Ian Plimer op-ed in The Australian again presents long list of false claims about climate

Pollution by plastics, sulphur and nitrogen gases, particulates and chemicals occurs in developing countries. That’s real pollution.

Strangely, Ian Plimer uses the «no true Scotsman» logical fallacy here to imply that because these forms of pollution are an issue, carbon pollution is somehow insignificant.

There are no carbon emissions

So absurd as to almost defy comment. Humans are burning coal, petroleum products, and natural gas. Very basic chemistry tells us that a bi-product of this is the creation of carbon dioxide gas.

There are plenty of reliable resources (such as the United Nations Inventory Submissions) that readers can check to find out that there are CO₂ emissions. Furthermore, in the last paragraph the author states himself that there are emissions (using China as an example).

If there were [carbon emissions], we could not see because most carbon is black.

Carbon dioxide, the main gas that makes up «carbon emissions», is colourless and odourless.

Most carbon is not black. Black carbon itself results from incomplete combustion of carbon-based fuel such as fossil fuels or biomass. Ironically, it is also a significant contributor to global warming due to its ability to reduce the albedo of ice-covered areas.

Great Barrier Reef bleaching that has really been occurring for hundreds of years

The recent paper that made this claim was some of the worst science to be published in a reputable journal in many years. The authors of all of the datasets they misused wrote the editors calling for the paper to be retracted but the journal decided not to do so. Instead, a rebuttal paper¹ provides all the reasons why that paper is wrong and should have been retracted.

• 1- Hoegh-Guldberg et al (2019) Commentary: Reconstructing Four Centuries of Temperature-Induced Coral Bleaching on the Great Barrier Reef, Frontiers in Marine Science

The reef’s overall habitat status has been downgraded to «poor» for the first time in this year’s Great Barrier Outlook Report, citing hundreds of peer-reviewed papers. The report considers the condition and outlook of coral reef habitats specifically to be very poor in the northern two-thirds. The assessment clearly states the greatest threat to the Great Barrier Reef’s long-term outlook is climate change.

fraudulent changing of past weather records

A lie, referring to the homogenisation of weather records to remove biases. This is nothing more than a conspiracy theory.

the ignoring of data that shows Pacific islands and the Maldives are growing rather than being inundated

The dynamics of shorelines of low-lying Pacific Islands are complicated and influenced by many local factors. Climate change and associated sea-level change are the underlying trend that will “win” over long time scales. There are many wiggles and local anomalies that, if taken out of context and analysed over short timescales, might hide the overall trend.

unsubstantiated claims polar ice is melting

What’s unsubstantiated about polar ice melting? We can literally sea Arctic sea ice decrease. Regarding ice caps, there are plenty of studies with different methodologies indicating Greenland and at least parts of Antarctica are losing ice.

This is wrong. Satellite measurements show a decline in Greenland and Antarctica ice mass balances.

any claim of unusual weather can be made sensational

Plimer deliberately conflates weather and climate.

We’ve had reefs on planet Earth for 3500 million years. They came and went many times.

Yes, and when they went away during periods of mass extinctions, they were gone for millions of years. Is Mr. Plimer suggesting doing away with the GBR for millions of years is an appropriate price to pay for short-term fossil fuel profits?

The big killer of reefs was because sea level dropped and water temperature decreased

No, reefs were lost during major extinction events caused by high levels of CO₂ and runaway warming. Sound familiar?

In the past, reefs thrived when water was warmer and there was an elevated carbon dioxide content of the atmosphere.

Marine heatwaves have been a major driver of coral bleaching¹.

• 1- Frölicher et al (2018) Marine heatwaves under global warming, Nature

Today’s reefs are suffering from the fast rates of change. Temperatures are rising too fast to adapt to these changes easily. This results in more frequent and more intense heatwaves and therefore mass bleaching. Much slower warming as in the geological record give ecosystems a chance to adapt. In addition, fast increases in CO₂ will reduce carbonate ions in the surface waters which makes the waters more corrosive. If CO₂ increases at slower rates, other (slow) feedbacks restore carbonate ions.

Reef material is calcium carbonate, which contains 44 per cent carbon dioxide. Reefs need carbon dioxide; it’s their basic food.

This is not correct. CO₂ dissolves in seawater, forming carbonic acid, bicarbonate ion, and carbonate ion. During these reactions, free hydrogen ions are released, which lower the seawater pH and result in ocean acidification. Corals form from calcium carbonate, however, due to the increase of dissolved CO₂ in seawater and the resulting increase in hydrogen ion, the dominance of dissolved CO₂ species shifts from carbonate ion to bicarbonate ion to maintain chemical equilibrium. This is nicely illustrated in the Bjerrum plot. Therefore, in fact, increasing CO₂ levels is not food for corals, but makes the dissolution of CaCO₃ more likely.

We are not living in a period of catastrophic climate change. The past tells us it’s business as usual.

Absent emission reductions, global mean temperature will likely rise by 3 to 5 °C by 2100 or so. That’s not business-as-usual. It’s a change of geological proportions, almost instantaneous on geological timescales. The last time the Earth was this warm was millions of years ago, and the face of the Earth was markedly different.

Current CO₂ concentrations have not been encountered by Earth for at least 3 million years. Last time the climate was in equilibrium with today’s CO₂ concentrations, sea levels were much higher (order of magnitude of 10 meters), temperatures were well beyond the Paris Agreement. The rates of change are unprecedented. Current rates of change in CO₂ are at least 10 times faster than in any records of past climate.

It has never been shown that human emissions of carbon dioxide drive global warming.

Literally the whole field of climate science for the last 30 years has shown this.

This is wrong and has been shown in multiple publications, including the IPCC fifth assessment report.

Mark Richardson, Postdoctoral scholar, Jet Propulsion Laboratory, California Institute of Technology:
Among other evidence, we have directly measured the amount of heating caused by CO₂, using instruments pointed at the sky¹. We know the CO₂ rise is due to human activity, and this heating is sufficient to explain the observed warming.

• 1- Feldman et al (2015) Observational determination of surface radiative forcing by CO₂ from 2000 to 2010, Nature

Climate models have been around 30 years. They have all failed.

See this previous Climate Feedback review for rebuttal.

Global warming is happening essentially as projected by climate models. The mean warming, the spatial and temporal pattern of that warming, the impact on the water cycle, etc.

Mark Richardson, Postdoctoral scholar, Jet Propulsion Laboratory, California Institute of Technology:
The models projected warming, with faster warming at the northern high latitudes. This page includes studies showing that Plimer’s statements are inaccurate.

Modellers assume carbon dioxide drives climate change

This is not an assumption. Modellers simply implement the basic laws of physics and chemistry into these numerical models, which then show what we’ve known for over a century—CO₂ is a powerful greenhouse gas, which has the potential to change the climate if its concentration in the atmosphere is significantly increased.

Mark Richardson, Postdoctoral scholar, Jet Propulsion Laboratory, California Institute of Technology:
This is false.

The models include quantum physics and the transfer of heat and radiation according to the laws of physics. They also include things like changing solar activity. That CO₂ is the single largest cause of CO₂ is an output of the calculations.

The role of the sun and clouds was not considered important by modellers. They are the major drivers for the climate on our planet.

The role of solar variations is considered in climate-model simulations of the past, and projections of future climate change¹.

Clouds are considered extremely important by all climate modellers. (See, for example, here.)

Variations in solar irradiance have caused only a very small change to the planet’s overall energy balance over the last century or so. On the other hand, greenhouse gas emissions have caused a much larger change to the planetary energy balance, and this has led to global warming.

Clouds provide an important feedback to climate change, but they cannot reasonably be described as a «driver» of climate change. There must be some other factor that causes the clouds to change. (E.g. changes in the surface temperature owing to greenhouse-gas emissions).

• 1- Matthes et al (2017) Solar forcing for CMIP6 (v3.2), Geoscientific Model Development

Mark Richardson, Postdoctoral scholar, Jet Propulsion Laboratory, California Institute of Technology:
This is false, and it’s just as false as the last time Plimer claimed this.

Solar activity and clouds are included in climate models. Here’s a paper from 2006 talking about how clouds are the largest source of uncertainty in the amount of future global warming¹.

• 1- Soden and Held (2006) An Assessment of Climate Feedbacks in Coupled Ocean–Atmosphere Models, Journal of Climate

We emit a trace atmospheric gas called carbon dioxide at a time in planetary history of low atmospheric carbon dioxide.

Ian Plimer contradicts himself within the same article, after previously claiming there are no carbon emissions.

Carbon dioxide levels today have exceeded 400 ppm (see measurements at Mauna Loa), whereas ice-core records show that such levels have not existed in the past 800,000 years (see data here).

The geological history of the planet shows major planetary climate changes have never been driven by a trace gas

This is incorrect. Concentrations of CO₂ and other trace gases are known to be important for climate change throughout Earth’s history, from the snowball Earth events hundreds of millions of years ago to the ice age cycles of the last million years. (In the latter case, changes in CO₂ concentration act as a feedback to changes in Earth’s orbit, but they must be considered in order to explain the observed changes.)

Climate change is normal and continual.

Mark Richardson, Postdoctoral scholar, Jet Propulsion Laboratory, California Institute of Technology:
Plimer’s argument is that «climate change is normal and continual» therefore we can’t or shouldn’t do anything about the current climate change that’s being caused by humans.

This is a bit like arguing that radiation is normal and continual, so if there was a risk of someone using nuclear weapons on your city then you shouldn’t try to do anything about that, either.

When cycles overlap, climate change can be rapid and large.

There is no evidence of any kind to suggest a combination of natural factors is in any way responsible for the current warming we are experiencing. Current warming is over 100% man-made.

Sporadic events such as supernovas[…] can also change climate.

No¹.

• 1- Dunne et al (2016) Global atmospheric particle formation from CERN CLOUD measurements, Science

volcanic eruptions can also change climate.

A non-sequitur. Volcanic eruptions cool the climate due to the emission of sulphate aerosols into the upper atmosphere. This is the exact opposite of the current warming we are experiencing.

The main greenhouse gas is water vapour[…]

The IPCC report clearly highlights that CO₂ is the most important greenhouse gas regarding the change in anthropogenic radiative forcing since 1750.

This entire paragraph is a non-sequitur. Water vapour’s role as a greenhouse gas is entirely irrelevant to the effect increasing atmospheric CO₂ concentrations are having on Earth’s radiative equilibrium.

What’s the point of all this? Is this somehow meant to convince readers that climate scientists don’t know about the water cycle and geophysical fluid dynamics? None of this contradicts the fact that increase greenhouse gas concentrations will warm the climate.

Carbon dioxide is a non-condensable atmospheric gas like nitrogen and oxygen

This is why it is more important than water vapour in forcing the climate to change.

If you add a lot of water vapour to the air, it rains out in hours to days, before it can trap enough heat to warm things up. When we burn fossil fuels, the amount of CO₂ in the air will remain higher for at least 100 years.

It sticks around for long enough to drive long-term changes in the climate.

Except that, unlike nitrogen and oxygen, carbon dioxide’s molecular structure allows it to absorb infrared radiation, thereby making it a greenhouse gas.

Without carbon dioxide, all life on Earth would die

And without water, humans would die but we still tend to avoid living under water.

This is one of the few things the author gets right. Unfortunately, he forgets the importance of «all things in moderation».

Mark Richardson, Postdoctoral scholar, Jet Propulsion Laboratory, California Institute of Technology:
This is ridiculous alarmism and irrelevant.

No one proposes removing all carbon dioxide from the atmosphere. It’s just that with more CO₂ in the atmosphere, Earth gets hotter and there are consequences of that.

Plants need almost three times today’s carbon dioxide content of the atmosphere to thrive. For decades horticulturalists have pumped carbon dioxide into glasshouses to increase yields.

Yes but in the natural world increased CO₂ concentration is associated with changes in climate that may be detrimental to plants (warming, changes in precipitation, etc.). In fact, there’s growing evidence that while increasing CO₂ has indeed been fertilizing vegetation globally in the last few decades, climate change is starting to negatively impact it.

In the past, warming has never been a threat to life on Earth. Why should it be now?

Maybe not slow, progressive warming. Abrupt warming probably is. There are past examples of that. Besides, the worry is not about «all life on Earth» (strawman argument): it’s first and foremost about human civilization, which has developed over the last 10,000 years in a very stable climate. A sedentary humanity with 8 billion people is likely going to suffer from a geological-scale +4 °C planetary warming within a couple centuries…

There are plenty of studies showing mass extinction events during past warming. Like during the Paleocene-Eocene Thermal Maximum, where warming was slower than today^1,2,3. The warming was eventually larger than we’ve seen so far, but it’s up to our policy choices as to whether we want to make things hotter than that extinction event or not.

• Arcila and Tyler (2017) Mass extinction in tetraodontiform fishes linked to the Palaeocene–Eocene thermal maximum, Proceedings of the Royal Society B
• Gibbs et al (2006) Nannoplankton Extinction and Origination Across the Paleocene-Eocene Thermal Maximum, Science
• Yamaguchi and Norris (2015) No place to retreat: Heavy extinction and delayed recovery on a Pacific guyot during the Paleocene–Eocene Thermal Maximum, Geology

No, in fact, past extinction of corals occurred at times of high CO₂ and runaway warming.

if we halved today’s atmospheric carbon dioxide content, all life would die.

This claim is contradicted by measurements: Ice core records show several periods within the past 800,000 years (see again here) where the carbon dioxide content in the atmosphere was about 200ppm, whereas today we have reached 400ppm (or 0.04% as the author writes below).

Our bodies contain carbon compounds. If we were so passionately concerned about our carbon footprint, then the best thing to do is to expire.

This is false. The natural carbon cycle keeps atmospheric CO₂ amounts approximately in balance.

The changes in atmospheric CO₂ are almost entirely due to releasing trapped carbon into the air. The single biggest contributor is digging up carbon that’s trapped in fossil fuels and then burning them to release the CO₂. A secondary one is releasing carbon trapped in things like forests and peat.

This is incorrect unless our bodies were sequestered into an isolated component of the carbon cycle such as buried fossil fuel reserves. Otherwise, carbon is cycled regularly between the different components of the carbon cycle, while as a whole the system is in relative equilibrium. This only changes when we liberate isolated reserves of carbon and add them to the more «active» pools, as we are doing with the extraction and combustion of fossil fuels.

In our lifetime, there has been no correlation between carbon dioxide emissions and temperature

This is false.

Our total emissions correlate strongly with temperature, just as expected.

The CDIAC global emissions data are only available until the end of 2014, but the total emissions correlate with global temperature. Over the last 50 years of the datasets the correlation coefficient is 0.93 (where 0 means no correlation and 1 means perfect correlation).

after a natural orbitally driven warming, atmospheric carbon dioxide content increases 800 years later

During natural climate variability, temperature and CO₂ are tightly linked, with feedbacks going both ways. Even if in some cases temperature increased before CO₂, the majority of warming occurred after the increase in CO₂.

Rather than atmos­pheric carbon dioxide driving temperature, it is the opposite.

The increase in atmospheric carbon dioxide concentration observed over the last century or so is entirely due to human activity. In fact, the natural world is currently absorbing carbon dioxide from the atmosphere, partly offsetting our emissions. An important question in climate science is the extent to which the natural world (oceans and biosphere) can continue to partially offset our emissions in the future, or if the natural world will become a source of carbon emissions,

Geology shows us again there is no correlation between atmospheric carbon dioxide and temperature

Thats is wrong. Ice cores show a tight correlation between temperature and greenhouse gas concentrations

Each of the six major past ice ages began when the atmospheric carbon dioxide content was far higher than at present.

No, the carbon dioxide concentration has not been higher for at least 800,000 years. There have been at least six ice ages in that time.

See here.

In the past decade China has increased its carbon dioxide emissions by 53 per cent, 12 times Australia’s total carbon dioxide output of 1.3 per cent of the global total.

The 1.3% become much larger if we look at per capita emissions. And much much larger when we include emissions from exported coal from Australia. Following that logic, I suggest we all stop paying taxes, because our individual contribution is much less than 1.3% and surely would not make a difference?