Thursday, July 28, 2016

Summer Field, New Hampshire

Via Ann L'Italien.

Roy Spencer Makes It Easy to Dismiss Him

Roy Spencer wrote a brochure on climate change for the Texas Public Policy Foundation.

I'm sorry, but in my opinion the graph on the right-hand side of this figure is beneath the dignity of any academic or scientist:

If you're writing a report like this, why make it so easy to dismiss you?

PS: More pertinent questions. Don't expect an answer.

Monday, July 25, 2016

Global Sea Ice Extent Sets a Record Low Early Maxima

Global sea ice extent -- the sum of Arctic SIE and Antarctic SIE -- has two maxima in a year: one, the smaller of the two, usually in July, and the second, larger maximum, usually in November.

I don't think there's anything deep about this; it's just the way the nonsymmetric timing for the two poles works out, and the Arctic thawing more than the Antarctic.

This year, the first, lower maxima is a record low:

The trend in this local maxima is -40,400 km2/yr. This year is low mostly because Antarctic sea ice extent is low -- it's current anomaly (7/24/16) relative to a 1981-2010 baseline is just slightly negative, but that's a big change from recent years. Indeed, the trend for Antarctic SIE from the beginning of its record in 1978 is +21,700 km2/yr, while the Arctic has an overall trend of -53,800 km2/yr.

The overall trend in global SIE is -24,300 km2/yr.

There has been a recent paper on Antarctic SIE, by Meehl et al, that puts the increase due to the negative phase of the Interdecadal Pacific Oscillation, which is like the Pacific Decadal Oscillation (but I've never been able to find the data page for the IPO; if you know it, please let me know).

Tuesday, July 19, 2016

Jupiter As Seen From the Bottom

Wow. Just wow.

Image via NASA.

First Half-of-Year Records in Temperature and Arctic Sea Ice Extent


On a NASA teleconference, Gavin Schmidt, Director of GISS, said this record is "Not solely due to El Nino event." GISS calculates about 40% of record is due to El Nino and 60% due to other factors, including very, very strong Arctic warming."

Other things he said:

"The trend is very clear, and it's due to greenhouse gases."

"2017 is not going to be as warm as 2016." [due to starting the year in a neutral or La Nina condition]

"If 2016 sets a record, it will be the third record year in a row, which is unprecedented in our record." (99% chance 2016 sets a record.)

"May have some cooling in coming years, but the trends are going to continue, obviously."

"Paris thresholds are long-term equilibrium temperatures changes.....We are dancing with those lower [Paris] targets."

"No statistically robust that there is a strong acceleration" of warming. [Natural noise too hard to disaggregate. Natural trends pretty stable....] "It's premature to talk about acceleration in the 21st century."

For Arctic sea ice:

Friday, July 15, 2016

"Hope is the thing that is left to us, in a bad time."

North Brooklin, Maine

30 March 1973

Dear Mr. Nadeau:

As long as there is one upright man, as long as there is one compassionate woman, the contagion may spread and the scene is not desolate. Hope is the thing that is left to us, in a bad time. I shall get up Sunday morning and wind the clock, as a contribution to order and steadfastness.

Sailors have an expression about the weather: they say, the weather is a great bluffer. I guess the same is true of our human society—things can look dark, then a break shows in the clouds, and all is changed, sometimes rather suddenly. It is quite obvious that the human race has made a queer mess of life on this planet. But as a people we probably harbor seeds of goodness that have lain for a long time waiting to sprout when the conditions are right. Man's curiosity, his relentlessness, his inventiveness, his ingenuity have led him into deep trouble. We can only hope that these same traits will enable him to claw his way out.

Hang on to your hat. Hang on to your hope. And wind the clock, for tomorrow is another day.


(Signed, 'E. B. White')
From Letters of Note, via a comment at Slate

Thursday, July 14, 2016

La Niña Forecast: a Little Less Likely Than Last Month's

The IRI -- International Research Institute for Climate and Society -- at Columbia University just issued their ENSO forecast. It shows a little less likelihood of a La Niña forming this fall -- "about a 55-60% chance of La Niña during the fall and winter 2016" -- compared to last month's forecast of about 70%..

For comparison, here's last month's forecast:

Why does this matter? Only because...some people...are going to interpret a natural cooling fluctuation -- a La Niña -- as indication that manmade global warming is over, or was wrong, or a hoax, or a conspiratorial meme beamed into people's heads via picowaves.

Of course, the last year and a half has been a natural warming fluctuation, too. Mostly. This El Niño saw significantly higher surface and lower tropospheric temperatures, by about 0.3-0.4 C, than were seen in the large 1997-98 El Niño, which itself was about the same margin ahead of the big 1982-83 El Niño.

A better question is if the next La Niña is warmer than previous comparable La Niñas.

But naturally, if you accept AGW science, you feel somewhat confirmed by warmer upward fluctuations, and warmer downward fluctuations. It's sort of like this: imagine you saw Usain Bolt run as an 8-year old. That kid's fast, you think to yourself. Then you see him again when he's 12, and he's running even faster. He keeps making progress. Sure, he loses sometimes, but more often than not he wins, and when he does lose it's not by the margins he once did. This goes on for years and years -- he sets new records regularly, and when he doesn't, his time still brings up his average. And so it goes.

When you expect someone to run ever faster, it's interesting when he does and sets new records. More interesting than when he loses, even when it's by ever smaller margins. I mean, did you see him burst away from the field in Beijing?

PS: Yes, Usain Bolt is getting older and will someday be past his prime. It's not a perfect analogy -- climates don't get "old." Maybe the stock market is better, where ever higher records are expected over sufficiently long time periods.

Wednesday, July 13, 2016

Arctic Ice Extent Since 1850

From a new paper in Geographical Review by Walsh et al, and a press release from the University of Colorado. Note this is ice extent, which is more than just sea ice.

I'm looking to see if there's a time series plot....

Added: Here it is:

For comparison, the minimum sea ice extent in September 2012 was 3.62 Mkm2 (average for the entire month), so the ice extent was almost all sea ice at that minimum.

More About the McMillan et al result for Greenland Mass Balance

After this post last night about a new paper on Greenland ice loss over 2011-2014, I wrote to the lead author, Malcolm McMillan of  the University of Leeds in the UK.

He told me (as I suspected)
We don't look for an acceleration because the 4 year time period of our altimeter observations is too short to reliably detect this, given the large year-to-year changes in annual mass loss. So I wouldn't say that there is no acceleration, rather that, given its likely magnitude, it is not possible for us to reliably measure it over such a short time period.

For assessing accelerations in mass loss you really need to use the longer 10-20 year records which are better able to resolve this. You may be aware of it already, but in case you're not, the attached paper gives a nice analysis of the time periods required to detect certain accelerations.

I'm not aware of any reasons to expect the long-term acceleration to go towards 0.

Tuesday, July 12, 2016

Another Result on Greenland's Melt Rate

There's a new paper in GRL by Malcolm McMillan et al, "A high-resolution record of Greenland mass balance." They studied the period 2011-2014, mapping "recent Greenland Ice Sheet elevation change at high spatial (5 km) and temporal
(monthly) resolution." (They even modeled the firn, the granularity of the snow, because it influences the backscattered radar echo.) Their rate of ice loss, -269 Gt/yr, is close to other recent values, and (added 7/7) equivalent to a global mean sea level rise over this period of 0.74 ± 0.14 mm/yr, "approximately double the 1992–2011 mean." They find regions where glacier velocity has increased significantly in recent years -- "...only 0.9% of the total ice sheet area, have contributed more than 12% of the total mass balance during our study period."

But they don't seem to find any downward acceleration in these years:

They don't calculate an acceleration in their paper.... Has melt acceleration stopped, or is this just a blip upward? I would be surprised if it has stopped -- this latest paper only covered a 3-year period, while the others (below) were all over 10 years. That makes it a difficult to detect an acceleration -- just look at any 3-year interval on their graph -- the all look straight.

In any case, here is my collection:

Note 7/13: this is a change from the earlier table; the "--" means the four years in the McMillan et al study was too short an interval to reliably detect an acceleration. See here

Added 7/13: I give some remarks and clarifications by Malcolm McMillan here.

Gauging Greenland's Melt

An interesting video by Peter Sinclair for Yale Climate Connections.

These guys in the field always seem to be having a great time out there....

One of the scientists says it's looking like meltwater runoff is greater than dynamical ice discharge. That's also what was found in the 2014 Enderlin et al paper I wrote about here.