This spring researchers from ETH Zurich report a very interesting behavior that Lars Chittka describes as “horticulture” . They observed bees deliberately damage flowers, apparently in order to make them bloom sooner, so the bees can get pollen sooner . <<link>>
This is a very nice study.
They induced bees to do this trick, and also tried to replicate the damage mechanically. The experiment showed that the bee damage induced flowers to bloom 30 days or more early! Interestingly, the human efforts to replicate the bees were far less successful, inducing flowers 5 days early.
The researchers demonstrate that this behavior is likely linked to a lack of pollen around. I.e., the bees are starving, so they prod key sources to speed up the arrival of food sources.
One of the interesting things is how specific, indeed, fiddly the damage is. Whatever the bees are doing, it really works. But the researchers couldn’t replicate it very well, so who knows exactly how it works? There is nothing obvious about the specific patterns that would seem to explain the effects.
This looks more like acupunture than horticulture to me!
Once again, bees seem to know something that we don’t know.
I’ve been wringing my hands about the loss of bees and other pollinators for several years now. But, of course, everything is under pressure from this plague of heavily armed, voracious primates.
This spring researchers report a metaanalysis of 166 long term studies across the globe . The combined data gives a comprehensive look at the abundance of insects of many kinds.
Overall, the picture is worrying, but it is also complicate. With zillions of species of insects in every niche possible, how could anything be simple?
The big finding is that there is a lot of variability, even places close to each other. This means that things are surely volatile, changing year to year and place to place. (It also suggests to me that it is difficult to precisely count insects.)
The other big finding is that, overall, species are declining on land, but increasing in fresh water. At a guess, I’d say that humans aren’t blighting the waters as much as the land, at least not in ways that kill insects. We may even be improving life for some water species.
Much of the change in abundance comes from heavily impacted North America and Europe, and the study notes that the trends are less visible in protected areas that presumably experience less pressure from “land use drivers”, i.e. human activities.
As for pollinators and bees: they are, of course, terrestrial species, and therefore in the cross hairs of this decline, whatever is driving it. And even if there are increased masses of gnats and other water bugs, that won’t really help sustain the terrestrial biosphere that humans live in.
The picture is complicated, but it’s not good news.
Roel van Klink, Diana E. Bowler, Konstantin B. Gongalsky, Ann B. Swengel, Alessandro Gentile, and Jonathan M. Chase, Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundances. Science, 368 (6489):417, 2020. http://science.sciencemag.org/content/368/6489/417.abstract
One of the coincidences of history was that the surge of immigrants to the Pacific coast in the nineteenth century happened at a historically wet period. This was taken as “normal”.
A century and a half of intensely destructive occupation later, the region seems to be sliding into a cyclical dry period. This is historically normal, but seems like a catastrophic change for the humans.
This region normally experiences long, deep droughts. But human activities have contributed to erosion, deforestation, and fires. So there is a question of just how much human activity is contributing to the drought.
This spring, researchers report on a study of the contributions of anthropogenic warming to recent climate changes in California and environs .
The study uses tree ring data to estimate summer soil moisture in every part of the region back to 800 CE. This data shows the wet and dry periods over that time, including several multidecade long “megadroughts”. On this chart, the current period is very similar to the onset of one of these periodic droughts.
They incorporate data from a model estimating soil moisture from weather records for the period 1901 to 2018. The datasets were aligned to be consistent for the twentieth century.
In the combined dataset, the current 19 year drought is comparable to a number of earlier droughts, and more severe than only a handful. In fact, current soil moisture levels are lower than all but the deepest drought in the tree ring data.
The study looked at multiple computational models of climate to estimate the effects on soil moisture of anthropogenic activity. Their conclusion is that about half of the effects is due to human activities.
In short, human generated warming has made the natural drought much worse than it would have been.
Obviously, there is little question that this area has been very dry for a couple of decades. Given the long term climate there, it’s plausible that there is one of many periodic events.
Is this the onset of a “megadrought”? That’s less clear, not least because we won’t know until it’s over how long it will run. Looking at the tree ring data, it certainly looks like we might be “due” for another big drought, lasting decades.
The estimates of human contributions are at least plausible. We know that human activity has contributed to warming, changes in precipitation, and other changes such as land cover. These changes, for the most part, would seem to reinforce any natural drying trend.
But it is true that the conclusions are base on computational models which are highly uncertain. At the very best, I wouldn’t bet heavily on specific numbers, e.g., “50%” due to human activity or something like that. But it’s hard to believe that human activity has had no contribution to the current drought.
Overall, I suspect that this region is heading into a long, deep drought. It has seen such in the past, so it can see it again.
A fifty or hundred year drought will make this area nearly uninhabitable.
Aside from the millions of people who would be displaced by such an event, this would be very unfortunate because I love to visit this part of the world, and that may soon be impossible.
A. Park Williams, Edward R. Cook, Jason E. Smerdon, Benjamin I. Cook, John T. Abatzoglou, Kasey Bolles, Seung H. Baek, Andrew M. Badger, and Ben Livneh, Large contribution from anthropogenic warming to an emerging North American megadrought. Science, 368 (6488):314, 2020. http://science.sciencemag.org/content/368/6488/314.abstract
In the past half century, one of the interesting developments in prehistory has been the discovery that the great forests of Central and South America were heavily populated for a long time. These areas were sparsely populated when Europeans arrived, and the tropical forest conceals and consumes remains. So, for a long time, these areas were assumed to be empty, inhospitable “jungles”, where no one lived.
Now, we know that there have been people in the Americas for tens of thousands of years. And tropical forests are huge, abundant areas. The apparent lack of occupation would only be due to the inability to master the challenges. Considering that humans occupied everyplace we know of, including deserts, mountains, tundra, and even icy polar regions; how could they not master the great forests of America?
This spring researchers report a large survey of the Southwest Amazon region which found thousands (4,700) sites that may have been occupied around 10,000 years ago . This research suggests another reason why early settlements were not noticed: not only is the environment poor fossil country, most of the settlements were built from local materials including wood and fiber, which do not leave spectacular ruins.
If you look for a city, you won’t find many. If you look for villages and farms, you might find a lot of them.
The research used satellite imagery to find “forest islands”, raised patches in the overall savanna. They classified some as anthropic, and dug cores at sites, and excavated at four locations. These sites feature ‘black dirt’—” deep dark sediments rich in organic matter, charcoal and burned earth” (, p. 1) a couple of meters higher than the surrounding plains, and generally covered with trees.
The samples indicate that the deposits date to 10,000 to 2,000 years ago. They include phytoliths from plants that were probably cultivated: ancestors of gourds, maize, palms, and more. These species became important foods throughout the Americas, and, after contact, throughout the world.
Perhaps the most interesting conclusion is that these “islands” were deliberate environmental modification and “that these savannahs began to be transformed by the arrival of very early human settlers” (, p. 3)
Overall, this survey suggests that “inland savannahs were a key region for the early occupation of the Neotropics” (, p. 3)
So–there were people there, a lot of people. Which really makes sense in the overall picture.
Umberto Lombardo, José Iriarte, Lautaro Hilbert, Javier Ruiz-Pérez, José M. Capriles, and Heinz Veit, Early Holocene crop cultivation and landscape modification in Amazonia. Nature, 2020/04/08 2020. https://doi.org/10.1038/s41586-020-2162-7
Flowering plants are one of the great glories of our planet. Personally, I think “Planet Earth” should rebrand as “Planet Flower”.
One of the surprising things about plants and flowers is how tough they are. They get gnawed on, blasted by weather, and stomped on by biggers like us. Yet they bounce back, often almost instantly. That’s pretty amazing, especially considering how fragile and squishy they are.
This spring researchers report on studies of just how plants recover from being crushed . In particular, flowers usually need to maintain proper orientation, to attract and mesh with pollinators, and so that pollen and nectar will be retained and deployed correctly.
Plants have the ability to orient, e.g., to follow the sun. This study explores how this type of mechanism works to reorient a flower after an accident. The research looked at 23 species from around the world, and found a variety of mechanisms (which they say “suggest[s] both multiple origins of the capacity to reorient flowers and its importance in successful plant reproduction in changing or unstable environments”. ( , p. 2 )
Part of the study was experiments that deliberately bent flowers, to observe the reaction. One important result is that different plants did different things. Some did not reorient at all—the flower remained out of position. Others responded to various degrees through four mechanisms they describe as: “peduncle bending, pedicel bending, pedicel rotation and bending/twisting of sexual organs”. (, p. 6)
(Penduncle: stalk of several flowers, Pedicel: stalk of individual flower, Sexual Organs: naughty bits)
The results are quite varied. Species with bilaterally symmetric flowers tend to reorient, and restore the “accuracy” almost completely. So do some with “radially symmetric fertile parts”. The researchers hypothesize that the former restores the geometry of the reproductive process, while the latter may be important to attract pollinators.
And, of course, some flowers only last a day or two, which probably isn’t long enough to reorient, even if there is a mechanism. In these species, perhaps new flowers bloom on the bent over plant.
The research raises other questions. How do pollinators deal with “misoriented” flowers? Are there relationships between the structure of flowers, the importance of orientation, and mechanisms for reorientation? I.e., are certain forms “easier” to reorient, or likely to coevolve with specific reorientation processes?
W. Scott Armbruster and Nathan Muchhala, Floral reorientation: the restoration of pollination accuracy after accidents. New Phytologist, n/a (n/a) 2020/04/06 2020. https://doi.org/10.1111/nph.16482
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 . 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 . 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.
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
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 . 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 .
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” (, 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.” (, 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.
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