USA For the first time, new research has compared the impact of bark beetle outbreaks versus climate on the occurrence of large wildfires across the entire western United States. The Clark University study points to climate, not beetles, as the main culprit, suggesting new approaches to managing forests and preventing wildfires.
Extensive outbreaks of bark beetles have killed trees across millions of acres of forests in western North America. The most extensive outbreaks have been of mountain pine beetle, mostly in forests dominated by lodgepole pine. These outbreaks have led to widespread fears about increased fire risk, especially in the wildland-urban interface, where wildfires pose particular risk to homes and communities. Consequently, local and federal policies and strategies have actively sought to cut down forests affected by outbreaks in order to reduce the risk of fires. Nevertheless, wildfires have become larger and more frequent across the region.
The study, published in the journal Ecological Applications, looked at the three-way interactions among fire, insects and climate. Compared to other studies, the Clark research covered the largest area and the longest time period, said Dominik Kulakowski, associate professor of geography at Clark. He co-authored the study with Clark doctoral student Nathan Mietkiewicz.
Over the last three decades, we have seen a stunning increase in wildfires and outbreaks of tree-killing insects across the western U.S. The combination has led to catastrophic losses of life and property. One common response has been to spend enormous financial resources cutting down trees that have been killed by insects, Kulakowski said. Unfortunately, a careful analysis of large wildfires over the past three decades shows that these fires have been driven by climate, not insect outbreaks.
Even as outbreaks have been getting larger, climate continues to have the dominant effect on wildfires. The study went on to examine the occurrence of large wildfires in the wildland-urban interface, where homes, communities and human life are especially at risk. In these critical areas, wildfires were also primarily caused by climate and not by beetle outbreaks.
There are many good reasons to cut down trees that have been killed by insects for example, to make sure that they dont fall and injure people. But if we want to address wildfires, we really need to be talking about climate and not bark beetles, Kulakowski noted. The simultaneous increase in wildfires and outbreaks is occurring because both disturbances are being driven by climate, not because outbreaks are increasing fires. Making this distinction and understanding what is actually going on is essential to successfully managing forests close to homes as well as in remote areas.
Winters have started approaching the northern region of India that also includes Delhi-NCR along with Punjab and Haryana. Due to this, minimums have also started dropping in many parts of North India including Delhi and NCR. In fact, as per the temperatures recorded on October 15 and October 17, the minimums ofDelhi and NCR went down to 17°C.
As per experts, an increase in the pollution level normally occurs during the winter months. However, there are a few reasons that could enhance the pollution level in Delhi and the adjoining areas. The very first reason that can be attributed to an increase in pollution level in the national capital is crop fires in the neighboring state ofHaryana andPunjab.
These two states lie in northwest proximity of Delhi and normal pattern of winds during this season is northwesterly. These winds drag the smoke and fine particles of the burnt crop and mix them with Delhis atmosphere. Moreover, the temperatures also start dipping, therefore, the air near the earths surface tends to condense leading to formation of haze.
Whenever the winds are light or calm, these air pollutants get mixed with the haze or mist and forms a blanket of smoke haze which remains suspended for few hours in the mornings. Thereafter, the haze disappears as the sun rises and temperatures increases during the day.
But as the winter progresses in the month of December and January, the duration of haze, mist or fog gets extended and these pollutants remain suspended in the atmosphere for longer duration of time. Other factors including the smoke emitting from vehicles and factories and dust from construction sites also add to the rising pollution levels.
Sometimes this situation can continue for days altogether. However, relief is expected only when a strong Western Disturbance gives rain over the region. It is then that these pollutants settle down for a few days.
Another criterion which reduces the pollution levels is the strong and moderate dry winds from northwest or west which carry away these pollution particles. In a nutshell, it can be said that in October, intensity and duration of pollution remain less though increases in November as winters sets in.
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