The Earth Story

Take a little trip and see

Antarctica is the most isolated continent on this planet not just for humans, but also for life in general. A strong ocean current circling Antarctica sets up a boundary called the Polar Front, where a single area in the ocean represents a sharp change in water temperature and there is very little exchange of water from North to South. Most organisms that live to the south of this line can be traced back through time with little exchange or interactions with species that live to the North, so aside from birds that fly over this layer and some deep water fish that can swim under it, the Polar Front is a major boundary for life.

However, every now and then an organism finds a way to cross that boundary. In 2017, scientists discovered bull kelp on an Antarctic beach that does not live on the South side of the Polar Front. Instead, it lives near the Kerguelen Islands in the Indian Ocean, and it must have traveled all the way to Antarctica across the Polar Front.

To track possible paths that could reach Antarctica, scientists led by a researcher at Australia National University created a detailed model of ocean currents and circulation patterns around Antarctica. They dropped a series of points into the ocean currents near one of the other islands that could supply life to Antarctia, In this case South Georgia Island, and allowed the ocean to scatter them over time. In this video, you can see how those points move around – the blue dots never make it to Antarctica, but the orange dots do with enough time.

The Kelp that was found in Antarctica was coated with barnacles, showing that it had been in the ocean for a long time. The shortest path the scientists found across the boundary to Antarctica took 489 days, and the other points took longer. However, once the kelp reached Antarctica, it still was alive and had the ability to reproduce before it washed ashore. The temperature in the Antarctic waters would have prevented this species from taking hold there, but only as long as it stays frozen.

As climate warms in Antarctica, therefore, there are paths to allow non-native or invasive species to reach that previously isolated continent. Life on the southern continents can reach Antarctica, but it doesn’t live there in part because the journey is hard and in part because the current climate is too rough. If the conditions become a little more favorable, life will move in, on paths like these.

-JBB

Original paper and video source: https://www.nature.com/articles/s41558-018-0209-7

Reference:

https://www.sciencedirect.com/science/article/pii/S0169534704003064

Computer animation of walking Argentinosaurus

Look, if you had a computer program designed to use the skeletal structure of a T-Rex to reconstruct its walk, at some point wouldn’t you also decide to make it breathe fire? I think we all would.

Scientists reconstruct footsteps of Earth's largest dinosaur. The greatest sauropod to ever walk the world has had its gait digitally reconstructed by a team at the University of Manchester in England providing new insights into the capabilities of vertebrate skeletal systems. The team laser scanned a specimen of the 94 million year old 38 metre long saurian and used the data and a huge amount ofcomputer processing power to re-create its movement pattern. Scientists have long debated how such huge creatures moved, even suggesting its weight must be overestimated, but this research proved it was quite capable of walking and running across the ancient Patagonian landscape, carrying its 80 ton weight at an estimated 8km/hour. The team plan to carry on further research on T. rex, Triceratops and Brachiosaurus. Loz Image credit of Argentinosaurus at the Carmen Funes museum in Plaza Huincul, Argentina: Bill Sellers/PA Original paper, free access: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0078733;jsessionid=3D366317387A8E9D0EC05CEE0C8AA245 http://www.manchester.ac.uk/aboutus/news/display/?id=10947 http://www.pddnet.com/news/2013/10/researchers-digitally-reconstruct-dinosaur-footsteps http://www.theguardian.com/science/2013/oct/30/dinosaur-skeleton-simulation

I’m currently hiding indoors from the rain bands of Harvey (landfall south of me, only a flooding threat for me), so here’s an animation of a hurricane viewed from space. I love how they threw in the ISS.

3-D computer imaging of a trilobite

A Jet of Iron

The Earth’s outer core is a liquid of molten iron and nickel. This iron is at temperatures of over 5000°C and convects, driven out some of the heat leftover from the original formation of the planet. That convecting iron drives the Earth’s Magnetic field, which both shields the planet from much of the incoming energy of the solar wind and draws compass needles in the direction of the poles.

This convecting core is 2900 kilometers below your feet right now. We can tell it is there and liquid due to the magnetic field and through seismic techniques, but we can’t directly probe the convection patterns in the core because it is so far away. We have no technique currently developed where we could send a signal of our own to interrogate the core. We can’t tell its exact composition, we can’t tell exactly where currents are in the core; we can’t predict how the magnetic field will change over time. The only probe we have of the core is something generated by the core itself, the magnetic field.

In 2013, the European Space Agency launched a series of three satellites known as the “Swarm” mission that carries equipment to detect the intensity and direction of Earth’s magnetic field. That mission has orbited the planet for years now, allowing it to measure tiny changes in the magnetic field.

Although it still always points generally north and south, there are subtle changes in the strength of the field The convection patterns in the core – what parts of iron are rising, sinking, and moving side to side – those patterns are the cause of this complexity at the surface. Using supercomputers, geophysicists can create simulations of flow in Earth’s core and see what types of complexity these patterns would create in the magnetic field at the surface.

Thus, these type of “synthetic simulations” give us a way to take the patterns observed at the surface and make statements about the convection patterns in the core. Scientists at the University of Leeds used this technique to investigate the cause of subtle features in the magnetic field of the northern hemisphere. Their best explanation for the cause was a “jet stream” in the core.

The atmosphere also convects – hot air rises and cold air sinks, in patterns. The jet streams in the atmosphere are rapidly moving winds that occur in-between these convection cells. The core likely generates convection cells just like these, where molten iron rises in one area and sinks in another. A Jet Stream, similar to the one generated in the atmosphere, is a plausible result of this fluid dynamics in the core. Superheated molten iron rising and sinking in cells creates an area in the Northern Hemisphere, with a rapidly moving stream of molten iron in-between these cells fits that pattern.

Supercomputers and satellites used to discover a stream of 5000°C iron. Sounds pretty neat to me.

-JBB

Image credit: ESA http://bit.ly/2jnB8E0

Original paper: http://go.nature.com/2kd3FZX

This is pretty neat. This video from RVX studios takes you through some of the shots used in the 2015 movie “Everest” and how the mountain was digitally created. They start with general shots that match the shape of the mountain and then fill in the gaps to the full shots from the film, and in the process capture some really neat views of “rocks” and “geologic layers” in the background

Timelapse

Last week, Google released an update to an app they originally put out in 2013 called Timelapse. The US Geological Survey’s Landsat program has been collecting orbital images of the planet Earth for decades, producing the longest running series of photos of Earth’s surface ever created. Landsat satellites have looked down on the planet as humans have fundamentally reshaped the landscape, and the Google Timelapse app is built to share that database.

In conjunction with computer scientists at Carnegie Mellon University, the programmers built up 33 images that are cloud-free mosaics covering the entire planet’s surface every year. Assembling these required sorting through millions of Landsat (and for 2015 images from the ESA Sentinel satellite program) to find frames that were cloud-free and covered the full planet. They then stitched them together and built an app that works like Google Earth – you can scroll to any place on Earth and watch that area evolve from 1984 to 2016.

This gif shows the development of the community of Fort McMurray, Canada, which grew massively over this time due to the development of bituminous sands as a resource that could be converted into gasoline. In 2016 this area was struck by a massive wildfire, with damage from that not yet caught in the frame.

Scroll through some of their selected images and you can watch the response to the 2004 and 2011 tsunami waves (the seashore changes are pretty remarkable), rapid growth of some cities, evacuations of others.

-JBB

Selected gifs: http://bit.ly/2gGwxJD Time Magazine Feature: http://time.com/timelapse2016/ Youtube highlights http://bit.ly/2gT5FJ9

This video is a high powered computer's simulation of the New Zealand Earthquake earlier this month. The video shows the initiation of the earthquake rupture and then tracks the motion of the planet up and down and side to side as the waves from the earthquake spread out from the rupture. The video is played at roughly 2x the speed the waves actually propagated outwards.

Simulations like this one are a key part of understanding earthquake behaviors. Geophysicists can input parameters including the shape of the fault, the portions of the fault that rupture, the amount of stress released, and the rock types along the fault and high-powered computers will turn those parameters into a simulated, synthetic earthquake. The simulation will then allow the energy from that earthquake to propagate out from the source, where in the simulation it eventually reaches places where there are actual seismometers capable of recording the quake. By tweaking the parameters of the earthquake to create waves that match those actually observed in the earthquake, the scientists can work backwards - taking seismic data recorded during the quake and using it to unravel what actually happened.

These synthetic earthquakes can therefore give information about fault rupture, wave propagation, and even the geology sitting underneath the seismic instruments. A high powered simulation of an earthquake like this one also can be used by engineers to predict the kind of ground motion they will see during future quakes - a key detail they need to know when designing buildings.

-JBB

Cloud patterns shifting due to climate changes

Although clouds may shift from one spot to another depending on the vagaries of any particular weather system, there are global patterns to clouds controlled by the major properties of the atmosphere. Areas where warm, wet air upwells on a regular basis commonly are covered by clouds, while areas with dry and sinking air are commonly cloud free.

As humans add more greenhouse gases to the atmosphere, it has been predicted that these patterns will change. Add extra heat in certain places, get more evaporation and more clouds. Add extra heat in one place and it pushes downwelling to other spots so that those areas see less clouds.

However, these patterns have proven difficult to detect in global satellite surveys. For example, there have been weather satellites that monitored global cloud distributions going back decades, but as the cameras on these satellites sit in space their detectors will slowly deteriorate. This type of issue has made it extremely difficult to compare cloud coverage from one point in time to another – how do you know if there are more or less clouds if your camera doesn’t see the clouds the same way?

A paper just published by a team led by a researcher at Scripps Oceanographic Institute in California realized that although they couldn't compare how bright weather images were across time blocks, they could compare one location to another to see how clouds moved. By removing the long-term trends across the planet and instead focusing on which areas had their average cloud cover change, they could test whether greenhouse gases were forcing clouds to move.

Using this processing technique, they found that in fact there were clear patterns over a 30-year period. Areas in the tropics and mid-latitudes were on average getting less cloudy, while areas at higher latitudes such as Europe and North America were on average getting cloudier.

The trend is only a few percent, but it is clear within the data and in the complexity of the data there are other trends associated with specific wind patterns and a clear increase in the average height of cloud tops. To verify the cause of these cloudiness changes, the scientists turned to climate models.

Using modern computer simulation tools, they tested increasing the amount of greenhouse gases in the atmosphere, along with several other scenarios such as changing ozone abundances and changing solar activity. They found that the climate models forced by a warming planet caused exactly the patterns of shifts they were seeing, while the others did not. In those models as the planet warms, the areas where airmasses meet and generate clouds were moving farther from the equator and cloud heights were increasing, just as seen in the real data.

They could not fully declare that greenhouse gas emissions were the only cause as decreasing volcanic emissions contribute a similar pattern. Volcanic emissions were particularly high in 1991 after the eruption of Mount Pinatubo, but the decrease in volcanic material in the atmosphere is not enough to explain the changes in cloud patterns they measured.

This measurement shows that the predictions of cloud behavior in climate models are accurate enough to be verified by global, multi-decade data. Developing models for cloud production has been difficult due to the complicated physics involved, so a direct verification of model predictions gives confidence that the physics in these models is becoming adequate for making predictions of future behavior.

This work further suggests important issues as climate continues to change. As the world continues to warm the models suggest these patterns will continue to intensify and this motion of clouds will likely change drought and severe weather patterns over these regions. Furthermore, since more sunlight hits the tropics than at high latitudes, shifting clouds towards the poles will actually act to heat the planet more, as more sunlight will hit the planet’s surface.

-JBB

Image credit: ISS/NASA http://bit.ly/29NgREU

Original paper: http://go.nature.com/29DKKpI

Press release version: http://bit.ly/29M405D

Fly over Everest and the nearby peaks in this 3-D animation. Watch for the different layers on Everest that represent igneous, metamorphic, and sedimentary bands.