7 reasons to be alarmed by record-setting levels of CO2

By Joe Romm, Climate Progress, June 2017:  Trump puts humanity back on track to CO2 levels not seen since it was 5° to 10°F warmer and seas were 75 to 120 feet higher.  

Carbon dioxide levels in the air over the past 400,000 years. CREDIT: NOAA

Despite the best efforts of the Trump administration to ignore or contradict scientific reality, carbon dioxide levels continue to soar far outside the bounds of what Homo sapiens have ever experienced.

Monthly levels of heat-trapping CO2 peaked at nearly 410 parts per million (ppm) in May, the month that levels peak each year at NOAA’s Mauna Loa Observatory in Hawaii.

CREDIT: Climate Central 

This is worrisome for several reasons. First, CO2 is the primary heat-trapping greenhouse gas humans spew into the air, mainly by burning fossil fuels. The higher CO2 levels are, the greater the warming.

Second, CO2 levels or concentrations in the atmosphere will keep rising until the world has reduced global CO2 emissions by more than 80 percent from current levels. CO2 concentrations are like the water levels in a bathtub, and annual emissions are like the flow from the faucet. The water going down the bathtub drain is like CO2 sinks such as the oceans, forests, and soils.

Third, the annual rise in CO2 levels has been speeding up, as long predicted by climate science. Indeed 2015 and 2016 were the two biggest annual jumps in CO2 levels on record. 

CREDIT: Climate Central

The fourth thing to worry about these record CO2 levels is that some of the Earth’s carbon sinks appear to be turning into CO2 sources, most notably the defrosting permafrost, which contains twice as much carbon as the atmosphere does today.

This thawing creates a dangerous amplifying feedback, as rising CO2 warms the planet, which thaws the permafrost, releasing carbon that further warms the planet, releasing more CO2, and so on.

The fifth thing to worry about is that, historically, record CO2 levels are accompanied by record temperatures and record sea level rise. We haven’t hit the temperature levels we can expect from current CO2 levels, and by the time we do, CO2 levels will be even higher. Sea level rise can take even longer to catch up but the latest science says we are headed towards worst-case scenario levels, 3 to 6 feet (or more), by century’s end. 

The sixth reason for concern is that CO2 levels (and temperatures) were relatively flat for the past 10,000 years — during which time modern civilization and agriculture developed capable of sustaining a population of billions of people.

But now CO2 levels have surpassed those seen not just during modern civilization, but during all of human evolution. Indeed, current levels haven’t been seen for many millions of years.


CO2 levels over the last 400 million years. At right are different projections of future CO2 levels. CREDIT: Yale e360.

The final thing to worry about is that by exiting the Paris climate deal, President Donald Trump has made it all but impossible to achieve the lower range of projections in the chart above (graph on far right). We are now exceedingly unlikely to stay below 500 ppm — and could go far, far higher if Trump were able to persist in his self-destructive policies over two terms.

The last time the Earth sustained CO2 levels near the 400 ppm range, a few million years ago, the Arctic was 14°F warmer, and “the West Antarctic Ice sheet did not exist,” according to a 2013 study in the journal Science. Sea levels were about 80 feet higher.

A 2009 analysis in Science found that when CO2 levels were sustained in the 400 to 500 ppm range some 15 to 20 million years ago, it was 5°F to 10°F warmer globally, and seas were also 75 to 120 feet higher.

That’s why a rational and moral society would be scrambling to strengthen Paris, not destroy it.

Also by Joe Romm on Climate Progress, 12 June 2017

Dust Bowl-ification of U.S. Southwest leads to 8-fold jump in Valley Fever cases: As the region dries out, infections from inhaling soil-dwelling fungus see stunning jump.

A massive dust storm sweeps across Phoenix in July 2012. CREDIT: AP/Mark Evans

The infection rate of Valley Fever in the Southwest United States has gone up a stunning 800 percent from 2000 to 2011, as dust storms have more than doubled.

New research directly links the rise in Valley Fever to the rise in dust storms, which in turn is driven by climate change. Valley Fever, which the Centers for Disease Control and Prevention calls “a fungal lung infection that can be devastating,” is caused by inhaling soil-dwelling fungus. When the soil dries out and turns to dust, the wind can make the fungus airborne.

“Dust storms are found to better correlated with the disease than any other known controlling factor,“ a new study led by NOAA scientists concluded

Dust storms spike with Valley fever cases. The largest number of dust storms from 1988 to 2011 are concentrated in the SW states reporting the highest numbers of fever cases. 

Moreover, the scientists emphasize that “this study provides direct evidence that dust storms in the southwestern United States have become more frequent in the past decade.”

Climate scientists have long predicted — and are now finally observing — the drying out of the Southwest from climate change. My 2011 literature review in Nature called this “Dust-Bowlification,” a term the new study picks up.

In recent years, multiple studies studies have confirmed that warming-driven climate change is already drying the American Southwest and other parts of the globe, spurring dust storms.

A 2016 study found that the semi-arid Southwest has begun to enter a “drier climate state,” which matches findings from a 2015 study documenting an expansion of the entire world’s dry and semi-arid climate regions in recent decades as a result of human-caused climate change.

The changes in precipitation that can be attributed to the changing U.S. climate. The data ends in 2010, so this chart omits the brutal SW drying seen since then. CREDIT: NCAR. 

The fact that climate scientists have turned out to be right about this drying trend means we must take seriously their current projections of widespread global megadroughts in the coming decades — including in our own breadbasket — if carbon pollution isn’t significantly curbed.

Here’s a 2015 NASA projection of what the normal climate of North America will look like on our current emissions path — an outcome made far more likely by President Donald Trump’s policies to prop up fossil fuels and his recent decision to withdraw from the Paris climate deal. The darkest areas have soil moisture comparable to that seen during the 1930s Dust Bowl.


Climate change is having a very immediate health effect on Americans — well beyond the alarming rise of Valley Fever. It has helped spread dengue fever in 28 states and is creating conditions for brain-eating parasites and a host of “neglected tropical diseases” to thrive.

But the biggest concern about modern Dust-Bowlification is the tremendous challenge of “feeding some 9 billion people by mid-century in the face of a rapidly worsening climate.” This is why climate action is so urgent and vital.