 44.960858° north latitude.)

So, there's a tiny chance of someone being hit by this satellite. 3% seems high -- but I doubt the chances are infinitesimal, even if I'm off by a factor of 10.

Still, good luck out there. Heads up.

Free, Online Climate Textbooks

I've recently come across a few free, online climate textbooks, and thought it worth mentioning here.

A great introduction to the basics:

Introduction to Climate Science, Andreas Schmittner, Oregon State University.

For more advanced students:

Introduction to climate dynamics and climate modeling, by Goosse H., P.Y. Barriat, W. Lefebvre, M.F. Loutre and V. Zunz, (2008-2010).

I guess I can mention Pierrehumbert's textbook Principles of Planetary Climate, though I'm not sure it's on the Web legally. I bought the hardback version and have learned a great deal from it. I heartily recommend it.

Sunday, March 18, 2018

My Plastic Brain by Caroline Williams

From my mailbox:

My Plastic Brain: One Woman's Yearlong Journey to Discover If Science Can Improve Her Mind by Caroline Williams.

Amazon
Barnes and Noble

Author's Web site

From Kirkus Reviews:

"Readers hoping to improve their own cognitive abilities may feel a bit of a letdown by the author’s old-fashioned, down-to-earth advice: exercise your body, preferably outdoors, learn mindful meditation but also allow your mind to wander, engage in a mentally challenging hobby, and pick the skill you want to improve and practice it in real life."

Valar morghulis.

Monday, March 12, 2018

When the Statue of Liberty Gets Sea Walls

Last night I started watching The Expanse on Amazon Prime. It's been really good scifi so far, and has that nitty-gritty view of future space travel, more Firefly than Star Trek, but even grittier. It's set 200 years in the future, and in an early episode there was this short cut of the Statue of Liberty, with sea walls due to (presumably) global warming:


Another good idea (for the story, at least) was "gravity torture," where those who grew up off-Earth in a lower gravitational environment are tortured by being hung in Earth's gravity for hours:


In Kim Stanley Robinson's Mars Trilogy, kids born on Mars (where g = 38% of that of Earth) eventually become significantly taller than Earthlings.

I appreciate when writers think about the little things and subtly put them in their stories. It's fun to notice them. The Expanse does this very well, so far.

Sunday, March 11, 2018

Question About My Blog's Appearance

When you read this blog, is the page too wide for your screen?

Do you have to scroll right in order to see what's beyond the post itself -- the "About Me" module, "Blog Archive," "Good Links," etc.?

I do. So I'm wondering if everyone has the same problem. Other blogspot blogs read fine in my browser.

Thanks.

Thursday, March 01, 2018

Equations That Changed the World

A few years ago, mathematician Ian Stewart published a book titled 17 Equations That Changed The World. It's an interesting list:


I would go beyond these 17 and add: 
  • 1+1=2, which some unknown someone realized long ago was profound and incredibly useful. The logical proof of this assertion, though, didn't come until Bertrand Russell and Alfred North Whitehead three-volume Principia Mathematica. It's a crazy book -- the text looks almost alien or elvish, and it took them several hundred pages of work before they could prove that 1+1=2. Russel said his work on this book "had actually damaged his brain." Here's an interesting discussion of the Principia Mathematica from NPR in 2010.
  • Newton's second law of motion, F=ma (really, F=dp/dt, the time rate of change of momentum).
  • Planck's Law of radiation (probably).
  • The Lagrangian of quantum electrodynamics, because it changed how quantum physics was done ever afterward.
  • Einstein's equations of general relativity, because they changed our view and understanding of the universe, and for their sheer elegance and sophistication. 
You?

Tuesday, February 27, 2018

Idiocy from Ed Berry, PhD

What can you even do when climate deniers won't agree to the basic rules of arithmetic??

Ed Berry is a physicist who earned his PhD back in the Mesozoic era. From Caltech, no less. He now lives in Montana as a mountain man, battling long-horned sheep for food, coming into town once a year for saltpeter and a ballot.

Ed is a hard core climate denier. (And, naturally, a hard core Trump supporter.) So hard core he doesn't care when he makes basic, boneheaded mistakes -- because, you know, one never admit error when a bear is charging at you, or someone who understands the science.

Q: How much has atmospheric CO2 increased since the pre-industrial era?

A: That's an easy calculation, right?

pct chg = change/initial_amount = (408 ppm - 280 ppm)/280 ppm = 46%.

That's simple, clearly.... But not in Ed's denier-land. This is from Ed's blog:



30%?? Whoa.... That's just a dumb arithmetic error. It comes from calculating

change/final_amount = (408 ppm - 280 ppm)/408 ppm = 31%

which is obviously NOT how to calculate a percentage change. You and I learned this in 5th or 6th grade. So did Ed. It's a trivial, arithmetic error.

But one that mountain men will not admit to. Ed is so much of an uber denier that he can't even admit to a simple arithmetic error, can't say, Oops!, you're right, let me fix this and go on.

Now, what can you do when a denier won't accept arithmetic?? I have no idea.

It's all part of Ed's Big Misunderstanding -- he writes, "Why human CO2 does not change climate." He's so sure of this, of course, just as he's sure that the increase in atmospheric CO2 is 30%, even though every 6th grader knows better. He's submitted a paper somewhere (he won't say where), and is proud that after 4 months it hasn't yet been rejected. Remarkable!

Sorry, but I don't accept PhDs in physics misunderstanding the basic science behind global warming -- the Earth emits infrared radiation, and the atmospheric GHGs absorb it. Rejecting that is bad enough. But claiming that our HUGE emissions of CO2 aren't piling up in the atmosphere -- somewhere -- that's is just, I'm sorry, pure stupidity. Dumb. Ignorant. Idiotic.

But what can you do when deniers won't accept the basic rules of arithmetic? Where do you even start?? Beats me....

Thursday, February 22, 2018

Fulgarite - When Lightening Strikes Sand


Via National Geographic

Obamacare Has Bent the Cost Curve


Data:
monthly health care costs - Altarum Institute
monthly inflation: Fred CPI-U

That Arctic Has Been Astonishingly Warm

This is an astonishing graph:


The Arctic is currently about 17°C (31°F) degrees above normal. The baseline (green line) is the 1958-2002 average. 

If that were happening where I live, today's high would have been 86°F. Normal high (1981-2010) for Salem, Oregon today is 53°F.

Reflecting this, Arctic sea ice has already reached a record low for the year, 2.5% below last year's record low. 

Saturday, February 17, 2018

Cool Integral

From KarlMagnus Petersson‏ on Twitter:


In the same way, you can show (I think) that


which is also cool, but not as cool, since "3" is not as cool as "e."

Note: 1/3 < 1/e. This makes sense, since for 0 < x <1, sqrt(x) < cuberoot(x) < fourthroot(x), etc.

Note II: Speaking of e, one of my best friends, a colleague in graduate school (we had the same advisor, and have gotten even closer since), once wrote a paper that contained the number e^e, which I think is about the coolest thing ever published in physics. I wrote about it here for Physics World.

Wednesday, February 07, 2018

Global Warming in Ursula Le Guin's 1969 Novel "The Left Hand of Darkness"

The science fiction writer Ursula Le Guin recently died (she lived in Portland, Oregon for decades), and since I hadn't read anything by her I thought I better get started. So I picked The Left Hand of Darkness, her breakthrough book published in 1969. She was on the ball, because even then she knew about CO2 and global warming. Here she writes about her fictional planet of Gethen.
Eskichwe rem ir Her hypothesized that the volcanic activity in N.W. Orgoreyn and the Archipelago has been increasing during the last ten or twenty millennia, and presages the end of the Ice, or at least a recession of it and an interglacial period. CO2 released by the volcanoes into the atmosphere will in time serve as an insulator, holding in the longwave heat-energy reflected from the earth, while permitting direct solar heat to enter undiminished. The average world temperature, he says, would in the end be raised some thirty degrees, till it attains 72°. I am glad I shall not be present. Ai says that similar theories have been propounded by Terran scholars to explain the still incomplete recession of their last Age of Ice. All such theories remain largely irrefutable and unprovable; no one knows certainly why the ice comes, why it goes. The Snow of Ignorance remains untrodden.
It's interesting that she associated CO2 warming with the Ice Ages, as science did for a good while back then, I think, while it grappled with understanding the Pleistocene.

More Humor from SpaceX

(Besides the orbiting red roadster, I mean)

Saturday, February 03, 2018

Saturday, January 27, 2018

Ocean Heat Content Reaches Record Highs

We all know by now -- or should know -- that ocean heat content (OHC) is easily the best metric of a global energy imbalance -- about 93% of the trapped heat goes there.

At least, The Guardian has caught on.

The OHC data for 4Q17 are in, and it shows that in 2017, the OHC of the top sixth and the top half of the global ocean both reached record annual values:


In 2017, the heat uptake for the 0-2000 m region -- the top half of the ocean -- was 1.6 W/m2 relative to 2016, and its acceleration, in just 12 years of data recording, is 0.039 ± 0.018 W/m2/yr.

Tuesday, January 23, 2018

Guesses for the New Doomsday Clock Setting?

Update 1/25: The Clock was set forward by half a minute, "amid increasing worries over nuclear weapons and climate change," so it's now at two minutes to midnight. Trump has at least 3 more years in office, so if this trend continues the Clock would be at a half a minute to midnight at the end of his first term. The fate of the world might hinge on defeating his bid for reelection (or on his impeachment and conviction -- one can always hope).

"'This is the closest the Clock has ever been to Doomsday, and as close as it was in 1953, at the height of the Cold War,'” said Rachel Bronson, president of the Bulletin of the Atomic Scientists." 

I certainly worry about nuclear Armageddon -- though not as much when I was younger, where for a few years after graduate school I would sometimes wake up screaming in the middle of a night after a dream -- but I don't think climate change will be "catastrophic." Difficult, costly, tragic in some situations -- but not catastrophic. By the 22nd century humans will probably know enough to do responsible geoengineering and prevent the 40 to 60 meters of sea level rise that would otherwise be coming over several millennia. Half of Florida might be gone by then, though. That alone is gonna cost trillions.

--

The Doomsday Clock is currently set to 2.5 minutes before midnight. It's maintained by the Bulletin of the Atomic Scientists, and will be reset this Thursday at 10 am ET, 7 am PT, 15:00 GMT. (No adjustment is also possible, as was done last year.) Watch online.

Any guesses on the new setting? I'm guessing 1.5 minutes before midnight, based solely on the fool now in the White House. (He'll probably consider this a positive sign of his worldwide fame.) A substantial jump forward, but still not too close to pure panic.

1.5 minutes before midnight would be the Clock's more dire setting ever. Here's its history:

Monday, January 22, 2018

Climate Models Are Doing Great

After 2017's annual temperatures came in, Gavin Schmidt posted this on Twitter:

Here, historical forcings are used prior to 2000 -- the actual GHG concentrations, volcanic eruptions, etc. After 2000 the comparison uses the old IPCC Scenario A1B -- "...very rapid economic growth, global population that peaks in mid-century and declines thereafter, and the rapid introduction of new and more efficient technologies." (Truth is, there isn't much of any difference in these old AR4 scenarios by this time.)

Looks equally good with the CMIP5 models.

The model/observation difference varies depending on the particular year (or couple of years), but over the long-term it's looking pretty good.

Certainly good enough to see that we have a big AGW problem on our hands.

Wednesday, January 17, 2018

Doomsday Clock

On January 25th at 10 am ET the Bulletin of the Atomic Scientists will reveal their annual decision about the hands of their Doomsday Clock: bit.ly/2Dp0wnS. It's currently set at 2:30 minutes before midnight.... I expect that will decrease to maybe 1:30 before midnight...simply because Trump is an ignorant, dangerous idiot.

It's stunning to me that we/Congressional representatives are letting such a clearly ignorant and unthinking man decide, minute by minute, the literal fate of the world.

The world must -- seriously -- I really mean, seriously -- outlaw all nuclear weapons for all time.

I'm not kidding at all. We're 7 billion strong...but never use it.

A Song About the Umpqua Shooting

By Patterson Hood and the Drive-by Truckers, my favorite band for the few years:


I used this song for an op-ed I wrote for the Salem Statesman Journal, published in November.

Michael Mann Has a New Blog

Michael Mann now has a personal blog. (Nothing there yet.) Here's the RSS feed.

Between Twitter, Facebook, RealClimate and now a blog, he must be the most socially connected scientist on the planet. And I see him quoted everywhere these days. And he still co-authors a lot of papers and articles.

Here was his recent rebuttal to an op-ed by Oregon's leading denier, Gordon Fulks.