From Science Today: “Recently, researchers discovered other effects of acidification on oysters and what the breakdown of the oysters’ calcium carbonate shells could mean for the acidic balance. Science Today sat down with the Academy’s own oyster expert, Dr. Peter Roopnarine, curator and chair of Invertebrate Zoology and Geology, to get some perspective on these recent studies.”
The following is a guest post by Darko D. Cotoras Viedma.
Imagine that somehow you have the chance to travel to the future. A time when you will be alone on this planet and humanity is part of a history that nobody will read. Your mission is to do a biodiversity inventory and try to answer one question: What was the signature of the presence of humans on Earth?
Enclosed on its natural environment the endangered Mauna Kea silversword (Argyroxiphium sandwicense subsp. Sandwicense) is protected with a fence from introduced feral animals. South slope of Mauna Kea. Big Island, Hawai’i.
Right before that future, humanity never took real responsibility for the environment. It centered its efforts on promoting a strongly industrial development which deepened social inequalities. However, this didn’t affect every aspect of life. The interest in market expansion favored the worldwide access to a whole “family” of products and services associated mostly with entertainment and luxury. Immediate desires related to those things could be satisfied in the same way pretty much anywhere in the world. In that sense the world became more “equal”.
As many science fiction authors predicted, the world became dominated by big corporations. In some places it was easier to get access to their products and services than to any other basic needs. Also the movement of people became extremely easy; the average person lived in three different cities during his/her life and one third of world’s population owned a second house.
Humanity gained complete independence from seasonality and weather. Everybody could get any kind of vegetable or fruit year around. Cities were founded in the middle of the deserts or deep in jungles. But, this way of life couldn’t last for long. When it spread to the entire world it was a matter of a century to reach a point of no return. Hundreds of thousands of years after that event your mission starts.
The first thing you notice is the reduction in species diversity. The long announced “Sixth mass extinction” happened and an important part of the biological patrimony was lost forever. In some cases whole branches of the Tree of Life were lost, while in others only some species. But, what really commanded your attention were the survivors. You expected to find hundreds of different species that evolved from the wide spread agricultural plants and animals, however they were all extinct. The domestication of these organisms made them absolutely dependent on us. On the other hand, other organisms dispersed unintentionally by humans had the distribution pattern you expected. The New World was populated by many new species of grasses coming from Europe, while the islands in Oceania were full of new species of rats, geckos and land snails coming from Africa, South America and Asia.
At the same latitude most of the low elevation environments had a similar biodiversity. The same thing happened in shallow waters in the ocean. Everywhere between 100 meters below to 1,500 meters above sea level, you were able to describe a very well defined biological community, the “Human-impacted community”. Interestingly within this community you found some species originally endemic to those very areas. They are the result of past human conservation efforts. Somehow, by establishing biological interactions with all the rest of introduced species they managed to survive.
Outside of the “Human-impacted community” there is another kind of survival species. Those areas weren’t affected directly by humans, but because of global changes extinctions also occurred. The survival species then had very small population sizes restricted to reduced patches of habitat in comparison to their original distributions.
At some point, standing in the middle of what once was a city you look around and only see an extensive forest, a forest comprised of species that initially were on the sidewalks of the streets or in the backyards of houses. This forest is replicated in all the former cities at this latitude, but now after thousands of years, each one has its own species that evolved from once widely spread ornamental plants.
The world you saw in the future was definitely a different place. Somehow less diverse, somehow more diverse. The same as five times before, life was able to recover from a cataclysmic event. After a period of exponentially rapid change, ecosystems evolved into a new configuration that was stable over units of geologic time.
In a geologic perspective it seems clear that life followed its own course. The main consequences of our activities affected us and the unfortunate species that happened to co-exists with us. The preservation of the environment it is not only a problem of sustainability for our own benefit, it is also a matter of respect for others and I am not talking about other humans.
Darko on Molokai
Darko Cotoras, originally from Chile, is a Ph.D. candidate in the Integrative Biology dept at UC Berkeley. He is interested in the historical processes that shape biodiversity, in particular on insular environments. For his dissertation he is studying the temporal dynamic of the adaptive radiation of an endemic group spiders (genus Tetragnatha) from the Hawaiian archipelago. He has also researched terrestrial invertebrates on the Juan Fernández Islands and Rapa Nui.
We celebrate Endangered Species Day on May 18th. We have reasons to celebrate because though human activities have many species on the brink of annihilation, there is serious commitment ranging from individuals to nations states to both protect those species, and to bring them back from the brink. Nevertheless, the threats to species are growing in number and severity. The following essay will not be cheery, and I hope to convince you that avoiding extinction is a very difficult problem and its consequences are severe. I will therefore begin with the optimistic message: The fact that we humans are the cause of the current species crisis is reason to be hopeful. We cannot save species from devastating physical events such as asteroids and volcanoes, but we can save them from ourselves.
It is well known, based on the fossil record, that the majority of species that have ever existed are now extinct. That’s why you will often hear the phrases, “99% of all species that have ever existed are extinct”, and “extinction is the fate of all species”. Let’s examine these statements for a moment. The first is a somewhat factual measure. No one knows if 99% is the correct figure, but we do know that most species that have ever evolved are now extinct. The reason that the Earth is still teeming with millions of species is, of course, because new ones evolve all the time. The second statement is a bit more problematic though; it’s an assumption, not an observation. To scientifically predict the fate of a thing is to presume that we know and understand all the forces controlling it, and that we know what those forces will do in the future. That of course is certainly not the case here. Even more problematic is the fact that even though changing conditions might cause the extinction of a species, changing conditions also drive evolution! In a sense then, extinction is an evolutionary failure. Okay, it’s not quite that simple, but here’s what I mean. Under what circumstances does evolution fail and lead to extinction?
Such cool headgear (Wikipedia)
Imagine that you are lucky enough to be a spectacular dinosaur living somewhere on the planet 65 million years ago (some of you know what’s coming…). You are the culmination of archosaurian evolution which got started some 175 million years before, in the wake of the devastating end Permian mass extinction. Unfortunately for you, today is the day that a giant asteroid from outer space collides with the Earth somewhere in the vicinity of today’s Yucatan Peninsula. The energy released by the collision is some 19,000 times greater than the explosive force of the world’s current nuclear weapons arsenal. The survival of your species depends on enough of its members surviving the ensuing environmental catastrophe, and that could happen in two ways. First, you could have the individual capacity to acclimatize to the changes happening around you. For example, it’s possible that many animals survived by taking advantage of underground dwellings, or their abilities to enter into some sort of resting phase. Second, your species could adapt to the changes. In either case, evolution is at work. The capacity to acclimatize is generally a function of the physiology, behaviors and so on that evolved in your ancestry, while adaptation is the result of current genetic variation and natural selection. Extinction will occur if the magnitude or severity of the environmental changes overwhelm your capacity to acclimatize, or your species’s capacity to adapt (e.g. limited genetic variation) or the rate at which it can adapt. Sadly, non-avian dinosaurs neither acclimatized nor adapted, and today exist only as fossils or in the movies. This has happened repeatedly during the history of life. The end Permian mass extinction of 251 million years ago resulted from overwhelming changes of climate, ocean conditions and atmospheric composition. Ultimately, it was driven by massive volcanism in the Siberian region. The mass extinction 65 million years ago was also the result of significant changes in climate, driven by massive volcanism in India’s Deccan region, coupled with that rock from outer space. That collision would have heated large regions of the North American continent, darkened the skies for months, and subsequently cooled the planet for years.
Today the Earth is on the brink of another mass extinction, but this time we humans are the volcanoes and asteroids. Driven by an exploding population and rapidly increasing rates of resource consumption, we are sequestering landscapes and habitats or destroying them outright, over-exploiting wild species, and changing the climate at rates that overwhelm the ability of species to acclimatize or adapt. Climate change is by far the most dangerous of the bunch because while we can confer protection from exploitation on landscapes and species, we cannot protect them from changing temperatures, seasons, patterns of rainfall and ocean acidification. Even as we work to curb our climate-changing habits by developing alternatives to fossil fuels, engineering more efficient transportation systems and planning our own socio-economic adaptations, species must also acclimatize and adapt. This will be accomplished either by species movement to track favourable climates, or staying put and acclimatizing and adapting. Unfortunately, there are severe limitations to each.
There is no doubt that many species are now on the move in response to climate change. Most pronounced are expanding ranges of many tropical or warm temperate species as tropical air and water temperatures expand outward from the equator. Examples include the Humboldt squid, normally restricted to waters of the tropical and south eastern Pacific, but is now a frequent and abundant species in waters as far north as Alaska. The increasing incidence of normally tropical diseases such as West Nile virus are also testimony to increasingly favourable conditions in regions that were previously too cool. Habitat expansion for those species occurs at the expense of other habitats of course. Regions of cooler temperatures are shrinking, leaving no room for migration of the species there. In alpine regions many species are moving upward, but of course can go no higher than the highest mountains. Polar species are not only faced with changing habitats, such as the drastic reductions of summer ice coverage in the Arctic Ocean, but must deal with the newcomers from warmer regions. And therein lies the another limitation. Given the rate at which conditions are changing, on a timescale of decades, there is absolutely no guarantee that a species will have the genetic capacity to evolve and adapt rapidly enough to survive. For scientists, the answer will in many cases be a wait and see experiment. The results will no doubt be intriguing and valuable, but that will be small comfort for any species that come up short.
There is a final limitation, and that’s based on relationships. No species exists in isolation, humans included. Every species interacts with other species and is dependent on other species for survival. That’s how we evolved! Species adapt to changing conditions, and in turn their new adaptations alter the world around them. We are united in a gigantic global network of biological relationships which includes production, predation, competition, parasitism, reproductive services, habitat engineering, and recycling. When species move, when they change, some of those relationships are disrupted. Even now we see the synchrony of spring flowerings, fruitings, nesting etc. becoming de-synchronized. And these relationships are not formed on the fly! They are the evolutionary result of species interactions occurring over time, and indeed the systems or networks that they produce are likewise products of evolution. In studies by myself and colleagues (see Further Resources below) of ecosystems in the wake of the end Permian mass extinction, we found that while the number of species recovered very quickly within a million years of the extinction, the networks of relationships so formed were unstable and weak. It took several million more years before system robustness recovered to pre-extinction levels. And during that time, the dominant vertebrates of the land, the ancient relatives of humans and other mammals, were eclipsed by the rise of the dinosaurs. They would have to wait another 175 million years before another opportunity for dominance would present itself. Those timescales would try the most patient of humans.
So what do we do? I believe that we must become better stewards of the planet. I know that some will argue that we should not be stewards at all, but consider this. Humans already occupy to varying extents some 48% of the planet’s dry surface and we directly utilize or otherwise co-opt 24-41% of global photosynthetic production. We are already stewards of the planet! The real problem is that we are rather poor stewards. We either absolve ourselves collectively of this responsibility or we embrace it. The choice is ours, and the fates of an uncounted number of species now depend on us. Therefore, let us indeed celebrate Endangered Species Day, for while it is a reminder of the dire state of our environment, it also recognizes our acceptance of an awesome responsibility.
Some of these are fairly technical (sorry!), but please feel free to submit any and all questions.
News from Nature.
“Global average temperatures are now higher than they have been for about 75% of the past 11,300 years, a study suggests. And if climate models are any indication, by the end of this century they will be the highest ever since the end of the most recent ice age.”
It’s no longer news that warming temperatures are not the only negative consequence of the increasing concentrations of atmospheric greenhouse gases. Add increased weather variance, changing rainfall patterns and sea level rise to the list. One of the most dire impacts, however, and one that seems to be rather inescapable, is ocean acidification. Ocean waters become more acidic as the amount of carbon dioxide dissolved in the water increases. This has been happening as the amount of carbon dioxide in the atmosphere has been increasing. The oceans have a tremendous capacity to absorb carbon dioxide, but we are rapidly exhausting that capacity. When the gas dissolves in seawater, it triggers a complicated set of reversible chemical reactions, sort of chain from carbon dioxide, to carbonic acid, to bicarbonate and hydrogen ions, to carbonate and more hydrogen ions. Normally, the system is driven toward the carbonate end of things, resulting in very moderate acidity (high pH, which is a measure of the concentration of reactive hydrogen ions in the water), and conditions suitable for the precipitation of carbonate minerals, most notably calcium carbonate. Calcium carbonate is the material used most commonly by marine organisms for building skeletons, for example animals such as corals, snails, clams, and numerous microscopic plankton. One of the great dangers that we face as the oceans become more acidic is that all these organisms, and the ecosystems that they are parts of, will decline.
The Science Today team at the California Academy of Sciences recently produced a very nice short video discussing these topics. View the full video, and leave comments here, or for the Sci Today team!
A new report from the CJR seconds an earlier report from The Guardian in the United Kingdom, that substantial millions of dollars are being donated anonymously, and often secretly, to support dissemination of the denialist point of view regarding climate change and global warming. One could also argue that large sums are donated to groups dedicated to getting the word out that the scientific evidence is overwhelming and that action must be taken. As noted in the reports, however, those groups tend to be more transparent. Regardless, advocacy for or against a problem is meaningless if there is firm evidence against your stance. Given the lack of any scientific support for a denialist position, one must therefore wonder about the motives.
A very nice report on the reports can be found in this article from Physics Today.
The dramatic recent decline in Arctic sea-ice cover is illustrated in new data from Europe’s Cryosat mission. The data currently consists of only a few years right now, so it’s not possible to say if this is a trend or not. Importantly, however, it does reveal that winter ice growth is not compensating for the increasingly dramatic loss of summer ice that is now, unfortunately, a well established trend. Also, the big differences already detected by this mission points to a high variability of seasonal ice growth and loss, a variability that could be indicative of a system in transition. Read more here.
Prominent climate scientists were unwilling Wednesday to do what New York Gov. Andrew Cuomo did: blame climate change for the devastating storm known as Sandy that wreaked havoc along the Eastern Seaboard. Read the full article here.
The declining areal cover and thickness of summer ice in the Arctic Sea continues, with 2012 shaping up to be another record-breaking year. Read the BBC summary here. These declines are of course predicted as a consequence of warming air temperatures due to anthropogenic global warming, but what really alarms me is the speed at which it is progressing. Basically, ice loss is accelerating every year, and has been since we noted a drastic speed-up in 2007. The consequences of an ice free Arctic will be far-reaching. First there are physical consequences. Losing the ice reduces the regional albedo, and creates a feedback that will continue the acceleration. Furthermore, thinner ice means that more light penetrates into the depths, warming the water beneath. The region’s biology is also changing, and this too will accelerate. Warmer, brighter waters will most likely increase biological productivity in the Arctic Sea, which will be good news for some human industries, but isn’t good news for all. The opening of the seaway, and increasing productivity, will change the ecology of the region, displacing many species, while allowing invasion from neighbouring waters in the northern Pacific and Atlantic. Geerat Vermeij and I wrote a predictive paper about this, oh, 4 years ago now. It is difficult to predict exactly what the consequences of those changes will be because of the problem’s complexity, but they will be large. And finally, of course, opening the sea exposes many many resources of interest to humans, including fossil fuel deposits and shipping lanes. Let the wrangling begin. Noe note though is that the Arctic Sea ice melting will not contribute significantly to sea level rise; that ice is already in the ocean.
Our planet continues to change in response to global warming, and it seems that some of those changes are accelerating. I cannot be certain, and we will only know this in hindsight, but in my opinion we are beginning to cross thresholds. The time for discussion is long past. Now is the time for increased mitigation and implementation of adaptive strategies. I don’t think that we are yet at the point where we need to consider drastic measures, such as extreme geoengineering. But, in the same way that a failure to agree upon and implement effective mitigating measures has brought us to this point, we may well be on our way to addressing this problem with technologically challenging, ecosystem-altering, economically difficult and socially painful actions.