Oceanic carbon sinks

So nature deals with increasing carbon dioxide emissions by sucking up more of it. Plants take more and grow faster. The increased partial pressure of CO₂ causes more of it to be absorbed by the oceans. On land more plants is a good thing, but in the oceans more CO₂ leads to increased acidity which can be devastating for the flora and fauna.

Recently there were two interesting papers, one in Nature and the other in Nature Geoscience, that looked at Earth's carbon sinks. I've written about the studies in The Economist's Babbage blog. I took the chance to speak to some of the leading researchers in the field: Ashley Ballantyne at the University of Colorado, Corinne Le Quéré at the University of East Anglia (and not involved in the climate scandal), Jean-Baptiste Sallée of the British Antarctic Survey and Jorge Sarmiento at Princeton University. The conversations helped me learn a number of things. I'm sharing those here:

1. The ocean in the southern hemisphere take up most of the CO₂ because of their large unbroken waters. But this absorbed gas is not evenly spread out. Some pockets have a lot more of it than others.
2. This ocean also absorbs a lot of the heat that is getting trapped because of excess greenhouse gases. By one estimate almost 70% of it. As oceans warm up, their capacity to hold CO₂ reduces. These carbon sinks could become carbon sources at some point.
3. The lack of an ozone layer leads to localised cooling in the Antarctic. Global warming causes most of the heating in the tropics. This temperature difference causes stronger winds which could whip up deeper ocean layers bringing up CO₂-rich waters which won't be able to absorb as much of it as they do now.
4. Land carbon sinks could become carbon sources, too. Increased temperature leads to growth of microbes in the soil. These will then consume more of organic matter and convert it into CO₂, which they do already but the plant consumption of CO₂ is able to keep that in check.

Climate change is a very complex phenomenon. I knew that but these conversations made me realise just how much we don't know (PS: this is not to doubt that humans are causing global warming). Only after a few questions, all researchers started answering the question by first saying 'We don't know, but one theory is...'. Oceanic carbon sinks, in particular, are a big area of debate, mostly because of the lack of hard data. Things are changing, but are they changing fasting enough?

A list of main references for The Economist piece:

1. Ballantyne et al., Nature, 2012, 488, 70
2. Salée et al., Nature Geoscience, 2012, ASAP
3. Climate change: What lies beneath - The Economist
4. Argo project, UK Met Office
5. Climate Variability and Predictability (CLIVAR)

Ballantyne AP, Alden CB, Miller JB, Tans PP, & White JW (2012). Increase in observed net carbon dioxide uptake by land and oceans during the past 50 years. Nature, 488 (7409), 70-2 PMID: 22859203

Sallée J-B, Matear RJ, Rintoul SR, & Lenton A (2012). Localized subduction of anthropogenic carbon dioxide in the Southern Hemisphere oceans. Nature Geoscience DOI: 10.1038/ngeo1523

Squirrels and climate change

Credit: Jeffrey Lane

Jan Murie, emeritus professor of biology at the University of Alberta in Canada, is passionate about squirrels. He has even written a book: The Biology of Ground-Dwelling Squirrels. Even after retiring he keeps up with his interest. With the lead author Jeffrey Lane, a biologist at the University of Edinburgh, he has published a paper in Nature on the effect of climate change on Columbian ground squirrels. I've written about it in The Economist's Babbage blog.

Here's the blurb:

Winter is a pain in the animal kingdom. Birds can flee it by migrating to warmer climes but grounded beasts, including mammals, have no choice but to stick around. To cope, many species have learned to hibernate. Some, like the Columbian ground squirrel, spend up to nine months of each year in their alcoves. This conserves energy but leaves them with only three months to plump up for the next winter and, crucially, to procreate. To make matters worse, climate change is leading them to emerge from hibernation later than usual... read more.

While chatting with him about the paper he told me that these squirrels in captivity live up to the age of 13 years, while in the wild their average is 6 years. Adult squirrels tend to cope well, but it's the juveniles that get hunted down. Although there's nothing surprising about that, it was a reminder of what can happen when you live in the wild. Especially, if you happen to be at the bottom of the food chain.

References:

1. Lane et al., Nature, 2012, ASAP  
2. Lane et al., J. Evol. Biol., 2011, 1949

Lane JE, Kruuk LEB, Charmantier A, Murie JO, & Dobson FS (2012). Delayed phenology and reduced fitness associated with climate change in a wild hibernator Nature DOI: 10.1038/nature11335

UK carbon capture competition for £1 billion becomes a one horse race

On the same day UK ministers revealed a £1 billion fund for the development of carbon capture and storage (CCS), power company E.ON UK announced it is pulling out of the government's national CCS competition, leaving just one company in the race. In 2007 the government announced a competition to build one of the world's first commercial scale CCS demonstration plants in a bid to strengthen the UK's position as a world leader in cleaner fossil fuel technology. Before E.ON's departure from the race, energy firms BP and Peel Power had already pulled out of the competition in 2008 and 2009 respectively... read more.

How did our nitrogen cycle evolve?

In trying to feed our growing population, we now add twice as much nitrogen to the soil (after chemically ‘fixing’ it to make fertilisers) as microbes fix from the atmosphere. Human activity has skewed the balance in the earth’s nitrogen cycle. But how did the modern nitrogen cycle evolve? A recent review published in Science tries to answer that question and make suggestions about the future. ...read more.



Canfield, D., Glazer, A., & Falkowski, P. (2010). The Evolution and Future of Earth's Nitrogen Cycle Science, 330 (6001), 192-196 DOI: 10.1126/science.1186120