Oh, there are plenty. First of all, actual energy production with fossil fuel. Second, better insulation/ventilation of existing houses to reduce heating/AC costs. While we are at it, we can fit solar panels on roofs, it will give us more electricity hence less fossil fuel to burn. Electric cars too, the tech is already there. Steel production (and other heavy industry) accounts for 8% of global emissions afaik. Meat production estimates vary a lot: from 9% to 35% or so.

I know it is very controversial, but I'd rather go vegan than give up air travel.

Electricity production with coal.

From the top of my head is a two digit number, but I’m currently suffering from the aforementioned jetlag… so let check with that French guy jancovisi. He has a utterly pragmatic approch.

https://jancovici.com/en/climate-change/ghgs-and-us/how-do-g...

See : « CO2 emissions by activity since 1971 »

Transports comes third after power, and industrie.

As per someone above:

">emissions tend to do more damage at high altitude than they do at ground level

I've always been a bit dismissive of aviation as a carbon emissions contributor because globally it only accounts for around 2%. Thanks for pointing this out, I was unaware of this fact. Is the relationship between altitude and warming effect known? Are we talking linear or something worse?"

We should target industries where going 100% green only increases costs and doesn't result in a worse product or service, e.g., switching power plants from fossil fuels to renewables.