The main cause of global warming remains CO2, which results from the burning of fossil fuels for electricity, heating, cooling and transport, as shown by the studies. Studies by the Potsdam Institute for Climate Impact show that the value of 405 coins per million (ppm) of carbon dioxide measured in the atmosphere in 2017 was last seen on Earth three million years ago. At that time, in the Pliocene era, before humans had evolved, the average surface temperature was 2 to 3 degrees Celsius above pre-industrial levels, and the average sea level was up to 25 meters above the current level. The International Energy Agency`s 2008 World Energy Outlook report describes a “baseline scenario” for the world`s energy future “that does not involve new government policies that go beyond those already adopted until mid-2008,” and then a “550 Policy Scenario” that adopts other policies, a mixture of “cap-and-trade systems, sectoral agreements and national measures.” In the baseline scenario, between 2006 and 2030, the world invests $26.3 trillion in energy supply infrastructure; In Scenario 550, an additional $4 trillion will be spent over this period, mainly for efficiencies that will save more than $7 trillion.  The last time the planet had a concentration of 300 to 400 ppm of CO2 in the atmosphere was during the middle pliocene, 3 million years ago – recently enough that the planet was not radically different from what it is today. At that time, temperatures were 2 degrees c to 3 degrees C (3.6 to 5.4 degrees F) above pre-industrial temperatures (although more than 10 degrees C warmer in the Arctic) and sea level was at least 15-25 meters higher. The forest has grown in northern Canada and the prairies are rich all over the world; the Sahara was probably covered with vegetation. Homo habilis (also known as “handy man”), the first type of the gay line and probably the first users of stone tools, got a taste of this climate when they took to the stage 2.8 million years ago. Homo sapiens appeared at least 400,000 years ago. Scientific advisors from the Intergovernmental Panel on Climate Change estimate that limit values imply an atmospheric concentration of CO2 of up to 450 coins per million (for 2 degrees) or 430 ppm (for 1.5 degrees).
Contributions to climate change, whether they cool or warm the Earth, are often described in terms of the strength of radiation or imbalance they bring to the planet`s energy balance. Today and in the future, anthropogenic carbon dioxide is thought to be the main ingredient in this constraint, and the contribution of other components is often quantified in the form of “parts-by-million carbon dioxide equivalents” (CO2e ppm) or increased/reduced carbon dioxide concentrations that would produce a similar radiation engine. CO2 levels over the last 400 million years.