Friday, August 23, 2019

Are the Brazilian Wildfires Abnormal?

I don't anything more than what I read in the papers (+Twitter, blogs, etc), but this tweet is interesting. It comes from someone who says he's President, Founder, Senior Scientist @EarthInnovate and follows Amazon forest, climate change, low-carbon devt. The Earth Innovate seems to be a one-man show. Not to say he isn't credible. Unfortunately he doesn't give the source for his NASA data. (Added: source seems legit.)


Thursday, August 22, 2019

Another View of Arctic Sea Ice Extent Minimums

Monday, August 19, 2019

And Now Our Watch Has Ended

2019's Arctic sea ice extent was on a roll -- downward -- for longer than usual. But now it's pulling up short and looks very unlikely to fall below 2012's minimum (JAXA data):


2019 is still only a slight deviation, but 2012 was still melting rapidly at this time of the year, and I don't just can't see 2019 making headway against that.

(Added 10 pm Pacific Time: the JAXA number for 8/19/2019 SIE has decreased from -258 km2 below 2012 yesterday, to, now, -309 km2. That's a huge jump in one day. Puts a record even further out of reach. It's not going to happen.)

So when might 2012's record low be broken?

Below I've taken the annual lows since 1979, using NOAA's daily data, and, leaving 2012 out of the equation, calculated the trend in the annual minimum. (I'm switching between JAXA and NOAA data only because of where I have the relevant graphs; they don't differ by much, but the graphs not so easy to replicate):


This trend for the min is -78,000 km2/yr. Given 2018's min of 4.55 Mkm2, the trendline won't fall below 2012's min (3.34 Mkm2) for 16 years after 2018 -- that is, in 2034.

2012's summer was clearly extraordinary. There was a summer cyclone that chewed the ice up, meaning it had more surface area exposed to the air and sea and so melted faster. (Ice chips in your restaurant water melt faster than ice cubes.)

Of course, my calculation assumes no years between now and then will be extraordinary lows due to, say, the same kind of natural variability that was seen in 2012.

2012 was extreme natural variability in action. Similar to the average USA48 temperature that saw 1934 the warmest year for many decades after. (Probably aided some by [anthropogenic] Dust Bowl conditions.) It was only with the 1997-98 El Nino that its annual average was surpassed. But now 1934 ranks only 7th highest of USA48 average temperatures. There same will eventually happen with 2012's record SIE low.

Added 8/22: Here's the situation as of 8/21:


Sunday, August 18, 2019

"The Sillier It Looks"

I've never seen this particular quote before. It still seems true:
"The more success the quantum theory has, the sillier it looks."

- Einstein, 1912
from Pais A. (1982). ’subtle is the Lord...’: The Science and the Life of Albert Einstein. Oxford: Clarendon.

Thursday, August 15, 2019

GISS Also Find Hottest Month Ever

NASA GISS also found July 2019 to be the hottest month globally, 1.14°C above the 1880-1909 average.
  • GISS's land-only anomaly for July is 0.90°C relative to 1951-1980.
  • The YTD average land-only anomaly relative to the older baseline is 1.65°C.
  • That's 2.98°F!
  • With a 2nd-order fit, GISS's acceleration for the global average is 0.016°C/decade2.

NOAA: July Hottest Month in Their Records

NOAA says July was the warmest month in their records, which begin in 1880.

Relative to 1880-1909's average temperature, July was 1.18°C higher. (Same number as June.) NOAA hasn't had an anomaly less than 1°C since November 2014, using that baseline. This year's average-to-date is 1.20°C. Their warmest year was 2016 at 1.24°C (2.23°F). 

Warming above the 1°C benchmark is here, now, for good.



Wednesday, August 14, 2019

Things I've Noticed

The human side of the decline of coal.
*
In the first of the Big Boys to report, the Japan Meteorological Association finds July 2019 to be tied with July 2016 for the warmest July (and therefore the warmest month of any month), 1.05°C above the 1891-1920 baseline. Six of seven of this year's temperatures are above 1°C, using that baseline, and 3 of the last 4 years. NOAA reports tomorrow.
*
A very interesting op-ed in the New York Times saying that if we live in a simulated world (and are simulations ourselves), we shouldn't do any experiments to try to discover this.
*
Greta's influence: Swedes are flying less and taking more trains, even though it's more expensive and takes longer: "Passenger [train] numbers were up 10 percent in the first quarter of this year compared to the same time last year..... Meanwhile, the number of passengers at Swedish airports fell by 4.4 percent in the first three months of this year, the Swedish Transport Agency said."

Meanwhile, Greta Thunberg will be taking a zero-emissions yacht to the UN Climate Summit in September.

She's also been nominated for the Nobel Peace Prize. (I saw that coming.)
*
A machine learning water model correctly predicted the melting point of ice. And more. I find that very impressive.
*
Hockey stick confirmed again: The latest results from the PAGES 2k Consortium of the last 2000 years' average global temperature, using seven different statistical methods:


No global Medieval Warm Period. About -0.2°C cooling for a global Little Ice Age. They write, "A substantial portion of pre-industrial (1300–1800 ce) variability at multidecadal timescales is attributed to volcanic aerosol forcing."

Tuesday, August 13, 2019

The Invisibility of Relativistic Length Contraction

I have a feature article in the August issue of Physics World magazine: "The invisibility of length contraction," about how viewing relativistic length contraction is not at all the same as measuring it.

In actuality, a rapidly moving object (one with a speed a sizable fraction of that of light) would appear rotated instead of contracted.

Monday, August 12, 2019

Climate Data All in One Glance

Today AMS pubished their annual report State of the Climate in 2018, and Plate 1.1 page 52 has a nifty collection of graphs of climate data all in one place. I had to break their figure up into 3 pieces to capture it fully; the bottom figure shows the time scale (in years). Feel free to laminate this.




Thursday, August 08, 2019

Land vs Ocean Warming

Just posting a nice graph via Robert Rhode of BEST. It's often forgotten than land globally is warming about twice as fast as the ocean surface, because land has a smaller heat capacity. (To put it another way, heat more easily penetrates through the sea surface than through the land surface, and ice.) So we're now seeing a global land average of about 1.7 - 2.0°C relative to the 1850-1900 average. That's 3.0 - 3.6°F. More as you go northward, less in the tropics. Oregon has seen a temperature rise of 2.7°F since 1895. Alaska, which just had its warmest July ever, has warmed by 4.5°F since 1960. (I'm using Fahrenheit because it's more familiar to Americans, including me.) The continental US, which had only its 27th warmest July (of 125 years) has warmed by 1.8°F since 1895.

And so it goes.


Wednesday, August 07, 2019

Nick Stokes Finds July 2019 Was the Warmest


Tuesday, August 06, 2019

What RCP is the World Actually On?

(Skip to the bottom if you want to know the answer right away.)

As you probably know, the IPCC established four Representative Concentration Pathways (RCPs) for their 5th Assessment Report. The number after each "RCP" is the assumed amount of radiative forcing, in watts per square meter, from all greenhouse gases in the year 2100.

The pathways cover many variables all across the board, and are the inputs climate modelers use to do their calculations. Here are the actual numerical values of all the parameters that go into each RCP.

So which pathway will the world follow, at least approximately? Which pathway are we on so far?

I'm going to simplify this by looking only at atmospheric CO2 concentrations, because this is a blog, not a journal paper.

The RCPs don't begin to differ until about 2009 (and go all the way to 2500, when RCP 8.5 assumes CO2 would be 1,962 ppm), and then differ slowly, but by 2018 we have this:


I got the CO2 values for the year by taking the annual CO2 radiative forcing (RF) from NOAA's Global Radiative Forcing results and using the equation

RF=(5.35 W/m2)*ln(C/C0)

to calculate C, which here means CO2 and C0=278 ppm. (The latter is the value the RCPs take for their first year, 1765.)

So we're between RCP 6.0 and RCP 8.5. To find an actual value, I linear interpolated between their values for each year to get our actual RCP value:


The values were small in the beginning because there wasn't much variance between RCP 6.0 and RCP 8.5 in the beginning -- the difference is now 4.5 ppm CO2 -- and because our path was below RCP 6.0 in the beginning. But we made up for it and now the value is stabilized, for now at least, at 6.8.

So we're at RCP6.8.

Monday, August 05, 2019

Neil deGrasse Tyson's Stupid Tweet

Distressingly, 266,000 people have liked this tweet so far.

It's hard to understand how Tyson couldn't see his tweet's lack of empathy and its smart aleck-iness. Or his poor reasoning -- all of those problems are amenable to preventative actions except walking down an aisle at Walmart.

Tyson should apologize. Instead of his qualified apology (which are never real apologies).

Friday, August 02, 2019

How Large Is the Urban Heat Island Effect?

Does the urban heat island effects influence global temperature trends?

Roy Spencer claims, without proof, that they do. Berkeley Earth (BEST) found they do not, after having actually examined the global thermometer set six ways from Sunday with a skeptical eye:
"The Urban Heat Island effect is real. Berkeley’s analysis focused on the question of whether this effect biases the global land average. Our UHI paper analyzing this indicates that the urban heat island effect on our global estimate of land temperatures is indistinguishable from zero."
http://berkeleyearth.org/faq/#question-15

paper:
"Influence of Urban Heating on the Global Temperature Land Average using Rural Sites Identified from MODIS Classifications," Wickham et al., Geoinfor Geostat: An Overview 2013, 1:2
http://dx.doi.org/10.4172/2327-4581.1000104
https://www.scitechnol.com/2327-4581/2327-4581-1-104.pdf
And indeed, that's been the determination for some decades; here's a 1990 paper from Nature:
"The results show that the urbanization influence in two of the most widely used hemispheric data sets is, at most, an order of magnitude less than the warming seen on a century timescale."

"Assessment of urbanization effects in time series of surface air temperature over land," P. D. Jones et al, Nature, volume 347, pages 169–172 (1990).
https://www.nature.com/articles/347169a0
Is there a way to estimate the influence of the UHI? Here's my attempt.

At the Astrobiology conference I was at a couple of weeks ago, a speaker said that on Earth cities occupy 0.2% of the globe's surface area. (It was in the context of the possibility we might see lights on an exoplanet's surface.) I also learned a new word then: "ecumenopolis" -- a planet whose entire surface is covered by one gigantic city.

If there are no UHIs, i.e. no net UHI, then the global mean average temperature (GMAT) is


Now let's say there is a UHI, the same in all cities, and those cities occupy a certain area. Then the GMAT would be something like this weighted average:


(Apologies for the different font sizes.) So the difference in GMAT between a world with a UHI and one with no UHI is


The ratio on the right-hand side is 0.002, and the urban heat island effect is, what, about 5 K (=9°F)? Then


That's your UHI. The trend will change even slower than this, per decade.

Even if the area of all the cities doubles, it will still be only about 0.02 K << global warming of 1 K.

Just a back of the envelope calculation, but it suggests the UHI is indeed small-to-negligible. Because the Earth is vaaaaaaaaaaaaaast.