Showing posts with label habitability. Show all posts
Showing posts with label habitability. Show all posts

Tuesday, October 9, 2012

Terraforming Earth


Terraforming is a fascinating idea. Creating Earth-like conditions on other planets or on the moon, or inside structures built in space, that has long been a popular theme in many science fiction stories. 

What are habitable conditions? Many will point at the presence of water and certain minerals. Many will also point at some things our own Earth has, such as an atmosphere that spreads the heat from sunlight around the world, and that has levels of greenhouse gases that keep temperatures within a range that supports life on our planet.

Habitability at risk

At present, changes are taking place in the world that indicate the opposite is happening here on Earth. The conditions that make Earth habitable are at risk in many ways. One threat is the rise in the levels of greenhouse gases in the atmosphere. 

A safe operating space for humanity is a landmark 2009 study that identifies nine essential areas where sustainability is stressed to the limits, in three cases beyond its limits. In the image below, these areas are pictured as wedges. The inner green shading represents the proposed safe operating space for nine planetary systems. The red wedges represent an estimate of the current position for each variable. The boundaries in three systems (rate of biodiversity loss, climate change and human interference with the nitrogen cycle), have already been exceeded.

 From: A safe operating space for humanity, Rockström et al, 2009.

How to reduce the risk

Global warming is caused by emissions such as from burning fuel. Such emissions are still rising. Such emissions must obviously be reduced dramatically, while additional measures are needed to avoid runaway global warming and to bring the atmosphere and oceans back their pre-industrial state as soon as possible.

The table below shows these nine areas in the column on the left, while examples of technologies that could be helpful in the respective area feature in the column on the right. 

1. Climate changeCDR: biochar, carbon air capture, enhanced weathering, algae bags, EVs, renewable energy, clean cooking & heating, LEDs, etc.
SRM: surface and cloud brightening, release of aerosols
AMM & AWIM: methane capture, release of oxygen and diatoms, wetland management, river diversion, enhanced methane decomposition
2. Ocean acidificationenhanced weathering
3. Stratospheric ozone depletionoxygen release
4. Nitrogen & Phosphorus cyclesalgae bags, biochar, enhanced weathering
5. Global freshwater usedesalination, biochar, enhanced weathering
6. Change in land usedesalination, biochar, enhanced weathering
7. Biodiversity lossdesalination, biochar, enhanced weathering
8. Atmospheric aerosol loadingbiochar, EVs, renewable energy, clean cooking & heating, LEDs, etc. 
9. Chemical pollutionrecycling, waste management (separation)

A Comprehensive Plan of Action

At present, governments support polluting products in all kinds of ways, while they use international agreements or the lack thereof as excuses to avoid making the necessary changes.

To facilitate the shift from polluting technologies to clean technologies, political change is imperative and governments around the world should commit to a comprehensive plan of action such as articulated here.

Reducing emissions is obviously an important part of such a plan. This can be effectively achieved by imposing fees on the sales of polluting products, while using the revenues to fund rebates on locally sold clean alternatives. Each nation can start implementing such policies without the need to wait for other nations to take similar action. Clean products are in many respects already economically competitive. Active support by government is the long-awaited signal for local industries to make the necessary investments and create many local clean jobs in the process, while this also supports people's health and has many further benefits.

Moreover, there is a risk of runaway global warming. This risk is unacceptably high and needs to be dramatically reduced as soon as possible, which makes that geo-engineering will have to be an indispensable part of the necessary plan of action. International agreement must be reached on this, not only to minimize possible negative side-effects, but also to ensure that such geo-engineering will not be used as a way for a nation to avoid taking the necessary action to reduce emissions domestically.

Terra is Latin for Earth and sounds sufficiently ancient to indicate that it refers to Earth like it used to be when it was a habitable planet. Indeed, we need a massive effort to restore Terra to the way it used to be. We need to terraform Earth itself.