<
https://www.theguardian.com/environment/article/2024/aug/17/methane-climate-crisis-amazon-peat-permafrost-vegan-heat-pumps>
"Controlling methane provides our best, and perhaps only, lever for shaving
peak global temperatures over the next few decades. This is because it’s
cleansed from the air naturally only a decade or so after release. Therefore if
we could eliminate all methane emissions from human activities, methane’s
concentration would quickly return to pre-industrial levels. Essentially,
humans have released in excess of 3bn tonnes of methane into the atmosphere in
the past 20 years. Quashing those emissions within a decade or two would save
us 0.5C of warming. No other greenhouse gas gives us this much power to slow
the climate crisis.
If the Earth keeps warming, though, reducing emissions from human activities
may not be enough. We may also need to counter higher methane emissions in
nature, including from warming tropical wetlands and thawing Arctic permafrost.
The highest natural methane emissions come from wetlands and seasonally flooded
forests in the tropics – such as the Brazilian Amazon forest I recently visited
at the Mamirauá sustainable development reserve – and they are expected to rise
with warming. Tropical wetlands yield so much methane because they are warm,
wet (by definition) and low-oxygen environments perfect for growing
methane-emitting microbes.
On my most recent trip there a year ago in July, El Niño [warming of sea
surface temperatures] was strengthening and the tropical Atlantic was baking.
Ocean temperatures off the coast of Florida approached hot-tub levels of 40C
(104F) – close to temperatures suggested for cooking salmon and the highest
surface ocean temperatures measured.
Warm ocean waters in the tropical Atlantic often bring drought to the Amazon. I
sat in a boat in the Mamirauá reserve with my Brazilian host, hydrologist Ayan
Fleischmann, who directs climate research there. “Drought may be coming,” he
said and added: “Water levels several hundred kilometres upriver at a
monitoring station in Tabatinga, Brazil, are already as low as they’ve ever
been.” It was hard to envision drought as we floated past trees during the
seasonal floods.
“The worst Amazon droughts happen in El Niño years with warm Atlantic waters,”
Fleischmann said. The key ocean region is roughly the belt from the equator to
Cuba and southern Florida. The extreme drought triggered by the 2015–16 El Niño
featured record high temperatures, killed billions of trees and turned the
Amazon from a global carbon sponge to a vast carbon source. Amazon fires raged
in 2015 and 2016.
Fleischmann’s warning was prescient. In late September, just two months after I
left, the region baked in unprecedented drought. Water levels in the Amazon
system were lower than at any time since record-keeping began more than a
century ago. Brazil’s minister for the environment, Marina Silva, said: “We are
seeing a collision of two phenomena; one natural, which is El Niño, and the
other a phenomenon produced by humans, which is the change in the Earth’s
temperature.”
Air temperatures around Mamirauá topped 40C for days and the absence of rain
and clouds cooked Amazon waters in the sun. In Lake Tefé, a tributary of, and
gateway to, the western Amazon, where I first met Fleischmann, he measured
water temperatures above 40C between 3ft and 6ft underwater."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
