Does temperature control atmospheric carbon dioxide concentrations?
A record of temperature and atmospheric CO2 from Antarctic ice cores shows the tight relationship between the two over the past , Assuming that the relationship between CO2 concentrations and .. USHCN Temperature Adjustments vs Atmospheric CO2 content graph is. Davis, W.J. The relationship between atmospheric carbon dioxide concentration and global temperature for the last million years.
Second, the idea that there might be a lag of CO2 concentrations behind temperature change during glacial-interglacial climate changes is hardly new to the climate science community. Indeed, Claude Lorius, Jim Hansen and others essentially predicted this finding fully 17 years ago, in a landmark paper that addressed the cause of temperature change observed in Antarctic ice core records, well before the data showed that CO2 might lag temperature. In that paper Lorius et al.
Thus, both CO2 and ice volume should lag temperature somewhat, depending on the characteristic response times of these different components of the climate system. Ice volume should lag temperature by about 10, years, due to the relatively long time period required to grow or shrink ice sheets. Several recent papers have indeed established that there is lag of CO2 behind temperature.
Still, the best published calculations do show values similar to those quoted by Barton presumably, taken from this paper by Monnin et al.
But the calculations can only be done well when the temperature change is large, notably at glacial terminations the gradual change from cold glacial climate to warm interglacial climate.
So it is not as if the temperature increase has already ended when CO2 starts to rise. Rather, they go very much hand in hand, with the temperature continuing to rise as the the CO2 goes up.
In other words, CO2 acts as an amplifier, just as Lorius, Hansen and colleagues suggested. Now, it there is a minor criticism one might level at Gore for his treatment of this subject in the film as we previously pointed out in our review.
The record of temperature shown in the ice core is not a global record. It is a record of local Antarctic temperature change. The rest of the globe does indeed parallel the polar changes closely, but the global mean temperature changes are smaller.
The lag between temperature and CO2. (Gore’s got it right.) « RealClimate
This is a critical point. We cannot explain the temperature observations without CO2. But CO2 does not explain all of the change, and the relationship between temperature and CO2 is therefore by no means linear.
- Climate Science Glossary
- Rising Global Temperatures and CO2
That is, a given amount of CO2 increase as measured in the ice cores need not necessarily correspond with a certain amount of temperature increase. But as illustrated in the figure below, simply extrapolating this correlation forward in time puts the Antarctic temperature in the near future somewhere upwards of 10 degrees Celsius warmer than present — rather at the extreme end of the vast majority of projections as we have discussed here.
Global average temperature is lower during glacial periods for two primary reasons: Again, this was all pretty well known inat the time of the Lorius et al. It is to be noted that the same models predict a significant delay until equilibrium is reached, due to the large heat capacity of the Southern ocean. This is in very good agreement with the data, which show very modest warming over Antarctica in the last years.
In summary, the ice core data in no way contradict our understanding of the relationship between CO2 and temperature, and there is nothing fundamentally wrong with what Gore says in the film. Most of these important negative feedbacks are not adequately represented in state-of-the-art climate models.
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What is more, many related and totally ignored! Clearly, therefore, any number of combinations of these several negative feedbacks could easily thwart the impetus for warming provided by future increases in the air's CO2 content.Why don't CO2 and temperature correlate perfectly?
Growth-enhancing effects of CO2 create an impetus for cooling. Carbon dioxide is a powerful aerial fertilizer, directly enhancing the growth of almost all terrestrial plants and many aquatic plants as its atmospheric concentration rises. And just as increased algal productivity at sea increases the emission of sulfur gases to the atmosphere, ultimately leading to more and brighter clouds over the world's oceans, so too do CO2-induced increases in terrestrial plant productivity lead to enhanced emissions of various sulfur gases over land, where they likewise ultimately cool the planet.
In addition, many non-sulfur-based biogenic materials of the terrestrial environment play major roles as water- and ice-nucleating aerosols; and the airborne presence of these materials should also be enhanced by rising levels of atmospheric CO2. Hence, it is possible that incorporation of this multifaceted CO2-induced cooling effect into the suite of equations that comprise the current generation of global climate models might actually tip the climatic scales in favor of global cooling in the face of continued growth of anthropogenic CO2 emissions.
Rising Global Temperatures and CO2 | Climate Central
There is no evidence for warming-induced increases in extreme weather. In fact, many studies have revealed that the numbers and intensities of extreme weather events have remained relatively constant over the last century of modest global warming or have actually declined. Costs of damages from these phenomena, however, have risen dramatically; but this phenomenon has been demonstrated to be the result of evolving societal, demographic and economic factors.
Elevated levels of atmospheric CO2 are a boon to the biosphere. In lieu of global warming, a little of which would in all probability be good for the planet, where do the above considerations leave us? Simply with the biospheric benefits that come from the aerial fertilization effect of atmospheric CO2 enrichment: And these benefits are not mere predictions. Already, in fact, they are evident in long-term tree-ring records, which reveal a history of increasing forest growth rates that have closely paralleled the progression of the Industrial Revolution.
It also inhibits the growth of algae that consume CO2. Other factors held constant, increasing ice cover will lower the CO2 content of the atmosphere.
Of course, the processes identified above do not operate in isolation of one another. Sometimes they act synergistically and sometimes antagonistically. Much remains to be learned about these processes, and how they differed during ice ages compared to conditions that we observe today. The Sigman et al. One thing is certain: The leading actors involved physical, chemical and biological processes in the ocean.
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