For almost 10 years, we have been told that many people want to work on reducing their emissions before offsetting. We absolutely must do this, but it is naive to think that it is enough. So-called negative emissions are necessary to remove carbon already in the atmosphere. Quite simply, we need to compensate for our failure to reduce emissions sufficiently in good time. Now, the latest IPCC report underlines the importance of negative emissions to limit warming to 1.5 or 2 degrees. And now it is urgent.

Four main techniques are at issue

In short, it involves absorbing, capturing or otherwise dealing with carbon dioxide that we have already emitted. It is then stored, in biomass (such as trees) or underground. The result is expected to be less carbon dioxide in the atmosphere.

CCS is often referred to as carbon capture and storage ( CCS) technology. If the emissions come from biomass - and then the acronym becomes BECCS instead. BECCs are currently not available on a large enough scale.

Biochar is also defined as negative emissions. It is carbon dioxide that is sequestered as carbon and stored in the soil and remains there for hundreds or thousands of years. There are several super cool small-scale plants here.

Reforestation is today considered to be the option that is enough we can actually use, right now. Tree planting is an important "technology" that globally produces negative emissions and, done right, tree planting also has the potential to contribute to climate adaptation and the global goals locally.

We do not have time to reduce our emissions alone. We must also ensure that the carbon dioxide emissions already in the atmosphere are absorbed.