Friday, May 01, 2015

Heat Changes Due to UAH's New Dataset

So how much less heat is in the lower troposphere (than what we thought) because of the changes in UAH's new dataset?

Very little.

The trend of the new dataset, from its beginning in Dec 1978 to March 2015 is +0.114 C/decade. The trend of their previous dataset was +0.140 C/decade.

Since the dataset is 36.33 years long, the new dataset has about 0.41°C of warming, and the old dataset had 0.51°C. So the difference is 0.1°C.

To get a sense of how much change in heat this represents, I'll assume the mass of the lower troposphere is the mass of the entire atmosphere (since it gets exponentially thinner as you go up in height), which is 5e18 kg. (It's easily estimated from surface pressure: g*matmo = Ps*surface_area_of_Earth, where g is the acceleration due to gravity at the surface.)

The heat capacity of air decreases below Earth's surface temperature, but not by alot, so I'll take it to be the average over the range, 1.0 kJ/kgK.

The atmosphere is 0.25% water by weight, and water vapor has a specific heat of less than 2 times dry air, so I'm going to ignore its presence in the atmosphere. (This is an order of magnitude calculation only.)

Then the heat change is ΔQ = mcΔT ~ 5e20 J, or, over the 36.3 years, ~ -4e11 Watts. Dividing by the Earth's surface, that comes to ~ -0.001 W/m2.

That's about the same as comes from the Earth's interior, which is 86 mW/m2.

So in terms of a planetary energy imbalance, this isn't a significant change at all -- it won't have been noticeable through changes in ocean heat content, which cannot be used to notice a missing milliwatt per square meter. (Added 5/2: And only about 4 times this much heat total has gone into the lower troposphere in the last 36+ years -- less than 0.01 W/m2.)

Of course, though the ocean is the best diagnostic for a planetary energy imbalance ("Global warming is ocean warming," says NOAA oceanographer Greg Johnson), we don't live in the ocean. But we also don't live atop it, and for the planet's land (well, the lower troposphere above it) UAH's new dataset has a trend of +0.19 C/decade.

And it's +0.20 C/decade for the Northern Hemisphere land. But the "2°C limit" refers to the globe, not just land.

Thursday, April 30, 2015

On Errors in Datasets

There's been one little error in UAH's new data for the lower troposphere -- the baseline (1981-2010) for the global lower troposphere didn't have an average anomaly of zero. That's pretty trivial.

It's being fixed. The data is a beta version, after all. This is why you put it out there

But this raises a larger question. How can we trust any dataset that's put out there -- not just UAH's, but any and all of them, dozens if not hundreds?

The algorithms now are so complex that to be sure -- really sure -- I'd have to acquire the raw data, construct a data model (algorithm), and run it. Obviously I cannot do this, likely even if I had the time, certainly not for 99% of the data out there, and you can't either.

If I had to guess, I would say that none of the datasets is exactly right. All of them will contain errors. The big errors are easy to catch, because they're big, but anyone who's ever coded and worked with data knows there is the possibility of a zillions of little errors where your computer spits out numbers and that makes you happy.

At some point, when you get results that look plausible -- no obvious errors, lots of internal checks, reasonable agreement with other work (if there is such) -- you stop and say, here are my results. But judgement necessarily includes your own biases -- you simply cannot help it. But that doesn't mean there are no more errors.

It'd be wonderful if there were observations or experimental results to compare to. But that's very rare, and if such data did exist, you'd have checked yourself and not published it if there wasn't agreement.

This is a big problem in science, or in any field that does data analysis, especially when the science has public implications. We all believe the data we think supports our views, and have to struggle mightily to deal with data that doesn't. But it is always going to involve trust, and past results, and reputations, and more.

So when I point out some big changes in UAH's dataset, I really have no idea whether their version 6.0beta is better than v5.6 or now. It agrees better with RSS, so that's a strong point in its favor. On the other hand, some of its corrections are greater than 1 C, which is bigger than the warming expected since the start of their dataset.

Science moves a lot slower than public opinion. That should be a good thing, except in an environment like today's.

Not Something to Be Skinned

"We have gotten past the stage, my fellow-citizens, when we are to
be pardoned if we treat any part of our country as something to be skinned for two or three years for the use of the present generation, whether it is the forest, the water, the scenery. Whatever it is, handle it so that your children’s children will get the benefit of it."

-- Teddy Roosevelt, Grand Canyon, May 6, 1903

Wednesday, April 29, 2015

Estimated GISS April Global Temperature Anomaly: +0.66°C

My estimate for GISS's global temperature anomaly for April is +0.66°C.

This is based on the daily reanalysis numbers published by the University of Maine Climate Reanalyzer, as described here. This makes April significantly cooler than March's +0.84°C, but it's still the 4th-warmest April since record-keeping began in 1880.

Year-to-date, i.e. for [only] he first four months of this year, this puts GISS at +0.13°C warmer than 2014. Assuming my estimate for April is correct, GISS only needs an average anomaly of +0.63°C for the rest of the year to establish a new record:


Reminder: GISS's baseline is 1951-1980.

I also estimate HadSST's April anomaly will be +0.40°C, which is the 4th-warmest April since 1850.

The Reanalyzer shows the El Nino really gaining steam (so to speak), which suggests a likelihood of warmer months ahead:


Remarkable Changes to UAH Data

A few more thoughts about the new UAH datasets (version 6.0, beta).

UAH calculates anomalies for 27 regions, of which some are subsets of a larger region.

Their dataset goes back 36.3 years. The period starting in December 1978, going to March 2015, consists of 11,772 data points.

All those data points get changed in the new dataset, v6.0 beta, from version 5.6.

Of those changes, 29 have a value greater than 1.0 C or less than -1.0 C.

Of those changes, 410 are greater than 0.5 C or less than -0.5 C -- that's 3.5% of their data points.

I find that pretty remarkable. And yet the usual suspects will swallow this without questioning it at all, and be thankful for it.


Some Big Adjustments to UAH's Dataset

The UAH group has released version 6.0beta of their temperature anomalies, doing an extensive rethinking and rewriting of their algorithm and code. It looks like a huge amount of work. You can read all about it (and should) at Roy Spencer's site.

The upshot is that the global trend for the lower troposphere decreases from 0.14°C/decade to 0.11°C/decade. That's over all 36.3 years of the record.

The new version is a beta version, so naturally there may be some kinks to work out. To far, there are some surprising large changes in both directions. (I'll only look at the lower troposphere, since that's of most populat interest.)

Here is their graph of the changes, for the monthly global numbers only:



First, here are the data:


Here are the comparisions, for each region. I've highlighted what seem to me to be surprisingly big increases, and in blue suprisingly big decreases.


Yes, some months change by more than 1°C -- the largest decrease of any month is -1.43°C, in the Arctic. +1.32°C for the Arctic Ocean.

Here are the monthly changes for the North Pole (60°N - 90°N):


The two most extreme changes are

+1.32 C for the North Pole ocean in Jan 1981.
-1.43 C for North Pole land in Nov 2003.

Many of the largest changes are from decades ago:

A change of +0.83 C for USA48 in 1/1979
A change of +0.85 C for USA49 in 2/1979
A change of -0.76 C for AUST in 12/1978
A change of -1.31 C for SoPol_Land in 9/1982

But even some recent changes are quite large:

A change of -0.31 C for NH_Ocean in 12/2014
A change of -1.40 C for NoPol_Ocean in 3/2010, and 
A change of -1.25 C for NoPol_Ocean for 2/2010
A change of -0.71 C for USA48 in 2/2009

I'm not saying there is anything wrong or untoward about these changes -- I have to trust the UAH group, just like I have to trust GISS, HadCRUT4, Cowtan & Way, etc. Of course, UAH's work needs to be published and peer reviewed, just like all the others.

This will be a litmus test for contrarians. Can you imagine the howling if GISS changed a past month by +1.32°C? Unfortunately, I expect they will convince themselves these changes are good, but adjustments to the surface dataset are not. In fact, they already are. 

Tuesday, April 28, 2015

Calbuco Volcano Not Likely to Affect Global Temperature

Calbuco eruption
A short NASA article says the Calbuco volcano in southern Chile has so far released 0.3-0.4 million tons of sulfur dioxide (SO2), as high as 21 km into the stratosphere.

By contrast, in 1991 Mount Pinatubo emitted 17 million tons of SO2, and that cooled the globe about 0.4°C from 1991 to 1993.

The NASA article says
The SO2 total is much lower than the recent Holuhraun eruption [August 29, 2014], which released about 11–12 [million tons], or 30 to 40 times more than Calbuco. “But the SO2 from Holuhraun was emitted over several months and was mostly confined to the lower troposphere, limiting its climate impacts,” [Simon] Carn noted. “In terms of climate impacts, Calbuco is probably more significant due to the stratospheric SO2 injection.”
So unless there are more massive eruptions in its near future, Calbuco doens't look likely to impact global temperatures. But
“Although a single eruption of this size is unlikely to have a measurable effect on climate,” Carn added, “recent work suggests that the cumulative effects of multiple volcanic eruptions of this size in the past decade may have slowed the rate of global warming due to the stratospheric sulfate aerosols produced.”

Friday, April 24, 2015

A Surprising Temperature Reconstruction, 100-2000 A.D.

There's a surprising paper in Geo Rev Letters, presenting this reconstruction of surface temperatures over the last 2000 years. I've taken the data and calculated its 10-year moving average:


Not surprisingly, it finds a warm Roman period, but then the reconstruction shows a dip in temperatures during the Medieval Climate Anomaly (MCA) of 1000-1200 AD. Then mild temperatures, then a sharp dip into the Little Ice Age, and strong warming since 1850 and the Industrial Revolution.

Not too surprising, except for the MCA. How did that come about?

--

Well, in fact it did not come about. Actually, this data consists of nothing but random numbers that I generated, between 0 and 1, one per year, with their 10-year moving average plotted above.

How do random numbers give a realistic looking temperature time series?

It's called the Slutsky Effect, which I just learned about from an article John Fleck sent me a few weeks ago:

"The myth of Europe’s Little Ice Age"
Morgan Kelly, Cormac Ó Gráda, 28 March 2015

Eugen Slutsky (1880-1948) was a Russian mathematician who did important work in economics and in the mathematics of time series, while trying to keep his head on his shoulders during the Russian revolution and the murdering afterward.

Slutsky showed that it's very easy to construct random times series that appear, when a moving average is calculated, to give results very reminiscent of economic business cycles. Here is a nice overview.

Or, here, a temperature time series.

The random data I generated, between 0 and 1, has an average of 0.490 and a standard deviation of 0.025.

Its trend from start to finish is -0.000003 -- essentially zero. Yet it shows what could easily be interpreted as meaningful intervals of warm and cold.

Kelly and Ó Gráda look at temperature reconstructions in Europe from 1300-2000, calculated 25-year moving averages, and find the following:



which looks meaningful, except it comes from this raw data, whose trend isn't statistically different from zero:


They've done more statistical analysis in a paper in the Annals of Applied Statistics, which I have not yet read but plan to.

So what to make of this?

I'm not sure. Patterns can be found in random data, that look meaningful. A series of random events can combine to look like a meaningful cycles in an economy, or a climate.

Is this all that modern global warming is, a time series analyzed so as to look meaningful? No, because its trend is statistically different from 0.

But other data? I think the lesson is you need to be careful. Kelly and  Ó Gráda conclude there was no Little Ice Age, in a statistical meaningful sense. There were, to be sure, decades of worse weather than normal, that affected crop production in regions and the people who depended on them.

But a widespread LIA? They say no.

More later.

For me this glass is already broken.

"You see this goblet?" asks Achaan Chaa, the Thai meditation master. "For me this glass is already broken. I enjoy it; I drink out of it. It holds my water admirably, sometimes even reflecting the sun in beautiful patterns. If I should tap it, it has a lovely ring to it. But when I put this glass on the shelf and the wind knocks it over or my elbow brushes it off the table and it falls to the ground and shatters, I say, 'Of course.' When I understand that the glass is already broken, every moment with it is precious."
via Kottke.org

Smoking Them Out, One at a Time

A correction in Newsweek:


Here is the good Dr. Simmons, another one who won't disclose.

Tuesday, April 21, 2015

Is it Fair to Now Blame China for Climate Change?

Perhaps in advance of the Paris conference this December, a spate of articles came out in the last few days claiming that "China to surpass U.S. as top cause of modern global warming." Is that fair? (No.)
(Reuters) - China is poised to overtake the United States as the main cause of man-made global warming since 1990, the benchmark year for U.N.-led action, in a historic shift that may raise pressure on Beijing to act.

China's cumulative greenhouse gas emissions since 1990, when governments were becoming aware of climate change, will outstrip those of the United States in 2015 or 2016, according to separate estimates by experts in Norway and the United States.

The shift, reflecting China's stellar economic growth, raises questions about historical blame for rising temperatures and more floods, desertification, heatwaves and sea level rise.
and
"A few years ago China's per capita emissions were low, its historical responsibility was low. That's changing fast," said Glen Peters of the Center for International Climate and Environmental Research, Oslo (CICERO), who says China will overtake the United States this year. 
Here's data on US and China cumulative emissions since 1990:


Yes, by this measure China will surpass the US by about 2016.

But, of course, the climate doesn't care about your silly accounting choices and conferences, it only knows how much CO2 is in the atmosphere. And the US has emitted a lot more CO2 over the last century than has China. Since 1900, the comparison comes out very nicely if you take the ratio of cumulative emissions:


CO2 emissions data: 
1900-2004 from World Resources Institute
2005-2012 from EIA
2013 from the Carbon Atlas Project
2014 from the EIA (for the US) and reported percentage increase in China (-2.0% compared to 2013).

That's not even to mention per capita emissions, which in 2014 were 16.9 tons CO2/person in the US and 7.2 tons CO2/person in China.

GCP Per Capita Consumption Emissions

And in 2012, 16% of China's emissions went to products exported elsewhere (not sure of this number for the US).

Ukcarbonexports7

Many like comparing national emissions, but it's not like an American has some exceptional right to emit CO2 that a Chinese citizen does not. We're the world's energy hogs, not them. And China's one-child policy probably did more to reduce emissions than all of the Kyoto Protocol.

(In James Hansen's book he writes that it's actually the UK that has the highest historical per capita emissions, but IIRC doesn't provide a source for that.)

So I don't think it's fair to start blaming China for global warming -- not even by 2025, when their cumulative emissions are projected to pass the US's (see above). But that seems like what some are trying to do already.

 GCP Territorial Emissions

 Figure via The Carbon Brief.