Saturday, 23 July 2016

Carbon Spikes over the Arctic, Africa, and the Amazon

From the Arctic to Africa to the Amazon, More Troubling Signs of Earth Carbon Store Instability

The time for debate is over. The time for rapid response is now. The Earth System just can’t take our fossil-fueled insults to her any longer.
(These Arctic and Siberian wildfires just keep getting worse and worse, but what’s really concerning is they’re burning a big hole through one of the Earth’s largest carbon sinks, and as they do it, they’re belching out huge plumes of greenhouse gasses. Image source: LANCE MODIS.)

22 July, 2016

Carbon Spikes over the Arctic, Africa, and the Amazon

Today, climate change-enhanced wildfires in Siberia and Africa are belching out two hellaciously huge smoke clouds (see images below). They’re also spewing large plumes of methane and carbon dioxide, plainly visible in the global atmospheric monitors. Surface methane readings in these zones exceed 2,000 parts per billion, well above the global atmospheric average.
Even as the fires rage, bubbles of methane and carbon dioxide are reportedly seeping up from beneath the tundra — generating big blisters of these heat-trapping gasses that are causing sections of the Arctic soil to jiggle like jelly. Greenhouse gas content in the blisters is, according to this Siberian Times report, 7,500 parts per million CO2 and 375 parts per million methane. That’s about 19 times current atmospheric CO2 levels and 200 times current atmospheric methane levels. Overall, these carbon jiggle mats add to reports of methane bubbling up from Arctic lakes, methane blowholes, and methane bubbling up from the Arctic Ocean in a context of very rapid Arctic warming.

(Methane spikes over Siberia, Africa and the Amazon correlate with wildfires and extreme drought conditions associated with human-forced climate change. Add in carbon dioxide spikes over the same regions of Africa and the Amazon and it begins to look like a visible amplifying feedback signal. Image source: The Copernicus Observatory.)

Meanwhile, a global warming-enhanced drying of the Amazon rainforest appears to be squeezing a substantial amount of these hothouse gasses into the Earth’s atmosphere. Copernicus Observatory surface monitors indicate pools of 600 to 800 parts per million CO2 concentrations near and around the Amazon rainforest. These 100- to 200-mile-wide spikes in CO2 concentration are 1.5 to 2 times current atmospheric concentrations. These very high CO2 levels occur even as methane readings over the Amazon are also abnormally high, a possible precursor signal that the NASA-predicted Amazon rainforest wildfires this summer may be starting to ignite.

Any one of these instances might be cause for some concern. Taking all these various observations together looks like a clear signal that the Earth is starting to produce an increasingly strong carbon feedback response to human-forced warming. If true, that’s some pretty terrible news.
Human-Forced Warming Warps the Carbon Cycle

Each summer, the boreal forests of the Northern Hemisphere take a big breath. In the warmer airs, leaves unfurl, grasses grow, and all kinds of CO2-respiring organisms take hold. Together, they produce a frenzy of activity, a riot of life gathering great stores of energy for the next plunge into winter. Over time, this natural capture of CO2 stores this atmospheric carbon in plant matter that ultimately becomes soil, permafrost, or is buried in the Earth in the form of various hydrocarbon stores.
It’s this annual great growth and greening that, in large part, drives the seasonal up-and-down swings of the global carbon cycle — a cycle that, under stable conditions, would generate an annual wave in atmospheric CO2 concentrations running over a long-term flat line.
(Surface CO2 readings show boreal forest uptake of CO2 over Siberia, Scandinavia, and parts of North America. Note the CO2 surface hot-spots over the fire zones in Central Africa and over the drought-stricken Amazon rainforest. Image source: Copernicus Observatory.)

Ever since the advent of the Industrial Revolution, human fossil-fuel burning has been adding carbon to the atmosphere. The result is that these seasonal swings, driven by plant respiration, have overlaid a significant upward trend in atmospheric carbon, one that this year pushed peak atmospheric CO2 values to near 408 parts per million. This is a level not seen in about 15 million years.

That increase in its turn has dramatically warmed the Earth — a result that has its own larger impact on plants, on the cycles that influence their ability to take in carbon, and even on the older carbon that was long ago stored in plants but is now sequestered in the soil, permafrost and oceans.
(LANCE MODIS satellite shot shows extensive wildfires spewing large plumes of smoke over Siberia and Africa. Meanwhile, very dry conditions in the Amazon appear to be generating understory fires even as carbon is baked out of the Equatorial soil. Click image to zoom in.)

Warm the world up, as humans have, and you generate what, in scientific parlance, is a carbon feedback. Overall, the ocean can take in less atmospheric carbon and increasingly bubbles with thawing methane, the soils can store less carbon even as more is baked out in the heat, the plants and peats on balance burn more than grow, permafrost thaws and releases its own carbon. It is this carbon-cycle response to warming that is expected to add more carbon dioxide and methane into the atmosphere on top of that already being released through the harmful processes of fossil-fuel extraction and burning.
Warming Forces More Carbon Out of Lands and Seas, Keeps More in the Atmosphere — But How Much is Still Pretty Uncertain

How much heat-trapping carbon the Earth System will ultimately add to human fossil-fuel emissions is kind of a big scientific question, which is answered in large part by how much fossil fuels humans ultimately burn and how much heat is ultimately added to the Earth’s oceans, glaciers, and atmosphere.
(A sampling of climate model-projected Earth System CO2 feedbacks to human-forced climate change. Note the high level of variation in the model projections. It’s also worth noting that these model projections did not include difficult-to-assess permafrost and hydrate responses to warming over the period through 2100. Image source: 

Back in 2007, the IPCC estimated that around 87 parts per million of additional CO2 would be added to the world’s airs by 2100 (under an apparent assumed final human-driven CO2 accumulation of 700 ppm) as a result of this kind of carbon feedback to human warming. This implied about a 20-percent positive CO2 feedback to warming. However, the model projections were wide-ranging (from 4 to 44 percent) and the overall assessment drew criticism due to a lack of inclusion of permafrost and hydrate feedback estimates.

In 2012, the IPCC produced a more uncertain, complex, and unclear set of projections that notably didn’t include permafrost carbon feedback or methane hydrate feedback model projections, the scientific understanding of which is apparently still developing. But despite a good deal of specific-issue uncertainty, the consensus appeared to state that over the medium- (21st century) and long-terms (multi-century), we’d have a significant amount of extra carbon coming from the Earth System as a result of responses to a human-warmed atmosphere and ocean.

(African wildfires, whose smoke plumes are visible here, are just one of many sources of carbon spikes around the globe triggered by human-forced climate change. Amazon rainforest next?

Overall, there’s a decent amount of support for the notion that the Earth System is pretty sensitive to warming, that it tends to respond to even a relatively small amount of initial incoming heat in ways that produce a good deal of extra carbon in the atmosphere. After all, only a small change in the way sunlight hits the Earth is enough to end an ice age and pump an additional 100 parts per million of CO2 out of the Earth’s carbon stores as a result. The added heat forcing provided by the current human fossil-fuel emission is far, far greater than the one that ended the last ice age.
It is in this understanding and context that we should consider what appears to be an increasing number of Earth System responses to a human-forced warming that has currently exceeded 1 degree Celsius above 1880s averages. It’s easy to envision that these responses would grow in number and intensity as the Earth continues to warm toward 2 C above 19th-century averages.

Hat tip to TodaysGuestis
Hat tip to Colorado Bob
Hat tip to DT Lange

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