"We are probably entering a new ice age right now. However, we're not
noticing it due to the effects of carbon dioxide," says Professor of
Physical Geography. Lars Franzén, from the Department of Earth Sciences
at GothenburgUniversity.
Peatlands grow in height and spread across their surroundings by
waterlogging woodlands. They are also one of the biggest terrestrial
sinks of atmospheric carbon dioxide. Each year, around 20 grams of
carbon are absorbed by every square metre of peatland.
The scientists have calculated that the potential is there for Swedish peatlands to triple in extent, enormously increasing their carbon sink effect. By extrapolating to include the rest of the world's high-latitude temperate areas - the parts of the globe where peatland can expand as it does in Sweden - they project the creation of an extremely powerful carbon sink. They theorise that this is the mechanism which tends to force the Earth back into prolonged ice ages after each relatively brief "interglacial" warm period. Carbon sequestration in peatland may be one of the main reasons why ice age conditions have occurred time after time.
With no other factors in play, the time is about right for the present interglacial to end and the next ice age to come on. Indeed, Franzén and his crew think it has barely been staved off by human activity. The researchers believe that the Little Ice Age of the 16th to 18th centuries may have been halted as a result of human activity. Increased felling of woodlands and growing areas of agricultural land, combined with the early stages of industrialisation, resulted in increased emissions of carbon dioxide which probably slowed down, or even reversed, the cooling trend.
Other scientists have attributed the Little Ice Age to a quiet period in the Sun's activity: others say it was purely a local effect in Europe.
Thus, on a global scale, carbon sequestration in peatlands may have had important climate cooling effects towards the ends of previous interglacials ... It cannot be ruled out that similar effects would be seen in a hypothetical Holocene lacking human presence.
It's probably worth noting that the great physicist Freeman Dyson long ago suggested that only relatively small amounts of new peatland would be enough to sequestrate colossal amounts of CO2 from the air. Other scientists have noted in recent times that brief warming spells like that observed at the end of the 20th century appear to have occurred towards the end of previous interglacial periods - just before the glaciers returned.
If Franzén and his team are right, the big chill is now under way, and is only just being held off by increasing human carbon emissions - perhaps explaining why temperatures have been merely flat for the last 15 years or so, rather than descending.
The scientists have calculated that the potential is there for Swedish peatlands to triple in extent, enormously increasing their carbon sink effect. By extrapolating to include the rest of the world's high-latitude temperate areas - the parts of the globe where peatland can expand as it does in Sweden - they project the creation of an extremely powerful carbon sink. They theorise that this is the mechanism which tends to force the Earth back into prolonged ice ages after each relatively brief "interglacial" warm period. Carbon sequestration in peatland may be one of the main reasons why ice age conditions have occurred time after time.
With no other factors in play, the time is about right for the present interglacial to end and the next ice age to come on. Indeed, Franzén and his crew think it has barely been staved off by human activity. The researchers believe that the Little Ice Age of the 16th to 18th centuries may have been halted as a result of human activity. Increased felling of woodlands and growing areas of agricultural land, combined with the early stages of industrialisation, resulted in increased emissions of carbon dioxide which probably slowed down, or even reversed, the cooling trend.
Other scientists have attributed the Little Ice Age to a quiet period in the Sun's activity: others say it was purely a local effect in Europe.
Thus, on a global scale, carbon sequestration in peatlands may have had important climate cooling effects towards the ends of previous interglacials ... It cannot be ruled out that similar effects would be seen in a hypothetical Holocene lacking human presence.
It's probably worth noting that the great physicist Freeman Dyson long ago suggested that only relatively small amounts of new peatland would be enough to sequestrate colossal amounts of CO2 from the air. Other scientists have noted in recent times that brief warming spells like that observed at the end of the 20th century appear to have occurred towards the end of previous interglacial periods - just before the glaciers returned.
If Franzén and his team are right, the big chill is now under way, and is only just being held off by increasing human carbon emissions - perhaps explaining why temperatures have been merely flat for the last 15 years or so, rather than descending.
3 comments:
Franzens work is not new. PGA vol 121 issue 3, 2010 has a topical perspective overview called "Quaternary climates: a perspective for global warming" The paper is mainly a review of currently held views. The references are several but mainly W.F. Ruddiman's dated 2001 to 2006. The main thrust is that Milankovitch orbital forcing acting on its own would take the Earth into the next stadial or glacial, but human deforestation starting 5000 years ago began to hold off the cooling trend, and then to reverse it more recently. It did this via increased CO2 from the vegetation destroyed.
What a good article and I suggest the present interglacial will end when the North Atlantic Polar Front is seen to move south, is anyone measuring the NAPF? Simon Mallon.
Yes, weather stations send up sondes twice daily since the 1940s so these track the jet stream. Richard
Post a Comment