Tag Archives: Matt McGrath

World-wide Winds Picking Up (Again)

I learn something every day.

I’ve always assumed that wind is about the same, on average.  Obviously, winds change from minute to minute and place to place, but, for a given place, the overall “average” wind over a year is about the same every year, no?  And therefore, wind power is wind power, on into the future.  Right?

Well, no.  Apparently, around 1980 there was a measurable slowing of average winds around the globe.

This may be important for many reasons, but is certainly is a major problem for wind power systems.  Diminishing winds mean less power from wind turbines.

This winter, and international team report that this trend reversed, and wind speed (over land) has increased since 2010 [2].  This is based on analysis of data from many ground stations.  This is a large and noisy dataset, so the study used statistical sampling to establish that the evidence for the global trend is robust.

These results suggest that there is a multi decade cycle of average wind speeds.  In fact, the data show that the increase is three times as fast as the decrease before it.

This reversal seems to rule some hypotheses about the earlier decline. In particular, urbanization and changing land cover cannot be responsible for the changes.

The researchers show that over this period the wind speeds are correlated with ocean-atmosphere oscillations, i.e., cycles of warming.  They note that many global models underestimate this relationship, probably due to limitations of the models.  It should also be noted that this study covers winds over mid-latitude lands (where there are lots of weather stations and wind turbines).

As Matt McGrath (no relation) puts it, this “rise” in global wind speed is a boost green power, at least for the short run [1].  In fact, the observed changes over the past few years amount to an increase of about 17%, which the study calculates amounts to an increase of about 2.5% in the US wind power.  Of course, this will go back down if and when the trend reverses.

If this finding holds up, it means that development of wind power will need to plan for these periodic changes.  The performance of systems should not be based on the trends from recent years, it should project the estimated cyclical behavior, which are predicted to follow the ocean-atmosphere oscillations.

And, of course, human activities may well be perturbing the ocean-atmosphere oscillations, so future rising temperatures could impact winds and wind power.  So we’ll need to see what happens.


  1. Matt McGrath, Renewable energy: Rise in global wind speed to boost green power, in BBC News – Science & Environment. 2019. https://www.bbc.com/news/science-environment-50464551
  2. Zhenzhong Zeng, Alan D. Ziegler, Timothy Searchinger, Long Yang, Anping Chen, Kunlu Ju, Shilong Piao, Laurent Z. X. Li, Philippe Ciais, Deliang Chen, Junguo Liu, Cesar Azorin-Molina, Adrian Chappell, David Medvigy, and Eric F. Wood, A reversal in global terrestrial stilling and its implications for wind energy production. Nature Climate Change:1-7, 2019. https://doi.org/10.1038/s41558-019-0622-6

Interesting New Study of Climate History

The records of recent climate show a consistent pattern of warming and related changes everywhere around the planet.  Indeed, this is one of the most consistent and most alarming findings:  in every study, every place, we see a pattern of unprecedented rapid change.  The pattern is complicated, and the rate of change varies, but this is no local or regional trend.

There have been periods of global climate change in the history of the Earth.  Within these global trends, there have also been local and regional periods of heating and cooling, which generally come and go relatively rapidly, and probably do not have major long term impacts.

The geological record of climate is, of course, a collection of specific data points, recording conditions at one time and place.  It is difficult to Infer regional and global conditions from a limited data sample.  This is all to say that the record of past climate change is uncertain and almost certainly incomplete, especially the farther back in time you go.

This summer an international team of researchers reports on a mathematical model of the global temperature over the last 2000 years [2].  Using hundreds of data sets, their model considers time and space, i.e., the climate in different places over time.   In particular, they calculate a “probable period of peak warming or cooling”, and within that period look at the average temperatures for regions.

The basic finding is that before the industrial age, there is little evidence of globally coherent changes.  Some places experienced warming, others cooling, but not all at the same time. In many cases, the changes seem to be linked to volcanic emissions [1].

This is a stark contrast, of course, with the picture since 1850.

They conclude that for pre-industrial times, “interpretation of individual palaeoclimate time series should not be forced to fit into global narratives or epochs” ([2], p. 553)  Data from these times should be considered likely to represent regional trends.

And, of course, the last 200 years have seen a completely different pattern of simultaneous, global increases in temperature.  This is a different pattern from previous eras, and further evidence that current warming is anthropogenic.

“Against this regional framing, perhaps our most striking result is the exceptional spatiotemporal coherence during the warming of the twentieth century. This result provides further evidence of the unprecedented nature of anthropogenic global warming in the context of the past 2,000 years.” ([2], p. 553)

I’m sure I don’t understand the details of this analysis.  But the main conclusions do make a lot of sense:  it is easy to assume that there is one, world wide, trend, but that seems not to be true.  Furthermore, it is a mistake to extrapolate from local data to infer a global trend, at least without supporting data from around the world.

If earlier episodes of warming were often triggered by large volcanoes, then it certainly seems plausible that consistent, growing, global human made “volcanoes”—industrial and technological emissions—could trigger similar episodes, everywhere all at the same time.


  1. Matt McGrath, Climate change: Current warming ‘unparalleled’ in 2,000 years, in BBC News – Science & Envrionmnet. 2019. https://www.bbc.com/news/science-environment-49086783
  2. Raphael Neukom, Nathan Steiger, Juan José Gómez-Navarro, Jianghao Wang, and Johannes P. Werner, No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature, 571 (7766):550-554, 2019/07/01 2019. https://doi.org/10.1038/s41586-019-1401-2

Climate change: Current warming ‘unparalleled’ in 2000 years

New Solar Tech Is Booming

It’s getting difficult to keep up with newest solar energy technology.

Solar and wind power are booming everywhere, even in Trump’s USA.  And that’s just the technology that was developed in the 1990s and 2000s.

There is a ton of new solar tech coming, which I’m sure we’ll see in the field in ten years or so.  This month I book marked several projects to look at.  In just one week, I saw several cool new technologies.  Wow!

Electricity plus clean water

Solar power is generally captured directly as electricity (photo voltaic reactions) or as heat which can be used to generate electricity.

Researchers at King Abdullah University of Science and Technology are combining the two technologies, with a layer of PV cells stacked on top of heating evaporative cells that use the otherwise unused heat to desalinate sea water [2].

These techniques have been used in separate systems, and, indeed, specialized versions can be more efficient that the hybrid.  But having everything in one system is an advantage for simple deployment with a compact footprint.

Window film

There is a lot of work on window treatments that capture solar energy while letting in light (here, here, here).

Researchers in Sweden report on an interesting chemical used as a film in windows [3].  The norbornadiene–quadricyclane molecular switch is embedded in a substrate such as polystyrene, to make a tinted window.  The chemical is orange when in the dark, but when the sun hits it, it changes state to be clear, storing energy in this state.  When the sun goes down, the chemical reverts, releasing heat.

The idea is to use these windows to store up heat during the day, and use it to heat the building at night.

While there are lots of materials that heat up in the sun and release heat later, these molecules are particularly suited to this role:  they absorb sunlight efficiently in natural daylight, they release heat over 6-8 hours, and they must be stable and cycle each day for long periods of time and in natural conditions.

The norbornadiene–quadricyclane molecule (NBD–QC) is a “molecular switch”, flipping between norbornadiene (low energy) and quadricyclane (high energy), which exposed to sunlight.  The molecule is “highly tunable”, so variants can be reliable and efficient.

The other tricky bit is to embed the liquid molecular switch in some solid material, so the composite has a reasonable lifetime (months or longer).  The researhers report that polystyrene is a good matrix.

The paper reports a solar energy storage efficiency of 3.8% (i.e., nearly 4% of the sun’s heat is caught in the window film. They report a version that has a lifetime of 10 months, which is getting to be useful.

Power storage

One of the biggest challenges of solar energy is that it is sporadic.  At noon in midsummer, there is a huge amount of energy available—on a clear day.  At night or in cloudy weather, there is less or no power to be generated.  Smoothing this out into a more constant, 24/7/365 source is a big deal.

The most direct approach is to store power when there is a lot of sun, and release it later when needed.  There has been a huge about of research and development of cost effective storage in batteries and other methods.

Along these lines, researchers in Australia are using the leftover heat not to desalinate, but storing it in chemicals (in the same vein as the window treatment).  At night, the chemicals are triggered to release the heat and generate electricity.  The cycle repeats daily, producing a steadier flow of electricity.

“All of the Above”

These technologies illustrate the point that there are many promising solar technologies, and they can be used together to create hybrid systems.  The most pressing reason to do so is to smooth out the peaks and valleys of power generation.  The window treatment is smoothing out the peaks and valleys of warmth.

But, most important of all, this approach also uses “more of the cow”, getting more use from the sunlight. I expect that there will be more and more combined systems. Imagine a building with solar windows like above, clever window shades, solar “paint” on the walls, and hybrid solar collectors on the roof.  (And maybe a wind turbine as well.)

It’s not a question of which technology is “the best”, let’s choose “all of the above”.


  1. Ben Coxworth, Cooling/heating window film captures and releases solar energy, in New Atlas. 2019. https://newatlas.com/most-solar-window-film/60477/
  2. Matt McGrath, Climate change: Water and green energy produced by a single device, in BC News – Science & Environment. 2019. https://www.bbc.com/news/science-environment-48910569
  3. Anne Ugleholdt Petersen, Anna I. Hofmann, Méritxell Fillols, Mads Mansø, Martyn Jevric, Zhihang Wang, Christopher J. Sumby, Christian Müller, and Kasper Moth-Poulsen, Solar Energy Storage by Molecular Norbornadiene–Quadricyclane Photoswitches: Polymer Film Devices. Advanced Science, 6 (12):1900367, 2019/06/01 2019. https://doi.org/10.1002/advs.201900367
  4. Wenbin Wang, Yusuf Shi, Chenlin Zhang, Seunghyun Hong, Le Shi, Jian Chang, Renyuan Li, Yong Jin, Chisiang Ong, Sifei Zhuo, and Peng Wang, Simultaneous production of fresh water and electricity via multistage solar photovoltaic membrane distillation. Nature Communications, 10 (1):3012, 2019/07/09 2019. https://doi.org/10.1038/s41467-019-10817-6
  5. Ryan Whitwam, New Solar Panels Use Waste Heat to Purify Water, in ExtremeTech. 2019. https://www.extremetech.com/extreme/294790-new-solar-panels-use-waste-heat-to-purify-water
  6. Lucien Wilkinson, Solar power system that works at night a renewable energy game-changer, in Phys.orb. 2019. https://phys.org/news/2019-07-solar-power-night-renewable-energy.html

 

Expert Hunches On Sea Level Rise

The ice is melting and Inevitably, the oceans will rise. Exactly how fast things will happen is hard to know.  I used to assume that I wouldn’t live to see it, but hey, who knows?  The crazy primates are monkeying with the planet, and we really have no clue what we are doing.

Case in point: we don’t really understand how the ice is melting, and how fast it is filling the ocean.  Uncertainty, thy name is ice.

This summer an international team report on a study that attempts to create probability distributions for the future behavior of the ice sheets. [1]  To assess the uncertainty about these questions, they use “structured expert judgement”, which asks experts to “quantified their uncertainties” for several scenarios.

The results were combined into (subjective?) probability distributions for the change in mean sea level (MSL), under an optimistic “Paris agreement” scenario (+2 degrees C) and a business as usual scenario (+5 degrees C).

These aren’t just guesses, they are based on current understanding of how the ice is changing, and making plausible calculations for the future, with plus and minus uncertainties.

The resulting distributions have long tails, which “reflects the experts’ joint view that large amplitude, nonlinear instabilities could be triggered at this higher temperature, even by 2050”.  I.e., given current uncertainties, they see a lot of possibility for faster melting that aren’t clearly understood today.

(Again, note that the idea is that these results are sanity checked,in that  they are all consistent with known physics.  They are theoretically possible, though the probabilities are certainly debatable.)

Obviously, this sort of subjective assessment has massive uncertainties of its own.  The researchers think it is important to note that in recent years there has been intensive attention to understanding the ice sheets and the processes of melting.  This study could be seen as capturing the tacit understanding of these workers, their “hunches” from worrying and working hard on the problem.  It’s not solid data, but it’s not nothing, either.

From this point of view, it is probably important that these experts seem to be more uncertain than in the past (which the researchers tag as “negative learning”).  This presumably reflects better understanding of the complexity of the processes, the appreciation of the range of possible outcomes, and how limited our understanding actually is.  (An expert is someone who isn’t certain of the answer, at deeper and deeper levels.)

We know we don’t know how bad it will be, but how bad could it get?

The main finding seems to be that, whatever current measured trends may be, there seems to be a reasonable probability that melting ice sheets will contribution to sea level rise of as much as two meters by 2100.  Glub.

The higher end estimates are roughly double predictions from current models.  These “one chance in twenty” outcomes are very dangerous—it might well mean hundreds of millions of people displaced, for instance.

So this isn’t exactly a prediction that the seas will rise, or that catastrophe is imminent. but it is, as the BBC phrased it, “Global sea level rise could be bigger than expected based solely on current models and data.  Maybe it won’t be so bad in the end, but when experts are worried, it’s probably not a good bet to assume that it can’t be that bad.

I’m a little disappointed that, most likely, I won’t live to see the really big floods. Rats.  After all my generation has done to make this happen, it’s a shame we won’t be there for the big show.


  1. Jonathan L. Bamber, Michael Oppenheimer, Robert E. Kopp, Willy P. Aspinall, and Roger M. Cooke, Ice sheet contributions to future sea-level rise from structured expert judgment. Proceedings of the National Academy of Sciences:201817205, 2019. http://www.pnas.org/content/early/2019/05/14/1817205116.abstract
  2. Matt McGrath, Climate change: Global sea level rise could be bigger than expected, in BBC News – Science & Environment. 2019. https://www.bbc.com/news/science-environment-48337629

Offshore Financed Ecotrashing Docuemtned

Grr.  Every now and again there is news that is just plain infuriating.

Evil money, evil business.

I don’t want things to be that simple, but sometimes it is just that simple.

All over the world, good people are behaving responsibly, trying to preserve the planet and, by the way, follow laws.

And all over the world, bad actors are shamelessly destroying nature and plundering resources. And, by the way, flouting laws.

How can this happen?

Simple:  lack of accountability.  And one of the most flagrant tools for flouting is ‘offshore finance’.

Offshore finance is bad for poor people, bad for the economy, and, it seems, bad for nature., too.

A new report suggests a clear link between tax havens (AKA offshore finance centers) and environment degradation [1].

Specifically, the study traces the financing for ecologically damaging enterprises, fishing and deforestation.  In both cases, there are good actors and bad actors, clean harvests and dirty harvests.  The data show that it is easy to trace the good actors behind clean activities.

But most dirty activities are funded by anonymous agents, hidden by offshore financial havens.  This means that bad agents are hard to trace.

Which, of course, is not a coincidence.

For one thing, a lot of the dirty harvesting is probably illegal.  And it would certainly be bad publicity.  So there is every reason to desire anonymity.

It is also true that, like many activities offshore, the profits are flowing away from the local economy, and often into the dark economy and dark regimes around the world.  This is stealing from the poor, the innocent, and the honest, and enriching the evil rich.  I’m not seeing any upside here.

In fact, environmental degradation is almost the least of the harms from this stuff.  These people literally don’t care about anything except money, so of course they don’t care about preserving forests or fisheries.


Finally, I’ll point out once again that cryptocurrencies are designed to be the perfect offshore financial system. Unregulated and untraceable transactions are the entire point of cryptocurrencies, and they are becoming popular in many of your favorite offshore destinations.

In this light, all the rhetoric in the world about supposed social benefits and transparency of cryptocurrencies ring hollow.  The last thing we need is lightning fast digital finance that is effectively “offshore” from everywhere.

Grr.


  1. Victor Galaz, Beatrice Crona, Alice Dauriach, Jean-Baptiste Jouffray, Henrik Österblom, and Jan Fichtner, Tax havens and global environmental degradation. Nature Ecology & Evolution, 2018/08/13 2018. https://doi.org/10.1038/s41559-018-0497-3
  2. Matt McGrath, Tax haven link to rainforest destruction and illegal fishing, in BBC News – Science & Environment. 2018. https://www.bbc.co.uk/news/science-environment-45172671

Plastic pollution: bad news

One of the problems with plastic is that it doesn’t biodegrade.  The world Is filling up with plastic junk, on land and in water everywhere.

Of course, plastics do degrade, if very slowly.

This summer, a new study suggests that decaying plastic releases an array of greenhouse gasses, including methane and other hydrocarbons [1].

The more interesting finding is that the decay is potentially much larger than previously known, and potentially important to the global climate.

“Our results show that plastics represent a heretofore unrecognized source of climate-relevant trace gases” (p. 1)

The new study shows that polyethylene emits greenhouse gasses much more rapidly when exposed to water and sunlight, and the emissions accelerate over time.  This means that the vast mush of plastic trash floating in the oceans and other water are likely generating considerable amounts of greenhouse gas.  (In addition to fouling the water and harming life forms.)

“low-density polyethylene emits these gases when incubated in air at rates ~2 times and ~76 times higher than when incubated in water for methane and ethylene, respectively.”

At this point, it isn’t known how much plastic trash is emitting, so it will be important to quantify just how much plastic is out there, and how fast it is rotting.

These findings were serendipitous, accidentally discovered using polyethylene bottles in a laboratory, where excess methane was detected.  The study required long exposure to sea water and sunlight, while measuring emissions.  Which is all to say that it was lucky to have well equipped scientists notice this unexpected phenomenon, and then carefully document it.  Well done.


  1. Matt McGrath, Plastic pollution: How one woman found a new source of warming gases hidden in waste, in BBC News – Science & Environment. 2018. https://www.bbc.co.uk/news/science-environment-45043989
  2. Sarah-Jeanne Royer, Sara Ferrón, Samuel T. Wilson, and David M. Karl, Production of methane and ethylene from plastic in the environment. PLOS ONE, 13 (8):e0200574, 2018. https://doi.org/10.1371/journal.pone.0200574

Ocean Currents Slowing, But No Ice Age Coming?

One of the big questions in Earth science is what is happening with the Ocean circulation systems, and what they are linked to.  These currents circulate around the oceans at the surface and deep below, moving vast amounts of water, nutrients, and, above all, energy around the world.  The appear to be linked to atmospheric conditions, and influence the climate on land directly and indirectly.

The Atlantic Meridional Overturning Circulation (AMOC) is a large current that flows North from the equator on the surface, cools and sinks, and then flows South deep in the ocean, where it eventually comes back up to complete a circuit.  This flow is driven by the differences in the density of warm, fresh water, and cool, salty water.  Heating the water absorbs a huge amount of the solar energy reaching Earth, energy that does not heat the atmosphere and land.  Changes to the current can potentially have widespread effects on climate, and the geological record appears to show cases when sudden slowing of the current has been associated with periods cooling in the Northern Hemisphere.

Melting Arctic ice floods the ocean with fresh water, diluting the salinity and potentially decreasing the downward pull, and slowing the AMOC.  This would reduce the transport of heat from the tropics, resulting in much cooler temperatures in the North.  Human generated warming is melting the Northern ice, which could lead to a sudden shutdown of the AMOC, triggering a new ice age.

This summer a new study based in part on new data from buoy arrays finds a more complex relationship between global temperatures and the AMOC [1].   The AMOC was at a minimum from 1975 to 1998, during which time the surface warmed.  From 1999 to 2004, the AMOC accelerated, and globally temperatures increased more slowly. The AMOC has now slowed again and is probably will remain at a minimum for a decade or more. This will almost certainly mean global temperatures will increase.

Basically, the AMOC (and probably other currents) appears to be absorbing the increased heat from the atmosphere, without triggering a sudden cooling during recent periods, and without sudden changes in the currents observed at some points in the past.  Probably no ice age in the near future.

In general, it seems that even if the current is transporting less heat to the North—which could generate a mini ice age there, the heat has to go somewhere.  If the ocean absorbs less, then the atmosphere will heat more.  The warmer air not only heats the middle latitudes, but also warms the North, too, which probably makes up for the cooler seas.

One interpretation of these hypotheses is that when the Earth is heating rapidly due to greenhouse gasses, the ocean current keep running, even as the ice melts.  Models of earlier eras may not reflect current conditions (no pun intended).

“Evidence from palaeoclimatology suggests that abrupt Northern Hemisphere cold events are linked to weakening of the Atlantic Meridional Overturning Circulation (AMOC)1, potentially by excess inputs of fresh water. But these insights—often derived from model runs under preindustrial conditions—may not apply to the modern era with our rapid emissions of greenhouse gases.” ([1], p.387)

It’s all pretty complicated, and we’ll have to see how these theories play out.

But I’d bet that things are just going to get hotter, the ice is going to melt, and the oceans are going to rise.


  1. Xianyao Chen and Ka-Kit Tung, Global surface warming enhanced by weak Atlantic overturning circulation. Nature, 559 (7714):387-391, 2018/07/01 2018. https://doi.org/10.1038/s41586-018-0320-y
  2. Matt McGrath, Slowing Gulf Stream current to boost warming for 20 years, in BBC News – Science & Environment. 2018. https://www.bbc.co.uk/news/science-environment-44875508