A tiny percentage of upper canopy leaves have already crossed that threshold, reaching temperatures so high — above 47 degrees Celsius — as to prevent photosynthesis, the study published in Nature reported.

Currently, some leaves exceed such critical temperatures only 0.01 percent of the time, but impacts could quickly scale up because leaves warm faster than air, the researchers said.

“You heat the air by two to three degrees and the actual upper temperature of these leaves goes up by eight degrees,” lead author Christopher Doughty of Northern Arizona University told journalists.

If tropical forest’s average surface temperature warms 4C above current levels — widely considered a worst-case scenario — “we’re predicting possible total leaf death,” he said.

The new research suggests that leaf death could become a new factor in the predicted “tipping point” whereby tropical forests transition due to climate change and deforestation into savannah-like landscapes.

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Since 2006, the amount of heat-trapping methane in Earth’s atmosphere has been rising fast and, unlike the rise in carbon dioxide (CO₂), methane’s recent increase seems to be driven by biological emissions, not the burning of fossil fuels. This might just be ordinary variability – a result of natural climate cycles such as El Niño. Or it may signal that a great transition in Earth’s climate has begun.

Molecule for molecule, methane is a much more potent greenhouse gas than CO₂ but it lasts slightly less than a decade in the atmosphere compared with centuries for CO₂. Methane emissions threaten humanity’s ability to limit warming to relatively safe levels. Even more troubling, the rate at which methane is increasing in the atmosphere has accelerated recently. Something like this has happened before: sudden surges in methane marked the transitions from cold ice ages to warm interglacial climates.

Methane was about 0.7 parts per million (ppm) of the air before humans began burning fossil fuels. Now it is over 1.9 ppm and rising fast. Roughly three-fifths of emissions come from fossil fuel use, farming, landfills and waste. The remainder is from natural sources, especially vegetation rotting in tropical and northern wetlands.

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Worth a read but no mention of heat from the earth’s core being a factor in planetary warming. ABN

Physicist, meteorologist testify that the climate agenda is ‘disastrous’ for US

Two prominent climate scientists have taken on new rules from the Environmental Protection Agency (EPA) on cutting carbon dioxide (CO2) emissions in electricity generation, arguing in testimony that the regulations “will be disastrous for the country, for no scientifically justifiable reason.”

Citing extensive data (pdf) to support their case, William Happer, professor emeritus in physics at Princeton University, and Richard Lindzen, professor emeritus of atmospheric science at Massachusetts Institute of Technology (MIT), argued that the claims used by the EPA to justify the new regulations aren’t based on scientific facts but rather political opinions and speculative models that have consistently proven to be wrong.

“The unscientific method of analysis, relying on consensus, peer review, government opinion, models that do not work, cherry-picking data and omitting voluminous contradictory data, is commonly employed in these studies and by the EPA in the Proposed Rule,” Mr. Happer and Mr. Lindzen wrote. “None of the studies provides scientific knowledge, and thus none provides any scientific support for the Proposed Rule.

“All of the models that predict catastrophic global warming fail the key test of the scientific method: they grossly overpredict the warming versus actual data. The scientific method proves there is no risk that fossil fuels and carbon dioxide will cause catastrophic warming and extreme weather.”

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This is from Epoch Times, usually a paywall site but I was able to read the article. A friend said he was able to listen to the audio. ABN

The prodigious evidence for water on Mars has eliminated scientific debate about whether Mars had a watery past. It clearly did. But it has left us with an awkward question: What exactly did that past look like? Some results argue that there were long-lived oceans and lakes on Mars. Others argue that the water largely consisted of ice-covered bodies that only allowed water to burst out onto the surface on occasions.

The picture is further confused by the fact that some or all of these may have been true at different times or in different locations. Creating a clear picture would help shape our understanding of an environment that might have been far more conducive to life than anything that exists on present-day Mars.

A new paper describes evidence that at least one part of Mars went through many wet/dry cycles, which may be critical for the natural production of molecules essential to life on Earth—though they don’t necessarily mean conditions in which life itself could thrive.

The results come courtesy of Curiosity, the older of the two operational rovers on the planet, which is exploring a site called Gale Crater. About 3,000 Martian days into its exploration, the rover was at a site that dates to roughly 3.6 billion years ago, during Mars’ relatively wet Hesperian period. And it came across what would be familiar to gamers as a hex grid: hundreds of hexagonal shaped rock deposits in the area of a few centimeters across and at least 10 centimeters deep.

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