Dinosaurs that roamed the Earth 250 million years ago knew a world with five times more carbon dioxide than is present on Earth today, researchers say, and new techniques for estimating the amount of carbon dioxide on prehistoric Earth may help scientists predict how Earth's climate may change in the future.

 

The findings are detailed in a recent paper published in the journal Proceedings of the National Academy of Sciences.

 

During the Jurassic Period, dinosaurs — ranging from the plant-eating Diplodocus and Brachiosaurus to the meat-craving Ceratosaurus and Megalosaurus — ruled the world. During this time, the Earth's interior was not standing still; rather, the supercontinent Pangaea had started to split into two smaller landmasses, called Laurasia and Gondwana.

 

These tectonic movements made the oceans close up and the tectonic plates sink into the Earth. This process, called subduction, led to volcanism at the surface, with rocks constantly melting and emitting CO2 into the atmosphere. Huge amounts of this greenhouse gas made the climate during the Jurassic Period extremely humid and warm, said geoscientist Douwe van der Meer, lead author of the study and a researcher at Utrecht University in the Netherlands. [Weather vs. Climate: Test Yourself]

 

Scientists have known for some time that a large amount of volcanic activity results in more CO2 than is present on Earth today, but with previous methods, it had been tricky to come up with a reliable estimate.

 

Looking deep inside

Van der Meer's team used a cutting-edge imaging technique called seismic tomography to reconstruct 250 million years of volcanic CO2 emissions.

 

To do so, the researchers analyzed earthquake waves traveling through Earth, to image the structure of the Earth's interior.

 

"This method is comparable to CT scans used in hospitals to image inside bodies," van der Meer said. "With sufficient earthquake wave travel times, one can create a velocity model of the Earth. Faster regions are more dense, colder material plates that sunk into the Earth."

 

The aim has been to demonstrate how variations in plate tectonics have led to variations in CO2 emissions from volcanoes 250 million years ago.

 

And the deeper the imaging equipment goes, the farther back in time scientists can see — as far back as 250 million years, said van der Meer. "Essentially, we can see the breakup of the supercontinentPangaea, and the opening and closing of oceans," he said.

 

In other words, the scans depicted the interior of the Earth, enabling the researchers to "see" the tectonic plates that have sunk into the planet over the past 250 million years.

 

The researchers then quantified the plates that have sunk into the deep Earth, and their calculations showed that the Earth produced twice as much CO2 as there is today.

 

The scientists then inserted this number into a comprehensive, commonly used paleoclimate model, to calculate how all the volcanic CO2 emissions at the time would have added up. Because there was also less CO2 being removed from the atmosphere by vegetation and by weathering rocks than today, total atmospheric CO2 levels were probably five times higher than at the present, the researchers said.

 

The findings suggest much higher CO2 levels than had been estimated in previous studies conducted in the 1980s and 1990s.  That research had been based on indirect data from sea-level variations. Since then, scientists' understanding of Earth has improved significantly, and researchers already had begun to suspect that the old estimates were imperfect.

 

"They were fundamentally flawed in hindsight," said van der Meer. "Especially in the Jurassic Period, major differences were seen between the old and the new estimates."

 

"The higher CO2 levels [must] have [had] significant effects on the planet's climate, and its flora and fauna," he said.

 

And, in general, the concept of plate tectonics through time is crucial for a variety of geological processes, said van der Meer.

 

"The rate of spreading plates dictates the height of mountains, the amount and location of ores, sea level and the magnetic field of the planet," he said. "For the first time, we have quantified in this study the link between plate tectonics and volcanic CO2 emissions — a major step forward in understanding and predicting the behavior of the Earth, and its consequences." [History's Biggest Earthquakes]

 

Future climate change

"The new estimates of CO2 emissions are crucial for determining the relationship between CO2 and climate," said climate researcher Appy Sluijs, also of Utrecht University and a co-author of the study. "Our new information from the deep Earth is independent of, and confirms existing data on, atmospheric CO2 levels as determined from fossils."

 

One of the researchers' goals is to understand the strong link between climate and volcanic CO2 emissions, and apply it to future climate-change predictions.

 

"As this study researched how much CO2 was emitted through time, we are now able to zoom into the most interesting time intervals," Sluijs said. "This will eventually lead to long-term predictions of future climate change."

 

"We are now producing more CO2 than all volcanoes on Earth," van der Meer added. "We will affect climate in ways that are unprecedented and unnatural. The question is how much climate will change. We can now answer this for the past and apply [it] to the future by extrapolation."

 

This story was originally written for LiveScience and has been republished with permission here. Copyright 2014 LiveScience, a TechMediaNetwork company.

Former Mexican President Felipe Calderon is spearheading a study sponsored by seven countries into the economics of climate change, seeking to set out the benefits of reducing carbon emissions.

Calderon’s panel aims to draw from the experience of companies and governments around the world in fighting off the ravages of storms and droughts and cutting greenhouse gases. It will also use academic research to show the costs and risks associated with climate change and efforts to stem it, publishing a report next September to guide policymakers.

The effort by a group that includes Unilever NV Chief Executive Officer Paul Polman and former leaders of Chile, New Zealand and Mozambique is designed to guide global envoys as they devise a new treaty to fight climate change in 2015. Britain, Colombia, Ethiopia, Indonesia, South Korea, Norway and Sweden are sponsoring the panel.

“For many decision makers in government and business there is a trade-off whereby combating climate change means sacrificing economic growth, job creation or business revenues,” Calderon told reporters on a conference call. “We believe that the trade-off between economic growth and fighting climate change is a false dilemma.”

The panel, called the Global Commission on the Economy and Climate, also includes business leaders such as Vattenfall AB Chief Financial Officer Ingrid Bonde, China International Capital Corp. CEO Zhu Levin and officials from the World Bank and International Monetary Fund.

Calderon’s Cridentials

Calderon a former chairman of state oil producer Petroleos Mexicanos, was Mexico’s president for six years through December 2012. He oversaw a UN climate change conference in Cancun in 2010 and pushed through Mexico’s first climate change law in 2012.

United Nations scientists this week are putting the finishing touches on their most comprehensive report into the science of climate change, and are due to publish a summary of their findings on Sept. 27. A draft of the document seen by Bloomberg shows sea level forecasts for the end of the century are higher, and temperature-rise predictions are lower than those made in the UN’s last major assessment in 2007.

The report will build on an effort in 2006 by the U.K. government led by former World Bank chief economist Nicholas Stern that said the impacts of global warming could cost the world as much as 20 percent of economic output, compared with the 1-percent cost of containing the problem.

Stern Report

Stern, a member of Calderon’s panel, said there’s been “a tremendous amount of experience both in what’s happened in the world and in terms of the analysis” since then.

“The whole problem looks even riskier than we described it in the Stern review,” Stern said. “Emissions are rising faster than had been anticipated and many of the things are coming through more quickly than we anticipated, an example being the Arctic ice,” which is melting faster than predicted.

The world has also seen “remarkable technological change” since 2006, with solar power prices coming down by a factor of six or seven, advances in hydraulic fracturing that’s using large amounts of water to tap new reserves of oil reserves and the recession all being events that need to be included in the new analysis, Stern said.

The research will be led by seven institutions around the world. They are: the Climate Policy Initiative in San Francisco, the Ethiopian Development Research Institute, South Korea’s Global Green Growth Institute, the Indian Council for Research on International Economic Relations, the Stockholm Environment Institute, Tsinghua University in Beijing and the Washington-based World Resources Institute.

“We know it is possible to have economic growth and job creation while fighting climate change as part of a new kind of economy: a growing economy with ever-lower carbon emissions,” Calderon said. “If we can demonstrate that that is possible, many decision-makers and businessmen can choose more responsible environmental policies.”