Archives par mot-clé : Trees

PAGES2K: North American Tree Ring Proxies

by Steve McIntyre, October 24, 2018 in ClimatAudit


The PAGES (2017) North American network consists entirely of tree rings. Climate Audit readers will recall the unique role of North American stripbark bristlecone chronologies in Mann et al 1998 and Mann et al 2008 (and in the majority of IPCC multiproxy reconstructions).  In today’s post, I’ll parse the PAGES2K North American tree ring networks in both PAGES (2013) and PAGES (2017) from two aspects:

Conclusions

  • ex post screening based on recent proxy trends necessarily biases the resulting data towards a Hockey Stick shape – a criticism made over and over here and at other “ske;ptic” blogs, but not understood by Michael (“I am not a statistician”) Mann and the IPCC paleoclimate “community”;

  • the PAGES 2017 North American tree ring network has been severely screened ex post from a much larger candidate population: over the years, approximately 983 different North American tree ring chronologies have been used in MBH98, Mann et al 2008, PAGES 2013 or PAGES 2017. I.e. only ~15% of the underlying population was selected ex post – a procedure which, even with random data, would impart Hockey Stick-ness to any resulting composite

  • despite this severe ex post screening (in both PAGES 2013 and PAGES 2017), the composite of all data other than stripbark bristlecones had no noticeable Hockey Stick-ness and does not resemble a temperature proxy.

Hunger Stones and Tree Ring evidence suggests solar cycle influence on climate

by Francis Tucker Manns Ph.D., September 30, 2018 in WUWT


Conclusions

Extreme weather events, mostly drought are considered, but floods as well, correspond to solar minima in more than 75% (18 out of 24 of the cases known).

Current concentrations of carbon dioxide cannot be invoked for extreme weather in the historical past.

The sun controls the climate of the Earth.

During summer it is inevitable that lightning storms ignite fires and produce heavy rain. The intensity of what we have come to call extreme weather is magnified by standing Rossby waves.

Sunspot research tends to emphasize sunspot peaks and sunspot numbers; more may be gained by evaluating trough events and peak and trough frequencies.

Global Tree Cover Has Expanded More Than 7 Percent Since 1982

by  Ronald Bailey, September 4, 2018 in Reason


Global tree canopy cover increased by 2.24 million square kilometers (865,000 square miles) between 1982 and 2016, reports a new study in Nature.

Researchers using satellite data tracked the changes in various land covers to find that gains in forest area in the temperate, subtropical, and boreal climatic zones are offsetting declines in the tropics. In addition, forest area is expanding even as areas of bare ground and short vegetation are shrinking. Furthermore, forests in montane regions are expanding as climate warming enables trees to grow higher up on mountain.

Carbon emissions in African savannas triple previous estimates

by Edinburgh University, August 24, 2018 in ScienceDaily


The findings highlight the extent to which humans are impacting one of the world’s major ecosystems — the Miombo woodlands, which cover 2.5 million square kilometres, across countries including Angola, Zambia, Tanzania and Mozambique.

At the same time, however, the growing number of trees in remote parts of these woodlands is helping to offset the emissions, researchers say.

The study is the first to provide an in-depth analysis of areas gaining carbon while also losing it through degradation — a process where some, but not all, trees are removed, usually as a result of logging and fire.

See original article in Nature

Scientists discover that the world contains dramatically more trees than previously thought

by Chris Money, September 2, 2015 in TheWashingtonPost


In a blockbuster study released Wednesday in Nature, a team of 38 scientists finds that the planet is home to 3.04 trillion trees, blowing away the previously 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.

“We can now say that there’s less trees than at any point in human civilization,” says Thomas Crowther, a postdoctoral researcher at the Yale School of Forestry and Environmental Studies who is the lead author on the research. “Since the spread of human influence, we’ve reduced the number almost by half, which is an astronomical thing.”

Trees and climate change: Faster growth, lighter wood

by Technical University of Munich (TUM), August 14, 2018


Wood density of European trees decreasing continuously since 1870

Trees are growing more rapidly due to climate change. This sounds like good news. After all, this means that trees are storing more carbon dioxide from the atmosphere in their wood and hence taking away the key ingredient in global warming. But is it that simple? A team analyzed wood samples from the oldest existing experimental areas spanning a period of 150 years — and reached a surprising conclusion.

But the most important finding for practical and political aspects is that the current climate-relevant carbon sequestration of the forests is being overestimated as long as it is calculated with established but outdated wood densities. “The accelerated growth is still resulting in surplus carbon sequestration,” says Pretzsch. “But scaling up for the forests of central Europe, the traditional estimate would be to high by about ten million metric tons of carbon per year.”

Once again, climate scientists use a single tree to define global change

by A. Watts, February 19, 2018 in WUWT


From Keele University and the “It’s like deja vu all over again”  department with the leader of the “ship of fools” thrown in for comic relief. Long-time WUWT readers surely remember the single “Most influential tree in the world” from the Yamal fiasco, where the “signal” in one tree (YAD06) biased an entire paper with a hockey stick shape, making it worthless. Well, here we are again with another single tree used to define the entire globe. Obviously they’ve learned nothing, then again, it’s Chris Turney.