Yosemite is burning while the climate is changing
Forest fires act in a synergistic manner in increasing the concentration of greenhouse gases
in the atmosphere
Quamrul Haider
Yosemite National Park in California is one of my favorite parks. I visited this crown jewel of Americas national parks several times. With the massive granite monoliths of El Capitan and Half Dome in the backdrop, the sublime beauty of the park thats unmatched on the globe and the dramatic change in its landscape from season to seasonare parts of its allure that draws hordes of tourists from all over the world every year.
Since 13 July 2018, a devastating fire is raging through this iconic park.The entire Yosemite Valley is now blanketed in plumes from the out-of-control wildfire. Dry conditions and triple digit temperatures added fuel to the fast-moving blaze, forcing closure of some of the tourist-favorite sites ‒ Half Dome, Sentinel Dome, El Capitan, Bridal Veil Falls, Yosemite Falls,to name a few. And there is no relief in sight.
In addition to the Yosemite fire, numerous wildfires are burning all over California ‒ from the forests in the mountains and canyons near San Diego in the south to Redding in the north.According to the U.S. Forest Service, more than 85 large wildfires, including four in Alaska,are currently raging through Western United States. Hot and dry weather are hindering efforts to slow the spreading of these fires.
What causes a forest fire? Human behavior, such as arson or tossing a burning cigarette in a forest or leaving a campfire unattended, can result in forest fires. The other cause is lightning, which is most likely to occur when the weather is hot and dry. The fires in Oregon have been started by a spate of lightning strikes from thunderstorms. The exact cause of the Yosemite fire has not yet been determined, but lightning is suspected to be the culprit.
Forest fires arent inherently bad. In fact, they are a natural and beneficial part of a forests ecosystem.When firesburn through a forest, they unlock heat-primed seeds and clean the forests floor by pruning the undergrowth that build up with the passage of time, therebycreating space for larger, more mature and fire-resistant trees. They also remove weak and disease-ridden trees, kill harmful insects, break down and return nutrients to the soil, and allow more sunlight in so that trees stay healthier. In other words, forest fires are eco-rejuvenating and are necessary for the forest to stay healthy.
However, in recent years, there has been an unnatural increase in the number of lightning-induced wildfires. Some of themare so intense and uncontrollable that entire forests are burning down.The number of lightning-induced fire is increasing because the climate in a forests environment is becoming hotter and drier due to global warming.A 2014 study published in the journal Science predicts that the number of lightning strikes could increase by about 12 percent for every degree Celsius of warming.
There is now ample data to suggest that climate change is indeed the biggest driver of out-of-control wildfires. How? In colder regions, an unusually warmer climate leads to earlier snowmelt and, consequently, spring arrives earlier. An early spring causes soils to be drier for a longer period of time. Drier conditions and higher temperatures increase not only the likelihood of a wildfire to occur, but also affects its severity and duration. This means when a wildfire breaks out, it expands faster and burns more areas as it moves in unpredictable ways. Eventually, it becomes an eco-devastator that bakes the soil and burns down trees that are hundreds of years old.
Thus, climate change isnot only increasing the number of wildfires, not just in the United States, but elsewhere around the world, it is also shaping fire seasons. Even in Greenland, where average summer temperature is around 20 degrees Celsius,there were a significant number of wildfires last year.
Forest fires act in a synergistic manner in increasing the concentration of greenhouse gases in the atmosphere. In a forest, trees and plants release water through tiny pores in their leaves called stomata. The higher the ambient temperature, the more water they release. Forest fires willcause these water to evaporate, including water from dead plants littering the grounds. It is well known that water vapor is one of the major greenhouse gases. Moreover, more fires meanmore carbon dioxide emitted into the atmosphere. The net result is a positive feedback in raising the global temperature.
Although climate change might also bring more rain to some areas, nevertheless, to offset the impact of temperature increase will require a lot of rainwater.
A Canadian study shows that a 15 percent more rainfall is needed to offset the increased risk of forest fires from a one degree Celsius rise in temperature.
Why are forest fires so hard to put out? As noted above, forest fires ignited by lightning occur during extreme weather conditions ‒ searing hot days with low humidity, droughtand high winds, all upshot of climate change. Under these conditions, the likelihood of fires quickly doubling in size is very high. They are also the conditions where it is most dangerous to put people in front of the fire. Furthermore, a lot of these fires start in very remote areas with rugged terrain, and just putting people on the ground under these circumstances comes with great risk.
According to the Intergovernmental Panel on Climate Change, since 1880, global temperature rose roughly 0.85 degree Celsius. Yet, raging wildfires, more droughts, once-in-a-thousand year storms, devastating floods, melting of Arctic ice at an alarming rate and lethal heatwaves are on the rise. If a less than one-degree rise in temperature is wreaking so much havoc, what will happen to our planet if we take the free pass of heating up theatmosphere by two degreesbefore the end of this century, as agreed upon by the stakeholders in the 2016 ParisAgreement?
Finally, how many Yosemites will have to burn before we act decisively? To say the least, this wont be the last blaze of a hot, dry summer. Scientists believe that forest fires that are more disastrous and more frequent will rage through Yosemite and other forests of the world in the future. The reason is simple: climate change is real and it is here to stay.
There is no turning around now because we have already gone too far. It will only get worse from here on. It is time for all of us,especially Americas stable genius and his basket of deplorables to wake upand face this stark reality.
The writer is a Professor of Physics at Fordham University, New York
