How have the levels of carbon dioxide in the atmosphere recently changed?

Answer 1

The level of carbon dioxide in the atmosphere has recently increased.

The planet has maintained a level of CO2 of around 280 parts per million by volume (ppmv) for the past few thousand years. This was 0.028% of the atmosphere.

Direct measurements of CO2 over recent decades show that CO2 has risen to nearly 390 ppmv. This is an increase of 39%, and observations show CO2 is still rising.

The change is small relative to the entire volume of the atmosphere, but the relative volume of CO2 has increased dramatically. This doesn't mean that historical CO2 has been constant forever. If we go back hundreds of thousands of years, we can see changes that correspond to past ice ages. Historical CO2 data is derived from ice cores in the Antarctic. The oldest record is from Vostok, but there are many others, and they show close agreement with each other.

Historical CO2 levels are not relevant to the theory of climate change, but they do allow us to constrain climate sensitivity. By examining how much past changes in temperature changed CO2 concentrations, and how those changes in CO2 also changed temperature, we can learn more about the feedback between temperature and CO2.

One common misconception is that the ocean can absorb all the CO2 we emit. This is clearly false, since CO2 levels are rising, and the extra CO2 can be traced to fossil fuel sources.

A:The planet has never maintained any consistent level of CO2. Vostok records are our only historical source of direct measurements and show variations of between 260 and 320 ppm over the past 650K years. Vostok is a remote location in Greenland where we obtain ice samples. Currently CO2 levels here are about 280 ppm.

Direct measurements of CO2 over recent decades show that CO2 has risen to nearly 390 ppmv in some areas such as Manua Loa Hawaii. This is an increase of 39%, and observations show CO2 is still rising there. The trend has been observed since 1979, when measurements started. The current belief is that this trend started as long as 10,000 years ago, shortly after the current warming trend started. Glacial samples agree that from a planetary stand point with this theory.

The change is extremely small relative to the entire volume of the atmosphere, but the relative volume of CO2 appears to have increased by as much as 0.007%. Historically CO2 levels have always followed temperature by as much as 800 years. Historical CO2 data is derived from ice cores in the Antarctic. The oldest record is from Vostok.

There is a general consensus that the levels of CO2 have indeed climbed and we understand this is a normal condition due to the warming of our oceans (The largest absorption of CO2 occurrs in our oceans). Wamer water absorbs CO2 more slowly. The current warming of our planet started roughly 10,200 years ago and could be a significant factor for this increase.