Mosaic (definition 3): A combination of diverse elements forming a more or less coherent whole. – Oxford New American Dictionary
By Bill Dawson
Texas Climate News
It’s not just tree-huggers who love trees. It’s safe to say that most of environmentalists’ strongest critics are also extremely fond of them. After all, this is the time of year when lots of people, regardless of their views on climate change and other environmental issues, bring an evergreen into their homes to decorate with ornaments and lights.
In keeping with this seasonal practice and with people’s affinity for trees in general, here’s a selection of recent news about the massive harm that climate change is already doing to forests, and some of the ways that scientists are projecting those damaging impacts to multiply as global warming intensifies.
This week, scientists from a number of universities and research centers published a research paper in the journal Nature Climate Change that predicted a “massive” die-off of needleleaf evergreen trees in the U.S. Southwest – a region defined as including part of Texas – because of rising temperatures.
“We have fairly consistent predictions of widespread loss of piñon pine and juniper in the southwest, sometime around 2050,” said McDowell. The paper concludes that the consequences could be vast, citing “profound impacts on carbon storage, climate forcing, and ecosystem services.”
A report by the Phys.org website elaborated on that point:
Loss of broad-scale forest cover over the Southwest could contribute additional carbon to the atmosphere, creating additional warming. This is because trees and understory vegetation, such as shrubs and bushes, sequester carbon from the atmosphere. Less vegetation means less carbon capture, which can create a negative feedback loop that can accelerate climate change, [University of Delaware’s Sara] Rauscher said.
All the forest news hasn’t been discouraging.
Earlier this month, 195 nations adopted a historic plan to limit warming to 2 degrees Celsius (3.6 degrees Fahrenheit) to avoid warming’s most catastrophic consequences to humans and natural systems.
It included important language on forests, in which national representatives pledged to reduce deforestation and forest degradation. This section of the agreement marked, the New York Times reported, the “most significant recognition” yet in a world climate agreement of “the role forests play in offsetting human actions” – the very “services” acknowledged in the study about Southwestern forests.
The Times added about the forest provision in the Paris accord:
It is meant as a political signal that countries should enact policies that have been developed over the last decade to save the world’s remaining intact forests. Tropical countries would likely be paid with both public and private money if they succeed in reducing or limiting destruction of their forests due to logging, or clearance for food production.
But the threats to forests addressed in the agreement are dauntingly vast in scope, according to several recent studies.
The Washington Post reported in August that a collection of studies in the journal Science had documented how “the world’s forests are in serious trouble.”
The research systematically examines how forests are being damaged by the combined impacts of a changing climate and more human incursions.
“These papers document how humans have fundamentally altered forests across the globe and warn of potential broad-scale future declines in forest health, given increased demand for land and forest products combined with rapid climate change,” note Susan Trumbore of the Max Planck Institute for Biogeochemistry and two coauthors in an overarching introduction to the suite of studies.
Regarding the Amazon region of South America, home of the world’s largest tropical rainforest, the New York Times reported last month that a study in the journal Science Advances had concluded that deforestation there threatens at least 36 percent and as much as 57 percent of tree species.
In a paper in Nature Climate Change in May, researchers at Los Alamos National Laboratory in New Mexico reported finding that drought and heat-caused tree death was speeding up in many forest regions because of global warming, which is “creating a threat to global forests unlike any in recorded history,” Science Daily reported.
Other studies by different researchers that were reported by Climate News Network in recent months have detailed various troubling aspects of the many problems forests are experiencing.
New research by U.S. scientists looked at decades of wildfire incidence in Alaska, and they have found that at least one region is now a net exporter of carbon.
This is a reversal of the normal arrangements, whereby trees photosynthesize tissue from the carbon dioxide in the atmosphere. As they absorb carbon, they sequester it in roots, timber and leaves, and then in leaf litter in the forest soils.
New research suggests that although increasing levels of carbon dioxide in the atmosphere can and do deliver extra fertilization and more vigorous growth, the effect may have been overestimated.
Highland tree species in the Andes are decreasing as global warming caused by greenhouse gas emissions forces lowland varieties to move upwards into cooler climes.
In the long term, many of the great oak forests of Europe or the giant redwoods and pines of America may not survive. U.S. researchers foresee potential widespread loss of the great temperate forests of both continents. Under the combined assault of increasing global temperatures and unprecedented drought, some forests could inexorably slide into savannah or scrubland.
Spring is arriving ever earlier as greenhouse gas levels rise and global temperatures warm, and the northern hemisphere growing season is now two weeks longer than it was in 1900. But, paradoxically, new research shows that forest giants that once responded to the early spring are beginning to slow down – because they miss the chill.
Even seemingly upbeat news – as when scientists reported in a paper published in September that there are more than six times as many trees on the planet as previously estimated – came with a worrisome proviso:
The Washington Post reported that in a “blockbuster study” in the journal Nature:
[…A] team of 38 scientists finds that the planet is home to 3.04 trillion trees, blowing away the previous estimate of 400 billion. That means, the researchers say, that there are 422 trees for every person on Earth.
However, in no way do the researchers consider this good news. The study also finds that there are 46 percent fewer trees on Earth than there were before humans started the lengthy, but recently accelerating, process of deforestation.
The researchers concluded that because of human and other causes, the world is experiencing a net loss of about 10 billion trees a year.
Bill Dawson, a veteran Texas journalist, is the founder and editor of Texas Climate News. (Full disclosure: He has liked trees and forests since he was a small boy.)