According to the Intergovernmental Panel on Climate Change (IPCC), a worst case could see the global average temperature rising to 5 degrees higher by 2081-2100. Photo: PA Images
One reason why many people fail to grasp the urgency of the climate emergency is that the numbers that describe it just seem too small to matter. Figures just released by the EU's Copernicus Climate Change Service show that last month was the hottest September on record worldwide, beating September 2019 by 0.05 degrees Celsius.
It is easy to think of such a tiny fraction as irrelevant and put it all down to a random blip. But place it within an undeniable broader trend, and things become far more alarming. This is the 44th September in a row—and the 429th month in a row—that global temperatures have topped the 20th century average. Throw in the fact that Arctic temperatures earlier this year eclipsed 30 degrees Celsius, and that the year as a whole is on track to be the hottest on record, and the picture becomes clearer and all the more disturbing.
A one degree rise?
It is easy to be fooled, too, into deriding the scale of temperature rise so far caused by global heating, and that predicted for the future. Since pre-industrial times, the global average temperature has climbed by a little over 1 degree Celsius. Set against daily and seasonal variability, this seems like nothing to get in a tizz over. But this is not how it works. Bear in mind that just 8 or 9 degrees Centigrade separates full Ice Age conditions from a hothouse planet with sea levels at nearly 20 metres, and the significance of that single degree becomes clear.This also puts into perspective predictions for how quickly and how high temperatures will climb as the century progresses. To a large degree, this remains an open question, as the answer depends upon how well we do in terms of embracing a greener lifestyle and slashing greenhouse gas emissions.
According to the Intergovernmental Panel on Climate Change (IPCC), a worst case could see the global average temperature rising to 5 degrees higher by 2081-2100; a catastrophic scenario that would surely bring about economic and societal breakdown. Even the IPCC's best case would see temperatures breach 1.5 degrees—this value is regarded as a critical "guardrail", above which dangerous, all-pervasive climate breakdown becomes inevitable. And that can only now be achieved via active measures to suck carbon from the atmosphere, either through planting trees or by artificial means.
The impact of carbon dioxide
As we continue to pump out around 40 billion tonnes of carbon dioxide every year, another way we can forecast future temperatures is by means of so-called climate sensitivity. This is a measure of the ultimate global average temperature rise if carbon levels in the atmosphere are doubled from the 280 ppm (parts per million) of pre-industrial times. One recent study proposes that there is a 90 per cent certainty that the value of climate sensitivity is somewhere between 2.3 degrees Celsius and 4.7 degrees, a range well above the 1.5 degrees guardrail. Furthermore, other predictions place worst-case estimates at above 5 degrees.As I write this, the level of carbon dioxide in the atmosphere is 411 ppm. Despite the impact of Covid lockdowns, this is close to 3ppm up on this time last year. Should carbon levels continue to increase at this rate, then doubling compared to pre-industrial times could be realised in a little over 50 years, well within the lifetimes of our children. Should the worst-case scenario for climate sensitivity be realised, then our fate—by then—could be sealed.
Saying this, it might be hard to believe that we will continue to pump out carbon at the current rate, given what we know. Then again, while there are promising signs of change in the way we generate energy, travel and live our lives, this has yet to translate to the stabilisation of annual greenhouse gas emissions, let alone any reduction.
Why geoengineering doesn't work
Equally worrying is the fact that plans to bring down global temperatures using artificial means—so called geoengineering—are gaining credence, at least in some quarters. One plan calls for mimicking a large volcanic eruption by pumping colossal amounts of sulphur dioxide into the stratosphere. Unlike carbon dioxide, the sulphur equivalent is especially effective at blocking incoming solar radiation, so leading to the cooling of the lower atmosphere and surface.The real-world consequences of such tinkering, however, are unknown and the risks, therefore, are extreme.
We know, for example, that planetary cooling caused by major volcanic eruptions, such as Tambora (1815), resulted in severe weather changes that brought failed harvests, famine and many thousands of deaths. Furthermore, the spoof volcano plan focuses solely on one symptom (rising temperatures) of global heating while ignoring the cause (increasing emissions).
In my new eco-thriller, Skyseed, an attempt to hack the planet, as a means to fixing soaring temperatures and wild weather, fails spectacularly. The catastrophic events that follow are, fortunately, confined to the realm of fiction, and that is exactly where any real-world plans to tinker with the climate should stay too.
