Our world is warming rapidly. This is caused by the so-called greenhouse effect. The sun warms our earth and the earth in her turn (which means the crust, oceans, clouds, plants, in short our whole eco-system) reflects parts of this radiation. Now, because of the great amounts of CO2 in the air, the solar radiation can’t be ‘sent’ out of the atmosphere. The CO2 prevents it from reflecting, and this causes global warming.  People are working on solutions to reduce the emission of CO2, while others are engineering solutions to stop the global warming as it is today. The eight part documentary of Discovery channel investigated and experimented with eight so-called geo-engineered solutions against global warming. Subjoined is a summary of these solutions and parts of the documentary.
 
1.Customing Clouds
With the usage of robot-driven ships on the oceans these scientists want to create more clouds above the oceans. Clouds reflect solar radiation and by creating more clouds they hope to reflect more solar energy. The advantage is that it looks like a quite simple and ‘natural’ solution. The disadvantage is that we don’t have a lot of knowledge about clouds. It might just be that creating clouds above the ocean creates dryness or maybe hurricanes in other parts on the globe. 
http://www.discoverychannel.co.uk/video/ways-to-save-the-planet-customis...
 
2. Sixteen trillion space-lenses
The idea is to put 16 trillion lenses in space that can reflect and/or change the direction of solar radiation before it even enters our atmosphere. The downsides of this project are that it costs billions and billions of dollars. The scientist are now trying to make the lenses smaller and lighter so that it won’t cost as much, although it’s still the question whether it will reduce the costs sufficiently. Another disadvantage is that it’s not even sure if it’s possible to bring that huge amount of lenses in space by space shuttles. Some say that if we were to invest so much money in this solution, it would be much better spent on wind energy and solar energy – development. 
http://www.discoverychannel.co.uk/video/ways-to-save-the-planet-16-trill...
 
3.Forest Bombs
Forests absorb a lot of CO2 and turn this into oxygen. Of all plants and trees, mangroves are known for their ability to absorb a lot of CO2. The plan of these investigators is to plant enormous amounts of mangroves all over our planet. This should be done from the air (bombing forests). Disadvantages are that, first of all, it’s difficult to aim for the right spot out of an airplane. Secondly, it will take a while before the mangroves are fully-grown. And finally, it’s a huge tree farm they create, not a forest. So it’s not even sure if it will have the same effect as forests. 
http://www.discoverychannel.co.uk/video/ways-to-save-the-planet-forest-b...
 
4.Fixing Carbon
David Keith invented a machine that will take up to fifty percent of the CO2 from the air and stores it. The advantage is that every country can decide for itself whether or not to have such kind of machines installed. Then, no world-cooperation will be necessary, which will speed up the process. The disadvantage is that the amounts of CO2 taken off from the air have to be stored somewhere. The danger in storing CO2 is that it might go wrong one day and the results of a mistake like this are inconceivable: humans and animals will suffocate. Another disadvantage is that this type of machine is technologically very hard to build. 
http://www.discoverychannel.co.uk/video/ways-to-save-the-planet-fixing-c...
 
 
5. Grow Plankton
In our oceans there’s a very small plant called plankton. These little plants are the food for many animals, but they also have another very important function. Phytoplankton absorbs CO2, turns it into oxygen, and when they die, the CO2 will sink to the bottom of the sea and stays there. These scientist want to grow enormous amounts of plankton so that more CO2 will be taken from the air. They want to do that by putting tubes into the ocean that will pump up food from the bottom of the ocean. This food will affect the growth of plankton. Sounds like a pretty natural solution, but opponents claim that there’s a big disadvantage. Since the oceans carry a whole eco-system of which we don’t know a lot yet, it’s a risk to change this system without being informed with the consequences. It might just be that this change affects the whole sea life and destroys it. Another negative effect that might come up is the development of algae, which are toxic for animals and humankind. Last but not least, it might also be that the CO2 stored at the bottom of the sea by this phytoplankton won’t stay on the bottom so that it will end up in the atmosphere after all.  
http://www.discoverychannel.co.uk/video/ways-to-save-the-planet-hungry-o...
 
6. Orbital Power Plant
When we use sun radiation as a source of energy, a lot of the radiation gets lost. When entering the atmosphere, 25% is being absorbed. The scientists of this plan are developing a shield around the world that catches the sun radiation before it enters the atmosphere and transfers the energy to the world. The big ‘but’ of this project is the politics: who will have the control over this shield, who will be held responsible for the division of its energy? What is needed is political and social stability before this plan can become a success. And then there’s also the question whether it’s really possible to beam energy out of the atmosphere to our planet. 
http://www.discoverychannel.co.uk/video/ways-to-save-the-planet-orbital-...
 
7. Infinite winds
Also based on natural sources is this plan: the usage of wind energy. Because of clouds, buildings and other ‘stuff on earth’ a lot of wind gets ‘lost’. For this reason, these scientists came up with flying wind turbines that will be sent high in the sky to collect wind energy and transfer it to houses. One turbine could provide 600 houses from energy. But here are also difficulties in developing it: technologically it’s a challenge against aerodynamics. Another, maybe more dangerous side effect, is that it’s not sure what this ‘taking of wind’ on a high scale will do to the climate: maybe the weather situation will change? 
http://www.discoverychannel.co.uk/video/ways-to-save-the-planet-infinite...
 
8. Wrapping Greenland
It’s known that light surfaces reflect more sunlight than dark surfaces. For that reason, ice and glaciers are very important. It actually is a negative spiral: ice melts because of the global warming and since water is darker than ice, it even warms more quickly. Now these scientist came up with the ‘simple’ solution to put hundreds of square metres of white (plastic) blankets over the ice, so the surface remains white and will be able to reflect sunlight as it used to. The side effect is, of course, that it needs to be done on a very large scale to have any effect. 
http://www.discoverychannel.co.uk/video/ways-to-save-the-planet-on-the-m...