Ruminations

Inexorable Climate Shift in Antarctica

"People will think of Antarctica quite rightly as a very icy place, but our work shows that parts of it are green, and are likely to be getting greener."
"Even those relatively remote ecosystems, that people might think are relatively untouched by humankind, are showing the effects of human-induced climate change."
"We're starting back on a journey toward that sort of environment [a different landscape]. Certainly, Antarctica has not always been the ice place it has been now on very long time-scales."
Matthew Amesbury, researcher, University of Exeter, Britain

Credit: University of Exeter Flickr

"This is another indicator that Antarctica is moving backward in geologic time -- which makes sense, considering atmospheric C02 levels have already risen to levels that the planet hasn't seen since the Pliocene, 3 million years ago, when the Antarctic ice sheet was smaller, and sea-levels were higher."
"If greenhouse gas emissions continue unchecked, Antarctica will head even further back in geologic time ... perhaps the peninsula will even become forested again some day, like it was during the greenhouse climates of the Cretaceous and Eocene, when the continent was ice-free."
Rob DeConto, glaciologist, University of Massachusetts, Amherst

Credit: NASA

"These changes combined with increased ice-free land areas from glacier retreat, will drive large-scale alteration to the biological functioning, appearance, and landscape of the [Antarctic Peninsula] over the rest of the 21st Century and beyond."
Antarctica research study, Current Biology

In the Arctic a greening trend on a very large scale has been captured by satellite photography where so much plant growth has appeared now that among some scientists there is hope that its presence might partially offset the loss of carbon from thawing permafrost under those plants. What has happened in the Arctic is also being reflected in its polar opposite geology, but on an infinitely slower time-scale.

Antarctica researchers have discovered the presence of growing banks of mosses on the northern peninsula whose presence is validation to their scientific minds of climate change impacting the iciest, most remote areas of Planet Earth. Throughout the last fifty years the gradual warming of the atmosphere has resulted in the presence of two varied species of mosses appearing in spurts of growth. Mosses which at one time grew at a rate of under a millimetre annually, now grow at a rate of over 3 millimetres on average, yearly.

The study by Professor Amesbury and his colleagues with Cambridge University, the British Antarctic Survey and the University of Durham just saw publication in Current Biology. The study has shown that in parts of the Antarctic Peninsula, mosses now grow on frozen ground, partially thawing in the summer months to the first foot of permafrost depth. The Antarctica is a unique place on this Earth upon which plant life grows on less than one percent of its icescape.

In the summer months when the ground becomes partially thawed, surface mosses build into a thin surface layer which then freezes in winter. Layer upon layer builds up with older mosses sinking below the frozen ground to be well preserved as a result of the temperatures, representing "a record of changes over time", like geological fossil records. Dramatic changes in growth patterns back to 150 years earlier were identified through an examination of soil samples from a 644-kilometre area on the northern portion of the Peninsula.

Latterly, the Antarctic Peninsula has seen relatively rapid warming with increasing numbers of days annually where above-freezing temperatures are recognized. According to the study, a four- to five-fold increase in the amount of moss growth has materialized as a consequence of that warming, reflected in the more recent portion of the climate record.

The researchers took cores of the moss bank to examine 150 years of data to discover "changepoints" that occurred in the final 50 years, demonstrating moss cover increase which Professor Amesbury spoke of as a signifier of change in the region. That plant life exists on an admittedly minuscule portion of Antarctica of roughly 0.3 percent of the continent, but researchers feel the likelihood of increase is assured as the region continues to warm.

An ecosystem shift appears inevitable, reflecting the situation that researchers have discovered in the Arctic, as land cover increases with ice and snow withdrawal and more heat absorbed in the area. "It’s a clear sign that the biological response to climate warming is pervasive around the globe. The Antarctic Peninsula is often thought of as a very remote and possibly even untouched region, but this clearly shows that the effects of climate change are felt here", stated Professor Amesbury.