The world’s coral reefs are undergoing a fourth mass die-off, driven by rapidly accelerating global heating. As Julian Cribb explains, the science is clear – and the political failure to respond is not defensible.

The corals of the world are telling us something that most government and politicians – whether through corruption, fear or impenetrable ignorance – are unwilling to divulge: our planet is now heating at catastrophic rates.

“Before the 1980s, mass coral bleaching and mortality events due to heat stress were rare. In the last four decades, these events have become increasingly frequent and severe. Ocean warming is now the foremost threat to coral reefs worldwide,” says an international team of scientists, after completing the most extensive survey of the world’s coral reefs ever.

The world is currently in the grip of the fourth great coral die-off of modern times. Researchers at NOAA’s Coral Reef Watch unit are tracking killer ocean temperatures at fine scale and in real time. They have recently completed an exhaustive study of the third great coral wipe-out, which took place between 2014-2017, when 80 per cent of the world’s corals bleached and 35 per cent died. As the planet heats, they fear the current episode may prove worse.

Corals are formed from a delicate partnership between the reef-building coral animals and their symbiotic algae – zooxanthellae – which feed them. When water temperatures rise above 32 degrees C, the partnership breaks down, the algae depart and the corals die unless cooler water quickly brings them fresh algae to nourish them. Demonstrably, the algae know things about the Earth’s changing climate that most politicians do not, or else pretend not to. They are a glaring red traffic light to our future.

Figure 1. The bleaching catastrophe of 2014-17 which killed over a third of the worlds’ corals.

Human observation supports what the algae are telling us: the trend line in  scientist James Hansen’s record of global temperatures (below) shows a dramatic acceleration in heating from +0.18 degrees a decade (green dotted line) to +0.3 degrees (mauve dotted line). If the current predictions of a new El Nino event prove correct, it is due for another big leap that will push the average world temperature above +1.7 degrees in 2027.

Figure 2. The Hansen projection anticipates global temperatures reaching +1.7 degrees C in 2027, driven by a new El Nino.

Coral bleaching is the clearest possible sign that the simplest lifeforms on the planet have noticed what is going on – and are responding to it by abandoning their homes.

Donald Trump – to name but one among the global climate-denying cohort of incompetent governance – is only trying to make things worse.

One example of this is his latest order to the US Environment Protection Agency to rescind the 2009 rule, known as ‘the endangerment finding’, which declares climate change to be a direct threat to US health and welfare. This rule underpins most of America’s subsequent climate legislation. Put simply, one impact of its cancellation will be to enable more Americans to drive dirtier cars and trucks, so hastening their country’s climatic destruction.

So what is it that algae know that most American politicians (plus Saudis, Russians, Indians, Brazilians, Australians and a host of others) apparently don’t?

The short answer is this:

The table, by the EU science agency Copernicus, shows the trend in global air temperatures in each of the past 86 years. Blind Freddy can see the direction it is heading, and so can the coral algae. But not the world’s political leaders, apparently.

The scientists, who have been warning us about this heating trend since the mid-1970s, are  now saying that the planet is approaching the “point of no return”, where it tips into a hellish state known as Hothouse Earth, of +2-3 degrees C.

This is a climate dramatically different from that of the past 11,000 years – the climate that supported agriculture and large-scale food production.

“At +3-4 degrees C the economy and society will cease to function as we know it,” they said recently in a warning aimed at the use of misleading economic models based on past events.

“Earth’s climate is now departing from the stable conditions that supported human civilisation for millennia,” they cautioned. Slashing fossil fuel use will not save us once the tipping point is past. “In short, we may be approaching a perilous threshold, with rapidly dwindling opportunities to prevent dangerous and unmanageable climate outcomes.”

“Policymakers and the public, however, remain largely unaware of the risks posed by such a practically irreversible transition,” the scientists baldly state.

You couldn’t put it any plainer. But the political mind is not equipped for reality. It dwells in realms of fantasy, self-deception and lies. To a politician, politics is the only reality. The world is what they imagine it to be – not what it actually is.

However, politicians are a relatively new evolutionary experiment – and very likely a spectacularly brief, failed one. They have only been around for a couple of thousand years.

Sunlight-harvesting algae, on the other hand, have undergone all manner of climatic dramas. They first emerged as the planet shook off a deep-freeze state known as  Snowball Earth, around 650,000,000 years ago – and then rode the fluctuations from blistering heat to ice-age chill over the ensuing eras. They recognise the signals.

Corals, too have been around for a long, long time – 542 million years at least. Enough time to suffer at least five major extinction events driven by global warming. Each time, however, they managed a come-back – though many individual coral species were lost at the time.

Figure 4. Corals have faced at least five major extinction crises driven by global warming in the past

These episodes of global warming were generated by natural fluctuations in the Earths’ climate, generally over millions of years, driven by things like volcanic activity and wobbles in the planet’s orbital axis.

This time round, however, global heating is mainly driven by “fossil fuel combustion, industrial activities, land-use change and deforestation”. And those in turn are driven, or encouraged by, politicians.

Today, politicians like Trump, Al Saud, Putin and Albanese are doing all in their power to accelerate global heating to levels which humans cannot withstand, as fast as they possibly can. Whether it is their intention is to wipe out human civilisation is unclear, to them as much as to anybody else. They have just got it into their tiny, pointed heads that only the short-term matters.

Our children and grandchildren, the ones left facing climate extermination, will disagree.

The algae and coral already do. And they are acting, as they have acted for millions of years, in quest of survival.

So yes, politicians are dumber than algae. QED.