All Things Sustainable

ecology, economy, community


Looking Back at Our Ancient Climate

Climate Change Challenges MOOC (2)
This week started with Professor Tim Lenton taking a look into deep time and the early state of planet earth.
In the beginning, well pretty early on anyway, the sun was much cooler than it is today, it was 25% -30% less bright so one would imagine the earth’s temperature would be much cooler but in fact it was actually warmer than today. This was due to a rather thicker blanket of greenhouse gasses, later some of these gases were slowly removed over time by the action of the carbon cycle.

(Professor Tim doesn’t like ‘greenhouse’ terminology but the rest of the world still uses it so it has become something of a lingua franca.)

The carbon cycle extracts carbon from the atmosphere basically by dissolving CO2 in the raindrops and forming a weak acid. This then weathers the rocks and that reaction ends up creating carbonate ions, which, in turn, are washed into the oceans and waterways. The next change is a bit murky, somewhere along the way the carbonate ions get snaffled up, often it seems by calcium, and then quickly converted into seashells or similar. Eventually the carbon becomes part of the lithosphere as it morphs into carbonate rocks, something akin to the famous white cliffs of Dover perhaps. The carbon cycle is a negative feedback and as such it tends to maintain an existing state. As the sun’s radiation increased and the earth warmed the reaction speed increased, removing CO2 and cooling the planet.

But negative “put it right” feedbacks do not always win. Back in deep time again (2.2 billion & 700million years back) the earth froze over. The trigger is not clear – it may have been something to do with the continents forming. In any event a positive “make it worse” feedback problem developed. The poles froze, the ice reflected more heat, the planet cooled further and froze and cooled some more and once the ice reached the tropics well that was it, a snowball.
http://www.bbc.co.uk/nature/ancient_earth/Snowball_Earth But not forever because – well it isn’t frozen now –and the earth still had at least one get-out-of-gaol-free card left. Volcanoes. Again this took an awful long time but the volcanoes slowly put lots of CO2 and other gases back into the atmosphere, which started the world warming again and as the ice melted under the warming blanket of gasses so the reflectivity of the globe reduced and a little more warmth got through, ice melted, water evaporated, warming increased and we were back in business.

There are several mechanisms that create natural climate variability. They are mainly long term changes triggered by changes to the earth’s orbit (Eccentricity), the tilt of its axis varying (Obliquity) and the wobble of the axis (Precession). These changes are regular and predictable albeit on long time scales. They are called Milankovitch Cycles.
Volcanoes and solar activity also influence the climate and they are not regular or predictable but we can pinpoint those events using tree rings and/or ice cores for proxy dating information and compare the results against historical records of climate events such as the mediaeval warm period. The signature of the Mt Pinatubo volcanic eruption in 1991 is visible as a 2 or 3yr dip in global temperatures but in general global temperatures are rising and CO2 emissions are increasing at a much faster rate than has happened with previous natural climate variation.
Studies of the Ice Ages go back quite a long way and there is now a recognized discipline, Paleoclimatology, thanks to Svente Arrhenius, who in 1895 suggested that a reduction in CO2 concentration in the atmosphere could account for the drop in temperature during the ice age. He was also the first person to investigate the effect that doubling atmospheric carbon dioxide would have on the global climate.
Comparing historical data with the temperature rise over the last 100 or 150 years it seems there is a mismatch, first there is an of excess CO2 in the atmosphere but also the changes are happening much faster than would be expected. http://earthobservatory.nasa.gov/Features/GlobalWarming/page3.php
The only way the models can reflect what actually happened is if the CO2 produced by the industrial revolution is included in the equation.

How right they were!

How right they were!

This is not surprising really because burning coal and oil is really releasing fossilized sunlight back into the atmosphere and the extra heat must go somewhere.

Advertisements


Aerosols, volcanoes and climate change

Volcanic eruptions produce dust and aerosols that act to provide short term cooling, however seems unclear as to whether there is any long term warming effect from the gasses emitted and also the effect of different aerosols and the interactions between them is unclear.

Most aerosols are of natural origin and key groups include sea salt, nitrates, sulfates, organic carbon, black carbon & mineral dust and they often clump together and form complex mixes. Sea salt, dust and volcanic ash are common types of aerosol, only about 10% of aerosols are of anthropogenic origin.

Different aerosols reflect or absorb sunlight depending on their make up. Large volcanic eruptions can cool the earth for a year or more while sulfate aerosols remain in the atmosphere, black carbon deposited on ice or snow can contribute to global warming by altering the albedo (reflectivity) of the planet. It is a complex area and potential impacts are not fully understood. It certainly makes me worry about potential Geoengineering solutions to climate change….

http://earthobservatory.nasa.gov/Features/Aerosols/


1 Comment

Can Myopic Markets Save the World?

On January 17th 2015 NASA reportedly announced that 2014 was the world’s hottest year ever recorded and that this formed part of a continuing trend. It was also noted atmospheric CO2 levels are continuing, intermittently, to reach 400ppm. We are currently on a trajectory widely agreed to be heading for a temperature increase of around 5degC.
So is it possible that the strength of market forces could change the future, moving us from a pathway heading into a climate change disaster to one that instead leads us through the minefield to a safe haven? There are people who think this is a reasonable assumption and while I can understand the reasoning I must admit to being rather more pessimistic.

There are certainly many lights shining on a multitude of hills. The Chinese are moving quickly to reduce the use of coal and to ensure they return the atmosphere in their cities to pure clean breathable air and they have done some remarkable work rehabilitating degraded land as in the Loess valley, the USA is promising to move swiftly to control its emissions and even if its federal government fails to act there are several states which together are moving to take control and reduce greenhouse emissions. There are reports that the German State of Schleswig-Holstein has achieved 100% renewable power in 2014 and intends to triple that total. It may not be enough to change everything but it will be a serious commitment and as such could lead the world into a renewable future.
Yet in spite of these hopeful indicators it seems that we are already into planetary overshoot with resource use and pollution exceeding the natural ability of the world to absorb the waste or maintain our economy on a sustainable basis. The myopia of the market is reflected in pressure from corporate and government interests to open more coalmines, to extract oil from deep undersea sources, to increase coal seam gas extraction. At the same time the science estimates that to have a 50-50 chance of a reasonable climate future, a third of the world’s oil reserves, half the gas reserves and more than 80percent of the coal reserves cannot be used.

To help us all to change on 13th & 14th February 350.org will run a worldwide ‘divestment day’ to help the world to break up with fossil fuels, so check where your superfund invests, change your bank, re-assess your share portfolio if you have one. Another straw in the wind that perhaps suggests impending change.

There are serious questions to be answered about food production as well. Not only does our current monoculture agribusiness approach make quite large contributions to emissions it is also likely to be disrupted by climate disasters with floods or droughts hitting major food producing areas in the USA, or Australia. Some analysts have linked the Arab Spring to food shortages, triggered by drought and the associated reduced harvest size and high wheat prices. Other factors that might drive wheat prices higher are the use of agricultural land to produce ethanol for transport and fodder for feedlot cattle. Of course we should not forget the anticipated world population increase. The UN Food and Agriculture Association Asia-Pacific suggests that to avoid political turmoil, social unrest and civil war the world needs to increase food production by 60% by 2050

All this needs to be done without further stressing our natural ecosystems
Paul Ehrlich & Anne Ehrlich in a Simplicity Institute paper “Can a Collapse of Civilization be Avoided?” published by the Royal Society in 2013 pinpoints the likely triggers for collapse and looks for major cultural change for the hope of avoiding disaster:
Abstract : Environmental problems have contributed to numerous collapses of civilizations in the past. Now, for the first time, a global collapse appears likely. Overpopulation, overconsumption by the rich and poor choices of technologies are major drivers; dramatic cultural change provides the main hope of averting calamity.

Such a cultural change could be based on an underlying human tendency to cooperate rather than to compete. Can I hear ribald laughter in the gallery at such an unreasonable suggestion? Quite possibly, however a paper in published in Nature seems to support the idea… and also that cooperative behavior cascades to extend its influence through a population (Fowler & Christakis)

Then there are also suggestions that the capacity and perhaps a need to cooperate was an effective driver of the success story for early mankind. And surely markets were a part of that cooperation, markets that traded obsidian across hundreds of kilometers at a time when foot traffic reigned supreme. And another gem that paleoanthropology has thrown up is the idea that past climate change was also a trigger for the rapid evolution that saw homo sapiens out compete its rivals. Perhaps we are set for a great leap forward into a sustainable future and not a blind stumble that lands us in the trash can. A nice thought to end on perhaps.