In Eric Worrall's logically fallacious opinion - aerosols and climate change

Some science deniers do not understand science. Some of them have made it their life's mission to not understand it. Others devote their retirement to writing nonsense on climate conspiracy blogs such as WUWT. One feature that's shared almost universally among climate conspiracy theorists is they excel at logical fallacies.

Figure 1 | Aerospan sun photometry station, Birdsville Australia. Credit: CSIRO

Take Eric Worrall at WUWT. In recent months Anthony Watts has been using Eric to write most of his very silly blog articles. Eric takes pride in his inability to reason. Today (archived here) he's written about a letter from a senior NASA scientist Brent Holben to Alex Wonhas, a senior CSIRO executive of CSIRO, which was published in the Sydney Morning Herald.  Dr Holben was requesting that CSIRO not stop its important work in researching aerosols.

CSIRO Aerospan Network

CSIRO maintains eight stations around the country which monitor aerosols (the Aerospan network). As it says on the CSIRO website:

The role of aerosol in moderating climate change is well recognised, both through the scattering and absorption of incoming solar radiation by aerosol (the so-called direct effect) and via the modification of cloud droplet size and cloud lifetime (the indirect effect). In the past, uncertainty as to the magnitude of these effects stemmed largely from the lack of a comprehensive knowledge of regional and seasonal characteristics of aerosol across the globe.

Sun photometer networks, such as the Aerosol Robotic Network (AERONET) operated by NASA GSFC, were established in the 1990s to address that need. At that time, little attention had been focused on the characterisation of Australian continental aerosol, even though Australia is a globally significant source of biomass burning aerosol, contributing about 10 per cent of global emissions, largely from seasonal savanna burning in the tropical north.

In addition, the Australian deserts are well known as sources of wind-blown dust, and constitute the largest dust source in the Southern Hemisphere. Although distant from most major aerosol sources in the Northern Hemisphere, it is clear that Australia is the recipient of long-range transport of aerosol from external sources, for example biomass burning in Southeast Asia.

Figure 2 | Aerospan station locations in the Australian network. Source: CSIRO.

This network contributes to a global monitoring program and helps in the validation of satellite observations. The current CEO of CSIRO, Larry Marshall, is behaving like a climate science denier. He doesn't appreciate the importance of the program to Australia and cares little about international obligations for climate research. (He is only a venture capitalist after all and has never managed an organisation of the size, mission or status of CSIRO. He is floundering about and making all sorts of bad decisions to stop a heap of climate science research. An example of the Peter Principle, having risen to the level of his incompetence.)

Over at WUWT Eric Worrall doesn't understand the first thing about aerosols, or climate models, or scientific uncertainty. In a flurry of fallacious logic he wrote:

In my opinion climate scientists can’t have it both ways.

If aerosols are an important but poorly understood component of the climate system, then climate modellers do not have the ability to forecast global climate – the science is not settled.

If poor understanding of aerosols does not have a significant impact on climate forecasts, then they are not that important.

One logical fallacy that you'll see immediately is Eric's "can't have it both ways". It's a non sequitur. His conclusion does not follow from his premise. The fact that scientists don't have a detailed understanding of everything does not mean that they have no understanding of anything. It doesn't mean that they don't have the ability to make climate projections. They have and they are quite close to observations.

Figure 3 | Global mean surface temperature and CMIP5. The CMIP5 multi-model mean has been updated with recent forcings and GISTemp data includes 2015 observations. Source: Stefan Rahmstorf, updated from Mann15 article in Nature's Scientific Reports.

Another point you may have noticed is that about the only people who get confused about what is and what isn't settled science are the climate science deniers. If all of science was understood and there was nothing new to be learnt, then there'd be no new research. Much science has been "settled" for a long time. For example, it is well known that adding greenhouse gases to the air will heat up the planet. Many aerosols have a cooling effect on the planet. Some don't.

It is not necessary to understand each and every detail of aerosol physics to be able to model climate. The large scale climate models used for climate projections plot climate change on a grid that is larger in size than small-scale interactions, such as cloud micro-physics. Reasonable approximations are built into climate models, based on what is understood. CSIRO's AeroSpan network is helping scientists improve the understanding of which aerosols are in the atmosphere, how they disperse, and the impact different aerosols have on climate.

The other crucial point to make is the importance of ongoing monitoring. Our climate is changing probably ten times faster than any change in the past 65 million years. If we don't keep our eyes on the changes, how can we hope to know:

• what we are going to have to adapt to, and
• how our efforts to mitigate are shaping up?

From the WUWT comments

There are only two so far. philipcolet doesn't understand what is settled and what is not, just like Eric Worrall. He planted his own goalposts, they aren't those of NASA, and then decided they had shifted. It's an example of a strawman logical fallacy:

May 13, 2016 at 3:34 am
If the science is settled, and everyone is so sure the world is going to end, no need for hundreds of climate scientists. Suddenly, the science is no longer settled, and more scientists are needed.
NASA Seems to have discovered something that moves faster than the speed of light: Goalposts.

daveandrews723 sees everything in terms of money. He doesn't know that in most cases, climate scientists could probably earn at least as much if not more in the private sector than they can earn as a scientific researcher. The work might not be as fulfilling, however:

May 13, 2016 at 3:40 am
The government climate scientists have rationalized that their work is so important to the future of mankind that money should not be a consideration. Plus the pay is pretty good in the meantime (better than they’d make outside of government)

References and further reading

• 'Dismay': NASA scientist appeals to CSIRO not to cut global climate efforts - article by Peter Hannam at Sydney Morning Herald
• Aerospan aerosol characterisation - CSIRO
• Aerosol Robotic Network - Goddard Space Flight Centre, NASA
• The 5 telltale techniques of climate change denial - article by John Cook at CNN, July 2015
• Marginalised, alienated and put upon: climate science deniers are not innocent - HotWhopper, August 2015