A science presenter, writer, speaker & former TV host; author of The Skeptic's Handbook (over 200,000 copies distributed & available in 15 languages).


The Skeptics Handbook

Think it has been debunked? See here.

The Skeptics Handbook II

Climate Money Paper




The nerds have the numbers on precious metals investments on the ASX



Welcome to the CO2 disaster — 4 billion tons more plants, more greenery

During the recent warmest decades on record, Earth suffered under the highest CO2 levels of the last 800,000 years. Life responded to this devastating situation by — flourishing. There are now some 4 billion tons more living matter on the planet than there was in 1993. What a calamity. (And what a lot of carbon credits.)

It has, naturally, got nothing to do with warmth and aerial fertilizer. The researchers tell us it due to that force of nature known as “good luck”. Remember, human CO2 emissions were pollution that was going to afflict life on Earth. After twenty years of predicting the loss of forests and species, it turned out that biology bloomed instead. Notch up another model “success”. The press release headline: Good luck reverses global forest loss. (What else would we expect from UNSW?)

To those who know basic biology — and that almost half the dry weight of plants is carbon, sucked straight out of the air — this is not so much good luck as one entirely foreseeable and foreseen consequence of rising CO2. Acquiring carbon is often a plant’s hardest task. When the sun comes up, a cornfield begins sucking, and by lunch time [...]

Plants suck half the CO2 out of the air around them before lunchtime each day

A paper that is nearly 60 years old shows us just how intrinsically important CO2 is to life.

An acre of corn is a living machine drawing CO2 from the air around it. In windless conditions, CO2 concentrations over a cornfield build up each night as CO2 diffuses from higher air and the organic matter and bacteria create CO2 from the soil.  A paper by Chapman et al  from 1954[1], shows that as soon as the sun comes up, to power-up those dormant photosynthetic cells, the plants rapidly draw down as much CO2 as possible, and when the CO2 levels fall too low, plant growth surely slows.

On a windless day CO2 values rose to 410ppm overnight and fell to 210ppm during the morning.

This graph shows CO2 content of the air over a cornfield on a still day (no wind). Sunrise occurs at 5am and CO2 levels plummet til 8am, reaching their lowest by 1pm, which is nearly half the CO2 concentration of the peak reached overnight. The corn is affecting CO2 levels in air even as high as 150m or 500ft above. These level out by around 8am and only start to increase again, a couple of hours [...]

Wetlands like CO2 — “Gimme 700ppm” say sedge-grass

scirpus olneyi | Smithsonian

Not only does one particular grass seem quite happy at 700ppm, it was absorbing 30% more carbon dioxide, and there was no sign that it might not be equally happy at even higher levels. Will disaster strike the world at 401ppm? This 19 year study suggests (again) it might not be so bad. Arguably, 700ppm might be better. Even the C4 plants (supposedly the ones which prefer low CO2) still absorbed 13% more CO2 at 700ppm. (Absorbing more carbon usually means growing faster.)

During the worst drought years, growth slowed dramatically, but drought-stricken plants with 700ppm of CO2 around them still absorbed 4% more.

From the Smithsonian

High CO2 Spurs Wetlands to Absorb More Carbon

Under elevated carbon dioxide levels, wetland plants can absorb up to 32 percent more carbon than they do at current levels, according to a 19-year study published in Global Change Biology from the Smithsonian Environmental Research Center in Edgewater, Md. With atmospheric CO2 passing the 400 parts-per-million milestone this year, the findings offer hope that wetlands could help soften the blow of climate change.

Plant physiologist Bert Drake created the Smithsonian’s Global [...]

Arid regions of the world are 11% greener, mostly thanks to CO2

Increasing CO2 makes life easier for plants that live in hot dry places.

Thanks to satellites we know the world has “greened up” since 1980, but we were not sure how much of that was due to the fertilizing effect of CO2. To solve that, one group suggests we need to look in warm arid environments where water is the predominant limiting factor. These are the areas which ought to show whether CO2 was really helping plants grow,  because when there is more CO2 it enables plants to use water more efficiently for photosynthesis. In places where there is already a lot of water, it won’t make as much difference. So Donohue et al. did that, studying regions with a low level of rainfall. They found that the fertilization effect is real and significant and that the cover in these arid zones  increased 11% from 1982 – 2010 and CO2 played a significant role.

(Thanks to pollution, trees are invading grasslands. Whatever will the Greens do to get us back to the Halycon pre-carbon days? Call Gunns?)

CO2 may be the only “pollution” that greens the deserts.

“Using gas exchange theory, we predict that the 14% increase in atmospheric CO2 [...]

Co2 is the magic gas that makes plants grow

A little under half (typically about 45%) of the dry weight of any plant is carbon, and almost all that “C” came from CO2 in the atmosphere. No wonder plants love more CO2.

Trees and bushes can grow out of cracks in rocks because they suck the carbon right out of the air. Likewise hydroponics is only possible because the building blocks come from liquid and aerial fertilizer.

CO2 is about the only “pollution” you can pump around plants and watch them grow faster, stronger, taller and indeed more resistant to most of the stresses that normally bother a plant.