Climate


Below is a terrific short video examining a missing persons mystery from 1926 using glacier modelling!

A large ice island has broken off the Petermann Glacier in northern Greenland.

NASA satellite image (MODIS).

This iceberg is about twice the size of Manhattan but approximately half the size of the previous recent break-off in 2010 (blog post here).  Unlike the 2010 event the current ice has broke off further up glacier and marks a retreat of the calving front of the glacier.  The crack and rift that led to this break off has been known and observed for some time and so this event was expected in this regards.  However, the question is still being asked as to how unusual these large calving events are and whether they were caused by climate change.  Certainly we can say that these changes have not been seen for at least a 150 years (see previous post and this discussion article).  However, we can’t say for certain that these two massive calving event are a direct result of climate change.  An interesting discussion on these questions is provided in this BBC article.

The Guardian has a little interactive page where you can watch the iceberg break off in context (click here).

Glaciologist Tim Creyts provides an insightful radio interview here.

What are climate models?  The UK Met. Office explains:

Here is another beautiful movie showing ocean fluid patterns (previous post here).  This time we have a numerical simulation of the discharge of fresh water from the Amazon River entering the saltwater of the Atlantic Ocean.  The ocean model (Mercator Ocean) simulates sea surface temperatures over a 3 year period.

HT FYFluidDynamics

Here is a neat little animation that illustrates the time history of atmospheric carbon dioxide (CO2) from 800,000 years ago until January, 2011.

The animation begins with the CO2 variability (based on direct measurements from key observation sites) from January 1979 until January 2011.  There are several patterns that are worth noting, firstly the relentless upward trend of the globally averaged carbon dioxide concentration beginning in January 1979 at 336 ppm (parts per million) and ending with a concentration of 391 ppm, the average in January 2011.  Strong inter-annual variability are also evident, particularly in the northern hemisphere – we are essentially seeing the Earth’s breathing pattern!  Fluctuations follow the growing season, peaking in spring with widespread plant greening and minimizing in autumn when biomass is greatest.  During the growing season photosynthesizing plants suck up CO2 whereas during the colder part of the year respiration dominates – plants and animals exhale CO2.  As shown on the graph these fluctuations are far greater in the northern hemisphere than the southern hemisphere (where land area and vegetation cover is much smaller in comparison).

To go back further in time from the preindustrial era to 800,000 years ago requires the careful analyse of ancient air trapped in ice-cores drilled from Greenland and Antarctica.  (Blog posts on detecting past climate information from ice-cores can be read here and here).  Long timescale variability reveals cycles of ~41000 years and ~100000 years, which mark the intervals of glaciations.

Finally, the data clearly shows that current concentrations of atmospheric carbon dioxide are at levels not seen in the last 800 thousand years (and actually most likely not even the past 20 million years).  This rapid rise of atmospheric CO2 to such heightened levels is worrying for our planet and those who (will) live on it.

Here is a really neat film illustrating the amazing surface flow patterns of the oceans.  The footage is generated from simulations of a NASA ocean circulation model.  Eddy swirls and current flow lines are beautifully visualized (some have noted a similarity to van Gogh’s Starry Night).  The most striking patterns of the global ocean circulation include the Gulf Stream, Agulhas rings, and the Kuroshio Current.