Look, there are this top studies suggesting that macroelgy farming, kelp farming may be a useful way to go. Kelp grows 30 to 60 times faster than land-based plants can grow half a metre a day. There are large parts of the oceans where you could have floating seaweed farms. If we could cover 9% of the world's oceans with seaweed farms, you'd draw down the equivalent of all global emissions going up as of 2015. So we're never going to get to 9% of the world's ocean covered in seaweed farms by 2050. That'd be an area four and a half times the size of Australia. Very, very large. But you see there an approach that offers us a way forward at scale. Beyond that there is the use of silicate rocks. These are a natural part of Earth's system for drawing CO2 out of the atmosphere. As they weather they absorb CO2. If you would have enhanced the weathering process by pouring the rock and then grinding it up and stirring it on beaches and so forth, if you did that with 5 or 6 gigatons of silicate rock you'd be drawing 3 or 4 gigatons of CO2 out of the atmosphere. Of course at the moment we burn fossil fuel to quarry so we have to green up our energy supply before we can apply that at scale. But there are also things like carbon negative concretes. Concrete are responsible for 5% of global emissions. The development of carbon negative concrete offers a huge opportunity now to both avoid emissions in the making of some ends in concrete but also to draw CO2 out of the atmosphere into the concrete as they cure and mature. There are direct technology such as plastics from atmospheric CO2, the manufacture of carbon fibers from CO2. These again open significant opportunities hard to imagine at the gigatons scale but they are there. On top of all of that we have to look at some of the carbon capture technologies which are also quite interesting.