Big foot-shoot:  New baseline shows SLOWER warming

The galoots behind the study below seemed to have been unhappy that 19th century steam trains might have affected the baseline against which global warming was measured.  They argued that temperatures in the period 1720-1800 would be a better criterion for what the temperature was before industrial influences cut in.

So they did the work of getting their new baseline temperature.  But what did they find? They found that the temperature in this pre-industrial period was "likely 0.55–0.80°C cooler than 1986-2005".  That compares with the usual agreed figure of about two thirds of a degree for global warming so far.

So at the lower end the new baseline shows LESS warming than previous studies.  They were a little bit cowardly, however, in that they stated a range rather than a single figure.  Previous authors have chosen a single most likely figure.

It's a bit rough but we could take an average of their two extremes as a single figure.  In that case we are back to the two thirds of a degree already accepted. So we are left with two possible conclusions from their study.  In the modern warming period, the amount of warming is uncertain or that it is still just about the two thirds already agreed.

But here's the killer: The conventional estimate of warming shows warming of two thirds of a degree over a period of around 100 years -- which is certainly a trivially slow warming.  But the baseline in the new work is around 300 years ago.  So if a change of two thirds of a degree over one century is trivial, what is the same change over a 300 year period?  It looks like these guys have really shot warmism in the foot.

But in their usual way, most Warmists will simply choose the starting point that suits them.  Sad for them that an earlier starting point did not help.

The authors must have known they were on dangerous ground so they included the El Nino effect (2015/2016) in their estimate of current temperature.  But that is rubbish and is increasingly being recognized as such.  But it's the only way they could get their final estimate of a one degree rise

But in the end, what the work below shows is that the temperature today is very similar to the temperature of 300 years ago.  Not the desired message, I think

Estimating changes in global temperature since the pre-industrial period

Ed Hawkins et al.


Better defining (or altogether avoiding) the term ‘pre-industrial’ would aid interpretation of internationally agreed global temperature limits and estimation of the required constraints to avoid reaching those limits.

The United Nations Framework Convention on Climate Change (UNFCCC) process agreed in Paris to limit global surface temperature rise to ‘well below 2°C above pre-industrial levels’. But what period is ‘pre-industrial’? Some-what remarkably, this is not defined within the UNFCCC’s many agreements and protocols. Nor is it defined in the IPCC’s Fifth Assessment Report (AR5) in the evaluation of when particular temperature levels might be reached because no robust definition of the period exists. Here we discuss the important factors to consider when defining a pre-industrial period, based on estimates of historical radiative forcings and the availability of climate observations. There is no perfect period, but we suggest that 1720-1800 is the most suitable choice when discussing global temperature limits. We then estimate the change in global average temperature since pre-industrial using a range of approaches based on observations, radiative forcings, global climate model simulations and proxy evidence. Our assessment is that this pre-industrial period was likely 0.55–0.80°C cooler than 1986-2005 and that 2015 was likely the first year in which global average temperature was more than 1°C above pre-industrial levels. We provide some recommendations for how this assessment might be improved in future and suggest that reframing temperature limits with a modern baseline would be inherently less uncertain and more policy-relevant.


No comments:

Post a Comment

All comments containing Chinese characters will not be published as I do not understand them