El Nino. This periodic warming of the Equatorial Pacific has long been known to trigger droughts, wildfires, and higher temperatures throughout the tropics. And, according to a new satellite data based report out of the scientific journal Nature, these very same El Nino feedbacks combined with record global heat to squeeze a massive volume of carbon out of the world’s tropical forests during 2014-2016. From the report:

The monster El Niño weather pattern of 2014–16 caused tropical forests to burp up 3 billion tonnes of carbon, according to a new analysis. That’s equivalent to nearly 20% of the emissions produced during the same period by burning fossil fuels and making cement.

Global Warming + El Nino Sparked Massive Fires, Droughts and Heatwaves in the Tropics During 2014-2016…

The monster El Nino of 2014 to 2016 created serious disruptions to the world’s weather and climate patterns. Emerging during a time when human-forced global warming was rapidly ramping up, this strong natural variability feature generated a severe heat spike in the tropical regions. With the heat near the Equator already at high tide due to human-caused warming, this very strong El Nino produced some of the most severe heatwaves, droughts and wildfires ever experienced during modern times in places like Brazil, Africa, and Southeast Asia.

(Massive Southeast Asia wildfires during a record warm El Nino like these in Borneo during September of 2015 helped to squeeze 3 billion tons of carbon out of tropical forests. A feedback feature related to El Nino and human-caused climate change. Image source: Earth Observatory.)

The Amazon Rainforest, according to a seperate study, experienced record-breaking heat and drought — with the area of drought stretching 20 percent further than during past El Nino years. Temperatures in the Amazon were 1.5 degrees Celsius warmer than during the extreme El Nino event of 1997-1998. Both signals that a climate change + El Nino interaction was amplifying the severity of impacts to this crucial tropical forest system.

In Africa and Southeast Asia, the heat was similarly intense — producing numerous 30-100 year or worse droughts, fires, and record high temperatures. Another signal that this harmful interaction was in full swing.

… This, in Turn, Generated a Major Release of Forest-Stored Carbon …

As the droughts and heatwaves were baking deep, and as the forests were stunting, burning, or exhaling more CO2, high overhead, one of Earth’s climate sentinel satellites — the Orbiting Carbon Observatory 2 — was dutifully taking measurements. And what it found was that all this extra tropical heat resulted in a severe loss of soil and vegetative carbon. That the heat and droughts were sparking forest fires, causing stress, and stunting forest growth. That these processes were dumping prodigious volumes of carbon back into the Earth’s atmosphere.

From the study:

Measurements taken by NASA’s Orbiting Carbon Observatory-2 (OCO-2) satellite, which measures the level of carbon dioxide in the atmosphere, suggest that El Niño boosted emissions in three ways. A combination of high temperatures and drought increased the number and severity of wildfires in southeast Asia, while drought stunted plant growth in the Amazon rainforest, reducing the amount of carbon it absorbed. And in Africa, a combination of warming temperatures and near-normal rainfall increased the rate at which forests exhaled CO 2 .

Overall, the Nature study notes that 3 billion tons of carbon were added to the atmosphere as a result of harm done to forests and soils during this particularly hot El Nino period.

… Which Helped to Spike Annual Rates of Atmospheric CO2 Accumulation

(Record rates of atmospheric CO2 accumulation during 2015 and 2016 correspond with large belches of carbon from tropical forests as a result of severe heat. Image source: NOAA ESRL.)

Elsewhere, this added burst of carbon did not go unnoticed. And measurements from NOAA’s Earth Systems Research Laboratory indicates that rates of atmospheric carbon accumulation sped up as El Nino and global warming based heat baked the tropical lands. During 2015, rates of atmospheric carbon accumulation accelerated to their fastest pace on record — growing at 3.03 parts per million per year. And in 2016, the second fastest rate of atmospheric CO2 accumulation on record was recorded — 2.98 parts per million per year. This compares to an average 2.2 parts per million annual accumulation that’s primarily driven by fossil fuel burning.

So what we have here is evidence that a heat and El Nino based carbon feedback occurred in the tropics during 2014-2016 and that this feedback resulted in a significant spike in the rate of atmospheric CO2 accumulation even as human based carbon emissions were leveling off (at record high ranges). With El Nino fading, that tropical carbon feedback should abate. But we shouldn’t allow ourselves to breathe too easy. For with Earth now in the range of 1 to 1.25 C warmer than preindustrial times, carbon stored in soil, forests, permafrost and oceans is now being placed under increasing heat related stress. And continuing to burn fossil fuels keeps adding to the heat gain that further increases the risk of a warmth-amplifying release from all of these stores.

Links:

Massive El Nino Sent Greenhouse Gas Emissions Soaring

Record Heat and Drought Seen in Amazon During 2015-2016 El Nino

NASA’s Earth Observatory

NOAA ESRL

Hat tip to mlparrish

Hat tip to Spike