The year is 3030 and the robots (who have replaced humanity as the dominant intelligent beings on Earth) have decided to build a Dyson sphere around the sun. They're planning on disassembling Venus for materials and building a sphere with a radius a bit less than the orbital radius of the planet they're consuming.
The sphere is opaque to all solar radiation, barring a few high-energy gamma rays that manage to punch through, and also blocks the solar wind. It's thin, so it will reach thermal equilibrium fairly quickly and radiate energy as a blackbody based on its equilibrium temperature.
Earth, prior to the construction of the sphere, has a climate similar to that of modern day Earth. Neither nuclear war nor pollution has catastrophically damaged the biosphere. The Earth of 3030 is about 3°C warmer than it is today and is home to a stable population of 11 billion humans.
How uninhabitable will the construction of the Dyson sphere render the Earth? It will block out all sunlight, but should ultimately radiate the same amount of energy it's absorbing, effectively replacing the Sun with a much larger, cooler star. What life on Earth would we expect to survive in the post-sphere era?