It was probably more hope than expectation, but in the early years of the 21st century, it looked as if atmospheric concentrations of the hyper-greenhouse gas, methane had pretty much stabilised. This was good news as the gas has the capability of sending planetary heating into overdrive. In the short term – say a decade or two – methane is capable of warming the planet up to 86 times more rapidly than carbon dioxide. The gas doesn’t hang around in the atmosphere for much more than ten years or so, but then it breaks down into carbon dioxide and water – both greenhouses – which means that its warming influence continues. Even after 100 years, in fact, the global warming potential of the gas is still more than 30 times that of carbon dioxide.


Now, both the hope and expectation seem short-sighted as new research reveals that methane levels in the atmosphere are on the rise again. A new open access paper published by the American Geophysical Union (1) provides evidence for atmospheric methane levels starting to climb once more in 2007 and accelerate significantly for the period 2014 – 17. Such a hike is unexpected and was not factored into the calculations that came up with the emissions reductions framework for the Paris Climate Agreement. Consequently, the probability that global average temperatures will rise far above the 2°C dangerous climate change guard rail is now even greater.


A big concern is that it is not clear where the methane is coming from. There seems to have been an especially significant increase in the gas across the tropics and sub-tropics and at northern mid-latitudes, and more intensive farming and the warming of methane-hosting swamps and bogs have been fingered as possible culprits. Far more worrying is the possibility that chemical changes in the atmosphere, as it warms, might make it more difficult to break down methane. If true, this would be very bad news indeed, because it would mean that this extremely potent greenhouse gas would hang around for longer, thereby significantly increasing its global warming potential.


And there could be plenty more methane to come. Trapped beneath the vast tracts of permafrost at high latitudes are colossal quantities of the gas. The geographic region of most concern is probably the submarine permafrost that floors the East Siberian Continental Shelf, where an estimated 1400 billion tonnes of carbon, in the form of methane, is lurking beneath a frozen carapace that is thawing rapidly. According to one research team as much as 50 billion tonnes of this is available for sudden release at any time, which would – at a stroke – hike the methane content of the atmosphere 12 times. A discrete methane ‘burp’ on this scale could, it has been estimated, advance global warming by 30 years and cost the global economy USD60 trillion – a figure close to four times the US national debt. The occurrence of such an outburst is far from certain and there are other issues to consider, including how much methane is absorbed by the ocean as it bubbles upwards. Nonetheless, this cataclysmic scenario provides yet another reason – if more were needed – why we must slash our own emissions to zero as soon as we can.


(1) Very strong atmospheric methane growth in the four years 2014‐2017: Implications for the Paris Agreement


Bill McGuire is Professor Emeritus of Geophysical & Climate Hazards at UCL and author of Waking the Giant: How a Changing Climate Triggers Earthquakes, Tsunamis and Volcanic Eruptions. He was a contributor to the IPCC 2012 report on Climate Change & Extreme Events and Disasters.




Going Under

By Bill McGuire

If your children or grand children live within sight of the sea, then be afraid. Very afraid. Sea-level rise is set to be one of the most devastating and disruptive consequences of climate breakdown and the prospect of the oceans drowning coastal communities by the end of the century is growing by the day. The prevailing view sees perhaps a metre or so of sea-level rise by the century’s end – enough in its own right to doom low-lying islands and coastlines – but the true picture may be far worse. A number of studies suggest that sea levels by 2100 could be two or three metres up on today; perhaps as much as five metres. A truly terrifying scenario.


How the UK would look on an ice-free Earth

Global sea levels rose by around 20cm during the 20th century and are climbing now at close to half a centimetre a year. Much of this is due to the expansion of the oceans as they warm, but melting ice is playing an ever more important role in hiking the rate of the rise. The problem is that the Earth is not heating up uniformly, and the bad news for us is that temperatures across the polar regions are climbing far more rapidly than anywhere else. Of course, this is where the vast majority of our world’s ice resides; in total, a staggering 24 billion cubic kilometres of it – close to seventy per cent of all the fresh water on Earth. The great ice sheets of Greenland and Antarctica have been bastions of stability since the end of the last Ice Age around 10,000 years ago. During the second half of the 20th century, however, and especially in the last few decades, they have started to crumble, shedding vast quantities of freshwater into the oceans.

Until recently, attention has been focused on accelerating melting of the Greenland and West Antarctic ice sheets, which are the most sensitive to rising temperatures. The last 20 years or so has seen a huge increase in the melting rate of the Greenland Ice Sheet, which is now shedding close to 400 billion tonnes of ice every year. Even more worryingly, the melting rate is increasing exponentially, which means it will continue to accelerate rapidly.

The news from West Antarctica is not good either. In the five years from 2012 to 2017, ice loss from the West Antarctic Ice Sheet shot up threefold, from 76 billion tonnes annually, to a colossal 219 billion tonnes. In total, more than 2.7 trillion tonnes of Antarctic ice has melted in the last quarter century, adding three-quarters of a centimetre to global sea level. At the new rate, the contribution over the next 25 years would be 1.5cm. Not really too much to worry about. If, however, the rate of increase is maintained over this period, then the annual rise by the mid-2040s – barely more than 20 years away – would be close toa catastrophic five centimetres a year. And this is without the growing contribution from Greenland and from the increasing expansion of sea water as the oceans continue to warm. It is not known how the melt rate will change in coming decades, but it is a sobering thought that even if the rate of increase stays as it is, low-lying lands and all coastal population centres would be threatened with permanent inundation by the century’s end.

As if this wasn’t bad enough, new research from East Antarctica paints an even more disturbing picture. The East Antarctic Ice Sheet dwarfs those of both Greenland and West Antarctica. Complete melting of the Greenland Ice Sheet would raise global sea levels by around seven metres, while melting of all the ice in West Antarctica would add another five or so. If East Antarctica lost its ice, however, it would push up sea levels by a staggering fifty metres or more. Until recently, the East Antarctic Ice Sheet was regarded as largely stable, and some studies even suggested that it might have been growing. The new study (1) reveals, however, that this is now changing, and changing with a vengeance. What was a sleeping giant is now beginning to wake up.

Satellite data reveals that a cluster of colossal glaciers, which together make up about an eighth of the coastline of East Antarctica, are starting to melt as the surrounding ocean gets progressively warmer. The loss of the giant (It’s about the size of Spain!) Totten Glacier – just one of the cluster – would, on its own, raise global sea levels by more than three metres. The new data show that it and its companions are now moving increasingly rapidly seawards and thinning as they do so, meaning that even the worst predictions for rising sea levels may be optimistic. As with the many other indicators that flag the remorseless breakdown of the stable climate that fostered the growth of our civilisation, the collapse of the polar ice sheets sends us the message that time has run out. Prevarication is no longer an option. Only serious and determined action now will give us any chance of avoiding a climate calamity that will swamp the world’s coastlines and displace hundreds of millions – if not billions – of people.



Bill   McGuire   is  Professor   Emeritus   of  Geophysical   &   Climate Hazards   at  UCL   and   author  of   Waking   the  Giant:   How   a  Changing Climate Triggers Earthquakes, Tsunamis and Volcanic Eruptions. He was   a   contributor  to   the   IPCC  2012   report   on  Climate   Change   &Extreme Events and Disasters.


The Bad, The Worse, And The Downright Criminal

By Bill McGuire


Forget the Good, the Bad and the Ugly- it’s the Bad, the Worse and the Criminal, we need to bring down.

I guess we’ve known it all along, but when it comes to greenhouse gas emissions it seems – as far as industrialised nations are concerned at least – that there just aren’t any good guys. Now it’s been confirmed by a new study just published in Nature Communications1, which forecasts what the end-century global average temperature rise would be, based upon the current emissions policies of individual nations. Heading the cast of scoundrels is a clutch of the usual suspects; China, Russia, Canada and Saudi Arabia – along with a bunch of smaller nations – whose policies, if matched globally, would see end-century temperatures climb to more than 5°C above those of pre-industrial times.

Not far behind is another gang of countries, including the United States and Australia, whose national climate targets, if matched worldwide, would see temperatures up 4°C or more by 2100. Before we cast stones, however, we in the UK don’t have much to crow about either. If the rest of the world followed our example, temperatures would still be 2.9°C higher by the century’s end – easily high enough to bring about catastrophic, all-pervasive climate breakdown2. And that’s with most of our manufacturing emissions outsourced to China and elsewhere.

The authors of the study make plain their hope that national emissions pledges, made as part of the 2015 Paris Climate Agreement, will be tightened in coming years so that the global average temperature rise may still be kept below 1.5°C. The way things are going, however, it would be fair to say that such a target remains pie-in-the-sky. For a start, there is no binding enforcement mechanism to ensure that pledges are kept. More importantly, they are simply not enough. Even if all signatories stuck to their emissions targets, the global average temperature rise would still be 3°C by 2100. If self-reinforcing feedback effects start to kick in seriously – as is highly likely – this could be a calamitous 4°C or even 5°C.

When set in the context of last week’s World Energy Outlook report, which predicts that global carbon emissions will still be heading skywards in 2040, the overall picture looks dire. Fiddling while Rome burns doesn’t even begin to describe the snail’s pace changes that are taking place across the energy and emissions reduction landscapes. We have to act big and act now. Rapid transitions that can change minds and change policies, virtually overnight, have happened before. Following Japan’s attack on Pearl Harbour in 1941, the US economy was re-jigged in just six months from its peacetime ambitions to a full-on wartime footing. If it happened then, it can happen now. We are, after all, in a war situation. A war that will end either with anthropogenic climate breakdown brought to heel or with our world and our society shattered. The focus of our government, and those of all nations, has to change NOW. Forget Brexit; forget GDP; forget growth for growth’s sake. The mindset has to be turned around so that success is measured by how much and by how quickly we slash greenhouse gas emissions – pure and simple. Net zero emissions by 2025 is the goal.

It’s a huge call, but history teaches that if we want it badly enough, it can be done.

Let’s go for it.



1du Pont, Y. R. & Meinshausen, M 2018 Warming assessment of the bottom-up Paris Agreement emissions pledges. Nature Communications  9. Article number 4810.