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We have known about climate change for 40 years or more, its impacts are already hitting Hawaii and the rest of the world, yet we’re still making things worse.

Despite all the rooftop solar, clean energy tax credits, efficient refrigerators and air conditioners, we as a planetary society are still burning more coal and gas and dumping more carbon dioxide into the atmosphere each year.

During the first years of this century, the world added CO2 at 2.5 parts per million. This year it will be 3 parts per million. In the United States, after several years of decline, we have started producing more in the past couple of years.

We continue to drive headlong at the cliff. How high is that cliff?

For as long as there have been humans, the carbon dioxide levels in the atmosphere have never been nearly as high as they are now. We are in uncharted territory. CO2 levels were last this high 4 million years ago.

As a species, we have never experienced this level, and we will never have experienced a planet as warm as it now inevitably will become.

How Bad Could It Get?

A that the planet Venus might once have been habitable by humans, before its own bout with climate change. Venus is nearer the sun. On Venus, the rate of spin is much slower than on Earth, allowing heat to build up. The sun’s heat burned off its oceans and drove a catastrophic carbon-dioxide climb, and now Venusian temperatures exceed 800 degrees Fahrenheit.

Earth’s mechanics are different, but we’re driving up carbon dioxide, and the heat is building.

In Hawaii, we are already seeing the impacts of the changing climate. Coastlines are eroding (shoreline roads and homes are washing away), mosquitoes are invading once-cool uplands (native bird populations are crushed by mosquito-borne disease), oceans are acidifying and warming (reef corals are dying, exemplified by a recent wave of coral bleaching), wind patterns are changing (the northeast trades have shifted significantly to warmer east trades) … all that.

And more changes are coming. New research suggests that a whole bunch of impacts are poised to trip.

A team of researchers looked at “tipping points,” which are systems that suddenly begin shifting very fast once a level is exceeded. Like a playground swing, if you add just enough weight to the light side, it can drop suddenly.

(Here is in the journal Nature that reviews the tipping point crisis. Here is a ScienceDaily on that Nature piece.)

The authors argue that for at least nine planetary systems, the current levels of CO2 and warming appear to be activating tipping points. The systems include: Arctic sea ice, Greenland ice sheet, boreal forests, permafrost; Atlantic Meridional Overturning Circulation, Amazon rainforest; warm-water corals (like this year’s Hawaiian bleaching coral reefs), West Antarctic Ice Sheet and parts of East Antarctica.

Why Are These Things Critical?

One reason: melting the three big ice sheets could raise ocean levels by 30 feet — yes, not 3 feet but 30 feet. And maybe as much as 60 or 70 feet over centuries, according to in Nature.

The tipping point article in Nature is entitled, “Climate tipping points — too risky to bet against; The growing threat of abrupt and irreversible climate changes must compel political and economic action on emissions.”

The authors are Timothy M. Lenton, director of the University of Exeterʻs Global Systems Institute, along with German, Swedish, Danish and Australian researchers Johan Rockström, Owen Gaffney, Stefan Rahmstorf, Katherine Richardson, Will Steffen and Hans Joachim Schellnhuber.

They explain that one of the most frightening aspects of tipping points is how one feeds another.

The Nature authors write: “Arctic sea-ice loss is amplifying regional warming, and Arctic warming and Greenland melting are driving an influx of fresh water into the North Atlantic. This could have contributed to a 15% slowdown since the mid-twentieth century of the Atlantic Meridional Overturning Circulation, a key part of global heat and salt transport by the ocean.”

Rapid melting of the Greenland ice sheet and further slowdown of the AMOC could destabilize the West African monsoon, triggering drought in Africa’s Sahel region. A slowdown in the AMOC could also dry the Amazon, disrupt the East Asian monsoon and cause heat to build up in the Southern Ocean, which could accelerate Antarctic ice loss.”

To be sure, not everyone believes that tipping points are a threat, but the Nature authors argue that the evidence points to it. And even if it isn’t absolutely certain, we can’t take the risk.

“If damaging tipping cascades can occur and a global tipping point cannot be ruled out, then this is an existential threat to civilization,” they argue. They call it a “planetary emergency.”

And yet, there is plenty of evidence that we’re not taking it seriously. The planet produced as much new coal-fired power as renewable energy in 2018, from none other than British Petroleum, BP, in its “BP Statistical Review of World Energy 2019, 68th edition.”

“The world is on an unsustainable path: the longer carbon emissions continue to rise, the harder and more costly will be the eventual adjustment to net-zero carbon emissions. Yet another year of growing carbon emissions underscores the urgency for the world to change,” wrote BP group chief executive Bob Dudley. He suggested that the 2018 results were in part because humanity was using fossil fuels to air condition and heat against the impacts of climate change: super-hot summers and super-cold winters.

It is hard not to call up the image of Nero, fiddling as Rome burned.

BP’s group chief economist Spencer Dale reiterated the message:

“At a time when society is increasing its demands for an accelerated transition to a low carbon energy system, the energy data for 2018 paint a worrying picture, with both energy demand and carbon emissions growing at the fastest rates seen for years,” Dale said.

Most of the coal burning growth was in India and China, but the United States isn’t doing so well. According to , the vast majority of our contributions to greenhouse gas came from burning fossil fuels. Forty-five percent of our fossil fuel burning was petroleum, 31% natural gas and 24% coal.

Most of that use is from transportation, with smaller amounts from industrial, residential and commercial applications.

And after years of decline, U.S. emissions .

Meanwhile, we are still flying, still driving, still doing all those things that burn fossil fuels. It is hard not to call up the image of Nero, fiddling as Rome burned.