Category Archives: Climate Change

”Global Warming ‘Hiatus’ Never Happened”


About that supposed pause in global warming:

Global warming ‘hiatus’ never happened, Stanford scientists say: An apparent lull in the recent rate of global warming that has been widely accepted as fact is actually an artifact arising from faulty statistical methods, Stanford scientists say. …The finding calls into question the idea that global warming “stalled” or “paused” during the period between 1998 and 2013. …

Using a novel statistical framework that was developed specifically for studying geophysical processes such as global temperature fluctuations, Rajaratnam and his team of Stanford collaborators have shown that the hiatus never happened.

“Our results clearly show that, in terms of the statistics of the long-term global temperature data, there never was a hiatus, a pause or a slowdown in global warming,” said Noah Diffenbaugh, a climate scientist in the School of Earth, Energy & Environmental Sciences, and a co-author of the study.

Faulty ocean buoys

The Stanford group’s findings are the latest in a growing series of papers to cast doubt on the existence of a hiatus. …

The Stanford scientists say their findings should go a long way toward restoring confidence in the basic science and climate computer models that form the foundation for climate change predictions.

“Global warming is like other noisy systems that fluctuate wildly but still follow a trend,” Diffenbaugh said. “Think of the U.S. stock market: There have been bull markets and bear markets, but overall it has grown a lot over the past century. What is clear from analyzing the long-term data in a rigorous statistical framework is that, even though climate varies from year-to-year and decade-to-decade, global temperature has increased in the long term, and the recent period does not stand out as being abnormal.”

[I omitted the detailed discussion of the research.]

”Global Warming ‘Hiatus’ Never Happened”
Mark Thoma
Thu, 17 Sep 2015 16:49:22 GMT


IER Comment on the “Social Cost of Carbon”

It is getting warmer.

The consequence of that and the value of the cost we should bear to reduce the warming are very open questions as far as I can tell.

If you are a true nerd about the global warming stuff, you should definitely get a cup of coffee some morning and spend a half hour carefully reading the Institute for Energy Research (IER) formal “comment” (submitted to the government) on the Social Cost of Carbon. However, if you have a shorter attention span, in two blog posts at IER I will summarize our key arguments.

Here’s the first post. An excerpt:

On the theoretical front, our main theme is that the “social cost of carbon” is not an objective fact of the world, analogous to the charge on an electron or the boiling point of water. Many analysts and policymakers refer to the “science being settled” and so forth, giving the impression that the SCC is a number that is “out there” in Nature, waiting to be measured by guys in white lab coats.

On the contrary, by its very nature the SCC is an arbitrary number, which is completely malleable in the hands of an analyst who can make it very high, very low, or even negative, simply by adjusting parameters. Precisely because the SCC even at a conceptual level is so vulnerable to manipulation in this fashion, the analysts giving wildly different estimates are not “lying.” As we will see, the estimates of the SCC in the peer-reviewed literature are all over the map, demonstrating that this is hardly a feature of the “outside world.”

IER Comment on the “Social Cost of Carbon”
Bob Murphy
Tue, 11 Mar 2014 21:29:17 GMT

Iceland in the Year 2050

That’s there’s climate changes seems clear, but its implications are less so.

The NY Times reports a type of James Bond story as a mysterious Chinese zillionaire seeks to purchase a large amount of rural Iceland to erect a snowy golf course.   Do you smell Dr. No?  I don’t.  I see a climate change adaptation bet.   Arbitrage is to buy low and sell high.  Perhaps because he read Climatopolis, Huang Nubo is making an investment that could earn a high return if Iceland’s quality of life improves relative to the rest of the world as climate change plays out.    New challenges create new opportunities.  While the NY Times views this story as just “weird”, I think it is a nice example of how those who form expectations of the future act upon those expectations.  Mr. Nubo could lose on this investment but he is experimenting and there are plausible scenarios under which he will become even richer. 
It is certainly possible that his “golf course” is an attempt by China to claim property rights to minerals that might be under the ground but any land owner always has this option.  I ask my students to solve for a price of gasoline such that Beverly Hills home owners would knock down their homes and drill for gas underneath the surface.  

Iceland in the Year 2050
Matthew Kahn
Sat, 23 Mar 2013 16:20:00 GMT

Climate Change


Recent studies add to the evidence that we are changing the world:



If you want to see what “climate change” really means, as in what will be changing where, check out the 2013 National Climate Assessment report. It’s fantastic, and chuck full of visualizations:


One side effect: More shipping in the Arctic:


Climate Change
Wed, 13 Mar 2013 19:37:39 GMT

2012 Shatters the US Temperature Record. Fox, Watts, and Spencer Respond by Denying Reality


The National Oceanic and Atmospheric Administration’s National Climatic Data Center (NCDC) recently announced that 2012 broke the record for the hottest average annual surface temperature for the contiguous United States by a wide margin – a full degree Fahrenheit (Figure 1).  Given that this is a very inconvenient fact for certain groups, we should perhaps not be surprised that the NCDC has come under attack for reporting this year’s record.

Most prominently, Fox News ran a story quoting Roy Spencer (a contrarian climate scientist at the University of Alabama at Huntsville [UAH]), Anthony Watts (a blogger and meteorologist), and Steven Goddard (a pseudonym for a climate blogger who goes to the extreme in denying human-caused global warming), all of whom directly or indirectly accused the NCDC of somehow fudging the data to introduce a false warming trend and make 2012 the record hottest year.

The biggest irony of all is that 2012 is the hottest year on record for the USA in Spencer’s own UAH lower atmosphere temperature dataset, and yet just a week after this announcement he accused NCDC of improper adjustments when their results matched his own.  Without those adjustments, the NCDC record would not match Spencer’s UAH dataset nearly as closely.  The UAH continental USA warming trend from 1979 to 2012 is 0.24°C per decade, while the trend in maximum daily unadjusted NCDC data over the same timeframe is just 0.11°C per decade.  Once the adjustments Spencer criticizes are implemented, the NCDC trend becomes much closer to the UAH trend, at 0.21°C per decade (Figure 1).

uah vs. ncdc

Figure 1: UAH continental USA lower troposphere temperature product (version 5.5; blue) vs. NCDC continental USA maximum daily surface temperature unadjusted (black) and adjusted (version 2.5; red), with linear trends from 1979 to 2012 (dashed).

Another major irony is that while these contrarians treat "adjustment" as a bad word, in their own scientific research they admit that such adjustments are actually very important, and Roy Spencer frequently makes similar adjustments to his own UAH temperature dataset.

These are the latest in a long line of efforts by climate contrarians to cast doubt on the accuracy of the instrumental temperature record, because if the temperature record is wrong, then poof – no more global warming to worry about.  If only life were so simple.

How We Know the Temperature Record is Accurate

The accuracy of the instrumental surface temperature record, which is compiled from thousands of thermometers in temperature stations around the country and the planet, has been confirmed time and time again by a number of scientific studies using a variety of different approaches.  Individuals have taken a do-it-yourself approach, comparing the raw, unadjusted temperature data to the final products from NCDC and other scientific organizations (Figure 2).  Skeptical Science’s Kevin C put together a do-it-yourself tool so that anybody can try this at home.

Figure 2: Comparison of land-only surface temperature reconstructions, 1900–2009

People have also compared the raw to the adjusted data and found that the adjustments don’t make a very big difference in the final temperature record product (Figure 3).

Figure 3: Comparison of global temperatures from raw (dark green) and adjusted (light green) Global Historical Climatology Network (GHCN) v3 data, 1880–2010 (analysis by Zeke Hausfather).

The Koch-funded Berkeley Earth Temperature Station (BEST) project also set out to test the surface temperature record accuracy by creating their own record using a novel and robust methodology (described in detail by Rohde et al.), and arrived at essentially the same result as NCDC (Figure 4).


Figure 4: Land temperature with 1- and 10-year running averages. The shaded regions are the one- and two-standard deviation uncertainties calculated including both statistical and spatial sampling errors. Prior land results from the other groups are also plotted, including NCDC in green.

Measurements made by satellites of the temperature of the lower atmosphere (the lower troposphere, or LT), including by Spencer’s UAH group, are also very consistent with the measurements made by thermometers on the ground (Figure 5).

Figure 5: Comparison of temperatures from surface stations and satellite monitoring of the lower troposphere (LT).

The NCDC temperature record has been compared to a number of reanalysis products (climate or weather model simulations of the past that include data assimilation of historical observations) by Vose et al. (2012), which also confirmed its accuracy, concluding,

"For the conterminous United States, the trend in the adjusted [U.S. Historical Climatology Network] (0.327°C/decade) is generally comparable to the ensemble mean of the reanalyses (0.342°C/decade). It is also well within the range of the reanalysis trend estimates (0.280 to 0.437° C/decade)."

A paper by Anderson et al. (2012) also created a new global surface temperature record reconstruction using 173 records with some type of physical or biological link to global surface temperatures (corals, ice cores, speleothems, lake and ocean sediments, and historical documents).  The study compared their reconstruction to the NCDC instrumental temperature record and found a strong correlation between the two, of 0.76 (Figure 6).

Fig 1

Figure 6: Anderson et al. (2012) Paleo Index (solid) and the merged land-ocean surface temperature anomalies (MLOST, dashed) relative to 1901-2000.

And of course natural thermometers clearly confirm the Earth’s general warming trend – vanishing ice, rising oceans, species migrations, earlier arrival of spring, etc.

From these results, it’s quite clear that NCDC is not introducing a fake warming trend.  So where does this myth come from?

Critical Data Adjustments

There are a number of adjustments that scientific groups like NCDC have to make to the raw temperature data.  For example, sometimes a temperature station will move, or the time of observation of the thermometer will change, or the type of temperature station will change.  These changes can introduce biases into the instrumental record which are not representative of actual temperature changes, so they must be accounted for and removed in order to get an accurate measurement of actual surface temperature changes.  For further details, see this post and Glenn Tamblyn’s excellent four-part series on the surface temperature record.

Coincidentally, a number of these factors have introduced a cooling bias into the surface temperature record in recent decades, and NCDC removes this cool bias with its adjustment methodology.  Certain individuals who want to deny that global warming is happening mischaracterize this removal of cool biases, claiming NCDC is introducing a false warming trend.

In reality the adjustments made by NCDC are based on sound science, and detailed in the peer-reviewed scientific literaure.  Their version 2 temperature dataset and processing steps are described in detail in Menne et al. (2009) and on the NCDC website, and details regarding some recent and relatively small revisions for version 2.5 of their dataset are described in two technical reports (Williams et al. 2012a and 2012b) and on the same NCDC website.

The general effectiveness of these adjustments has been confirmed by Peterson et al. (2003), Menne et al. (2010), and Fall et al. (2011).  Another paper currently in press, Hausfather et al. (2012), found that the NCDC adjustments are critical in removing the influence of artificial artificial heat sources on the thermometers (the urban heat island effect).

"…urbanization accounts for 14% to 21% of the rise in unadjusted minimum temperatures since 1895 and 6% to 9% since 1960. The USHCN-Version 2 homogenization process effectively removes this urban signal such that it becomes insignificant during the last 50-80 years."

In short, the adjustments made by NCDC to the raw temperature data are scientifically justified, very important, supported in the scientific literature, and their effectiveness has been confirmed by a wide variety of different approaches.

Watts’ False Accusations Ignite the Myth

The specific accusations about NCDC falsifying data to make 2012 the hottest year on record in the USA originated on Anthony Watts’ blog, where after finding discrepancies between temperatures listed in NCDC’s past monthly State of the Climate reports, and those in its climate database.  Watts immediately accused NCDC of "keep[ing] two separate sets of climate books for the USA", rather than simply contacting them to ask for an explanation.

That’s what I did, and NCDC provided the following response, explaining that the discrepancy was due to the recent switch from version 2 to version 2.5 of their methodology in October 2012 (as discussed above):

It is totally inappropriate to mix values from different data bases to identify records.  This is exactly what Anthony Watts has done.  He selected the mean monthly temperatures from an older data base (version 2 USHCN) and compared it to mean monthly temperatures in a newer data base (version 2.5 USHCN).  This is a fatal error.  For example, the US average temperature of July  2012 is the record warmest within both data bases.  Values in version 2.5 are different from version 2.0 for two reasons.  Different base periods are used in the two data bases to compute normals, which affect the monthly mean temperatures for all years.  Second, an improved correction algorithm has been applied to the newer data base.  NCDC has notified users on our web site back in September of 2012 of the differences in the two data sets.  All of NOAA NCDC analyses are based on peer-reviewed published work.  Please see for more details.

Contrarian Contradictions
Spencer’s Own Adjustments

Ironically, Roy Spencer’s own UAH temperature record adjustment methodology has undergone a large number of major revisions:

UAH corrections

Major corrections to the UAH temperature trend over the years.

There is of course nothing wrong with making these adjustments; quite the contrary.  Science advances, we learn, and we improve our understanding and methods.  But for Spencer to criticize NCDC for making the same sorts of scientifically justified adjustments is hypocritical and self-contradictory.

spencer v spencer

image created by John Cook
Watts’ Criminal Accusations

For his part, Anthony Watts suggested to Fox that NCDC’s adjustments are essentially criminal, even though he was a co-author on the Fall et al. (2011) paper which confirmed the general accuracy of the instrumental surface temperature record, and noted that the types of adjustments made by NCDC are necessary.

watts vs. watts

image created by John Cook

In both cases it would be hard to understand how these contradictory statements could come from the same person, except such contradictory arguments are the norm for climate contrarians.

Temperature Record is Reliable When Convenient

Additionally, the last mainstream media climate myth we addressed just last week incorrectly claimed that global warming has ‘stalled’, based almost exclusively on the instrumental surface temperature record (and a climate model run, which contrarians also claim are unreliable).  Now contrarians are arguing that the temperature record is unreliable.  Which is it?  The instrumental temperature record can’t be both the basis of an argument one week and completely unreliable the next week.

Yes, 2012 Was the Hottest Year on Record in the USA

To sum up,

  • The accuracy of the surface temperature record has been confirmed time and time again by a wide variety of methods, including comparisons with do-it-yourself temperature analyses, with satellite measurements, and with natural thermometers.
  • Scientific groups like NCDC make necessary, scientifically-justified adjustments to the raw data in order to remove biases introduced by factors like changes in temperature station locations, time of observations, and types of instrumentation. 
  • These adjustments are published in the peer-reviewed scientific literature, and their effectiveness has been confirmed by numerous peer-reviewed studies.
  • Spencer’s own UAH group has made many revisions to its own data adjustment methodology as well.
  • If climate contrarians dispute the validity of any of the adjustments made by NCDC, they should subject their criticisms to the scientific peer-review process rather than making unsubstantiated and unjustified accusations of malfeasance in the mainstream media.
  • The contrarians making these accusations are contradicting their own results and previous research, which support the effectiveness and importance of the adjustments made by NCDC.

Overall, the contrarians have given us no reason to doubt the accuracy of the instrumental surface temperature record or the fact that 2012 was the hottest year on record in the continental United States.  In fact, this result is consistent with Roy Spencer’s own UAH dataset.  We are instead left with just another mainstream media article full of denial, unsubstantiated assertions, contradictions, and conspiracy theories, misinforming the general public, and delaying our efforts to actually solve the climate problem by denying the reality that it exists and is a grave threat.

Also see this excellent post on the subject by Josh Timmer at Ars Technica.

2012 Shatters the US Temperature Record. Fox, Watts, and Spencer Respond by Denying Reality
Tue, 15 Jan 2013 02:37:08 GMT

Environmentalism and the environment

There is no point per the author.

The Economist has an interesting article on the gas boom in America:

Gas has wrought some remarkable changes. Over the past five years America has recorded a decline in greenhouse-gas emissions of 450m tonnes, the biggest anywhere in the world. Ironically, given its far greater effort to tackle climate change, the European Union has seen its emissions rise, partly because its higher gas prices (linked to oil) have led to an increase in coal-fired power generation.

So let’s review the facts:

1.  America is reducing greenhouse gas emissions faster than anywhere else because Bush/Cheney ignored environmentalists and went with the “drill baby drill” strategy.

2.  Europe is switching to coal because gas is too expensive.  But wait; doesn’t Europe also have lots of shale gas? They do. But they listened to the environmentalists, and have all but banned fracking.

3.  But wait; doesn’t Europe have lots of carbon-free nuclear power plants?  Yes, but countries like Germany have decide to close them all down, on the recommendation of environmentalists.  Other countries are also leaning that way.  I can sort of understand Japan, but when was the last time you heard about an earthquake in Germany or Sweden?

Now it’s true that the US still has a worse record than Europe, especially in high energy consuming states like Texas.  But the same issue of The Economist has another article with this interesting tidbit:

At a casual glance, Houston looks much as it ever did: a tangle of freeways running through a hodgepodge of skyscrapers, strip malls and mixed districts. A closer inspection, though, shows signs of change. The transport authority, which branched into light rail in 2004, is now planning three new lines, adding more than 20 miles of track. Most of the traffic lights now boast LED bulbs, rather than the incandescent sort. More than half the cars in the official city fleet are hybrid or electric, and in May a bike-sharing programme began. Every Wednesday a farmers’ market takes place by the steps of city hall.

Other changes are harder to see. The energy codes for buildings have been overhauled and the city is, astonishingly, America’s biggest municipal buyer of renewable energy; about a third of its power comes from Texan wind farms.

But are windmills actually that good for the environment?  Still another article in the same issue has this to say:

By 2009 Inner Mongolia had become China’s largest producer of coal. It is the biggest source of the world’s supply of rare earths. The coal bed around Xilinhot, the capital of Xilin Gol, boasts 38% of global reserves of germanium, a rare earth used in the making of circuitry for solar cells and wind turbines. Ripping up the grasslands and sucking up scarce water for thirsty mines has been part of the price of these “green energy” products.

Here are some comparisons between Inner Mongolia and Texas:

Texas is a state with 25.7 million people.  It started out as a ranching state and is now dominated by energy production.  It’s mostly hot and flat, and is growing much faster than the rest of the US.

Inner Mongolia is a province with 24.7 million people.  It started out as a herding state and is now dominated by energy production.  It’s mostly hot and flat, and is growing much faster than the rest of China.

Much faster?  How’s that possible given that China has grown at 10% per year for decades?  Because Inner Mongolia has grown at 17% per year since 2001.  Even Texans can’t say that.

PS.  People trying to convince you that China’s a bubble often show a video of Ordos, the almost uninhabited new city.  Ordos is in Inner Mongolia, and is hosting the Miss World pageant next month.  Let’s see what Ordos looks like in 10 years before we jump to conclusions.

PPS.  Do you recall that America’s had two Presidents named Bush, the second of which was governor of Texas?  China’s current President is named Hu, and another Hu is being touted as a possible future president.  He’s now the governor of Inner Mongolia.

PPPS.  Think about Mercedes, BMW and Audi.  Then think about the quality of the stuff you buy that’s made in China.  Do you sleep better at night knowing that Germany is shutting down its entire nuclear industry, and China is building nuclear plants at a rapid pace.

PPPPS.  Please don’t ask me what the point of this post is.  It’s Sunday. There is no point.

Environmentalism and the environment
Sun, 22 Jul 2012 21:03:39 GMT

Doom and Gloom maybe not, but a blow to our spirit

A new study has come out as they do maybe every decade or so that we are killing the earth.  The club or Rome in the 70’s said we’d run out of every thing by now, and the world would be worse now.

I think humanity will survive we’ll adapt.  The following elaborates pretty well why; but is that all we want to do?

Nature (an academic journal) is grabbing headlines with a new “big think” piece.  Here is a quote from the LA Times
“A group of international scientists is sounding a global alarm, warning that population growth, climate change and environmental destruction are pushing Earth toward calamitous — and irreversible — biological changes.
In a paper published in Thursday’s edition of the journalNature, 22 researchers from a variety of fields liken the human impact to global events eons ago that caused mass extinctions, permanently altering Earth’s biosphere.
“Humans are now forcing another such transition, with the potential to transform Earth rapidly and irreversibly into a state unknown in human experience,” wrote the authors, who are from the U.S., Europe, Canada and South America.”
These scientists could certainly be right about their predictions about global climate patterns but how do they know that we (both people and creatures) have such limited ability to adapt to the “new normal”?   I don’t see any social scientists involved in this project.   I would like to see these 22 researchers tell a convincing story for how the trends they highlight will decimate our world and that we will be defenseless to protect ourselves in the face of this change.
I would like to see these “crystal ball” researchers explain in nitty/gritty details the “calamitous” scenarios they envision for us and creatures.  If they foresee this tragedy, are there really no pathways to adapt? 
To quote these guys again,
“The swiftness of climate change is likely to outpace the ability of species to adapt, especially as natural habitat becomes more fragmented, Barnosky said.
All this could produce a biologically impoverished Earth that would rob humans of vital ecological services such as insects that pollinate crops, forests that provide clean water, and tropical species that are the source of new drugs.
“We have created a bubble of human population and economy … that is totally unsustainable and is either going to have to deflate gradually or is going to burst,” said co-author James Brown, a distinguished professor of biology at the University of New Mexico. “If it’s going to burst, the consequences are really going to be grim for people as well as biodiversity and the rest of the planet.”
So, take a look at the middle paragraph. If we anticipate that Mother Nature won’t be providing these services anymore, isn’t there a profit opportunity for innovators who can deliver a substitute?
I disagree with Prof. James Brown.  He needs to take a class in econ 101 at the Economics Department at UNM.   Capitalism will be the solution here not the problem.

Doom and Gloom and the Absence of Social Scientists
Matthew E. Kahn
Fri, 08 Jun 2012 22:41:00 GMT

I think we can likely get by with less biodiversity, but you can live without a lot of things, you just might not want to.

The diversity of life on this planet makes it a lovely place.  Maybe it reminds that we are just one species.  Maybe it reminds us to be humble and that we are gifted with out existence by God.  If we as humans come to be kings of a domain with few any subject left, I think we’ll regret that.

Down with particle physics, up with Big Energy Research!


via Down with particle physics, up with Big Energy Research!.

Currently, thousands of our best physicists are being shunted into careers in experimental particle physics, spending their lives working at CERN or Fermilab. These are our very best physics brains, and they are a very scarce commodity. In my opinion, we need these people to be working on solar power, biofuels, and nuclear power. Applied physics is not as intellectually thrilling or as nerd-glamorous as fundamental physics, but we can ill afford to pay our super-nerds to indulge their philosophical whimsy at a time like this.

So I am suggesting, not an abandonment of Big Particle Physics, but a pause. If and when energy stops getting more expensive and resumes its march toward abundance, our species will have the breathing room to look for answers to questions like how to combine gravity with the Standard Model.

If I took issue it might be because arguably applied physics and science are what private industry does the best job of capturing value from and has an incentive to do so. It’s pure science that does have the same attraction for private money; so pure science has the best case to be subsidized.

A Difficult Question Shouldn’t be answered with a delusion

There’s more and more evidence of the reality of climate change see:

A Message from a Republican Meteorologist on Climate Change

Acknowledging Climate Science Doesn’t Make You A Liberal

The one thing not well addressed is how to respond.  The article seems to suggest we need to respond, but I think it may understate the extent that human kind and nature will adapt as climate is and has been dynamic.

How to deal with the problem is a hard question, but we should acknowledge not evade the question.

Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas


The GRACE program is a triumph of our technology – a pair of satellites nicknamed ‘Tom’ and ‘Jerry’ that act like a pair of scales for the Earth below them. They have weighed Australia getting heavier as floodwaters rose, the Earth getting fatter thanks to ice cap melt, and the drying up of Texan water supplies.

Now scientists have produced the first global map of change in the mass of land ice on Earth for 2003-2010 (Jacob et al, 2012), see it in all its glory in Figure 1. Unfortunately the resolution of the GRACE satellites means they can’t reliably measure ice areas smaller than 100 km2 (almost 40 square miles), so these are not included in the study.

Figure 1map of changes in ice thickness estimated by Jacob et al. Blue means losing ice and red means gaining ice. Changes in geology and groundwater have been accounted for (supplementary information). The red spot in Africa is an artifact. The units are ‘centimetres of water equivalent per year’: the change in water thickness that would be needed to cause the measured mass change.

Biggest ice sheets: melting faster than 2007 UN figures, no surprise there!

The first things that jump out at you are probably the big blue areas around Greenland and Antarctica. The new results are similar to those already covered at skepticalscience, such as Garder et al, 2011‘s work on Baffin & Ellesmere islands, plus other measurements of Greenland and Antarctica. It’s no longer news that the 2007 UN Intergovernmental Panel on Climate Change (IPCC) computer simulations were far below what has happened.

Greenland and Antarctica have lost almost 400 billion tons of ice every year according to these measurements, twice the loss expected from all the world’s other glaciers. This helps to explain why sea levels are rising at the high end of IPCC expectations.

Figure 2tide gauges (red), satellite measurements of sea level (blue) and IPCC computer model expectations (grey area) from Allison et al, 2009.

Worldwide glaciers mostly in retreat – down 1.2 trillion tons in 8 years

For the first time entire mountain ranges of glaciers have been weighed. There are at least 160,000 glaciers worldwide and in the World Glacier Monitoring Service’s last update only 136 were weighed. Thousands have been pictured by satellites (e.g. Le Bris et al, 2011, Paul & Svoboda, 2011, Narozhney & Zemtsov, 2011) and found to be mostly shrinking in area, but photos can’t measure thickness and therefore total weight.

GRACE shows about 150 billion tons a year of glacier melt which is actually less than some expected. It seems that glaciers in the high mountains of Central Asia (around the Himalayas) only lost about 4±20 bn tons of ice a year. Previous work expected closer to 50 billion tons of loss.

Relative stability in Asia is the surprise, and steals the media spotlight

500 billion tons of ice a year of land ice is being lost, whilst one region is doing about 50 bn tons/yr better than expected. Naturally, the anti-climate science editorial policies of Fox News, the UK Telegraph and Daily Mail ensured headlines focused on the Himalayas result, while some others like Reuters took a more complete view.

At Skeptical Science we think it is important to look at all of the data, which is why this post started with the big view. However, the Asian result is interesting and new so it’s definitely worth exploring.

What’s going on in Asia?

In 2010, Matsuo & Heki used GRACE to calculate a loss of almost 50 billion tons a year in the same region until 2009, compared with 4 billion in the new study (with a large range of possible values).

The new work includes some extra areas which Matsuo and Heki didn’t, so if you do an apples-to-apples comparison then the difference is 47 versus 11 billion tons a year.

It appears that North India has been using more groundwater than expected and this has now been better measured, explaining about 25 bn tons of the difference. The rest might be because of extra heavy snowfalls in 2010, data which wasn’t available to Matsuo & Heki.

Figure 3Change in mass of glaciers in High Mountain Asia as measured by GRACE. 1 Gt = Gigaton, or billion tons. Matsuo & Heki calculated 50 billion tons/year of ice loss, but they didn’t have the 2010 data which saw 400 billion tons of accumulation in one season: more than the total loss they expected over 8 years! This shows that short term trends are not reliable indicators.

GRACE weighs everything and the scientists subtract the effect of changes in the Earth’s crust or stored water, which introduces the possibility of error. The new study considers changes in melt lakes, plus underground water storage and erosion and conclude that they don’t make a big difference. The effect of rising or sinking rock due to tectonic activity or changes in glaciers is included by the scientists using a computer model – if this is found to make mistakes then the results could change (possibly drastically) in future. This is why other measurements are needed to confirm these results, and why other methods are often considered more reliable than GRACE only measurements.

We can also see that 8 years isn’t necessarily enough to make solid conclusions about the long term response of a single area, especially when weather can cause glaciers to grow or shrink by hundreds of billions of tons in a season.

The results aren’t a complete surprise: scientists had already reported that the westerlies which feed the Karakoram have brought cooler, cloudier and snowier conditions to some regions (Archer & Caldeira, 2008) which may or may not be a long term effect but could partly explain how the very highest glaciers are storing water (Scherler et al, 2011).

The big picture

We now have the first global map of glacier weight change. The ice sheets are doing much worse than 2007 predictions and glaciers in most of the world are doing just as badly as thought. However, glaciers in the high mountains of Central Asia appear to have been stable for 8 years when old measurements would have expected 400 billion tons of ice loss. Meanwhile, over 4.2 trillion tons of ice have melted worldwide over 8 years.

2003-2010 is a short time though, so it’s too soon to say anything about what will happen next here.

Seas are rising faster than computer simulations had expected, and these simulations are also lower and slower than has happened in the past (Vermeer & Rahmstorf, 2009). It’s possible that the simulations didn’t properly include the processes that shrink ice sheets so these results are consistent with faster future sea level rise. Figure 4 shows that the rate of melt in the big ice sheets is much larger than the swings caused by seasonal weather and the long term trend is obvious.

Figure 4Change in the ice mass of Greenland (blue) and Antarctica (orange). Notice how the trend is much larger than seasonal changes, and how each vertical dash is now 200 billion tons, versus 100 billion for the glacier graph in Figure 3.

Many of those gushing over this new scientific work have also claimed that global warming has stopped. In Figure 5 we’ve worked out how much energy was needed to melt the ice that’s gone since 2003 and wondered what would happen if that heat had been put into the atmosphere instead. The calculation assumed a constant rate of ice loss and used the latent heat of fusion for water. The heat is enough to warm the atmosphere more than 0.3 C in 8 years – faster than atmospheric global warming since the 1970s.

Figure 5The blue circles are the changes in heat content of the atmosphere (estimated from NASA GISTemp global data) over a period that some say global warming has ‘stopped’. The red line adds the heat that has been used to melt ice over the same period.

When you look at the full picture, you see that the Earth is still building up heat and claims to the contrary rely on selectively ignoring data. The good news is that the highest mountains in Asia seem to be almost 50 billion tons a year better off than expected. But this is small change next to the 500 billion tons a year being lost elsewhere.

A calculation error was pointed out by the commenters Eric (skeptic) and Sphaerica. This was noted and corrected on 25/02/2012. Figure 5 was changed and the penultimate paragraph also corrected.

Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
Sat, 25 Feb 2012 07:50:36 GMT