Hint — It’s accelerating.

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To be a climate scientist, to read the science, or to otherwise track today’s unfolding global disaster brought on by fossil fuel burning, is to witness a historical event beyond the scope anything encountered by human civilization.

(July 14th’s record low Arctic sea ice ringed by far northern wildfires and related smoke plumes is just one signal of a rapidly heating global climate. Image source: NASA Worldview.)

Over the past Century, heat trapping pollution has forced the world to warm by about 1.1 degrees Celsius. That’s 1/4 the difference between what humans are used to and an ice age — but on the side of hot. Seas, swollen by this heat and by thawing glaciers, have risen by an average of about 17 centimeters since 1900. Nine trillion tons of ice — the equivalent to 9,000 mountains — have melted from those glaciers into our oceans. Wildfires in the U.S. now burn twice the number of acres as they did 30 years ago. Flood events are more than twice as frequent as during the 1980s. Strong hurricanes have doubled in frequency in the North Atlantic over a similar period. The Arctic’s sea ice is in full retreat.

And if we continue burning fossil fuels, this is just the beginning.

June of 2019 was the hottest June ever recorded in the 139 year global climate record provided by NASA. It was about 1.15 C hotter than 1880s averages and exceeded the past hottest June — 2016 — by a full 0.11 C margin. In climate terms, this was a big jump upward.

(Distribution of hotter and colder than average temperatures shows most of the globe sweltering under greenhouse gas induced heating. In particular, the Arctic has been hit quite hard in the most recent round of extreme temperatures. Image source: NASA GISS.)

Perhaps more importantly to the larger trend, the first half of 2019 was the second hottest first six month period on record. Meanwhile, 2019’s heat comes in the context of the past five years. All were one of the five hottest years ever recorded. And NASA GISS head Dr. Gavin Schmidt’s projection is pointing toward a potential second hottest 2019 as well. Dr. Schmidt stated as much to the Guardian, saying:

“It is clear that 2019 is shaping up to be a top-five year – but depending on what happens it could be second, third or fourth warmest. The warmest year was 2016, which started with a big El Niño, which we didn’t have this year, so a record year is not particularly likely.”

With the global climate system so large and subject to swings (produced mainly by El Nino and La Nina), consecutive hot years are a signal of accelerating global heating. A trend born out by NASA’s global temperature record. In the 1990s, decadal temperatures averaged around 0.61 C above 1880s readings. The 2000s — 0.8 C hotter. The 2010s thus far — 1.08C hotter. In other words, the global heat gain from the 1990s to the 2000s was approximately 0.19 C while the heat gain so far from the 2000s to the 2010s is about 0.28 C. A near doubling of past 0.15 C decadal temperature increases.

(Record hot July may follow record hot June…)

This apparently accelerating global heating is driven by rising atmospheric greenhouse gas concentrations. Dr Michael E. Mann noted to Mashable today:

“As we have shown in recent work, the record warm streaks we’ve seen in recent years simply cannot be explained without accounting for the profound impact we are having on the planet through the burning of fossil fuels and the resulting increase in atmospheric greenhouse gas concentrations.”

Carbon dioxide, which is the primary driver of heat gain, is now at around 411 parts per million — 37 percent higher than during any period in the last 800,000 years. This level of heat trapping gas is unprecedented in human terms — likely about as high as readings seen during the Middle Miocene 15 million years ago and at least as high as those seen during the Pliocene 3 million years ago.

Methane — another very potent greenhouse gas and the second strongest overall contributor to the climate crisis — is also continuing to rise in concentration. This rise, along with increasing CO2, has been the cause of some anxiety among scientists who monitor the global climate system.

(Rising atmospheric CO2, primarily driven by fossil fuel burning, is the main driver of the global heating crisis we are now experiencing. Image source: NOAA ESRL.)

Together with other trace heat trapping gasses, the global CO2 equivalent heat forcing is around 499 ppm during 2019 (extrapolated from NOAA data). In other words, we’ll be crossing the ominous 500 ppm CO2e threshold very soon.

What all this data means is that we have now turned the ratchet of climate crisis at least once. A set of serious impacts are now locked in. Indeed, we are seeing them. But if we keep burning fossil fuels and turn the ratchet again, it gets much worse from here on out.

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