Countering Climate Skeptics

Countering Climate 'Skeptics' - Why Ignoring Climate Reality is Delusional
by Moses Seenarine, 11/16/17

In the face of insurmountable evidence, climate 'skeptics' such as Roy Spencer maintain that the climate system is insensitive to humanity’s GHG releases. Global warming deniers assert that the earth is not heating up. One frequent claim is that the Earth has not warmed recently, which it clearly has. Deniers refer to surface temperatures, which is only 2% of where the warming is going, and they have still warmed 0.2°C (0.36°F) over the last 15 years. 

Another common tactic is to question whether alteration of the climate is natural, or as Spencer argues, “If we don't know how much of recent warming is natural, then how can we know how much is manmade?” There is little doubt remaining and climate science is almost unanimous on this point. The IPCC AR4 report clearly states, "Most of the observed increase in global average temperatures since the mid-20th century is very likely [90% confidence] due to the observed increase in greenhouse gas concentrations.” 

The report continues, "It is extremely likely [95% confidence] more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the increase in greenhouse gas concentrations and other forcings together." Observational evidence shows that anthropogenic CO2 discharges are causing the climate to warm. Specifically, there is less heat escaping to space and larger amounts returning to Earth. Nights are warming faster than days, and winter is warming faster than summer. There is less oxygen in the air, and there are greater quantities of fossil fuel carbon in the air, trees, and coral. 

The Earth had about 0.6°C (1.08°F) average global surface warming over the past 60 years. During that time, the IPCC's best estimate is that GHGs have caused about 0.9°C (1.62°F) warming, which was partially offset by about 0.3°C (0.54°F) cooling from human aerosol pollution. 

Other natural external factors have had no net influence on global temperatures, in particular, solar activity has been flat since 1950. And since warm and cool ocean cycles cancel each other, internal variability has no long-term influence on average global temperatures. Equally, the urban heat island effect does not have a profound influence on the surface temperature record. Climate deniers falsely state that climate models are unreliable, and have failed in hindcast to explain the lack of a notable temperature rise over the last 30 plus years. The evidence is that global surface temperatures have climbed above 0.5°C (0.9°F) over the past 30 years, and this ascent is momentous. And, climate models have accurately reproduced this slope. 

It is the skeptics themselves who have done poorly, having universally predicted less warming than has been observed. McLean's prediction that 2011 would return to 1956-level temperatures sticks out in particular. And Akasofu predicted only a 0.5°C (0.9°F) rise between 2000 and 2100. Skeptics frequently question whether models can accurately predict future climate. Be that as it may, climatologists use observational and real world methods in their projections. 

One common reference climatologists use is warming from the enhanced greenhouse effect of a doubling of CO2, around 560 ppm, or the 'climate sensitivity' effect. Climate sensitivity incorporates feedbacks which can either amplify or dampen warming due to a doubling of CO2. This is salient because if sensitivity is low, as some climate skeptics argue, then the planet will warm slowly and humans will have extra time to adapt. On the other hand, if climate sensitivity is high, the Earth will warm more quickly and humans will have less time to respond and adjust. 

Observational evidence suggests that it is high. Paleoclimate data from ice cores and other sources across a range of geologic eras are very consistent, finding between 2°C and 4.5°C (3.6 – 8.1°F) global surface warming in response to doubled CO2. Climate models likewise reproduce these findings. However, climate projections have vastly underestimated the role that clouds play, and future warming could be far worse. A doubling of CO2 could result in a global temperature increase of up to 5.3°C (9.5°F) – far warmer than the 4.5°C older models predict. 

Excerpt from "Meat Climate Change: The 2nd Leading Cause of Global Warming," by Dr. Moses Seenarine.