First things first: Does atmospheric CO\u2082 historically lag the Earth\u2019s temperature?<\/p>\n
Based on ice core data from the Vostok Station in Antarctica, Georgios Florides and Paul Christodoulides (see section 2.4)<\/a> provide a positive answer to our question: During the last three glacial-interglacial transitions over the past 420,000 years, an elevation in CO\u2082-concentration lags global warming.<\/p>\n That is to say, CO\u2082 cannot have initiated<\/em> the end of historical glacial periods. What seem to explain the rise and fall of ice ages are the Milankovitch cycles<\/a>. These cycles describe the effects of deviation in the Earth\u2019s eccentricity<\/a>, obliquity<\/a> and precession<\/a> on how much insolation is reaching the Earth\u2019s surface.<\/p>\n L\u00e9a Gest et al.<\/a> draw the same conclusion when looking specifically at the end of the last deglaciation<\/a>, which occurred between 18,000 and 11,000 years ago. Going even further back in time to the late Pliocene, i.e. between 2.3 and 3.3 million years ago, Vakulenko Nadezda et al.<\/a> also reveal a positive answer when considering large timescales of 100,000 to 500,000 years.<\/p>\n In a more recent past, such causal relationship between temperature and CO\u2082 continues to exist. According to Ole Humlum<\/a> et al., fluctuations in global temperature exert a significant influence on atmospheric CO\u2082 variations between January 1980 and December 2011.<\/p>\n Fig. 1. Ice core data from the Antarctic Vostok Station signal that CO\u2082 lags temperature during deglaciation periods. (Source: weather-research.com<\/a>).<\/p><\/div>\n Since these findings go against most climate reports in the last 150 years, it is no surprise then that our climate contrarian rushed to bring up this argument. And it looks like he is not the only one<\/a>.<\/p>\n It appears from his reasoning, though, that our climate change denier neglects feedback systems and radiative forcing<\/a>.<\/p>\n Feedback systems can amplify the initial cause of climate change. As a case in point, the augmented CO\u2082 levels due to global warming further push the temperature up through the greenhouse effect. Radiative forcing looks at the difference between the radiation absorbed by the Earth and that sent out back into space.<\/p>\n For instance, Jeremy Shakun et al.<\/a> demonstrate that increased atmospheric CO\u2082 levels generally precede more elevated temperatures during the course<\/em> of the last deglaciation. When examining multi-millennial timescales in Vostok Antarctica and Greenland ice cores, Knut Seip et al.<\/a> identify several periods within the last 400,000 years during which global warming lags CO\u2082.<\/p>\n Even though he is right in that CO\u2082 did not cause the onset<\/em> of deglaciation periods, our climate skeptic forgets about physics<\/a>, which tells us that CO\u2082 is a greenhouse gas<\/a>. This means that CO\u2082 molecules absorb the longer wavelengths of radiation\u200a\u2014\u200ainfrared radiation\u200a\u2014\u200aemitted by the Earth.<\/p>\n Absorption takes place because a CO\u2082 molecule possesses an oscillating dipole by virtue of its bending and asymmetric stretching abilities<\/a>. The dipole ensures that the vibrating molecule creates an oscillating electric field, which interacts with the electromagnetic field of infrared light.<\/p>\n Subsequently, CO\u2082 molecules effectively prevent a good portion of these specific electromagnetic waves from escaping into space. Instead, they re-emit that heat back into the atmosphere. Part of that heat finds its way back to the Earth\u2019s surface and warms it. This is in essence the greenhouse effect<\/a>.<\/p>\n Fig. 2. Annual mean energy fluxes in the Earth\u2019s climate system (in W\/m\u00b2). (Source: Paper Stephen Schwartz<\/a>).<\/p><\/div> One way of measuring the greenhouse effect, according to the related study<\/a> of Fig. 2, is taking the difference between the emitted longwave energy flux at the surface, i.e. 385 W\/m\u00b2, and the exiting flux at the top of the atmosphere, i.e. 239 W\/m\u00b2. This gives us a greenhouse effect of \u00b1146 W\/m\u00b2.<\/p>\n We have now established that atmospheric CO\u2082 can indeed shape our natural climate.<\/p>\n But what our climate skeptic categorically repudiates is the role that human-produced CO\u2082 emissions play in global warming. In other words, he denies the enhanced<\/em> greenhouse effect by fossil fuel emissions.<\/p>\n Let us now sink a little deeper in the lion\u2019s climate change denying den.<\/p>\n The entire controversy in the human-caused climate change debate largely evolves around the following reasoning. Due to fossil fuel-driven industrialization processes, higher levels of anthropogenic CO\u2082 emissions, especially since the 1960s and 1970s, propel the atmospheric CO\u2082 concentration upwards, which, successively, brings about global warming. More elevated temperatures may then inflict a devastating impact upon our climate and ecosystem.<\/p>\n Fig. 3. Top: CO\u2082 Atmospheric Concentration (Source: University of California<\/a>). Middle and Bottom: Log scale of fossil fuel CO\u2082 emissions and global surface temperature relative to 1880\u20131920. (Source: Paper by Hansen, J. et\u00a0al.<\/a>).<\/p><\/div> As a reminder, the skeptical claim at the beginning of this article holds that, because of the historical evidence that atmospheric CO\u2082 lags temperature, man-made CO\u2082 emissions cannot alter our climate system.<\/p>\n First off, we already confirmed in the previous section that CO\u2082 can actually precede global warming.<\/p>\n What we need to look at now, is how man-made CO\u2082 emissions relate to CO\u2082 concentration.<\/p>\n In science, the causal link between fossil fuel emissions and atmospheric CO\u2082 is shown via the isotopic signature \u03b4\u00b9\u00b3C<\/a>, which involves the ratio \u00b9\u00b3C\/\u00b9\u00b2C. As the process of burning fossil fuels shrinks<\/a> the relative amount of isotope \u00b9\u00b3C, we expect to see a declining tendency in \u03b4\u00b9\u00b3C, given the recent surge in global emissions (Fig. 3). Indeed, referring to Fig. 4, R.J. Francey et al.<\/a> state that, \u201cThe overall decrease during the last 1\u20132 centuries is attributed to anthropogenic emissions.\u201d<\/p>\n Interestingly, already back in 1976, Charles Keeling et al.<\/a> put forward that, \u201cthe observed long term trend of rising CO\u2082 appears clearly to be in response to increasing amounts of industrial CO\u2082 in the air on a global scale.\u201d<\/p>\n In lending further support to the link between fossil fuel emissions and atmospheric CO\u2082, David Hendry and Felix Pretis<\/a> recognize a significant human contribution of industrial production processes to the recent burgeoning atmospheric CO\u2082 levels between 1982 and 2003. Michael Raupauch et al.<\/a>, too, corroborate the essential role of anthropogenic drivers in CO\u2082 build-up for the period 1959\u20132006.<\/p>\n Fig. 4. The complete record of CO\u2082 and the isotopic signature \u03b4\u00b9\u00b3C. (Source: Paper R.J. Francey et\u00a0al.<\/a>).<\/p><\/div> But I already hear our climate contrarian asking: Does all that we spew out of CO\u2082 emissions in the air really stays in the air? The CO\u2082 airborne fraction<\/a> displays precisely that and helps us answer this question.<\/p>\n The airborne fraction is important as \u201cit provides the gateway between the anthropogenic forcing and the atmospheric response of the carbon cycle\u201d, according to Raupauch et al<\/a>.<\/p>\n More technically, it is defined<\/a> as \u201cthe rate of increase of atmospheric CO\u2082 concentration divided by the rate of released CO\u2082 by anthropogenic emissions\u201d.<\/p>\n Currently, about 45%<\/a> of our total human-produced CO\u2082 emissions stays in the atmosphere, while the Earth\u2019s land, i.e. the land sink, and oceans, i.e. the ocean sink, absorb 31% and 24%, respectively.<\/p>\n Fig. 5. Fossil fuel CO\u2082 emissions (1959\u20132015) together with the El Ni\u00f1o\u2013Southern Oscillation cycle (lower) and the airborne fraction (upper inset). Variability in the land uptake is correlated with the El Ni\u00f1o cycle with more fossil fuel CO\u2082 remaining in the atmosphere during El Ni\u00f1o periods as a result of reduced land uptake and the opposite in La Ni\u00f1as. (Source: Paper Piers Sellers et\u00a0al.<\/a>).<\/p><\/div> The controversy is partly reflected in the debate on whether the airborne fraction is moving up or has remained constant.<\/p>\n On the one hand, Wolfgang Knorr<\/a> provides the claim that the fraction of anthropogenic CO\u2082 emissions remained constant since 1850. Given a higher amount of fossil fuel CO\u2082 emissions in the last few decades (see Fig. 3), this could imply that the Earth\u2019s carbon cycles<\/a> absorb with enhanced efficiency large chunks of what we put out there. Although Mikkel Bennedsen et al.<\/a> encounter the same result for the period 1959\u20132016, the research also demonstrates evidence for a dwindling<\/em> rate at which ocean and land take up CO\u2082. In contrast, Margreet van Marle et al.<\/a> affirm an improved<\/em> efficiency in that same rate, while Emanuel Gloor et al.<\/a> argue against a deteriorating rate.<\/p>\n On the other hand, Michael Raupauch et al.<\/a> register an upwards trend between 1959 and 2006 in the total airborne fraction, which comprises man-made emissions from both fossil fuels and land-use change. According to the authors, a rising fraction asserts that the growth in total emissions surpasses that of carbon sinks. And more authors arrive at similar conclusions, including Josep Canadell et al.<\/a>, Corinne Le Qu\u00e9r\u00e9 et al.<\/a> and Peter Rayner et al<\/a>.<\/p>\n When we turn our attention to the existing climate models, Chris Jones et al.<\/a> indicate that, \u201cAll models agree that the future airborne fraction depends strongly on the emissions profile with higher airborne fraction for higher emissions scenarios.\u201d<\/p>\n If we conservatively assume that the airborne fraction has remained fairly constant since the mid-nineteenth century, it may be tempting for our climate change denier to think that it will also stay this way in the future. As a result, he might conclude that, regardless of the amount of fossil fuel CO\u2082 emissions that we pump into the atmosphere, the natural carbon cycle will keep the climate system in check.<\/p>\n But such conclusion would be impetuous. Per definition, the airborne fraction depends on the land and ocean sinks. In turn, these carbon sinks are themselves dependent on climate<\/a>. Such climate-carbon cycle feedback<\/a> suggests that, \u201cAn increase in atmospheric CO\u2082, which results in a climate change via the greenhouse effect, may therefore change the carbon storage in the ocean and on land and therefore modify the CO\u2082 concentration of the atmosphere producing a further change in climate.\u201d<\/p>\n In other words, a constant airborne fraction does not imply that fossil fuel emissions cannot cause an alteration in the carbon cycle. And this goes to the heart of the climate change controversy.<\/p><\/blockquote>\n Fig. 6. Schematic view of a climate-carbon cycle feedback. (Source: Paper Richard Williams et\u00a0al.<\/a>).<\/p><\/div> Perhaps all the above does not impress much our climate skeptic. After all, he might argue, the atmospheric CO\u2082 concentration has been higher in the past as well as the variation in temperature. And the planet is still here, right?<\/p>\n I come back to higher CO\u2082 levels in the next section. Let us first have a closer look at the historical record of the Earth\u2019s temperature.<\/p>\n Christopher Field<\/a> indeed points out that the Earth has gone through comparable and even greater temperature fluctuations in the past 65 million years. But the catch is that they spread out over tens of thousands and even millions of years and did not materialize within a timespan of several decades.<\/p>\n What is unprecedented in the past 100 years is the rate of change in temperature.<\/em> As Field elucidates, \u201cWe find periods of Earth\u2019s history where the global temperature change was of similar magnitude, but the rate was an order of magnitude slower.\u201d<\/p>\n This unparalleled rate of global warming is reflected in what scientists have coined the \u201chockey stick<\/a>\u201d effect. That phenomenon refers to the temperature\u2019s evolution whereby it was gradually receding in the past thousands of years to only take a drastic upturn in the twentieth century. The corresponding graph bears the resemblance of a hockey stick (see Fig. 7).<\/p>\n Fig. 7. Estimated average global temperatures as anomalies relative to 1880\u20131920 for the Holocene period. (Source: Paper by Hansen, J. et\u00a0al.<\/a>).<\/p><\/div>\n Let us now bring back feedback systems and radiative forcing into the discussion.<\/span><\/p>\n What is equally unique about the recent past is that CO\u2082 and other greenhouse gasses now seem to act as an anthropogenic radiative forcing mechanism on the global temperature instead of a feedback system to external natural forcing.<\/span><\/figure>\n External natural forcing mechanisms can produce disruptions in the Earth\u2019s energy balance, eliciting climate change. Examples of such external forcing include solar radiation variation<\/a>, the Milankovitch cycles, cosmic rays<\/a> or the upper atmosphere\u2019s absorption of ultraviolet light<\/a>.<\/p>\n Usually, atmospheric CO\u2082 acts as a feedback mechanism to climate change, as we have seen previously. However, in light of the temperature\u2019s unmatched behaviour in the recent past, the intricate relationship between fossil fuel emissions and CO\u2082 concentration as well as the knowledge that CO\u2082 can precede global warming, atmospheric CO\u2082 has taken on the role of external radiative forcing whereby man-made emissions are reinforcing the greenhouse effect.<\/p>\n In fact, the smoking gun for human-driven global warming<\/em> appears to be the following. The empirical evidence of the rising temperature records since the second half of the twentieth century can only be explained by incorporating anthropogenic CO\u2082 emissions into the climate models. David Archer of the University of Chicago clarifies this to us in greater detail in below video.<\/p>\n https:\/\/www.youtube.com\/watch?v=OSaCI5S8cKs&t=5s<\/a><\/p>\n<\/div>\n If a climate contrarian works out an alternative explanation for the recent climate change, they have two tasks: firstly, to disprove why anthropogenic CO\u2082 emissions explicate so well the ascending temperature trend in the models and, secondly, to prove how the provided explanation fits the data.<\/p>\n As a reassuring side note on the robustness of climate modelling, Zeke Hausfather et al.<\/a> highlight that, \u201c[the] climate models published over the past \ufb01ve decades were generally quite accurate in predicting global warming in the years after publication, particularly when accounting for differences between modeled and actual changes in atmospheric CO\u2082 and other climate drivers.\u201d<\/p>\n Let us move on to the second part of the climate skeptical statement: if CO\u2082 is truly responsible for a runaway climate effect, then we would have witnessed such effect on various historical occasions, especially during times of much higher CO\u2082 levels than today.<\/p>\n What is essentially being misunderstood here is that atmospheric CO\u2082 is not the only driver of climate change. And to some extent, the physics of the greenhouse effect<\/a> is also being challenged.<\/p>\n As a matter of fact, a runaway climate effect did not occur at any moment in history, but not because the greenhouse effect is not physically real.<\/p>\n It is good to bear in mind that higher CO<\/em>\u2082 concentrations in the past in absence of such runaway effect do not imply that CO<\/em>\u2082 does not cause global\u00a0warming.<\/em><\/p><\/blockquote>\n For the record, at January 18 2020, the Mauna Loa Observatory registered a CO\u2082 concentration of 413.39 parts per million (ppm)<\/a>. The last time that this level was attained or exceeded happened well before the human species roamed the Earth. Yet, it is no sinecure to determine an exact time window. For instance, Greta Bartoli et al.<\/a> demarcate a time period within the Pliocene, i.e. between 2.0 and 4.6 million years ago, whereas Aradhna et al.<\/a> tie that timeframe to the Middle Miocene, i.e. 11.6 to 16.0 million years ago.<\/p>\n The greenhouse effect was in full swing also back then. But the point that our climate contrarian is overlooking is that the climate conditions were very different at different times in history.<\/p>\n Around 3 million years ago during mid-Pliocene, with CO\u2082 levels oscillating between 365 and 415 ppm for several thousands of years, the global temperatures even outstripped those of the pre-industrial era by 2\u20133\u00b0C, according to Adam Csank et al<\/a>. And the Arctic temperatures were superior to current measurements by no less than approximately 11\u201316\u00b0C. Harry Dowsett et al.<\/a> contend that greenhouse forcing was indeed one of the main drivers of this global warming. Nonetheless, a runaway climate effect did not ensue because of time-specific climate conditions that were primarily dominated by a larger obliquity signal<\/a> from the Milankovitch forcing.<\/p>\n Fig. 8. Estimates of Pliocene atmospheric CO\u2082 with pre-industrial and present day levels (horizontal dashed lines) for comparison; dark blue dots, \u03b4\u00b9\u00b3C<\/a>; green band, \u03b4\u00b9\u00b9B<\/a>; pink band, alkenone<\/a>; red band, alkenone<\/a>; orange band, stomata<\/a>; yellow band, \u03b4\u00b9\u00b9B<\/a>; blue band, Ba\/Ca<\/a>. (Source: Paper Alan Haywood et\u00a0al.<\/a>).<\/p><\/div>\n At the Middle Miocene Climate Optimum (MMCO) around 15 million years ago, CO\u2082 concentration measured roughly between <\/span>430 ppm<\/a> and <\/span>800 ppm<\/a>, with global temperatures <\/span>3\u00b0C above<\/a> current levels. <\/span>Yougui Song et al.<\/a> suggest that also now higher CO\u2082 levels may be responsible for this global warming. Again, a runaway climate effect was not observed, in view of other more potent climate change drivers, such as <\/span>a shift in solar insolation<\/a> caused by a transition from an obliquity-driven to a eccentricity-driven forcing, <\/span>deep oceanic circulation variations<\/a> and <\/span>a CO\u2082 drawdown<\/a> by organic carbon burial in the eastern equatorial Pacific. The MMCO is then followed by the <\/span>cooler<\/a> Middle Miocene Climate Transition (MMCT).<\/span><\/figure>\n Fig. 9. Proxy-based CO\u2082 records during the Miocene. (Source: Paper Shunchuan Ji et\u00a0al.<\/a>).<\/p><\/div>\n Lastly, we stumble upon a more extreme example during the Late Ordovician, circa 444 million years ago. It is estimated that the atmospheric CO\u2082 reached astounding levels between <\/span>2240<\/a> and <\/span>5600 ppm<\/a>. Despite the elevated CO\u2082 concentrations, a runaway climate effect did not come to pass. At the contrary, a period of glaciation surprisingly arose around 440 million years ago for which possible explanations include <\/span>a 4.5% reduced solar luminosity<\/a> relative to present levels, <\/span>the combination of reduced volcanic activity and continuing silicate rock weathering<\/a> and <\/span>enhanced oceanic circulation<\/a>.<\/span><\/figure>\n Fig. 10. A: Comparison of the best-guess atmospheric CO\u2082 predictions through the Phanerozoic of GEOCARB III with a smoothed representation of the proxy record (10 my time-steps are used in both curves). B: Intervals of glacial (dark blue) or cool climates (light blue). (Source: Paper Dana Royer et\u00a0al.<\/a>).<\/p><\/div><\/figure>\n Another point that we have to make is that positive feedback in the context of global warming usually does not equal a runaway effect<\/a>.<\/p>\n In a positive feedback system<\/a>, the effect strengthens the cause, which generates a stronger effect. Such unstable systems are more often than not characterized by exponential growth or chaotic behaviour.<\/p>\n Suppose for a moment that we live in a world without any anthropogenic CO\u2082 emissions, but with climate conditions similar to present times. And now we put a substantial amount of fossil fuel emissions into the atmosphere. A simplified positive climate feedback works as follows. Adding fossil fuel emissions to the atmosphere enhances the greenhouse effect. As a result, the additionally trapped infrared radiation boosts the Earth\u2019s temperature, which warms the oceans<\/a> and thaws previously frozen permafrost<\/a>. These events discharge more CO\u2082, which causes the temperature to climb even further.<\/p>\n However, against the backdrop of global warming, as this positive feedback system advances with time, the incremental effect of every feedback loop diminishes in strength. And partly, we owe it to physics: the Stefan-Boltzmann law<\/a>, which is derived from Planck\u2019s law<\/a>, acts as a negative feedback mechanism<\/a>. It states that, for a given rise in the Earth\u2019s temperature, the equivalent outgoing longwave infrared radiation\u200a\u2014\u200aheat\u200a\u2014\u200aincreases exponentially. Insomuch as a part of that outgoing heat is siphoned off from the Earth\u2019s atmosphere into space, the Stefan-Boltzmann law partially counters the greenhouse effect.<\/p>\n In other words, under the scenario of a single perturbation of human-produced CO\u2082 emissions, the entire climate system tends to evolve towards a new unique thermodynamic stable state<\/a>, which is controlled by negative feedbacks, at a higher temperature<\/a>.<\/p>\n Does this then mean that the Earth will also progress towards a new steady state<\/a> regardless of the quantity of anthropogenic emissions that we release into the atmosphere? No, simply because of the fact that we keep on adding<\/em> more CO\u2082 to the atmosphere.<\/p>\n That is, we are continually introducing one perturbation after the other into the Earth\u2019s climate system. We are de facto depriving the Earth of the possibility to form a relatively stable state. And this is the crux of the climate change debate.<\/p><\/blockquote>\n Fig. 11. A schematic representation of a positive feedback mechanism triggered by anthropogenic CO\u2082 emissions. (Source: Climate Council<\/a>).<\/p><\/div><\/figure>\n It is perhaps not unwise to mention that a positive feedback can prompt a runaway scenario, if the reinforcing signal is powerful enough. Put differently, this might occur if the expanding cumulated amount of anthropogenic CO\u2082 emissions in the atmosphere warms the Earth until a point of no return.<\/p>\n A runaway climate effect is what transpired on planet Venus<\/a>. With a rising temperature, a greater amount of water vapor enters the atmosphere. In turn, this raises the chances for water vapor to come into contact with ultraviolet radiation, which breaks up the water molecules. Key is that hydrogen atoms move fast enough to escape into space\u200a\u2014\u200aboth Venus and Earth have matching escape velocities<\/a>. In this way, water was gradually lured away from Venus, leaving it without the means to maintain a biosphere.<\/p>\n Yes, there is academic research that does not grant much significance to an anthropogenic contribution to the climate change narrative or even questions the physics of the greenhouse effect. Specific literature includes, among others, Georgios Floridos<\/a>, Jamal Munshi<\/a>, Thomas Allmendinger<\/a>, Hermann Harde<\/a> or Mike Hulme et al.<\/a><\/p>\n Nevertheless, there is also global growing confidence<\/a> among scientists that a human influence is noteworthy in global warming. As a matter of fact, this meta-study by John Cook et al<\/a>. even finds a 97% consensus in published climate research on the importance of anthropogenic drivers in climate change.<\/p>\n The authors furthermore pinpoint that this consensus is not widely known. And that is precisely the reason, they argue, why the global population is susceptible to the climate skeptics\u2019 argument that there is no scientific consensus on human-induced global warming.<\/p>\n I am grateful for the conversation that I had with our climate contrarian, for it allowed me to explore the lion\u2019s den and ponder about the debate around human-driven climate change.<\/p>\n![\"Vostok](\"https:\/\/i0.wp.com\/acircleisround.com\/wp-content\/uploads\/2020\/01\/Schermafbeelding-2021-09-14-om-09.25.36.png?resize=629%2C382&ssl=1\")
Physics Is Everywhere<\/strong><\/h2>\n
![\"Annual](\"https:\/\/i0.wp.com\/cdn-images-1.medium.com\/max\/800\/1%2AlZJ3Iz424Orf2nyRPwhwwA.png?resize=575%2C353&ssl=1\" "\\"Annual")
The Contested Relevance of Anthropogenic CO<\/strong>\u2082 Emissions<\/strong><\/h2>\n
![\"Trend](\"https:\/\/i0.wp.com\/cdn-images-1.medium.com\/max\/800\/1%2AOIJote3s1bjtf_uu17O-ww.png?resize=629%2C595&ssl=1\" "\\"Trend")
Our Human Fingerprint<\/strong><\/h4>\n
![\"The](\"https:\/\/i0.wp.com\/cdn-images-1.medium.com\/max\/800\/1%2AX5GOWHZH1X0tCRObLoer3A.png?resize=508%2C394&ssl=1\" "\\"The")
The Crucial Point of Intersection<\/strong><\/h4>\n
![\"Fossil](\"https:\/\/i0.wp.com\/cdn-images-1.medium.com\/max\/800\/1%2AUBDK1xCG77t5OVvxnVC4dQ.png?resize=591%2C383&ssl=1\" "\\"Fossil")
![\"Schematic](\"https:\/\/i0.wp.com\/cdn-images-1.medium.com\/max\/800\/1%2AYJuMYYcIesvHfYMThRxi9w.png?resize=604%2C269&ssl=1\" "\\"Schematic")
Rising Temperatures<\/strong><\/h4>\n
![\"Estimated](\"https:\/\/i0.wp.com\/cdn-images-1.medium.com\/max\/800\/1%2ANwk6KvqzloBTY7eBrruJKg.png?resize=520%2C322&ssl=1\" "\\"Estimated")
\n
\nThe Climate Is Not Going Anywhere. Or Is\u00a0It?<\/strong><\/h2>\n
Runaway Climate: Not So\u00a0Much<\/strong><\/h4>\n
![\"Estimates](\"https:\/\/i0.wp.com\/cdn-images-1.medium.com\/max\/800\/1%2ALggBJiIR6a-INMe1WGUyUg.png?resize=586%2C319&ssl=1\" "\\"Estimates")
![\"Proxy-based](\"https:\/\/i0.wp.com\/cdn-images-1.medium.com\/max\/800\/1%2Av8kLTbkHec-kFSyDRCp_uw.png?resize=488%2C322&ssl=1\" "\\"Proxy-based")
![\"Best-guess](\"https:\/\/i0.wp.com\/cdn-images-1.medium.com\/max\/800\/1%2ANHGsCxyCODFFvUqbUF1p-A.png?resize=453%2C343&ssl=1\" "\\"Best-guess")
Planck to the\u00a0Rescue<\/strong><\/h4>\n
![\"A](\"https:\/\/i0.wp.com\/cdn-images-1.medium.com\/max\/800\/1%2AKmsQkrAWRDeGn5hO-ChEhQ.png?resize=629%2C478&ssl=1\" "\\"A")
How Valid Is the Climate Change Denying Statement?<\/strong><\/h2>\n
Is the Knot Untangled?<\/strong><\/h2>\n