200+ US evangelical scientists call on Congress to act on climate change.  This is what they say in the opening paragraph

As evangelical scientists and academics, we understand climate change is real and action is urgently needed. All of God’s Creation – humans and our environment – is groaning under the weight of our uncontrolled use of fossil fuels, bringing on a warming planet, melting ice, and rising seas. The negative consequences and burdens of a changing climate will fall disproportionately on those whom Jesus called “the least of these”: the poor, vulnerable, and oppressed. Our nation has entrusted you with political power; we plead with you to lead on this issue and enact policies this year that will protect our climate and help us all to be better stewards of Creation.

Here is a copy of the full letter together with the list of signatories, which includes very prominent climate scientists, such as Tom Ackerman and Katherine Hayhoe.

Hayhoe’s work has been shared here before (see blog post An Evangelical Climate Scientist), but Ackerman has also written and spoken on his perspective as a climate scientist and an evangelical Christian (see webpage).  His views are outlined in the paper

T. Ackerman. Global Warming: Scientific Basis and Christian Responses. Perspectives on Science and Christian Faith, 59, 250-264, 2007.

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 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.

Here’s an interesting analogy to explain the differences between weather and climate, it’s taken from the Norwegian TV series Siffer.

The video was featured in a recent New York Times blog Can Better Communication of Climate Science Cut Climate Risks? by Andrew Revkin.  The communication of climate science for public consumption remains a major task, especially in light of current political inaction.  A recent (Jan 2012) editorial in Nature urges Scientists to Reach Out about Climate stating:

 “… scientists and their organizations need to do more to help citizens engage with the issues and not be misled by travesties of the evidence.”

Climate communication outreach projects such as the website http://climatecommunication.org/ have some great resources.

This is the best animation I’ve seen of changes in Arctic Sea Ice. The video clearly shows the dramatic seasonal changes in sea ice cover, as well as the general decline in sea ice extent. Perhaps most importantly it captures the reduction of old ice. The decline of multiyear ice reveals how weak the ice coverage has become, older ice that survives the summer provides stability by creating thicker and stronger ice. Thanks to NOAA Climate Services for putting this together:

The sea ice declines are accentuated by the albedo feedback. Open ocean water has a significantly darker surface than an ice covered sea and therefore absorbs much more of the sun’s heat than the reflective ice covering. This creates a positive feedback whereby the extra absorbed solar radiation triggers further sea ice melt.

A recent study in Nature suggests that both the duration and magnitude of the current decline in sea ice is seemingly unprecedented for the past 1450 years [1].  An ice free Arctic in the summer may occur within the next 30 years [2].

There has been speculation of a possible Arctic sea-ice ‘tipping point’, whereby a threshold is reached such that sea-ice loss is irreversible leading to permanent ice free summers.  However, recent modelling studies suggest this is not the case and that sea-ice recovery from a prescribed ice-free summer is possible within two years (see [3] and [4]).

A great resource for tracking sea ice changes and further reliable information on this topic is the National Snow & Ice Data Center (NSIDC) website.

There is also a free iphone app called Arctic Watch that uses data from the National Oceanic and Atmospheric Association (NOAA) and provides daily updates on Arctic sea ice area (you have to pay $0.99 for the Antarctic data).


[1]  Kinnard, C., C. M. Zdanowicz, D. A. Fisher, E. Isaksson, A. de Vernal and L. G. Thompson (2011), Reconstructed changes in Arctic sea ice over the past 1,450 years. Nature, 479, 509-512, doi: 10.1038/nature10581.
[2]  Wang, M., and J. E. Overland (2009), A sea ice free summer Arctic within 30 years?, Geophys. Res. Lett., 36, L07502, doi:10.1029/2009GL037820.
[3]  Tietsche, S., D. Notz, J. H. Jungclaus, and J. Marotzke (2011), Recovery mechanisms of Arctic summer sea ice,Geophys. Res. Lett., 38, L02707, doi:10.1029/2010GL045698.
[4]  Armour, K. C., I. Eisenman, E. Blanchard-Wrigglesworth, K. E. McCusker, and C. M. Bitz (2011), The reversibility of sea ice loss in a state-of-the-art climate model, Geophys. Res. Lett., 38, L16705, doi:10.1029/2011GL048739.