Climate change is really, really, really bad and we need to face the obvious fact that this is not going to end well for us. Humans need to pull it together, and work with each other to mitigate this looming catastrophic disaster that no sane person would ever want to face.
We are part of the biosphere’s web of life which sustains us, and every other creature on earth. The challenges we face today are many including food production, the unsustainable numbers of our population, either too much rain or too little, the decimation of our fellow species, depletion of the aquifers, epidemic diseases, the warming and acidification of the planet’s oceans and the changing climate. Humanity has had it easy since the last interglacial ice age 11,000 years ago due to our climate being surprisingly stable considering the ebb and flow of the great ice sheets (NASA). This stability has allowed us to build the civilization that we enjoy today, we can farm and raise livestock because rainfall is generally predictable. But now we find ourselves at the most dangerous moment modern humans have ever faced.
Like “rats inside the experiment,” Neils Bohr Institute glaciology professor Jorgen Peder Steffensen says of us humans when he considers the risks of a sudden reconfiguration of global circulation which could, among other things, cause long-term drying across America’s breadbasket states.
“That’s going to impact the entire world,” Steffensen cautions in recognizing that the 11,000 years of the interglacial period since the last ice age “has been unreasonably stable. And we don’t know why” or how long that stability may persist.
Researchers from the Woods Hole Research Center and Boston University published a new study and Cosmos reported on yet another tipping point that we have crossed.
The world’s tropical forests are often described as the planet’s lungs; but now, due to human activity those lungs are emphysemic, with new research indicating they are no longer the globe’s great carbon sink. Instead, the rate of forest destruction, degradation and disturbance means they are emitting more carbon than they capture.
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Importantly, the analysis shows the clear dangers of deforestation – long recognised by the public and policymakers – are now overshadowed by the more subtle consequences of forests being degraded and disturbed. According to their calculations, degradation and disturbance account for 69% of total carbon losses from the world’s tropical forests.
“It can be a challenge to map the forests that have been completely lost,” says one of the paper’s authors, Wayne Walker, a scientist with WHRC. “It’s even more difficult to measure small and more subtle losses of forest. In many cases throughout the tropics you have selective logging, or smallholder farmers removing individual trees for fuel wood. These losses can be relatively small in any one place, but added up across large areas they become considerable.”
By providing a far more accurate picture of the state of tropical forests and their stunted role in the global carbon cycle, the findings are significant, striking and credible, says Pep Canadell, a climate scientist with Australia’s CSIRO and executive director of the Global Carbon Project.
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The conclusion that tropical forests are now emitting carbon rather than removing it from the atmosphere is due to the carbon in the forest biomass lost being greater than the carbon that can be absorbed by the remaining forest.
The paper notes that removed biomass may not necessarily be immediately released back into the atmosphere, as would occur if a tree was burnt. “Above-ground biomass may first transition to other carbon pools or be removed from the forest without release to the atmosphere.” But temporary carbon storage via the use of a tree trunk for wood products such as furniture and construction materials, they calculate, constitutes just 4-14% of losses.
Bottom line: a tree lost in a forest stops being a carbon absorber and, sooner or later, ends up emitting its stored carbon, either quickly through incineration or slowly through decomposition.
New Study Shows the Amazon Makes Its Own Rainy Season
“A new study gives the first observational evidence that the southern Amazon rainforest triggers its own rainy season using water vapor from plant leaves. The finding helps explain why deforestation in this region is linked with reduced rainfall.” according to a NASA study.
The study analyzed water vapor data from NASA's Tropospheric Emission Spectrometer (TES) on the Aura satellite, along with other satellite measurements, to show that at the end of the dry season, clouds that build over the southern Amazon are formed from water rising from the forest itself. The research is published in the journal Proceedings of the National Academy of Sciences (PNAS).
It's been a mystery why the rainy season begins when it does in the Amazon south of the equator. In most tropical regions, two factors control the timing of the rainy season: monsoon winds (a seasonal change of direction in prevailing winds) and the Intertropical Convergence Zone (ITCZ), a belt of converging trade winds around the equator that shifts north or south with the seasons. The southern Amazon experiences both of these. But they don't occur till December or January, while the rainy season currently starts in mid-October -- two or three months earlier. So what does set off the increase in rainfall?
John Worden of NASA's Jet Propulsion Laboratory in Pasadena, California, developed a data analysis technique for TES that enabled Fu, study first author Jonathon Wright (Tsinghua University, Beijing) and colleagues to pinpoint the moisture source. The technique distinguishes between hydrogen and its heavier isotope deuterium, which combines with oxygen to make heavy water. Lighter isotopes evaporate more easily than heavier isotopes. That means water vapor that evaporated into the atmosphere has less deuterium than liquid water. For example, water vapor that evaporated from the ocean has less deuterium than water that's still in the ocean.
Water that is transpired by plants, on the other hand, has the same amount of deuterium as water that's still in the ground -- the plant sucks water out of the ground like a straw, no matter which isotope the water contains. That means water vapor transpired from plants has more deuterium than water vapor evaporated from the ocean.
This difference is the key that allowed the scientists to unlock the rainy-season mystery. The two isotopes have different spectral "signatures" that can be measured from space by the TES instrument. The measurements showed that, during the transition from dry to wet season, transpired water becomes a significant moisture source for the atmosphere, and in particular for the middle troposphere, where the increasing water vapor provides the fuel needed to start the rainy season.
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The finding raises another question: Why do plants start to grow and transpire more during the dry season, before there's an increase in rain? That's still a subject of research, Fu said. "This may be the way the forests optimize their growth. In the late dry season, plants still get sunshine, and they could anticipate the coming rainy season because they are adapted to the seasonality of the rain."
That seasonality has been changing in recent decades, however. The rainy season in the southern Amazon now starts almost a month later than it did in the 1970s. There's evidence that if the Amazon dry season becomes longer than five to seven months, the forest will no longer receive enough rain each year to keep trees alive, and the region will transition from forest to grassy plains. Over a large fraction of the southern Amazon, the dry season is now only a few weeks shorter on average than this transitional threshold. There has already been some irreversible damage to the forest. The loss of a major Amazonian forest ecosystem could increase Brazilian droughts and potentially disrupt rainfall patterns as far away as Texas.
The reasons for the delayed onset of the wet season are not completely understood, but the new study adds evidence to the idea that deforestation is playing a role. Reducing the trees available to produce moisture would naturally reduce the forest's cloud-building capacity. If deforestation slowed the increase in transpiration to the point that it could no longer trigger a rainy season, rains wouldn't begin till the ITCZ arrived at the end of the year.
The finding highlights how closely connected the rainforest ecosystem is with climate, Fu said. "The fate of the southern Amazon rainforest depends on the length of the dry season, but the length of the dry season also depends on the rainforest."