It’s the plants’ fault
The Nature report that has found that plants give off methane in the lab is getting a bit of a run in the media today. Radio NZ reports:
New Zealand scientist who peer reviewed a study into greenhouse gases, says it casts doubt over the benefit of plants to combat global warming.
European scientists at the Institute of Marine and Atmospheric Research have found that plants emit methane, a gas which contributes to global warming.
The research, which is published in Nature magazine today, suggests methane can be created in oxygen.
Dr David Lowe from the National Institute of Water and Atmospheric Research, says it raises serious questions. He says scientists need to now work out how much methane is produced by vegetation, compared with a plant’s absorbtion rate of carbon dioxide.
Dr Lowe says the research could have a profound effect on the global battle against greenhouse gases and climate change.
Happily, the study’s author is countering the convenient political conclusion. From the same story:
Dr Roeckmann also advises people not to take the research too literally. He says it would be stupid to cut down trees to reduce the effects of global warming.
This report does lend credence to a greenist criticism of Kyoto - that net emissions (i.e. carbon emitted minus new carbon sinks created) isn’t what should be reduced, but gross emissions. In other words, forget about how many new trees are being planted and just stop burning so much fossil fuel.
An email correspondent read out on RNZ’s Summer Report this morning raised some good points; that this is a lab result using individual plants that may or may not be able to be extrapolated out to the whole ecosystem level, that it raises more questions than answers, an aspect of experimental science much exploited by climate change deniers and that it is quite convenient that it is being published while the ‘alternative to Kyoto’ Asia-Pacific climate partnership meeting is on in Sydney.
I previously blogged on a study that suggested the latitude of forests play a role in whether they are helping or hampering climate change. What’s clear from all this stuff is that the whole scenario is very complex.
To that end, I can recommend a book I’m half way through - The Weather Makers by Tim Flannery. In terms of today’s debate, it reports an interesting observation on when exactly *global warming* actually began. The “Anthropocene” climate era (the age of humanity) was originally judged to have started about 1800AD with Industrial Revolution. But then (from pg 64 on):
Charting the levels of two critical greenhouse gases - methane and CO2 - in air bubbles trapped in the Greenland and Antarctic ice sheets, [environmental scientist Bill] Ruddiman discovered an anomaly. The ice reveals that until around 8000 years ago the volume of methane in the atmosphere was mostly controlled by Milankovich’s 23,000-year-long [Earth] orbital insolation cycle. This makes sense, for methane is produced in large volumes by swamps, so warm, wet times (when swamps abound) produce more methane than dry, cold times.
At the onset of the last insolation cycle, which commenced 8000 years ago, Milankovich’s mechanism lost control of methane emissions. Had the insolation cycle controlled them, methane should have commenced declining around 8000 years ago, and gone into rapid decline by 5000 years ago. Instead, after taking a shallow dip that bottomed out 5000 years ago, methane concentrations begin a slow but emphatic rise. This, Ruddiman argues, is evidence that humans had wrested control of methane emissions from nature, and so we should mark the Anthropocene’s dawn as occurring 8000 years ago rather than 200.
It was the beginning of agriculture - particularly wet agriculture such as that practised in flooded rice paddies in eastern Asia - that tipped the balance, for such agricultural systems can be prodigious producers of the gas. It’s fair to note too that farmers of other crops that require swampy conditions were making thier own contributions at around this time.
The Wiki entry on the “Anthropocene” has links to the counter to this argument.
January 12th, 2006 at 1:47 pm
You might also want to check out more on the Gaia-effect at http://www.newscientist.com/channel/life/dn6953. Oz’s Great Barrier Reef seems to regulate its microclimate by producing cloud-making dimethyl sulphide. While not a greenhouse gas per se, it’s a further example of just how beyond human control this Climate Change thing is.
No matter where one may point the finger, the incontravertible conclusion remains that we are at the mercy of Darwinian evolution; adapt or go dodo.
January 12th, 2006 at 2:19 pm
The basic fact is that a whole lot of organic carbon got locked away in the Cretaceous and we are releasing it into the biosphere as CO2. Energy sustainability (and sustainability in general) is about the rate at which we use energy relative to the rate at which other living systems use energy.
The best way to illustrate this is that a 30 fold increase in human energy use (say due to cheap fusion) would generate a runaway greenhouse effect at current levels of atmospheric CO2. This is a result of the extra waste heat generated each day!
Sooner or later we are going to have to find ways to make do with less energy use per day or deal with the consequences.
January 13th, 2006 at 7:46 pm
While scientist run experiments to tease out the details on this issue, the case for ending deforestation is stronger than ever. Whether we talk about global warming or climate change, the role of forests is more important than it was aa century ago. Extreme weather (evident in more frequent hurricanes/typhoons, and torrential rainfall) has less impact when the area has a high or reasonable level of original forest cover. Mudslides and landslides are usually greater and more destructive after logging.
The ensuing aid missions may use up fossil fuels at afaster rate than what is normal for the area. And it is not only rural communities (and endangered species) that are at risk.
The deforestation around the Panama Canal has had an economic impact on the efficiency of the canal. The cultivated areas are unable to delay runofff at times of high rainfall, so Lake Gatun no longer enjoys a year-round stability of the water level. Some of the electricity generated in Panama now has to be used (wasted) to correct the imbalance caused by deforestation. The recent scientific finding is likely to be seized on by those keen to exploit logging. prepare for battle!