{"id":6778,"date":"2013-04-02T10:07:32","date_gmt":"2013-04-02T15:07:32","guid":{"rendered":"https:\/\/uwm.edu\/news\/?p=6778"},"modified":"2015-11-12T08:01:42","modified_gmt":"2015-11-12T14:01:42","slug":"cracking-the-ice-code","status":"publish","type":"post","link":"https:\/\/uwm.edu\/news\/cracking-the-ice-code\/","title":{"rendered":"Cracking the ice code"},"content":{"rendered":"
\"\"<\/a>
Geosciences professor John Isbell (left) and postdoctoral researcher Erik Gulbranson look over some of the many samples they have brought back from Antarctica. The two are part of an international team of scientists investigating the last extreme climate shift on Earth, which occurred in the late Paleozoic Era. (Photos by Troye Fox<\/em>)<\/figcaption><\/figure>\n

What happened the last time a vegetated Earth shifted from an extremely cold climate to desert-like conditions? And what does it tell us about climate change today?<\/p>\n

John Isbell is on a quest to coax that information from the geology of the southernmost portions of the Earth. It won\u2019t be easy, because the last transition from \u201cicehouse to greenhouse\u201d occurred between 335 and 290 million years ago.<\/p>\n

An expert in glaciation from the late Paleozoic Era, Isbell is challenging many assumptions about the way drastic climate change naturally unfolds. The research helps form the all-important baseline needed to predict what the added effects of human activity will bring.<\/p>\n

Starting from \u2018deep freeze\u2019<\/strong><\/p>\n

In the late Paleozoic, the modern continents were fused together into two huge land masses, with what is now the Southern Hemisphere, including Antarctica, called Gondwana.<\/p>\n

During the span of more than 60 million years, Gondwana shifted from a state of deep freeze into one so hot and dry it supported the appearance of reptiles. The change, however, didn\u2019t happen uniformly, Isbell says.<\/p>\n

In fact, his research has shaken the common belief that Gondwana was covered by one massive sheet of ice which gradually and steadily melted away as conditions warmed.<\/p>\n

Isbell has found that at least 22 individual ice sheets were located in various places over the region. And the state of glaciation during the long warming period was marked by dramatic swings in temperature and atmospheric carbon dioxide (CO2<\/sub>) levels.<\/p>\n

\u201cThere appears to be a direct association between low CO2<\/sub> levels and glaciation,\u201d he says. \u201cA lot of the changes in greenhouse gases and in a shrinking ice volume then are similar to what we\u2019re seeing today.\u201d<\/p>\n

When the ice finally started disappearing, he says, it did so in the polar regions first and lingered in other parts of Gondwana with higher elevations. He attributes that to different conditions across Gondwana, such as mountain-building events, which would have preserved glaciers longer.<\/p>\n

All about the carbon<\/strong><\/p>\n

\"\"<\/a>
Figuring out the natural carbon cycle from the late Paleozoic forms the baseline needed to predict what the effects of human activity will have on today’s climate, says Professor John Isbell.<\/figcaption><\/figure>\n

To get an accurate picture of the range of conditions in the late Paleozoic, Isbell has traveled to Antarctica 16 times and has joined colleagues from around the world as part of an interdisciplinary team. They have regularly gone to places where no one has ever walked on the rocks before.<\/p>\n

One of his colleagues is paleoecologist Erik Gulbranson, who studies plant communities from the tail end of the Paleozoic and how they evolved in concert with the climatic changes. The information contained in fossil soil and plants, he says, can reveal a lot about carbon cycling, which is so central for applying the work to climate change today.<\/p>\n

Documenting the particulars of how the carbon cycle behaved so long ago will allow them to answer questions like, \u2018What was the main force behind glaciation during the late Paleozoic? Was it mountain-building or climate change?\u2019<\/p>\n

Another characteristic of the late Paleozoic shift is that once the climate warmed significantly and atmospheric CO2<\/sub> levels soared, the Earth\u2019s climate remained hot and dry for another 200 million years.<\/p>\n

\u201cThese natural cycles are very long, and that\u2019s an important difference with what we\u2019re seeing with the contemporary global climate change,\u201d says Gulbranson. \u201cToday, we\u2019re seeing change in greenhouse gas concentrations of CO2<\/sub> on the order of centuries and decades.\u201d<\/p>\n

Ancient trees and soil<\/strong><\/p>\n

In order to explain today\u2019s accelerated warming, Gulbranson\u2019s research illustrates why glaciers alone can\u2019t tell the whole story.<\/p>\n

Many environmental factors leave an imprint on the carbon contained in tree trunks from this period. One of the things Gulbranson hypothesizes from his research in Antarctica is that an increase in deciduous trees occurred in higher latitudes during the late Paleozoic, driven by higher temperatures.<\/p>\n

What he doesn\u2019t yet know is what the net effect was on the carbon cycle.<\/p>\n

While trees soak in CO2<\/sub> and give off oxygen, there are other factors to consider, says Gulbranson, like the soil. CO2<\/sub> emissions also come from soil (as microbes speed up their consumption of organic matter with rising temperatures).<\/p>\n

\u201cThe high latitudes today contain the largest amount of carbon locked up as organic material and permafrost soils on Earth today,\u201d he says. \u201cIt actually exceeds the amount of carbon you can measure in the rain forests, for example. So what happens to that stockpile of carbon when you warm it and grow a forest over it is completely unknown.\u201d<\/p>\n

The two scientists\u2019 work is complementary. Dating the rock is essential to pinpointing the rate of change in the carbon cycle, which would be the warning signal we could use today to indicate that nature is becoming dangerously unbalanced.<\/p>\n

\u201cIf we figure out what happened with the glaciers,\u201d says Isbell, \u201cand add it to what we know about other conditions \u2013 we will be able to unlock the answers to climate change.\u201d<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

John Isbell, an expert in glaciation from the late Paleozoic Era, is developing a baseline for understanding present-day climate change.<\/p>\n","protected":false},"author":836,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":"","uwm_wg_additional_authors":[]},"categories":[174,175],"tags":[],"section":[140,139],"display_categories":[],"related-coverage":[],"uwmnews-feed":[158,161],"class_list":["post-6778","post","type-post","status-publish","format-standard","hentry","category-news","category-research","section-science","section-science-technology","uwmnews-feed-letters-science","uwmnews-feed-hard-science"],"yoast_head":"\nCracking the ice code<\/title>\n<meta name=\"description\" content=\"John Isbell, an expert in glaciation from the late Paleozoic Era, is developing a baseline for understanding present-day climate change.\" \/>\n<meta name=\"robots\" content=\"index, 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