November 9, 2012
Carbon Emissions, Global Warming Could Save Us From A Future Ice Age
April Flowers for redOrbit.com — Your Universe Online
We hear reports every day about the dangers and evils of carbon emissions, but could there be a good side? A research team at the University of Gothenburg thinks so. Their new study, published in Mires and Peat, suggests that mankind's emissions of fossil carbon, and the temperature rise that accompanies it, could prove to be our salvation from the next ice age. The current increase in peatland extent could reverse this effect, however.
The earth has experienced at least 30 periods of ice age, known as ice age pulses, during the last three million years. The time between ice age pulses are known as interglacials. The team believes that human activity might have halted the Little Ice Age of the 16th and 18th centuries with increased felling of woodlands and growing areas of agricultural land. Combine these with the early stages of industrialization and the result is an increased emission of carbon dioxide, which probably slowed down the cooling trend.
"It is certainly possible that mankind's various activities contributed towards extending our ice age interval by keeping carbon dioxide levels high enough," explains Lars FranzÃ©n, Professor of Physical Geography at the University of Gothenburg.
"Without the human impact, the inevitable progression towards an ice age would have continued. The spread of peatlands is an important factor."
Acting as carbon sinks, peatlands absorb carbon dioxide from the atmosphere. They currently cover around four percent of the earth's landmass in the temperate areas just north and south of the 45th parallel. Peatlands are a dynamic landscape element.
Approximately 16 percent of Sweden's landmass is covered in peatland, which grow and spread across their surroundings by waterlogging woodlands. Peatlands are one of the biggest carbon sinks on land. Around 20 grams of carbon are absorbed by every square meter of peatland every year.
"By using the National Land Survey of Sweden's altitude database, we have calculated how much of Sweden could be covered by peatlands during an interglacial. We have taken a maximum terrain incline of three degrees as our upper limit, and have also excluded all lakes and areas with substrata that are unsuitable for peatland formation."
What they found was that approximately half of Sweden could be covered by peat, in which case the carbon dioxide sink would increase by a factor of somewhere between six and ten.
"If we accept that rising levels of carbon dioxide in the atmosphere lead to an increase in global temperature, the logical conclusion must be that reduced levels lead to a drop in temperature."
The relationship between temperature and carbon dioxide is non-linear. Lower levels of carbon dioxide result in a greater degree of cooling than the degree of warming gained by a corresponding increase in emissions.
"There have been no emissions of fossil carbon during earlier interglacials. Carbon sequestration in peatland may therefore be one of the main reasons why ice age conditions have occurred time after time."
The research team is producing a rough global estimate of the carbon sink effect if all temperate peatlands were to grow in the same way.
"Our calculations show that the peatlands could contribute towards global cooling equivalent to five watts per square metre. There is a great deal of evidence to suggest that we are near the end of the current interglacial."