Carbon Dioxide Hits New Milestone and Continues to Impact Climate

Atmospheric carbon dioxide (CO2) has reached a new milestone, mainly due to the burning of fossil fuels and the destruction of forests.

This May, CO2 has reached 421 parts per million (ppm), which means that for every million molecules in the air, 421 are carbon dioxide.

That probably seems like a tiny amount, but since carbon dioxide is a heat-trapping greenhouse gas, it has a huge effect. In addition to being a key ingredient in plant food, CO2 is necessary for life as we know it.

Combined with water vapor and methane, CO2’s greenhouse capabilities help keep planet Earth at a comfortable 60 degrees Fahrenheit. If somehow all the CO2 disappeared overnight, the Earth’s temperature would drop to near zero within a few decades.

But too much of a good thing is not good. Since the dawn of the industrial revolution, CO2 has risen from 280 ppm to 421 ppm, an increase of 50%. Over the past 800,000 years, CO2 has rarely even exceeded 300 ppm. In fact, carbon dioxide is higher today than it has been for over 4 million years.

This increased the amount of heat stored in the Earth system and raised global temperatures by about 2 degrees Fahrenheit.

In the graph below you can see just how abnormal this abrupt increase in heat has been over the past 2000 years, with blue bars representing temperatures below modern normal and reds indicating temperatures above the normal.

Credit: Warming Stripes by Ed Hawkins

Two degrees may not seem like a lot, but if your body temperature climbs from 99 to 101, you will definitely feel sick.

At the current rate of increase in greenhouse gases like CO2, the planet is heading for at least another 2-3 degrees Fahrenheit of warming this century. Earth fever would then be comparable to a human fever of 104. This is the kind of Earth fever in which interconnected support systems and ecosystem services collapse.

Understanding that carbon dioxide has warmed the Earth is not new science. This has been well known since the 1960s. But despite this knowledge, humanity has not slowed down the burning of fossil fuels and as a result heat trapping in the climate system continues to increase.

A NOAA study published a few days ago shows that greenhouse gas pollution traps 49% more heat today than just 30 years ago, in 1990.

While not an easy task, if humans were able to quickly stop dumping excess carbon pollution, Earth’s temperature would stop warming almost immediately, although many impacts would persist for decades. and centuries, such as sea level rise.

The image below shows the choice humanity has before it. On the left, the map shows the projected temperature increase if we drastically reduce the burning of fossil fuels and therefore emissions soon. On the right, the map shows what happens if humans continue to emit greenhouse gases at the same rate as today.

What we decide can mean the difference between an inconvenience (left) and a disaster (right).