If we want a 50% of keeping global warming to within 1.5º C (as compared to the pre-industrial average), we need to reduce CO2e emissions by 50% by 2030. And we need to reach net-neutral emissions by 2050.
This is an extremely hard problem. To understand why it is so difficult, take a second to look at the IPCC figure (above-right). This depicts the share of global emissions from different sectors: Transportation, Industry, Buildings, Agriculture and Land Use, and Electricity and Heat generation.
Notice that the "grid" (i.e. electricity and heat production) only accounts for 25% of total emissions. If we replaced all coal, gas, and oil plants with renewable sources, we would only be part of the way there. In this light, the central challenge of decarbonization is this:
To solve decarbonization, we have to solve many problems, many big, small, technical, political, financial, and behavioral problems.
Most people have some feeling for the broad, big-picture problem areas: fossil fuels are bad; cows are bad; solar and wind are good; we need more batteries... Unfortunately, these kinds of feelings are hardly a useful way to finding real solutions. To make headway with problems as complex as these, we need to chunk them into smaller, bite-sized pieces. Everyday progress is solving many little problems: it's removing a regulatory block that makes it hard to install solar, it's making percentage point improvements on battery costs, and it's allocating bits of public spending towards installing charging stations.