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The global CO2 rise: the facts, Exxon and the favorite denial tricks

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The basic facts about the global increase of CO2 in our atmosphere are clear and established beyond reasonable doubt. Nevertheless, I’ve recently seen some of the old myths peddled by “climate skeptics” pop up again. Are the forests responsible for the CO2 increase? Or volcanoes? Or perhaps the oceans?

Let’s start with a brief overview of the most important data and facts about the increase in the carbon dioxide concentration in the atmosphere:

  1. Since the beginning of industrialization, the CO2 concentration has risen from 280 ppm (the value of the previous millennia of the Holocene) to now 405 ppm.
  2. This increase by 45 percent (or 125 ppm) is completely caused by humans.
  3. The CO2 concentration is thus now already higher than it has been for several million years.
  4. The additional 125 ppm CO2 have a heating effect of 2 watts per square meter of earth surface, due to the well-known greenhouse effect – enough to raise the global temperature by around 1°C until the present.

Fig. 1 Perhaps the most important scientific measurement series of the 20th century: the CO2 concentration of the atmosphere, measured on Mauna Loa in Hawaii. Other stations of the global CO2 measurement network show almost exactly the same; the most important regional variation is the greatly subdued seasonal cycle at stations in the southern hemisphere. This seasonal variation is mainly due to the “inhaling and exhaling” of the forests over the year on the land masses of the northern hemisphere. Source (updated daily): Scripps Institution of Oceanography. [Read more…] about The global CO2 rise: the facts, Exxon and the favorite denial tricks

The claim of reduced uncertainty for equilibrium climate sensitivity is premature

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A recent story in the Guardian claims that new calculations reduce the uncertainty associated with a global warming:

A revised calculation of how greenhouse gases drive up the planet’s temperature reduces the range of possible end-of-century outcomes by more than half, …

It was based on a study recently published in Nature (Cox et al. 2018), however, I think its conclusions are premature.

[Read more…] about The claim of reduced uncertainty for equilibrium climate sensitivity is premature

References

  1. P.M. Cox, C. Huntingford, and M.S. Williamson, "Emergent constraint on equilibrium climate sensitivity from global temperature variability", Nature, vol. 553, pp. 319-322, 2018. http://dx.doi.org/10.1038/nature25450

Forced Responses: Jan 2018

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This is a new class of open thread for discussions of climate solutions, mitigation and adaptation. As always, please be respectful of other commentators and try to avoid using repetition to make your points. Discussions related to the physical Earth System should be on the Unforced Variations threads.

Unforced Variations: Jan 2018

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Happy new year, and a happy new open thread.

In response to some the comments we’ve been getting about previous open threads, we are going to try separating out OT comments on mitigation/saving the planet/theories of political action from ones related to the physical climate system. This thread remains a place for climate science issues, questions, & news, but we have started a new Forced Responses thread where people can more clearly discuss mitigation issues. We realise that sometimes it can be hard to cleanly separate these conversations, but hopefully folk can try that out as a new year’s resolution!

Note we will be updating the Model/Data comparisons over the next few weeks as the various observational data sets get updated for calendar year 2017. The main surface temperature datasets will be released around Jan 18.