From devastating flooding and mudslides to raging wildfires to the increasing prevalence of extreme storms and weather, it is almost as if nature is trying to tell us we need to change course if we want to avert disaster. Just like a person suffering from chronic illness who sees a worsening of symptoms, the natural world is displaying symptoms, and climate change is the disease.
Climate change is altering forests
One of the most prominent ways that we can see the effects of climate change is how trees and forests are changing over time. It is estimated that there are three trillion trees on the planet, comprising more than 60,000 species. But the rate of deforestation, drought, wildfire and disease changes these numbers on a daily basis.
Each year the planet loses 15 billion trees.
That’s more than 40 million trees per day!
Trees take carbon dioxide out of the air
Trees are important when it comes to the environment because they absorb carbon dioxide, that invisible gas you have heard so much about when it comes to global warming, and they emit oxygen. Just as humans inhale oxygen, trees ‘inhale’ carbon dioxide to power their metabolic processes such as adding new leaves in the spring and storing energy in their roots over the winter (if you live in the Northern Hemisphere).
Studies estimate that globally, trees absorb 7.6 billion metric tonnes of carbon dioxide each year, equivalent to 150% percent of annual emissions from the United States. Therefore, it is becoming more and more important to ensure that deforestation slows down and actually reverses. On a side note, there is a huge global push to plant billions, if not trillions, of trees over the next several years to mitigate the worst effects of climate change, and some innovative startups have even developed mechanical trees which pull carbon dioxide out of the air at an accelerated rate. At Leaf Score, we are doing our small part in this effort in partnership with American Forests. Our site donates 10% of all profits to planting trees, with each dollar we donate putting a new sapling in the ground.
Climate vs. Weather
Before we discuss how climate change is impacting trees, it is important to note the difference between weather and climate. Weather refers to the short term atmospheric conditions (like if it rains today) while climate refers to long-term changes in atmospheric conditions (over many hundreds or thousands of years, like when the rainy season occurs during the year). If one year has a lot more sunny days than last year, that does not mean climate change is the main culprit, so keep that in mind the next time you hear a claim about climate change when referring to a very short timespan.
Trees are some of the first climate migrants
When we look at how the climate has changed over the long-term, we are seeing a shift in the range of where species can tolerate atmospheric conditions, such as trees that thrive in cooler climates moving towards the poles or up mountains to higher elevations. A recent publication has found that the extent of the ideal human climate ‘niche’ (where temperature and precipitation has been optimal for humans over thousands of years) has shifted towards the poles. This will have adverse consequences as humans follow this path and clear existing, forested areas for agriculture and cities. To the more extreme, the changing climate is exposing vast swaths of forested areas to abnormal temperatures and droughts, which leads to more stress on these forests making it more susceptible to harm from pests, diseases and wildfires.
An example of this is the mountain bark beetle infestation in the Mountain West, which has impacted four million acres across numerous states and been one of the reasons for the devastating wildfires over the last several years. Over the long term, as trees continue to be exposed to harsh environmental conditions, they weaken, get sick or infected and eventually die. This is what we are currently seeing in places like the west coast in the United States and across Europe and Australia. The trees are sending a very clear message to us that if we continue treating the environment as business as usual, we will be next.
Why you should care
But if the trees die, won’t new trees take their place? Usually, this is the natural cycle of forests, but as it becomes more and more inhospitable for forests, this cycle will become more broken or invite invasive species to take root in areas with little or no natural population checks. Trees store large amounts of carbon in their trunks and below ground. When events like massive wildfires burn millions of acres in a year, millions of tons of carbon are released into the atmosphere and the ground beneath becomes destabilized, leading to soil erosion, runoff and mudslides, which further exacerbates carbon release. This is an example of a positive feedback loop: as more carbon is released into the atmosphere, the climate continues to change, thus leading to more carbon being released, and so on. It is imperative that we break this cycle and really pay attention to what trees are trying to tell us: stop treating the environment as an inexhaustible resource where we take and take and give nothing back.
The importance of tree equity
Some critics of planting trees as a strategy for fighting climate change argue that trees, standing alone, can’t possibly take enough carbon dioxide out of the atmosphere to solve the climate emergency. This argument misses the point. Of course planting trees isn’t a substitute for ending our reliance as a society on fossil fuels, however, trees don’t just take carbon dioxide out of the air, they also provide needed protection as heat waves become hotter and more dangerous. The team at American Forests has done an excellent job highlighting the lack of tree canopy in many urban and disadvantaged neighborhoods, which sadly, are often the communities most vulnerable to increasing incidents of extreme weather. American Forests built a Tree Equity Scoring Tool which evaluates the tree cover of various neighborhoods. Neighborhoods that lack trees are often several degrees hotter than more affluent neighborhoods with mature trees. In a hotter world, the ability of trees to cool down neighborhoods and provide shade from blistering sun can make a big impact on the parts of our cities which bear the brunt of extreme heat. In these cases, planting more trees fights climate change by making stressed environments more livable. Areas in cities that become hotter due to a lack of trees are known as Urban Heat Islands.
On average, urban heat islands are 5 to 7 degrees warmer during the day, and can increase temperatures by as much as 22 degrees at night. If actions aren’t taken to slow climate change, heat-related deaths from 2031 to 2050 could be 57 percent higher than they were from 1971 to 2000. Planting and conserving trees is one equitable way to reduce urban heat islands and save livesAmerican Forests – What is the urban heat island effect?
It’s not all bad news
Fear not, because while nature is clearly sending a signal that our current ways of treating nature as an inexhaustible resource cannot last, there are many international efforts currently underway to halt deforestation or promote tree planting such as the 30×30 campaign from the United Nations, the Great Green Wall project in Africa or the Trillion Tree Campaign.
Whether you are already part of a tree planting program or interested in learning more, it is important to do your homework and make sure that the right trees are planted in the right places, they are monitored over time and they are not being counted twice if they are part of a carbon credit program.