I am glad to see Gates throwing his money and influence in a progressive direction. > we need to be able to power all sectors of the economy with sources that

I am glad to see Gates throwing his money and influence in a progressive direction. > we need to be able to power all sectors of the economy with sources that do not emit any carbon dioxide. Yes. That said, I think a lot of the optimistic future trajectories for world climate models rely on the assumption of CCS technology permitting negative net carbon emissions later in the century. On the positive side: hypothetically if the technology were to exist we could get away with some emissions; negative side: this technology doesn't actually exist. > But when it comes to preventing the worst effects of climate change, the investments I make will matter much less than the choices that governments make. I completely agree. A global price on carbon would help here. It's going to be difficult for clean-energy alternatives to compete with existing energy sources such as coal, that (i) are priced in a way that ignores the negative externalities of greenhouse gas emissions, and (ii) are heavily subsidised. The global economy needs to be appropriately regulated in order to coerce it into doing more useful activities. > Scientists generally agree that preventing the worst effects of climate change requires limiting the temperature increase to 2 degrees Celsius, and that doing so requires the biggest emitters to cut emissions 80 percent by 2050 and all countries to essentially eliminate them by the end of the century. Indeed! > These are solvable problems. Here I disagree. We are not going to limit temperature rise to 2 degrees Celsius. We missed that window by a few decades. It would still be a VERY good idea to limit temperature rise to +3 degrees Celsius, or something, instead of ending up with a world where it is +4 degrees C and still rising. I recently finished reading the book "Windfall: The Booming Business of Global Warming" by McKenzie Funk. I am actually more optimistic about the future now: we still have geoengineering options available, such as pumping sulphur into the atmosphere to reduce the amount of sunlight heating the world by a fraction of a percent. It's worth pointing out, however, that: * geoengineering gives us a means to partially/completely address one of the symptoms (temperature rise) of the problem, and continue to avoid addressing the causes. other symptoms: nitrogen cycle disruption, species mass extinction, extinction of non-renewable resources, extinction of renewable resources (global fish stocks), ... * geoengineering options will also cause some climate change, and these changes will not be uniformly or fairly distributed over the world. All things being equal, powerful countries will run geoengineering projects, and as far as it can be predicted and controlled, the climate will be adjusted to preferentially favour the countries running these projects. * the long-term, large-scale secondary consequences of things we do that seem like a good idea are not always anticipated! * geoengineering options are akin to patching a highly complex system by adding more complexity to patch a symptom. this requires upkeep and potentially makes the entire thing more fragile.