To prevent Earth’s average temperature from rising more than 2 degrees Celsius above pre-industrial levels, several teams of researchers say that cumulative carbon emissions must be limited to no more than 1 trillion metric tons. The findings, released April 30 in the journal Nature, are daunting because human activity has already exhausted more than half that allotment since the Industrial Revolution began. Human activity will likely emit the rest of that budget in just a few decades, even if emissions are held at the current rate. The two-degree limit comes from the most recent report by the Intergovernmental Panel on Climate Change as a target to reduce the impacts of climate change.
The ceiling for carbon dioxide emissions “treats emissions as an exhaustible resource,” says David Frame, an atmospheric scientist at the University of Oxford and a coauthor of the Nature papers. “If you burn a ton of carbon today, then you canāt burn it tomorrow.”
During the past century, the global average temperature rose about 0.74 degrees C. That increase, IPCC scientists say with 90% certainty, is linked to the rising concentrations of carbon dioxide and other greenhouse gases. Carbon dioxide levels now sit above 380 parts per million and are rising about 2 ppm each year; before the Industrial Revolution, atmospheric concentrations of the gas averaged about 280 ppm.
“If you want to limit the risk of exceeding 2 degrees C global warming to one in four, or 25 percent, then total CO2 emissions over the first half of the 21st century have be kept below 1,000 billion tons,” said Malte Meinshausen, a climatologist at the Potsdam Institute for Climate Impact Research in Germany and another co-author. “Only a fast switch away from fossil fuels will give us a reasonable chance to avoid considerable warming.”
Writing in a commentary in the same Nature issue, Gavin Schmidt of NASA’s Goddard Institute for Space Studies in New York City and David Archer of the University of Chicago state that “unless emissions begin to decline very soon, severe disruption to the climate system will entail expensive adaptation measures and may eventually require cleaning up the mess by actively removing CO2 from the atmosphere.”
The researchers also estimate that limiting cumulative carbon dioxide emissions between now and 2050 to no more than 1 trillion tons would actually leave three-fourths of the world’s known reserves of oil, gas and coal in the ground unburnedāunless techniques for capturing and sequestering carbon dioxide underground rather than dumping it into the atmosphere become commonplace in the future. (Science News, April 29)
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A half gigaton of carbon is enough
“We now have evidence from the Earth’s history that a similar event happened fifty-five million years ago when a geological accident released into the air more than a terraton of gaseous carbon compounds. As a consequence the temperature in the arctic and temperate regions rose eight degree Celsius and in tropical regions about five degrees, and it took over one hundred thousand years before normality was restored. We have already put more than half this quantity of carbon gas into the air and now the Earth is weakened by the loss of land we took to feed and house ourselves. In addition, the sun is now warmer, and as a consequence the Earth is now returning to the hot state it was in before, millions of years ago, and as it warms, most living things will die.” (The Revenge of Gaia)
By the way, the above study didn’t take into consideration that not all carbon in the air is created equal. Methane (CH4) is 70 time more powerful as CO2 over the first twenty years, but has the same amount of carbon as CO2.
Modelling Mania
Hey folks, this is more modelling and the models are not getting it right in the real world. This is just another push on the way to the Copenhagen Conference in December, because the evidence that CO2 doesn’t drive the temperature of the planet is becoming more obvious and more people are starting to realise that. The warmers are getting worried because they need to get the politicians on-side for a post Kyoto agreement. Since Kyoto, CO2 has continued to increase but temperatures are cooling so there is a disconnect that the average guy in the street is starting to notice.
These two Potsdam scientists work for Greenpeace but hide away at Potsdam which is committed to social change and global governance. Google for “Meinshausen, Hare, Greenpeace”.
Another idiot heard from
We love people who think that “Google it” is a credible source.
OK, we tried.
“No results found for “Meinshausen, Hare, Greenpeace”
Thank goodness.