Co2 concentrations in the air had begun to be measured in 1958. It stood at 316 parts per million then, but had touched 400 parts per million by 2016.
Natural sources of CO2, from forest fires to soil and plant respiration and decomposition, are much bigger — about 30 times larger than what mankind produces each year. But natural sinks, like plant growth and the oceans, tend to soak that up. The excess produced by mankind’s thirst for energy is what makes the CO2 concentration in the air go up and up. Once in the air, that gas can stay there for millennia.
As atmospheric carbon dioxide concentrations increase, there will be near-term or “transient” warming (range of projected temperatures in blue) which is only about half as large as the total or “equilibrium” warming (range of projected temperatures in red) that will eventually occur if concentrations are stabilized at those values.
That implies that the current level of concentration of CO2 in the atmosphere of 400 + parts per million, which caused 1 degrees C warming in its transient phase, will end up causing 2.5 C warming as it stabilizes in the atmosphere.
The graphs on the right show how changes in greenhouse gas emissions (top panel) are
related to changes in atmospheric concentrations (bottom panel). It would take an 80%
reduction in greenhouse gas emissions (green line in top panel) to stabilize atmospheric
concentrations (green line, bottom panel).
That implies to me that if today we miraculously cut down our emissions by 80 %, THEN our atmospheric concentrations would stabilize at the current level, resulting in a final temperature rise of 2.5 degrees C.
My husband asked that given current projections, when are we expected to raise the earth's overall surface temperature further, and by how much. The graph below gives the current projections. By 2030, we may be warmer by 2 degrees C overall, as the latent equilibrium warming described above may add to the 1.5 degrees C we are expected to hit anyway.
By 2040, we may be hitting 2.5 degrees C, combining the 2 degrees C with latent warming. And by 2050, 3 degrees C temperature rise, overall. Current trends are on track to raise temperatures, overall, by 5.5 degrees C by 2100 if drastic measures are not taken immediately.
Based on current understanding, the warming levels we are gaining are expected to be nearly irreversible for more than 1,000 years.
That implies to me that if today we miraculously cut down our emissions by 80 %, THEN our atmospheric concentrations would stabilize at the current level, resulting in a final temperature rise of 2.5 degrees C.
My husband asked that given current projections, when are we expected to raise the earth's overall surface temperature further, and by how much. The graph below gives the current projections. By 2030, we may be warmer by 2 degrees C overall, as the latent equilibrium warming described above may add to the 1.5 degrees C we are expected to hit anyway.
Based on current understanding, the warming levels we are gaining are expected to be nearly irreversible for more than 1,000 years.
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