Tag Archives: Jonathan Amos

Scanning for Stranded Whales

In recent years, there have been many reports of stranded whales all around the world.  No one really knows why whales founder, and we don’t really know if there are more whales foundering, or if this is a statistical illusion.

The problem is that there is a lot of coastline and shallows, so its hard to know about every stranded whale.  It is also possible that the apparent uptick in strandings may represent an increase in events near populated areas, or improved observation and communications, or some other artifact.

So, just how many whales get in trouble, and where?

This fall, researchers report on an effort to detect whale strandings using satellite data [2].  If this works well, we might be able to assemble some comprehensive data of how many and where whales are beaching.

The key, of course, is high resolution satellite imagery, which is now commonly available with half meter resolution.  This is sufficient to spot whales from space, at least in some cases.

The study compared aerial survey with satellite imagery of a mass stranding of hundreds of whales in Patagonia.  In the images, the whales are easily detected by human eyes, but apparently do not have a simple characteristic spectral signature.  Piles of rotting whales do not all look the same, and do not necessarily look much different from a beach with no whales, at least to an algorithm.

The animals turn a pinkish orange when they decompose (Scale bar: 20m) (Image credit: Satellite image ©2019 Maxar Technologies) (From [1])
In this study, they had only two images to work with, so it’s small wonder that they couldn’t get a good algorithm.  There isn’t, and probably never will be, a huge collection of images to train from.  So, garden variety machine learning techniques will not “just work”, without some serious effort.

Glancing at example images, I’m pretty sure that algorithms should be able to detect and count dead whales.  So, as more data is collected, there will be algorithms.  And that will make it possible to survey large areas and maybe get some solid data.

I was wondering if multispectral data (e.g., IR) might improve the performance of the algorithms, if it were available at sub-meter resolutions.  I don’t really know if partly submerged carcasses would have any distinctive signature, probably not.  So, never mind.

Mainly, we need more data, not just a few lucky images.

  1. Jonathan Amos, Satellites to monitor whale strandings from space, in BBC News – Science & Environment. 2019. https://www.bbc.com/news/science-environment-50040890
  2. Peter T. Fretwell, Jennifer A. Jackson, Mauricio J. Ulloa Encina, Vreni Häussermann, Maria J. Perez Alvarez, Carlos Olavarría, and Carolina S. Gutstein, Using remote sensing to detect whale strandings in remote areas: The case of sei whales mass mortality in Chilean Patagonia. PLOS ONE, 14 (10):e0222498, 2019. https://doi.org/10.1371/journal.pone.0222498


Interesting Research on “Deep Carbon”

With all the talk about Carbon emissions and Carbon neutrality and even Carbon sequestration, there is a big question that needs answering:  just how much Carbon is there on Earth, where is it, and how is it moving around.

The Deep Carbon Observatory has been studying this for the last decade and this fall they have published a set of papers in a special issue of Elements  [2].  (What is a cool name and topic for a journal!)

Carbon is one of the most important elements on Earth. It is the basis of life, it is stored and mobilized throughout the Earth from core to crust and it is the basis of the energy sources that are vital to human civilization. This issue will focus on the origins of carbon on Earth, the roles played by large-scale catastrophic carbon perturbations in mass extinctions, the movement and distribution of carbon in large igneous provinces, and the role carbon plays in icehouse–greenhouse climate transitions in deep time. Present-day carbon fluxes on Earth are changing rapidly, and it is of utmost importance that scientists understand Earth’s carbon cycle to secure a sustainable future.   ([4], p. 301)

There is good news and bad news.

The good news is that there is a lot of Carbon on Earth, but most of it is locked up underground.  Less than 1% is at the surface where we humans interact with it, the “terrestrial biosphere”.  Far more is present in rocks, with perhaps 90% of it in the molten core, and most of the rest in the crust including ocean sediments.

So, with this full accounting, we can see that all of our monkeying around with the planet is actually fiddling with the merest sliver of all the Carbon.

The bad news is that the distribution of this tiny fraction has massive effects on climate and the biosphere and on us.

So, we don’t have to touch all that underground Carbon to mess up the climate.  (Just because the ocean has a lot more water, doesn’t mean you can’t drown in a bathtub.)

What is the Science?

The DCO has been working to carefully estimate where all the Carbon is, how it got there, how it has changed over the history of the Earth, and what the effects of the changes are.  A lot of this research is described in the book “Deep Carbon” [3] (available as Open Access here)  (Note:  No, I have not read more than the abstracts.)

The book goes into details about the challenges of figuring all this out. We know quite a bit about geochemistry, what rocks contain Carbon.  But estimating the total mass of all the rocks is an extrapolation from our limited samples on the surface, mining, and digging.

It is even more difficult to try to trace the history of the Earth at these scales, because the Earth and the rocks move and change.  Sometimes the change is slow, sometimes it is fast, and in most cases we have only faint traces from which to infer what geological events have happened.

Much of the history of the Earth’s Carbon occurs in the core and mantle, which are hostile and alien environments to us, and difficult to access.  The physics of these regions is extreme (by the standards of the surface where we dwell) and not as well understood.   And we have only recently discovered that there is life down there, implying that there are poorly understood biological processes at work as well ([3], p. 2)

Building on earlier work, the special Journal issue (Open Access [3]) reports on hypotheses about the perturbations over time of Carbon distribution and flows, e.g., volcanoes, impacts, and rampaging primates.  As in earlier work, this is challenging and there are plenty of uncertainties.

We are most familiar with what they refer to as “terrestrial biosphere”, which has Carbon flows that occur over tens or thousands of years.  The DCO studied the longer term geologic carbon cycle, which involves volcanoes, weathering, ocean sediments, and other transfers.  Changes in the long term system will produce large changes in the short term surface systems.  Hence, the research.

“The long-term, or geologic, carbon cycle encompasses the emission of CO2 from volcanic sources (e.g., spreading ridges and volcanoes at subduc- tion zones); carbon drawdown via silicate weathering and the formation of carbonates, or carbon drawdown via the photosynthesis of carbon by phytoplankton and plants; its burial as either organic carbon or inorganic carbonate; its subduction into the mantle; its eventual return to the atmosphere via volcanic and metamorphic outgassing sources. ” ([4], P. 302)

Figure 1. Carbon reservoirs and cycles in the Earth. The figure shows short- and long-term cycles; “surface” and “deep” carbon reservoirs and fluxes, and the relative sizes and residence times (y axis) of respective carbon. Numbers in brackets refer to the total mass of carbon in a given reservoir, in Pg C (1Pg C = 1015 g carbon). All reservoirs are pre-industrial. Abbreviations: Corg = organic carbon; DIC = dissolved inorganic carbon; MOR = mid ocean ridge; seds = sedimentary rocks. Adapted from Lee et al. (2019 and references therein). (From [4])
The main findings indicate that there have been episodes of sudden, rapid changes in Carbon, often due to massive volcanism.  These can produce long term changes in the surface environment (global warming and cooling), and are often correlated with mass extinctions.

The study found that recent anthropogenic Carbon emissions seem to be of the same speed and magnitude of historic episodes which have led to major long term changes including mass extinctions.  This suggests that all the little apes with their billions of “little volcanoes” spewing are equivalent to a massive geological catastrophe.

Figure 2. Histograms of carbon influx (positive values) and outflux (negative values) to the atmosphere and the oceans. Units are in Pg C/y. (A) Carbon fluxes based on steady state models. Abbreviations: MOR = mid ocean ridge; org carbon = organic carbon. (B) Carbon fluxes as a result of large-scale perturbations to the carbon cycle. Total outgassing refers to events listed in Figure 2A; anthropogenic is human contributions; Chicxulub (Mexico) refers to the end-Cretaceous asteroid impact and resultant mass extinction; average LIP refers to the input from large igneous provinces. Data from Kawaragi et al. (2009), Lee et al. (2019) and Black and Gibson (2019 this issue). (From [4])
Phew!  There is so much more here that I haven’t had time to look at in detail.

Bottom line:  the Carbon cycles that we typically worry about are only a tiny fraction of the whole picture.  Get over yourselves, you little monkeys!

This is good news, in that it means that, however out of whack we drive the biosphere, the overall Earth system can potentially come back into balance.  The bad news is that that would be on geologic time scales, if it even happens.  And other events (an extraterrestrial collision, major volcanism) could occur that would drive the surface climate even warmer.

* Note:  This research is available to all via open access.

  1. Jonathan Amos, Scientists estimate Earth’s total carbon store, in BBC News – Science & Environment. 2019. https://www.bbc.com/news/science-environment-49899039
  2. Marie Edmonds, Adrian P. Jones, and Celina A. Suarez, Catastrophic Perturbations to Earth’s Carbon Cycle (Special issue). Elements, 15 (5) October 2019. http://elementsmagazine.org/past-issues/catastrophic-perturbations-deep-carbon-cycle/
  3. Beth N. Orcutt, Isabelle Daniel, and Rajdeep Dasgupta, eds. Deep Carbon: Past to Present. Cambridge University Press: Cambridge, 2019.  (Open access: https://www.cambridge.org/core/books/deep-carbon/2DD590DAC33871A821E7C9D2826C40D3)
  4. Celina A. Suarez, Marie Edmonds, and Adrian P. Jones, Earth Catastrophes and Their Impact on the Carbon Cycle. Elements, 15 (5):301-308, October 2019. http://elementsmagazine.org/2019/10/02/earth-catastrophes-impact-carbon-cycle/


New Baby Iceberg, D28

And another big berg calves in Antarctica!

Ice berg D28 has split from the Amery Ice Shelf [1].  At 1600 sq km, it’s only a third the size of the mighty A68.  But still, it’s a big one, so watch out!

The EU’s Sentinel-1 satellite system captured these before and after images (Image Credit COPERNICUS DATA/SENTINEL-1/@StefLhermitt) (From [1])
(Oooh!  Such a big girl! Who’s a good baby iceberg?  You’re a good baby iceberg.  Isn’t she cute?? )

As far as I can tell, this ice sheet is ‘in balance’, i.e., shedding bergs at a rate to balanced with the inflowing glaciers.  So this part of the ice isn’t going away, at least not at the ice sheet.  (I dunno if the glaciers might be thinning or growing inland.)

  1. Jonathan Amos, 315 billion-tonne iceberg breaks off Antarctica, in BBC News – Science & Environment. 2019. https://www.bbc.com/news/science-environment-49885450


Iceberg A68 on the move

We’ve all been tracking A68 (nee Larsen C), the Manhattan sized iceberg that was born in 2017 and is slowly heading North into the Atlantic ocean.  She’s a big girl, and she moves at a stately pace.

She’s two years old now, and finally on the move.  Cryophile Adrian Luckman assembled a nice sequence from satellite imagery.

(Images from [2])

This gif shows A68 has been caught in the Weddell Gyre, a giant ocean eddy that has pulled her 250 km north.  Cruising at a sustained 1/3 km per hour, trillion tonne A68 or her children will likely reach the South Atlantic eventually, there to menace shipping as she melts.

You go, girl!!

  1. Jonathan Amos, A68: World’s biggest iceberg is on the move, in BBC News – Science & Environment. 2019. https://www.bbc.com/news/science-environment-48920168
  2. Adrian Luckman, Happy second birthday, Iceberg A68, in Ade’s glacier gallery. 2019. https://adrianluckman.wordpress.com/2019/07/11/happy-second-birthday-iceberg-a68/


PS.  Wouldn’t  “The Weddell Gyre” be a good name for a band?

Under the Ice In Greenland

Greenland’s ice is melting rapidly. That much is clear.  And the implications could be dramatic, as much as 7 meters higher sea level, and drastic changes in the climate of Europe and North America if the major ocean currents change.

But much of the action is happening under the ice, melting from below.   And there are lakes and rivers of liquid water under the ice, which seem to be growing.  This melts the ice from below, creating more water.  This water also lubricates and lets the ice sheets and glaciers slide along faster, down to the sea.

There are computational models of these processes, but there is little solid data on conditions under the ice, so it’s hard to confirm the details.  And the details matter because small differences could make huge knock on effects in the rate of change in the ice.

So, getting under the ice is a high priority for understanding Greenland.  It isn’t easy to get down under kilometers of ice, and it isn’t easy to get data back out.

This year teams from the UK are testing out sensors to be dropped down under the ice, to report on conditions and movements of the water [1].  The concept has been under development for a number of years [2], and it’s finally time to try them out for real.

The instruments will measure pressure, temperature, and conductivity of the water, and will report back with low frequency radio links that should work under kilometers of ice. The “cryoegg” has to be tough enough to be crushed by a glacier, and keep working as long as possible to report where it is pushed to.

“One of the joys of environmental science engineering is that it can be quite ‘Heath-Robinson’ – you won’t immediately find everything you need ready-made in a Campbell Scientific (instrument) catalogue.”  (Dr Mike Prior-Jones, quoted in [1])

This summer will see two tests to see how the design works, in preparation for wider surveys to see what we can find out about the water down there.

  1. Jonathan Amos, ‘Cryoegg’ to explore under Greenland Ice Sheet, in BBC News – Science & Environment. 2019. https://www.bbc.com/news/science-environment-48638958
  2. E. A. Bagshaw, B. Lishman, J. L. Wadham, J. A. Bowden, S. G. Burrow, L. R. Clare, and D. Chandler, Novel wireless sensors for in situ measurement of sub-ice hydrologic systems. Annals of Glaciology, 55 (65):41-50, 2014. https://www.cambridge.org/core/article/novel-wireless-sensors-for-in-situ-measurement-of-subice-hydrologic-systems/3DB2AA304A87519CBF9AB72579E3FDB3


Robot Wednesday

Satellite Heroes of Antarctica

The ice is melting everywhere.  In Antarctica, the glaciers are moving and the ice melting faster than snow is accumulating.

How do we know?  In Antarctica, primarily through long term observations from space.  Antarctica is so huge, so remote, and so hostile, that sattellite observation is about the only way to get an overall picture of what is happening.

This year the UK Antarctic Place-names Committee (APC) is naming seven glaciers in Antarctica after important Earth observation satellites that have contributed to measurements of Antarctic ice over the last few decades [1].

From [1]. Credit A. E Hogg/ Centre for Polar Observation and Modelling
I’m particularly pleased for LANDSAT to be honored.  The granddaddy of all EO satellites, launched in 1976, it was a true heroic pioneer.  (It is so old that computers didn’t have lower case letters yet! : – ) )  Fortunately, we have been able to launch follow on missions to keep up a continuous record of the land, sea, and ice. (I contributed to the maintenance of the HDF software that has been used to manage the massive data accumulated by LANDSAT.)

The other spacecraft have added to the record with specialized instruments to measure the amount and movement of the ice.

Well done, satellites!

ERS, Envisat, Cryosat, Grace, Sentinel, Alos, Landsat

  1. Jonathan Amos, Antarctic glaciers to honour ‘satellite heroes, in BBC News – Science & Environment. 2019. https://www.bbc.com/news/science-environment-48547803


Climate Effects Of The Depopulation of Americas

I tend to be rather cautious about grand theories connecting everything to everything.  So I wanted to look very closely at a new study arguing that “America colonisation ‘cooled Earth’s climate’” [1].

This winter researchers from the UK report evidence that the “Great Dying” in the Americas following European contact caused a period of global cooling [2].

“The Great Dying of the Indigenous Peoples of the Americas resulted in a human-driven global impact on the Earth System in the two centuries prior to the Industrial Revolution. “ ([2], p. 13)

Following the contact and invasions of the early 1500’s, vast numbers of Americans died from European diseases, particularly in the Caribbean, Southeast US, Central America and Northern South America.. This depopulation had crippling effects on the social, political, and economic lives, and left the people open to relatively easy conquest.

The new paper seeks to estimate the ecological effects of this massive tragedy.  Specifically, the sudden disappearance of the human inhabitants led to large areas of land reverting from agriculture and other human uses to regrown forests.  In short, the paper interprets this as an accidental episode of mass reforestation.

Coinciding with this era, analysis of ice cores indicates a drop in atmospheric CO2, and historical records document a cool period, the Little Ice Age. Are these events connected?

This hypothesized connect involves a chain of connections. First, the pre-Colombian population would have to be large enough, and use enough land for the dieback to have an impact.  Second, the dieback and putative reforestation would have to be large enough to account for the uptake of that much CO2.  The study musters evidence for these factors, and models the probably effects on climate.

There are limited historical records from the pre-Colombian period, and no population censuses.  However, many methods have been used to estimate the populations of the Americas from archeological remains.  Combining these estimates, this study finds the population to be something like 60 million people (which might have been about 10% of the world’s human population).

“all 1492 CE population estimates require data to be combined with assumptions to arrive at estimates. “ ([2], p. 15)

Other studies have estimated the amount of land used to support these populations. These estimates are difficult to make precisely, because they rely on assumptions about not only populations, but also agricultural and cultural practices.  This study proposes that the total land under human use was about 50 million hectares (about the extent of France or Texas).

The Great Dying was a massive disaster for the American peoples, but estimates of the magnitude of the disaster vary. This study considers a number of studies and takes the median of the estimates:  which is 90% death rate!  This would make the post contact (circa 1600) population about 6 million people, which is at the low end of previous estimates.

Finally, when there was a depopulation, the land use reverted to forest.  Obviously, this process is specific to different locations. In some locations, there is evidence of the reduction of fires, which may be due to the end of intentional burning. Archaeological pollen indicates that some areas had significant reductions in cultivated plants at the time of the die off.  There is also archaeological evidence of abandoned settlements and apparent agricultural and other infrastructure.

Taking the estimated population decline and the estimated cultivation per capita, this study suggests that over 50 million hectares of agricultural land was abandoned due to depopulation.  (This is about 1% of the total land of the Americas.)

These estimates rely on a variety of assumptions and imperfect data.  The total abandoned land is higher than some estimates, but roughly in the midst of other estimates.

So, if 50 million hectares reverted to forest in a relatively short period, what might the effect have been?  The researchers indicate that carbon uptake increases rapidly in the first 20 years of such a transition, and slower after that.  With plausible estimates for different areas, this study yields an estimate of about 7.4 petagrams of Carbon sequestered in the abandoned lands.  This is higher than some estimates, partly because it depends heavily on estimates of the population loss and corresponding area of abandoned land.

At the end of this long chain of inference, the estimated Carbon uptake corresponds to a decrease in atmospheric CO2 of 3 ppm or more.

In fact, ice core data shows a sudden decrease of atmospheric C02 during that period. How much of this can be attributed to the effects of abandoned land, rather than other sources? The researchers argue that the isotope data from ice cores indicates that the decrease in atmospheric CO2 during the was due to uptake in soil and vegetation

“This unusual event of a rapid and large increase in terrestrial carbon stocks is consistent with a role for secondary succession following epidemics in the Americas after the arrival of Europeans, although there are other potential interpretations in the literature which we discuss in the next section. “([2],  p. 27)

Data from many studies shows that there was atmospheric cooling coinciding with the decreased atmospheric CO2, indeed “1577-1694 CE is the only period of significant global cooling within the past two millennia”, and is recognized as “the Little Ice Age”. This cooling is in alignment with theoretical models of the effects of decreased CO2. The researchers find that is no evidence for similar changes in total solar irradiation or volcanic aerosols during this period.

“Through multiple routes we arrive at the conclusion that LUC [land use change[ in the Americas played an important role in driving lower atmospheric CO2 in the late 1500s and early 1600s.” ([2], p. 29)

Altogether, the study concludes that the Little Ice Age was probably caused by the depopulation of the Americas and corresponding changes in land use.

This result, if sustained, is an interesting perspective on the complex world-wide effects history of the European invasion of the Americas.  It is already known that the transfer of species (e.g., food plants) changed diets and health.  It is also known that the massive transfer of precious metals, particularly silver, generated substantial inflation throughout Europe, and increased trade between China and the world.

If the American genocide triggered or exacerbated the Little Ice Age, then its indirect effects included bad weather and famine in Europe and elsewhere, with concomitant social stress and unrest. Karma, anyone?

This is a fascinating study, connecting two obvious dots with a line through a variety of evidence.  (I’m a big fan of using multiple lines of evidence.)  They make a plausible case.

We’ll have to see how well this holds up.

There are competing hypotheses, starting with disagreements about the supposed dating of the “Little Ice Age”.  And while 1492 is pretty firmly dated, the course of contact and depopulation (and subsequent population increase from European immigration) are far harder to date because they occurred over the whole western hemisphere for several centuries.

In addition, estimates for the pre-contact populations and land us are uncertain, as are the estimates for the magnitude and pace of the die off.  In short, refined estimates for these factors could change the conclusions.

And, of course, the climate models used to connect the dots from depopulation to cooling are uncertain. However plausible the hypothesis, there is a huge amount of uncertainty in the argument.

Nevertheless, this study certainly lays out an interesting case. The Little Ice Age does not seem to have a clear cause.  And the Great Dying was a once-in-history “cause”, potentially of just the right magnitude.  If there isn’t a connection, it’s a hell of a coincidence.

The authors also point out that the scenario in this study gives perspective on current preoccupation with reducing atmospheric CO2 [1].  This was a massive unplanned reforestation (of an area equivalent to all of France) which had a strong, almost immediate effect on the atmosphere and climate.  That’s good, but only a drop in the bucket compared to current emissions of Carbon.  It’s going to take a heck of a lot of reforestation to put a dent in our current situation.

  1. Jonathan Amos, America colonisation ‘cooled Earth’s climate’, in BBC News – Science & Environment. 2019. https://www.bbc.com/news/science-environment-47063973
  2. Alexander Koch, Chris Brierley, Mark M. Maslin, and Simon L. Lewis, Earth system impacts of the European arrival and Great Dying in the Americas after 1492. Quaternary Science Reviews, 207:13-36, 2019/03/01/ 2019. http://www.sciencedirect.com/science/article/pii/S0277379118307261