Global warming dramatically changed ancient forestsNovember 14, 2005
The findings, which appear in this week's issue of the journal Science, provide the first evidence that land plants changed drastically during a period of sudden global warming 55 million years ago, said Jonathan Bloch, a University of Florida vertebrate paleontologist and member of the research team.
"It indicates that should we have a period of rapid global warming on that scale today, we might expect very dramatic changes to the biota of the planet, not just the mammals and other vertebrates, but forests also completely changing," said Bloch, who is a curator at the Florida Museum of Natural History on the UF campus.
Scientists have known there was significant turnover in mammals during this rapid period of global warming called the Paleocene-Eocene Thermal Maximum, in which temperatures rose by perhaps as much as 10 degrees in the relatively short time span of 10,000 years, then lasting for another 80,000 to 100,000 years, Bloch said.
Global warming allowed mammals to emigrate across northern land bridges, marking the first appearance of perissodactlys in the form of the earliest known horse; artiodactyls, a group of even-toed ungulates that includes pigs, camels and hippos; as well as modern primates, he said.
But until now, no clues were available as to what happened to plants during this shift, considered one of the most extreme global warming events during the Cenozoic, the "Age of Mammals," Bloch said. "It was very puzzling because it looked like there was nothing going on with plants, which was rather strange and disconcerting."
Excavations by team leader Scott Wing, a paleontologist at the Smithsonian Institution, in the Bighorn Basin of northwestern Wyoming uncovered fossil leaves and pollen alongside fossilized mammals in rocks that were deposited during this turbulent geologic interval.
"Up until this point we have not had a place in which we have mammal and plant remains preserved in the same rocks spanning what we call the Paleocene-Eocene boundary," Bloch said. "Amazingly, these plants came from what would have been more tropical environments."
Some of the plant remains resembled those found in rock deposits of similar age unearthed in Mississippi, Louisiana and Texas, including relatives of poinsettia and sumac, Bloch said.
However, plant fossils found in the same area dating immediately before and after this period of rising temperatures reflected typical mid-latitude forests of the time and included relatives of dawn redwood, alder, sycamore and walnut, Bloch said. As temperatures cooled, floral newcomers appeared from Europe, including species of linden and wing nut. These plants probably emigrated along the same land bridges that animals traveled, he said.
Because his research specialty is mammals, Bloch said he is particularly interested in understanding how the movement of plants affected the earliest evolution of modern primates, which first appeared throughout the world during this period.
"I would very much like to know what these forests were like when these first modern primates were coming in because it has implications for how these animals lived and behaved right from the beginning," he said.
If the landscape evolved from an initially drier habitat, with patchy open spaces, into a more lush tropical forest with densely packed trees, it might have played a role in the evolution of primates' climbing skills, Bloch said. The ancestors of living primates would have been leaping through the tree canopy, foraging for fruit and insects, he said.
Partly because of the dramatic change in mammals, including the first appearance of modern primates, and also because of the interval's rapid temperature change, there has been a wide range of scientific interest in the Paleocene-Eocene boundary, Bloch said.
The warming was caused by a gigantic release of carbon dioxide into the atmosphere that was comparable to the atmospheric effects expected from human burning of fossil fuels, he said.
"You can't predict the future, but there has been a time in the past where we had similar type of conditions, and we might look to that experience," Bloch said.
University of Florida
Related Global Warming Current Events and Global Warming News Articles
Wildfires emit more greenhouse gases than assumed in California climate targets
A new study quantifying the amount of carbon stored and released through California forests and wildlands finds that wildfires and deforestation are contributing more than expected to the state's greenhouse gas emissions.
Burying the climate change problem
Burying the greenhouse gas carbon dioxide, a byproduct of burning fossil fuels, has been mooted as one geoengineering approach to ameliorating climate change.
'Warm blob' in Pacific Ocean linked to weird weather across the US
The one common element in recent weather has been oddness. The West Coast has been warm and parched; the East Coast has been cold and snowed under. Fish are swimming into new waters, and hungry seals are washing up on California beaches.
More food, low pollution effort gains traction
Nitrogen fertilizers make it possible to feed more people in the world than ever before.
Deforestation is messing with our weather -- and our food
New research published today in Nature Communications provides insight into how large-scale deforestation could impact global food production by triggering changes in local climate.
Atmospheric energy escaped from the Tibetan Plateau
The increase of green-house gases in the atmosphere reduces outgoing radiation and thus causes global warming.
Good luck and the Chinese reverse global forest loss
Analysis of 20 years of satellite data has revealed the total amount of vegetation globally has increased by almost 4 billion tonnes of carbon since 2003.
Glimpses of the future: Drought damage leads to widespread forest death
The 2000-2003 drought in the American southwest triggered a widespread die-off of forests around the region.
Climate change does not cause extreme winters
Cold snaps like the ones that hit the eastern United States in the past winters are not a consequence of climate change. Scientists at ETH Zurich and the California Institute of Technology have shown that global warming actually tends to reduce temperature variability.
New research identifies diverse sources of methane in shallow Arctic lakes
New research into the changing ecology of thousands of shallow lakes on the North Slope of Alaska suggests that in scenarios of increasing global temperatures, methane-generating microbes, found in thawing lake sediments, may ramp up production of the potent greenhouse gas - which has a global warming potential 25 times greater than carbon dioxide.
More Global Warming Current Events and Global Warming News Articles