28 January 2011
Far off Galaxies and Hockey Sticks of Arctic Plankton-Lots of wild science this week.
Posted by Dan Satterfield
It’s Friday, and there has been some really fascinating science news this week. So here is a quick summary of what caught my eye (and links to find out more about it).
In A GALAXY FAR, FAR AWAY
First, is the announcement in NATURE that the most distant galaxy known has been detected. It’s 13.2 billion light years away, and since the Universe itself is 13.7 billion years old, we are seeing it as it looked just 500 million years after the Big Bang. The galaxy’s red shift is estimated at 10.3.
Red shift (abbreviated as z=10.3) is how astronomers measure very distant objects. They take the light from an object and send it through a prism. The light is broken down into it’s individual colors and very fine lines are apparent. Every element produces it’s own characteristic lines, and this is how we know the sun is made of hydrogen and helium.
Since the Universe is expanding, the more distant an object, the faster it is moving away from us. This causes a Doppler shift in the spectrum lines. A red shift of 10.3 means it is shifted by a factor of 11.3 (compared to an object like the Sun which is not moving away from us).
Richard Bouwens et.al, of the Univ. of California, used a technique called the “J125 dropout” to measure the distance. Astronomer Phil Plait at Bad Astronomy has an easy to understand explanation of it here. I highly recommend reading his post. SCIENCE NOW has a great piece on it as well.
A PLANKTONIC HOCKEY STICK?
The other WOW paper this week is in SCIENCE. It’s about the temperatures of the Arctic Ocean near Svalbard. Here’s the title and abstract :
Enhanced Modern Heat Transfer to the
Arctic by Warm Atlantic Water
Robert F. Spielhagen,1,2* Kirstin Werner,2 Steffen Aagaard Sørensen,3 Katarzyna Zamelczyk,3 Evguenia Kandiano,2 Gereon Budeus,4 Katrine Husum,3 Thomas M. Marchitto,5 Morten Hald3
The Arctic is responding more rapidly to global warming than most other areas on our planet. Northward flowing AtlanticWater is themajor means of heat advection toward the Arctic and strongly affects the sea ice distribution. Records of its natural variability are critical for the understanding of feedback mechanisms and the future of the Arctic climate system, but continuous historical records reach back only ~150 years. Here,we present a multidecadal-scale record of ocean temperature variations during the past 2000 years, derived from marine sediments off Western Svalbard (79°N). We find that early–21st-century temperatures of Atlantic Water entering the Arctic Ocean are unprecedented over the past 2000 years and are presumably linked to the Arctic amplification of global warming.
Here’s what they did; They took a sediment core from the ocean floor in the Fram Strait, near Svalbard island in the Arctic Ocean. They looked at species of Plankton called Foraminifera in the core.
These plankton species have a narrow temperature range, so if the water gets colder, a new cold tolerant species takes over (Just the opposite occurs in warmer times). These tiny microscopic plankton fall to the bottom when they die, and (in this core at least) accumulate at a rate of between 18 and 27.7 cm per 1000 years.
They used two methods to deduce the past ocean temperatures in which the forams lived. First, they looked at the species that were living at different levels of the core (The present time is at the top of the core and the oldest forams are at the bottom).
They also used ratios of the magnesium and calcium in the forams (This ratio is dependant on temperature!) to come up with the temperature of the water the forams were living in. Techniques where there is a proxy for temperature are also used to measure the climate from ice cores in Greenland and Antarctica.
What did they find? It seems that modern temperatures of the Atlantic water are the warmest in 2,000 years. The graph is very similar to Michael Mann’s famous “hockey stick” graph that is one of the most famous science images of the last 20 years. When a result from one method is confirmed by others, the confidence you are doing it right is much higher. This is true in any science, not just paleoclimatalogy.
Science: It’s the greatest of all detective stories.
We truly are living on a changing planet.