why carbon sinks?

Everybody is talking about reduction of green house gases and carbon-cuts. What a lot of people don't realise is that even if carbon amounts in the atmosphere are reduced today, the effects of current levels of carbon already present is going to be felt for atleast 100 years - this is how long it takes for carbon to dissipate. In other words: even if we reduce carbon emissions now, the carbon already present can contribute to global warming.

This realization is the reason why there is a current scramble for carbon sequestration technologies. The idea behind this is to capture carbon and then bury it under the earth, in the sea-bed or to come up with a method where the conversion of carbon is accelerated.

Currently forests have been acting as a great 'carbon sink' whereby carbon is naturally captured. However due to global warming there have been speculations that forests could release huge quantities of carbon and create a situation in which they do more to accelerate warming than to slow it down. While deforestation is responsible for about 20% of greenhouse gas emissions from human activities, forests currently absorb more carbon than they emit.

But the problem is that the balance could shift as the planet warms, the report concludes, and the sequestration service provided by the forest biomes could be lost entirely if the Earth heats up by 2.5C or more. Droughts, more pest invasions, and other environmental stresses would trigger considerable forest destruction and degradation. This could create a dangerous feedback loop, it adds, in which damage to forests from climate change would increase global carbon emissions that then exacerbate global warming.

The other biggest natural carbon sink are the oceans of the world which are already showing stress due to acidification because of excess carbon. Plankton in the ocean also act as a carbon sink and they will slowly die as the oceans become more acidic and warm up. The other big carbon sink is the permafrost which is said to contain large amounts of methane. Global warming will cause it to melt which will release all the methane which is more potent than CO2 as a GHG.

The need for reducing carbon emissions as well as to reduce the amount of carbon already in the atmosphere is pressing. So there is a twin objective to be met in order to combact enhanced global warming. Does this make it harder to reach our objectives? Perhaps. But it also impresses upon us the incredible delicacy of the Earth's natural regulating systems.

geo-engineering - the great big hope?

Recently almost all the enviro articles that I've been reading involve the topic of geoengineering so its about time that its blogged. Geoengineering would involve the deliberate modification of Earth's environment on a large scale 'to suit human needs and promote habitability' according to wiki. Typically, the term is used to describe proposals to counter the effects of human-induced climate change.

Some techniques are based on carbon sequestration that seek to reduce GHGs in the atmosphere. They also include ocean iron fertilization, solar radiation management etc. Ocean iron fertilization is at the final stages of research and so far no large-scale geo-engineering projects have been planned.

Ocean iron fertilization is introduction of iron to the oceans. Fertilization supports the growth of marine phytoplankton blooms by physically distributing microscopic iron particles in nutrient-rich, but iron-deficient, ocean waters. An increasing number of ocean labs, scientists and businesses are exploring it as a means to revive declining plankton populations, restore healthy levels of marine productivity and sequester billions of tons of CO2 to reduce global warming and ocean acidification. Since 1993, ten international research teams have completed ocean trials demonstrating the effect. However, controversy over its safety and efficacy remain. Whilst increasing plankton population in the oceans will solve one half of the problems associated with climate change, the problem of already acidic oceans cannot be solved through this method.

In order to neutralize the oceans, scientists now propose adding limestone to restore the oceans to their previous alkaline state. Limestone mining however is an energy intensive process. Adding iron to oceans can increase algal blooms. My head refuses to wrap itself around the avoidance of negative affects by adding stuff to over 70% of the Earth's environs or even how you can experimentally prove the same on a scale as large as this with so many parameters for control.

Other geoengineering projects in the pipe-line include brightening clouds in order to increase cloud reflectivity so the albedo of the Earth is altered. Whilst I applaud all the technology and acknowledge that in the times of little hope, this offers a glimper of something like it; I remain dubious on the side-effects - are we planning on jumping from the frying pan into the fire?

the biggest oxymoron

Adding to the list of 'healthy fast-food', 'good government', 'peacekeeping force' and... 'Microsoft works' there is the newest oxymoron: clean coal. Coal of course has been one of the earliest sources of energy and at one point it was known as 'black gold'. Nowadays it is being rebranded as 'clean coal'.

Clean coal is an umbrella term used to promote the use of coal as an energy source by emphasizing methods being developed to reduce its environmental impact. These efforts include chemically washing minerals and impurities from the coal, gasification, treating the flue gases with steam to remove sulfur dioxide, carbon capture and storage technologies. Major politicians and the coal industry use the term 'clean coal' to describe technologies designed to enhance both the efficiency and the environmental acceptability of coal extraction, preparation and use, with no specific quantitative limits on any emissions, particularly carbon dioxide.

Even if clean coal technologies can be developed and deployed at a commercial scale in power generation, they will do nothing to make the mining of coal a less polluting activity. As 25.5% of the world's electrical generation in 2004 was from coal-fired generation, reaching the carbon dioxide reduction targets of the Kyoto Protocol will require modifications to how coal is utilized. Carbon sequestration technology has yet to be tested on a large scale and may not be safe or successful. Sequestered CO2 may eventually 'leak' up through the ground, may lead to unexpected geological instability or may cause contamination of aquifers used for drinking water supplies.

The byproducts of coal combustion are considerably hazardous to the environment if not properly contained. Coal-fired power plants are the largest aggregate source of mercury: 50 tons per year come from coal power plants out of 150 tons emitted nationally in the USA and 5000 tons globally. There are forms of clean energy such as geothermal, biomass, solar, wind and hydroelectric and other renewable energy sources which are supported by many of the environmentalist groups and campaigns. Critics of the planned power plants assert that there is no such thing as 'clean coal' and that the plant will still release large amounts of pollutants compared to renewable energy sources such as wind power and solar power.

By this technology, emissions and wastes are not avoided, but are transferred from one waste stream to another. As coal-fired power plants work to create cleaner skies, they'll likely fill up landfills with millions more tons of potentially harmful ash. Chemicals are injected into plants' emissions to capture airborne pollutants. That, in turn, changes the composition of the ash and cuts its usefulness. It can't be used in cement, for example, because the interaction of the chemicals may keep the concrete from hardening.

That ash has to go somewhere - so it usually ends up in landfills, along with the rest of the unusable waste. Essentially, replacing an air problem with a land problem - a disposal problem. The chemicals added to clean up emissions - such as ammonia, lime and calcium hydroxide - make the ash worse, because they take toxins such as mercury out of the air but leave higher levels of it in the ash.

Coal works because it is cheap - but does it really? Ultimately there is no such thing as 'clean coal' and it is about time politicians stop pushing the agenda of coal industrialists. Give them all a new business plan - switch to renewable energy sources. If the so-called developed countries still continue to use outdated technologies, they cannot expect the less-privileged countries to give up the same cheap technology. Out with the old, says I. What says you?

Coen Brothers' TV advert for clean coal