That new land has thin, acidic, waterlogged soil with few nutrients, is unstable and prone to collapse (see thermokarst), with photoperiods not suited for what those crops need. What's next is a world of hurt, especially if approached with techno-optimist myopia.

In the global share of primary energy solar is this very small player (less the hydro, much less then coal, or natural gas, or oil), data from 2024.

https://ourworldindata.org/energy-production-consumption

How much does the increase solar production decrease world-wide CO2 emmisions? Because CO2 emissions in 2025 were still increasing. I see that in many growing countries solar power is not seen as a replacement for fossil power, but as an addition to fossil power.

https://www.iea.org/reports/global-energy-review-2026/co2-em...

There are many places where the photosynthesis is not limited in CO2 amounts, but in amounts of other elements, like iron (about one third of the surface ocean), phosphorus (tropical rainforests).

https://www.us-ocb.org/microbial-iron-limitation-otz/

https://www.jircas.go.jp/en/release/2022/press202218

Warming of Siberia could increase methane leakage, which could increase global warming and then increase in methane leakage, the “methane time bomb”

https://www.smithsonianmag.com/smart-news/ticking-timebomb-s...

In the Earths history, we know of periods of emission of large magnitudes of CO2. One of them is Permian–Triassic extinction event (level of atmospheric carbon dioxide rose from around 400 ppm to 2,500 ppm), extinction of 57% of biological families, 62% of genera, 81% of marine species, and 70% of terrestrial vertebrate species.

https://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extin...

Lets hope we don't reproduce the PT event.