The Earth's climate has been, and always will be changing naturally. The sun's energy reaching the Earth's surface (insolation), volcanoes, and greenhouse gases are the main factors in forcing climate changes, and all three are always in play. It's not just one, it's all three all the time. And all three are always changing. When the Earth's orbit moved it further from the sun, as it does periodically, insolation dropped, causing an ice age and CO2 levels had little effect even if they were very high. As the Earth's orbit moved it closer to the sun, insolation increased and high CO2 levels would increase the warming. For the past 10k-11k years, insolation and CO2 levels have been relatively stready, but volcanic activity caused some short-lived climate changes like the Little Ice Age. Since about 1860, CO2 levels started to rise. Around 1950, CO2 levels had apparently risen high enough (300 ppm) to start AGW. And during the 1980's, CO2 levels and AGW had risen high enough to cause climate change. Right now CO2 levels are about 412 ppm and rising 2-3 ppm per year. If somehow we could reduce the CO2 level back down to the 1950 level of 300 ppm, AGW would probably stop and plant life would still thrive. If we had started 30-40 years ago, we might be there today. But, it's too late now.

I'm sure you remember how the tobacco industries hid the dangers of smoking for decades, and even targeted teens with ads that portrayed smoking as cool and sexy. Consequently, countless young people got hooked early and smoked their entire lives until they died from lung cancer. Well, the fossil fuel industries have borrowed the same playbook. They have been hiding the climate crisis for decades, and consequently, humanity will see a era of climate catastrophe unfold over the coming generations. It's already baked in the cake. They have been hiding it through a massive campaign of disinformation and propaganda spread via MSM and YouTube channels. An "ice age is coming," and "the world is cooling not heating" are part of that campaign.

However, the UN and the global elites have known since at least the end of WWII that global warming would lead to a climate crisis. They have also known that our current economic system that depends on infinite growth on a finite planet was not sustainable. They developed Agenda 21/30 as a framework for a sustainable civilization during an era of climate catastrophe. By the time this agenda has been implemented to near completion, fossil fuels will have been used up and we will have transitioned largely to renewable and nuclear energy. The climate catastrophe will depopulate the poorer undeveloped countries. The wealthier developed countries will have institutionalized population controls (two children per family limit) but will not have suffered nearly as much. In 1992, Severn Suzuki gave the world an early warning of the impending climate crisis, but not much has been done since then. That's why we have a climate crisis staring us in the face now. Greta is giving us a final warning. If we act on time, we will end up with a zero-growth Agenda 21/30 society. The alternative is near-term human extinction, probably before 2100.

Dealing with the climate crisis will require a herculean mobilization of industry. We'll need to 1) install carbon removal and storage mods in coal-fired power plants to reduce emissions, 2) build many direct-air-capture plants around the world to remove CO2 from the atmosphere, and 3) restore natural carbon sinks (trees) on a massive scale. It'll cost in the trillions of dollars spread over decades, so governments will need to legislate funding. This won't happen unless the activists led by Greta are able to awaken and motivate enough people who pressure governments to act. Everything depends on the activists.