A sunshade out in space, denser and more reflective clouds,
and a sulphur blanket - big ideas to reduce the power of the sun.
But the sun itself is not the only problem, mankind has pumped too much carbon dioxide into the atmosphere, exacerbating the greenhouse effect,
if only we could engineer a way to take it out again.
On first impressions urine may not seem like the most promising solution, but one of its components, urea,
is a nitrogen rich fertiliser that helps plants grow, and plants absorb tons and tons of carbon dioxide.