Extreme Temperature Diary- Saturday August 26th, 2023/Main Topic: A Heated Warning Concerning Tropical Trees

The main purpose of this ongoing blog will be to track planetary extreme, or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: A Heated Warning Concerning Tropical Trees

Dear Diary. The study I came across this morning makes sense but is a horror to think about. In light of eye-opening, horrendous heat waves currently happening around the planet with some even going on in the Southern Hemisphere’s winter, it could potentially get so hot in the Earth’s tropical zones that photosynthesis will be interrupted in association with tropical plants. I’ve often written that if our rainforests become toast, we will be too.

Apparently, the threshold temperature for photosynthesis breaking down in the tropics is 116°F. Thankfully, average temperatures across most of the tropical region are not nearly that high, but we are beginning to see signs that on the edges of the tropics, like in Argentina or in Africa’s Sahel, record temperatures are getting set at that level of heat.

For more on this new study, here is a Business Insider article:

Extreme heat could make photosynthesis impossible for tropical trees and plants that may all die as a result, a new study found. (businessinsider.nl)

Extreme heat could make photosynthesis impossible for tropical trees and plants that may all die as a result, a new study found.

Maiya Focht

26 Aug. 2023

Visitors walk through the world heritage listed daintree rainforest on November 14, 2012 in Mossman Gorge, Australia. Foto: Getty Images/Mark Kolbe

  • Trees stop making food for themselves when they get too hot, a new study shows.
  • If tropical air temperatures reach 116 degrees Fahrenheit, a lot of the rainforest could die. 
  • This is the first study to narrow in on a threshold that we need to avoid. 

When trees get hot, their leaves begin to sweat. If they stay hot for too long, they deplete their water supply, exhausting themselves.

It’s then that photosynthesis, the backbone of plant life, breaks down. 

The plant stops being able to care for itself, and begins to die, scientist Gregory Goldsmith, an assistant professor of biology at Chapman University, said in a press briefing.

So what happens in a world that by all signs, will continue to get warmer?

For a new Nature study, scientists across the country found that photosynthesis begins to fail in tropical trees at 116 degrees Fahrenheit (46.7 degrees Celsius). 

The researchers also found that a small percentage of leaves — .01% — have already surpassed this limit at least once per season.

If the world continues to grow warmer, massive amounts of the tropical canopy could die off. However, in the paper, researchers state that “it is still within our power to decide the fate of these critical realms of carbon, water, and biodiversity.

What we didn’t know

Chloroplasts carry chlorophyll which makes them green. These chloroplasts actually circulate around within each cell. Foto: NNehring/ Getty Images

Scientists already knew extreme heat makes leaves unable to photosynthesize, said Goldsmith, a co-author of the study. But “this study is really the first study to establish how close tropical forest canopies may be to these limits,” he said. 

To determine the threshold for what too hot really means, the researchers used data from climate monitoring satellites, temperature towers in tropical forests, and countless sensors they taped onto individual leaves in the canopy.

They studied five forests in Brazil, Puerto Rico, Panama, and Australia, ScienceAlert reported.

These three perspectives combined to give them an idea of when the leaves, which are harbingers of health for the rest of the tree, begin to malfunction.

Without change, we’re headed toward disaster

The nutrients a tree needs to sustain itself are created when it photosynthesizes. So if photosynthesis is interrupted, a plant will essentially starve to death. 

Since plants take in carbon dioxide when they photosynthesize, they can help moderate the amount of greenhouse gases in the air.

But if a plant dies, all the carbon it’s stored in its body gets released into the atmosphere. 

Tropical forests make up about 12% of the Earth’s land surface. So if this heat threshold is reached, that whole chunk of Earth’s surface might begin to die off, releasing greenhouse gases into the air with it, said Christopher Doughty, a professor of ecoinformatics at Northern Arizona University. 

If all the trees in the tropical rainforests died off, that would release an estimated 228.7 petagrams of carbon into the atmosphere, according to a 2012 study.

One petagram of carbon is equal to 1 Gigaton (or a billion metric tons), so 228 petagrams are equivalent to six times the amount of carbon emissions emitted worldwide in 2022, alone.

“If that all went into the atmosphere, that would accelerate climate change,” Doughty said. He was the one up in the trees, taping each sensor delicately to the tropical canopy.

Though the researchers found that .01% of the leaves in the tropical rainforest have reached their heat-induced limit, there is room for error in the measurements, Doughty cautioned.

They arrived at their measurements based on the data they were able to gather from key areas globally, but they weren’t able to actually measure all the tropical leaf temperatures across the globe.

A photo of the canopy of the Amazon rainforest. Foto: Ignacio Palacios/Getty Images

They estimated them by combining their ground data with satellite data, but there might be slight deviations from their estimation. 

Even so, if no action is taken to prevent further climate change, Doughty said it’s possible their predictions will come true.

But making even moderate changes, like enforcing our current climate agreements and reducing tropical deforestation, would help. 

These sorts of changes could give us a good chance of avoiding what would be a tragic loss of some of Earth’s most biologically-rich ecosystem. This makes Doughty hopeful.

“I feel optimistic,” he said.

Read the original article on Business Insider


Here are some “ET’s” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:

Here is more July 2023 climatology:

Notes on the active tropics:

Here is more climate and weather news from Saturday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

Today’s News on Sustainable and Traditional Polluting Energy from Fossil Fuel:

More on the Environment:

More from the Weather Department:

More on other science and the beauty of Earth and this universe:

If you like these posts and my work on record temperature ratios, please contribute via my PayPal widget on this site. Thanks in advance for any support. 

Guy Walton… “The Climate Guy”

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