Anonymous
By Harrison Tasoff, UC Santa Barbara
When you walk through a forest, you are surrounded by carbon. Every branch and every leaf, every inch of trunk and every tendril of unseen root contains carbon pulled from the atmosphere through photosynthesis. And as long as it stays stored away inside that forest, it’s not contributing to the rising concentrations of carbon dioxide that cause climate change. So it’s only natural that we might want to use forests’ carbon-storage superpower as a potential climate solution in addition to reducing human greenhouse gas emissions.
But climate change itself might compromise how permanently forests are able to store carbon and keep it out of the air, according to a new paper by researchers at University of Utah and UC Santa Barbara. The study considered how different regions and tree species will respond to climate change. The authors found a wide range of estimates for the amount of carbon that forests in different regions might gain or lose as the climate warms. Importantly, the researchers found that regions most at risk of losing forest carbon through fire, climate stress or insect damage are precisely those regions where many forest carbon offset projects have been set up.
“Forest health and carbon-storage potential is evolving rapidly due to climate change,” said co-author Anna Trugman, an assistant professor at UC Santa Barbara. “The balance of increasing productivity from higher CO2levels and accelerating losses from disturbances will determine the fate of forests as a carbon sink.”
Anna Trugman (Photo: UCSB)
The study appears in Nature Geoscience. The authors also created an interactive tool showing aboveground, live carbon storage potential in forests across the contiguous United States by the end of the century.
“This tells us there’s a really urgent need to update these carbon offsets protocols and policies with the best available science of climate risks to U.S. forests,” said University of Utah’s William Anderegg, the study’s senior author.
A multi-perspective modeling approach
The researchers hoped to forecast changes in the amount of aboveground carbon storage in forests of different regions in the U.S. Aboveground carbon refers to any living parts of a tree that are above ground, including wood and leaves or needles.
Scientists can look at the future of forests under climate change in a few different ways. They can consider historical and future projections of the climate, or examine datasets from long-term forest plots. They can also use machine learning to identify which climate niches different tree species most prefer. Or they can use complex models that include interactions between the ecosystem and the atmosphere.
Anderegg and colleagues, including first author Chao Wu, chose all of the above. “Each different method has inherent advantages and limitations,” said Wu, a postdoctoral scholar at University of Utah. “No model is perfect.”
“By bringing in many different approaches and different model types and comparing them,” Anderegg said, “we can get a sense of what the different models are telling us and how we [can] learn to improve the models. And we might have much more confidence if all of the models and all of the approaches tell us the same story in a given region.”
The researchers found that, although the models’ forecasts differed in some ways, they showed some consistency in predictions of how different regions’ carbon storage might change in the future. The Great Lakes and Northeastern U.S., for example, as well as parts of the Southeastern U.S. and the northern Rockies, consistently showed carbon gains in future projections.
Forests have been decimated by fires and bark beetles in northern New Mexico. (Photo: Curt Dvonch)
But the models also revealed significant risks of losing carbon from forests through the triple threat of fire, climate stress and insect damage. Without these stresses, forests might be able to pack away 9.4 petagrams of carbon nationwide by the end of the 21st century. A petagram is equal to a quadrillion grams — about 25 times the mass of all humans on Earth. However, with these risks, the models projected a net gain in forests of between 3 and 5 petagrams.
The researchers also applied their analysis to 139 current projects aiming to offset carbon emissions by increasing the carbon stored in forests. “For carbon offsets to be effective,” Anderegg said, “they have to store carbon for a pretty long amount of time — multiple decades to centuries. So if fire’s burning them down or insects are wiping out different areas, it could vastly undermine their effectiveness as climate change solutions.”
Depending on the model method and the climate scenario, the researchers found that large numbers of carbon offset forest projects, particularly in the Southeastern U.S. and on the West Coast, are projected to lose carbon by the end of the century.
What we still need to know
The results highlight that different climate and ecological models have different strengths and weaknesses, and considering them together reveals the areas of research needed to improve climate projections.
Tree demographic models, for example, include simulations of forest dynamics as old trees die and new trees grow. “But these current models didn’t consider the disturbance-vegetation feedback,” Wu said, referring to the different types of vegetation besides trees that appear following a disturbance like a forest fire and how they might influence the odds of another disturbance. “Also they didn’t consider CO2 fertilization,” or the potential for rising carbon dioxide levels to actually improve plant growth.
The authors identified three research questions that could help elucidate the situation. First is the extent to which plants and trees might benefit from rising CO2 concentrations, as the compound is vital for photosynthesis. Second is a need for better data on climate-driven tree mortality from fire, climate stress and insects to inform their understanding of these threats. Last, scientists need a better account of how biomes will shift. For example, some forests may be able to grow back after a disturbance, but others may transition to grasslands and be lost entirely. “These are some of the biggest unknowns that the field is really racing to tackle,” Anderegg said.
In the meantime, while science works to understand how climate change affects forests, society can help by slowing the pace of climate change. “Working to tackle climate change as quickly as possible and move to a lower carbon future massively decreases the risks that forests are likely to face in the 21st century,” Anderegg said, “and increases the potential benefits that we might get from forests.”
Funny the earth would be completely fine without us living on it. All the other animals would live like nature intended, almost like native Americans. Humans are a cancer consuming the earth. “Life after people” is a cool documentary.
Without humans, all life on earth will eventually become extinct. Unlike any other animal we have the potential ability to make life interplanetary and last longer than our planet / solar system will allow. We’ve been able to use earths resources to significantly increase our intelligence and understanding, to make amazing technological innovations that wouldn’t have been possible without fossil fuels. It is a fact they’ve enabled humanity to thrive. What if Earth does have the only life in our universe and we’re intended to consume earths resources in order expand life throughout the universe?
I’ve been called a ‘carbon shill’ and ‘oiler’ for saying this exact same thing. “ The balance of increasing productivity from higher CO2levels” which is saying earths plants are more productive with higher co2 levels. Nature is self balancing, higher co2 levels lead to more productive plant life (photosynthesis) which leads to plants being able to sequester more carbon, and crops being able to provide more food, per acre. No, this fact based and accurate comment doesn’t mean we should forgo trying to minimize our impact on our environment (I’m looking at those EdScolds who think any critique means I’m embrace the extreme opposite), but it does mean the “it’s a climate apocalypse we’re all going to die from rising sea levels in 7 years if we don’t take immediate and drastic action (to the detriment of the middle / lower classes and developing nations throughout the world)” are anti-science sensational propagandists. This article used a ton of words to say “we don’t know”, yet so many are so sure an environmental apocalypse is upon us.
11:39 – But your major premise is false. Plants do not benefit from increasing CO2 above a certain concentration, and the adverse effects on the weather are far worse for agriculture and plant productivity. You are, indeed, a shill for the carbon industry, or at least a dupe.
Climate myth #43: https://skepticalscience.com/co2-plant-food.htm
VOR, you should really stop with this whole ridiculous “Edscolds” thing, at least until you stop being one.
“Edscolds” – from the guy who breaks down in tears about “name calling” and “hate” from the left.
Shouldn’t take deep scientific research to confirm you might lose some CO2 capture in a tree that burns down or stricken and killed by insects. Or are you saying these occurrences are actually something new? In the meantime, I’m told the ice cap in antarctica is now growing. What?!!! The plot thickens.
In the last couple thousand years, forests experienced more severe rains and droughts than anything in living memory. What the forests did not experience, particularly in the western US, is a lack of fire. For approximately 100 years, humans have been very effective at snuffing out every fire that starts in the forest. As recently as the 20s and 30s, over 20,000,000 acres of forests burned in the US every year. In recent years that number has been reduced to 1,000,000 or less through intensive mechanized intervention although that figure has been increasing slightly. Thankfully the national park service saw the light and abandoned the destructive intervention of extinguishing natural fires, but fire suppression continues for most of our forested lands. This results in infestations of pests, unnaturally dense growth, and lots and lots of dead trees. During climate fluctuations in centuries past, more extreme than any experienced in living memory, frequent low intensity fires kept the forests healthy and resilient. In the future, fire will once again be the key to preserving and protecting healthy forests.
How can ice be increasing, yet decreasing?
It’s long past time to call climate change skeptics anything but idiots.
The surface extent of the ice may increase, but if it’s thinner, the total amount of ice decreases.
WATCHER – while there is some increasing of the ice, the overall trend is going down, not up. See for yourself how it can increase and decrease over time:
https://climate.nasa.gov/vital-signs/ice-sheets/
RUBAIYAT – look at the graph. A little bit grows, then it melts. So, it increases a little, then decreases a lot. It’s a bit inaccurate to say the overall ice cap is increasing in size.
We can be experiencing a drought while it’s flooding too. It’s really trendy to redefine words these days.
Voice. If humans were more like insects ,so to speak, yes we could all have a common goal. We would all be driving nuclear vehicles. But we are not and will continue to fight and destroy each other. Have you ever flown into LAX it looks like skin cancer on the earth.