More Scientific Evidence For CO2’s Dubious Climate Impact Emerges
Image Source: Robertson and Chilingar, 2017
According to the most basic precepts of anthropogenic global warming (AGW), variations in CO2 concentrations exert significant control on sea surface temperatures, glaciers, sea levels, and generalized climate dynamics (i.e., precipitation patterns).
In particular, high CO2 concentrations, driven by human activity, are presumed to cause dangerously warming ocean waters, rapid glacier melt and sea level rise, and overall disruption to the Earth’s biosphere.
Newly published scientific papers wholly undermine this popularized conceptualization.
In fact, according to Bertrand et al. (2017), there has been a “marked cooling” of sea surface temperatures in the southernmost South America region during the last ~800 years — 3°C to 4°C colder than during the Medieval and Roman warm periods — that has continued unabated into “the most recent decades”.
Furthermore, abrupt glacier melt periods during Holocene warming events (as well as rapid glacier advances during Holocene cooling events) that easily exceed modern glacier morphology occurred in this region without any significant changes in CO2 concentrations.
To top it off, estimates of global sea levels during the last 4,000 years indicate that modern variability has been modest, at best. Since 1900, sea levels have changed by less than 0.2 of a meter (IPCC, 2013). During the Holocene, sea levels rose and fell by meters over a span of centuries.
In other words, the much higher CO2 concentrations that exist today relative to the last 10,500 years have effectively had no impact on sea surface temperatures, glacier melt, or sea levels.
During the last 4000 years, particularly low [sea surface temperature] values occur at 3500-3300 cal yr BP and during the most recent decades, and high values persisted between 2400 and 1600 cal yr BP.
[I]t is likely that the abrupt increases in SST around 3300-3200 and 2400-2200 cal yr BP participated in triggering the meltwater events at 3250-2700 and 2000-1200 cal yr BP, respectively. … [O]ur sediment record clearly shows that CDI outlet glaciers melted rapidly at 3250-2700 and 2000-1200 cal yr BP, but re-advanced to calving locations relatively soon afterward (Neoglacial III and IV).
[T]he marked cooling of the last ~800 years may have very little to do with meltwater input and may rather represent the regional decrease in ocean temperatures during the last ~900 years (Caniupan et al., 2014).
Another new paper published by Oliveira et al. (2017) suggests that climate dynamics — precipitation, annual temperature, and forest cover changes — in the Mediterranean/Western Europe/North Atlantic region “have no apparent relationship to atmospheric CO2 concentration”. CO2 forcing is even characterized as “negligible” for this region. Instead, climate dynamics are primarily induced by changes in solar activity.
[T]he millennial-scale vegetation changes in SW Iberia under warm interglacial climate conditions might be essentially generated by hydrological changes primarily induced by insolation [solar variability], as they are reproduced in the simulations despite the absence of ice sheet dynamics and all associated feedbacks in our experiments.
The transient simulations under the combined effect of insolation and CO2 indicate that the interglacial vegetation and climate dynamics over SW Iberia have no apparent relationship to atmospheric CO2 concentration, as suggested by the pollen-based reconstructions. Although the direct impact of CO2 changes on the vegetation growth is not included in the model, a prominent example for this negligible CO2 forcing is given by its relatively high concentrations over the end of the interglacials, in particular for MIS 1 and MIS 11c, while the forest cover, annual temperature, and annual precipitation achieved minimum values.
We find that the vegetation and climate changes at this time scale are mainly driven by astronomical forcing, in particular [solar] precession, in agreement with the strong impact of precession on the climate of the Mediterranean region south of 40°N.
The negligible impact of CO2 concentration variability on the Mediterranean/Western Europe/North Atlantic climate has also been documented by other scientists for recent decades.
According to models, the dramatic rise in human CO2 emissions after the 1940s should have had a discernible effect on climate. And yet for this region, it has not. Temperatures are no warmer now than they were in the mid-20th century despite this ostensibly strong human influence.
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