Fighting global warming requires technologies that we don’t have

Global temperature change in 1850−2016

On April 22, 2016, participants in the Climate Conference in Paris signed the Paris Agreement , which regulates measures to reduce carbon dioxide in the atmosphere since 2020. Today, the Paris Agreement is the main hope of mankind to stop warming before we reach the “point of no return” as an irreversible process that sustains itself (warming will cause melting of glaciers and thawing permafrost, which will increase the amount of CO ₂ emissions, the greenhouse effect will increase, further warming will occur, and so on).

The purpose of the agreement is to keep the growth of the global average temperature below 2 ° C and “make an effort” to limit the temperature rise to 1.5 ° C (see spiral chart). To this end, the parties to the agreement agreed after the “as soon as possible” achievement of the peak of CO ₂ emissions to begin reducing carbon dioxide emissions.

Unfortunately, not everything is so simple. Reducing CO ₂ emissions may not be enough to stop the Earth warming up. This topic is addressed in the report on technologies of "negative emissions", compiled by scientists from more than 20 countries that are members of the Scientific Advisory Board of European Academies. By "negative emissions" is meant the purification of the atmosphere from greenhouse gases, first of all - carbon dioxide.

In their report, academicians once again say well-known things: at the moment humanity is not making enough efforts to stop global warming. We didn’t even come close to the trajectory that would limit the heating of the atmosphere to 2 ° C.

Worse, recently scientists have been discussing the theory that even reducing CO ₂ emissions will not be enough to stop the heating coil. Climatologists believe that we have already driven ourselves into a rather difficult situation - little time is left. And now, in order to fit into the 2 ° C framework, it will be necessary not only to reduce emissions, but also to actively remove greenhouse gases from the atmosphere, otherwise the process of heating the planet will become irreversible.

This poses a difficult question for humanity: will we be able to develop and scale technologies for removing CO ₂ from the atmosphere in a fairly short period of time, before the irreversible warming up has begun? The report discusses seven ways to remove CO ₂ from the atmosphere:

• Reforestation
• Rational soil treatment to increase the carbon content there
• Bioenergy with carbon capture and storage (BECCS)
• Extreme weathering (when silicates or carbonates dissolve in rainwater, CO _{2 is} absorbed from the atmosphere)
• Direct air trapping and carbon storage (DACCS)
• Ocean fertilization (plankton and other plants capture CO ₂ from the atmosphere and convert it into organic matter)
• Carbon Capture and Storage (CCS)

For each of these technologies, scientists publish a realistic analysis and forecast. Unfortunately, the forecasts are disappointing.

To reach the trajectory of limiting heating within 2 ° C, by 2050 at least 11 billion tons of CO ₂ must be removed from the atmosphere annually to compensate for emissions. Scientists believe that in practice these indicators will be difficult to achieve for various reasons. For example, the restoration of forests in the required amount to bind carbon dioxide from the atmosphere will require sowing new forests from 320 million to 970 million hectares, which is 20-60% of the arable land of human civilization. At the same time, it takes decades for forests to grow, there is a risk of CO ₂ release as a result of fires and other problems. There are successful examples of restoration: for example, China has invested more than $ 100 billion in forest restoration on an area of ​​434,000 km² . But these are isolated examples.



Experts believe that only some of these options can be scaled and removed from the atmosphere a maximum of 3-4 billion tons of carbon dioxide. But this is a theoretical possibility. In reality, none of these options are currently progressing on a global scale and are not developing at a sufficient pace. It would seem that reforestation and carbon accumulation in the soil seem to be the simplest options. But in fact, humanity at the moment is doing the exact opposite: it cuts down forests and contributes to soil degradation. Because of this, carbon dioxide emissions are only increasing, not decreasing.

Scientists believe that in order to prevent further global warming, it will be necessary not only to reduce CO ₂ emissions, but also to apply the whole arsenal of technologies that are available to mankind.