Should we rely on negative-emissions technologies?

 Short answer: no.

From Dr Aaron Thierry

"The Integrated Assessment Models informing policy-makers assume the large-scale use of negative-emission technologies. If we rely on these and they are not deployed or are unsuccessful at removing CO2 from the atmosphere at the levels assumed, society will be locked into a high-temperature pathway"

(From UNEP)

Look how large negative emissions have to be to achieve net-zero by 2070 (never mind 2050!) on current pathways  — almost as large as positive emissions in 1980.  We should not rely on negative emissions to stop the climate catastrophe, because we almost certainly won't be able to achieve them.  To save ourselves, we must cut actual emissions.   Now.  Forget pie-in-the-sky schemes to offset emissions and start working on replacing fossil fuels in our economy.