Can we (humans) do anything about it?

The thing we can - must - do about it is immediately and rapidly reduce emissions of CO2 and other greenhouse gases.

This means looking across all areas that emit greenhouse gases, that is not only energy production but agriculture, manufacturing and transportation, and seeking reductions. For energy production, this means capturing more CO2 at source, and moving more energy production to sources that don’t emit CO2 in the first place (solar, wind, nuclear) or could even reduce CO2 (using biomass energy, where biomass that has absorbed CO2 from the atmosphere is burnt for energy, and the CO2 captured and stored). For agriculture it means reducing the huge impact of cattle (as Bill Gates pointed out [32] , if cattle were a country, they would be the third largest offender behind China and the US).

The Paris Agreement of 2015 is the commitment of all countries to do this, each country setting both its own goals (known as National Determined Contributions), and the means of achieving them. These aren’t binding, there’s no penalty clause, but it’s a stated commitment (bit like a marriage). In 2015, the US (under the Obama administration) committed the US to reducing greenhouse gas emissions by between 26-28% by 2025, relative to emissions in 2005. [2]

Given the rate of reduction during the previous 10 years (about 12%) we were on track to meet that goal when the agreement was signed.

Since the Paris Agreement, both NCA4 and the IPCC special reports are quite clear on the level of action needed to address. They looked at what the world needs to do to limit warming to 2 °C, or even just 1.5 °C.

• To limit warming to 2 °C, by 2030 we need to reduce CO2 emissions by 25%, and by 2070 be net zero.
• To limit warming to 1.5 °C, by 2030 we need to reduce CO2 emissions by 45%, and by 2050 be net zero.

(reductions are relative to 2010 levels).

Others put it even more strongly - Harvard scientist James Anderson believes “Recovery is all but impossible without a World War II-style transformation of industry” [3]

So to limit warming to 1.5 °C - the stated goal - countries need to do more than committed to in the Paris Agreement.

But what of another approach? Continue as we are, pumping CO2 in the atmosphere, and then later remove it, and shove it somewhere. Certainly there is research into carbon capture technology, but it has yet to be proven at the scale needed. And given that the storage is generally in an underground geological formation, often an old oil or gas well, there’s something insane about digging carbon up from the ground, burning it, then trying to recapture all of the carbon again and burying it back in the exact same place! At least, insane whilst there are alternative sources of energy as yet underutilized. There is also research into climate engineering (a scary term if I ever heard one). For example, pumping aerosols into the upper atmosphere can increase the percentage of radiation reflected back to space, much as occurs following large volcanic eruptions.

Whilst it is looking increasingly likely that such drastic approaches might be necessary, the more we can dramatically reduce emissions, the less we will need to incur the costs and huge risks of such extreme measures.