There are large regions of the globe where observations indicate there has been no warming (even cooling) during the last decades to century. Climate models rooted in the assumption that fossil fuel emissions drive dangerous warming dismiss these modeling failures and project temperature increases of 3° – 10°C by 2100 for these same regions anyway.
Four decades of Southern Ocean cooling
After warming from the 1940s to the mid-1970s, the Southern Ocean has been cooling since the late-1970s, which has consequently resulted in an increase in sea ice extent (Fan et al., 2014; Purich et al., 2018; Latif et al., 2017; Turney et al., 2017 ).
In their paper entitled “Natural variability of Southern Ocean convection as a driver of observed climate trends”, Zhang et al. (2019) suggest that the Southern Ocean cooling was driven by natural processes.
“Observed Southern Ocean surface cooling and sea-ice expansion over the past several decades are inconsistent with many historical simulations from climate models. Here we show that natural multidecadal variability involving Southern Ocean convection may have contributed strongly to the observed temperature and sea-ice trends.”
Climate models, in contrast, had projected a rapid warming and significant decreases in sea ice extent during the last few decades.
Image(s) Source: Zhang et al., 2019
The East-Central U.S. has been cooling (about -0.6°C) since the 1950s
“We present a novel approach to characterize the spatiotemporal evolution of regional cooling across the eastern U.S. (commonly called the U.S. warming hole), by defining a spatially explicit boundary around the region of most persistent cooling. The warming hole emerges after a regime shift in 1958 where annual maximum (Tmax) and minimum (Tmin) temperatures decreased by 0.46°C and 0.83°C respectively.”
Image Source: Partridge et al., 2018
“From 1910- 1949 (pre-agricultural development, pre-DEV) to 1970-2009 (full agricultural development, full-DEV), the central United States experienced large-scale increases in rainfall of up to 35% and decreases in surface air temperature of up to 1°C during the boreal summer months of July and August … which conflicts with expectations from climate change projections for the end of the 21st century (i.e., warming and decreasing rainfall) (Melillo et al., 2014).”
Image Source: Alter et al., 2017
Climate models project 3°C – 10°C warming in the Midwest (U.S.) by 2100
Even though climate models failed to simulate the last 50 to 100 years of temperatures for this region, hindcasting a dramatic warming instead of the observed cooling, the projections for 2100 are still predicated on CO2 emission scenarios (RCP4.5, RCP8.5) as the determinant of regional surface temperatures. Consequently, the regional models project a warming of 3°C – 10°C over the next 80 years.
“For the two most widely used greenhouse gas concentration scenarios, Representative Concentration Pathways (RCP) 4.5 and 8.5 (Moss et al. 2008) (representing “medium” and “high” twenty-first century greenhouse gas concentration trajectories respectively), the Midwestern United States is projected to experience profound changes in climate by 2100, especially for (T). Projections for annual mean T over the Midwestern United States from 31 global climate models (GCMs) for the RCP8.5 scenario show an ensemble mean increase in T of about 6.5 °C (11.7 °F) by 2100 relative to the historical 1971–2000 baseline (Fig. S1) (Byun and Hamlet 2018). The projected change in the annual ensemble mean T for RCP4.5 over the Midwestern United States is about 3.3 °C (5.9 °F) by 2100 relative to the 1971–2000 baseline. The upper tail of the annual mean T distribution, represented by the 97.5th percentile of the 31 GCM projections for RCP8.5 (i.e., a “worst-case” scenario), is nearly 10 °C (18 °F) warmer than the historical baseline by 2100.”
Image(s) Source: Hamlet et al., 2019
The North Atlantic hasn’t warmed since the 1800s
Image Source: Grieman et al., 2018
Image Source: Birkel et al., 2018
Climate models project 3°C warming in the North Atlantic by 2100
“Recent studies have documented the development of a warming deficit in North Atlantic sea surface temperatures (SST) both in observations of the current climate (Rahmstorf et al. 2015; Drijfhout et al. 2012) and in future climate simulations (Drijfhout et al. 2012; Marshall et al. 2015; Woollings et al. 2012). This “North Atlantic warming hole” (NAWH) is characterized in the observed record as a region south of Greenland with negative trends in SSTs of 0.8 K century-1 (Rahmstorf et al. 2015). In fully coupled global climate model (GCM) future simulations, the NAWH is seen as a significant deficit in warming within the North Atlantic subpolar gyre (Marshall et al. 2015; Winton et al. 2013; Gervais et al. 2016). This local reduction in future warming is communicated to the overlying atmosphere and may impact atmospheric circulation (Gervais et al. 2016), including the North Atlantic storm track (Woollings et al. 2012).”
Image Source: Gervais et al., 2018
Hansen (2013): CO2 emissions will cause 20°C of global warming by ~2130
Back in 1989, Dr. James Hansen, the former head of NASA, predicted that New York City’s West Side Highway would be underwater within 20 years due to rapid global warming and the consequent rising sea levels.
A few decades later (2012), Hansen was the lead author of a paper published by The Royal Society (2013) that indicated ever-growing fossil fuel emissions would lead to a nearly five-fold rise in atmospheric CO2 concentrations (to 1,400 ppm) within 118 years.
He then projected this CO2 increase and presumed 9 W m-2 forcing would cause a global surface temperature warming of 20°C by about 2130, with 30°C warming at the poles.
Image Source: Hansen et al., 2013
“Let us now verify that our assumed fossil fuel climate forcing of 9 W m−2 is feasible. If we assume that fossil fuel emissions increase by 3% per year, typical of the past decade and of the entire period since 1950, cumulative fossil fuel emissions will reach 10 000 Gt C in 118 years [2012 + 118 years = ~2130 C.E.] … [T]he fossil fuel source required to yield a 9 W m−2 forcing may be closer to 5000 Gt C, rather than 10 000 Gt C.”
“9 W m−2 forcing requires approximately 4.8×CO2 [1400 ppm] … Our calculated global warming in this case is 16°C, with warming at the poles approximately 30°C. Calculated warming over land areas averages approximately 20°C. … Such temperatures would eliminate grain production in almost all agricultural regions in the world. Increased stratospheric water vapour would diminish the stratospheric ozone layer. More ominously, global warming of that magnitude would make most of the planet uninhabitable by humans.”
“Given the 20°C warming we find with 4.8×CO2 [1400 ppm], it is clear that such a climate forcing would produce intolerable climatic conditions even if the true climate sensitivity is significantly less than the Russell sensitivity, or, if the Russell sensitivity is accurate, the CO2 amount required to produce intolerable conditions for humans is less than 4.8×CO2 [1400 ppm].”
“Are there sufficient fossil fuel reserves to yield 5000–10 000 Gt C? Recent updates of potential reserves, including unconventional fossil fuels (such as tar sands, tar shale and hydrofracking-derived shale gas) in addition to conventional oil, gas and coal, suggest that 5×CO2 (1400 ppm) is indeed feasible.”
Given the documented modeled forecast failures and lack of extreme or dangerous warming in recent decades, is there good reason to assume that Hansen’s prediction of a 20°C warming over the next 110 years will be realized?
At what point do modeling failures lead to a reconsideration of the forcing mechanisms?
January 14, 2019 at 05:39AM