Climate threats?

In my last lecture on Holocene climate variations, what particularly caught my attention was that small changes in forcing can lead to instability. Hmmm..

Whilst doing some further reading, I found this article by Crowley and North that discussed climate variations and its relation to extinction. Instead of posing obvious connections between climate change and extinction, they mentioned that the magnitude of Late Permian extinction seemed to be too great for the area of land to be affected by glaciation. Also, there was no major extinction event during the Late Carboniferous (330 Ma) glaciations, but a significant reduction in some faunal groups. Certainly, some evidence for the three of five extinction events shows connection to the evolution of Cenozoic climate at about 2.4 to 3.0 Ma.

An interesting fact - climate change does have an impact on extinction. Many extinctions occurred at the early stages of cooling millions years ago, with each cooling event removing the most vulnerable species. As species that are more adaptive remained, the effect of climate change on extinction has been smaller since then. 

At least, one of the mass extinctions - the Mid-Jurassic, was argued to be triggered by massive climate change, a mega monsoon. Dr Ruben Cuneo explained the possibility on BBC.

Fuelled by my personal interest on animals, I spent some time to look up some endangered species on WWF's website.

Although there are many other deadly threats that centre around endangered species (some poses connections to the possibility of next extinction), climate change is certainly regarded as one of the major causes. Under changing climate, the proportion of female and male turtle hatchling leads to unstable population.  Poloczanska, Limpus and Hays stated in the past 100 million years, turtles had to move to tropics to establish nesting grounds during glacial periods. Ambient surface air temperatures were naturally higher as global temperatures rose, which consequently reduced the likelihood of male hatchlings. Small changes in temperature close to the pivotal level (29°C) have proved to have great impact in distorting the sex ratios of turtle hatchlings. 

Worryingly, these marine turtles are only the tip of the iceberg of endangered species in the world..

So, back to the question - Does climate change lead to a mass extinction? Perhaps so, to the extent that it is gradually forcing some species to the edge of a wipeout, but certainly not sudden mass extinction events. 

Deadliest Eruption

#throwbackthurday... The following are the famous five extinctions - Ordovician Silurian mass extinction, Late Devonian mass extinction, Permian mass extinction, Traissic - Jurassic mass extinction and Cretaceous - Tertiary mass extinction. The last three of them are closely related to flood basalt eruptions… 

One of the episodes (Season 2, episode 11) from How the Earth Was Made, “Earth's Deadliest Eruption”, gave a clear picture of how a flood basalt eruption can be extremely "deadly".  This "dramatic chapter" of earth caused by the volcanic eruption in Siberia nearly had everything on the planet wiped out. Without too many technical terms, the episode described some findings from the research of the geology at Siberia Traps (It took them 7 days just to get there!). The eruption in Siberia happened 250 million years ago, and lasted for a million years. Yes, a million years. Never have I imagined that a volcanic eruption could last over a month, never mind a million years. Without doubt, it has been the largest lava flow on land in history. What is noteworthy is that carbon dioxide released from magma was another significant cause of extinction, as it raised global temperature by a total of 5 degrees. The warming effect also led to oxygen shortage and disruption of sea currents, as water stopped flowing between the Pole and the Equator. Then, marine life became part of the Permian-Triassic extinction.

Further on the effect of carbon dioxide, Whiteside et. al., 2010 confirmed the catastrophic effect of CO2 on marine and continental extinctions. This links to our current state of affairs on earth..
Facts show that high levels of carbon dioxide in the atmosphere are harmful to the earth as a whole. Alarminly, the level of carbon dioxide in the atmosphere has been increasing exponentially.
If the rise of emission of carbon dioxide continues, it is likely that temperatures would consequently rise. Would this pave the way to the next extinction?

Back to volcanic eruptions. Based on the information of another basalt, Kilauea Volcano in Hawaii, which is currently forming, because it is 500,000 times smaller in scale than that of Siberia Traps, it is unlikely to be the main threats behind the "Sixth Extinction". Yet, studies about the indirect impacts of volcanic eruption definitely alert us about the hazards of rising carbon emission..

Till next time x

Further on Methane..

A professor from Northwestern University explaining the theory I mentioned in my previous blog..

Hopefully this gives a better idea of the "methane theory"!

Laters x

Mega Methane

Reading BBC news is one of my habits, but it was only yesterday did I find out that BBC actually provides a lot more than news! Under the section of Nature, there are theories of prehistoric life including some about mass extinction ones. So I decided have a look for some ideas to the blog.

First idea that I came across was the Catastrophic methane release. Methane clathrate forms when temperature is approximately at the freezing point, and the pressure of overlying water and sediment creates the right condition. A simple theory as to how it may lead to mass extinction: temperature increases and causes methane in the clathrate to be released as gas. As a result, global warming occurs and causes further methane release. This creates a vicious cycle. The change of the environment caused by rising temperature brings plant and animal life onto the route of extinction.

A theory cannot be valid without evidence. Kemp, Coe, Cohen and Schwek conducted a quantitative research in UK. Carbon-isotope (δ13C_org) shifted A, B and C in Toarcian (Early Jurassic) as shown below. The only reason why it happened was through methane hydrates. The stratigraphic relationship established (Left of Figure 1) between the three pulses and the cyclostratigraphy (Right of Figure 1.) shows a direct link of methane hydrate to astronomical forcing. In addition, the shifts of A and B, studied by the authors, coincided with losses of 67% and 50% respectively of marine invertebrate species in Yorkshire. These data, together with a proportion of terrestrial organisms being extinct, can be identified as mass extinction being caused by methane release. Great increases in atmospheric methane and CO₂ caused severe greenhouse effects after the first pulse of methane release. This is similar to the state of present world. As we are experiencing global warming, is it therefore a precursor to the next mass extinction?

Figure 1. Data are from Hawsker Bottoms and Port Mulgrave in Yorkshire in Kemp et al, 2005

One of the five extinctions, Permian extinction, directly relates to methane release. Ryskin explained that if the water were prone to stagnation and anoxia, dissolved methane accumulated in oceanic water would be explosive. Large part of the ocean was anoxic and possibly stagnant at the Permian-Triassic boundary. These parts constituted the eruption region, which consisted of large amounts of methane and other gases in the atmosphere. Methane concentration between 5%-15% would cause explosions and destroy most of the terrestrial life. It is believed that either the explosion caused firestorms with dust and smoke and result in darkness and global cooling, or resulted in global warming with carbon dioxide and remaining methane. Both cooling and warming can contribute to the extinction.

Theories and empirical studies show that methane can be a cause of extinction. But can it be the reason for our next approaching one?

Interestingly, concerns about extinction are very widespread that The New Indian Express published a relevant article recently. They argued that methane could be the key contributor to the 'Sixth Mass Extinction. However, the difference today is the root of recent rise in methane concentrations lies with human activity.

This next extinction, if we are impending one soon, methane will definitely not be the only reason.

Extinction, how?

My last blog was 7 years ago. It was a random blog about high school gossips and irrelevant lyrics… This one is different. In this blog, I will be focusing on the myths being extinction, and perhaps some interesting stories about endangered or extinct species. My interest in these topics first sparked watching the movie - Night at the Museum. The dinosaur reminded me of Natural History Museum and made me think - How can massive animals like dinosaurs just disappear?

So first of all, How did the first ever extinction happen? Scientists have put forward a lot of theories on this topic. Russell and Tucker suggested that supernovae could be one of the main reasons for extinction - including the extinction of dinosaurs. This theory was also discussed by Ellis and Scheramm more than 20 years later. There have been other causes of extinction being thrown about -  human hunting, invasive species.. So then I realised the question of why extinction occurred is still a mystery today! 

I knew that TEDtalk always invites interesting speakers, so while doing some research to start this blog, I surfed TED's website and came across this one by Peter Ward explaining extinction by hydrogen sulphide. 

Enough of theories for extinction for now. Throughout this blog I plan to introduce some endangered animals and some possible reasons that have pushed them towards the edge of extinction. Nature or human? There are more than a dozen of arguments but who has the right theory? Most importantly, is the sixth mass extinction fast approaching?