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2020-08-24

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  • Kalifornia 2020
  • Australien
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  • Kalifornia 2020

    "Fires have burned 1.3 million acres of California’s forests over the last month. That’s one million acres more than burned last year, and is an unusually high number for this early in the fire season.

    California political leaders including Governor Gavin Newsom and Senator Kamala Harris, the Democratic vice presidential candidate, blame climate change."

    "But every school child who has visited one of California’s redwood parks knows from reading the signs at the visitor’s center and in front of the trailheads that old-growth redwood forests need fire to survive and thrive. 

    Heat from fire is required for the release and germination of redwood seeds, and to burn up the woody debris on the forest floor. The thick bark on old-growth redwood trees provides evidence of many past fires."

    "Nor is it the case that California’s fires have “grown more apocalyptic every year,” as The New York Times reported. In fact, 2019 saw a remarkably small amount of acreage burn, just 280,000 acres compared to 1.3 million and 1.6 million in 2017 and 2018, respectively.

    What about this year’s fires? “I see [the current California fires] as a normal event, just not one that happens every year,” Jon Keeley, a leading forest scientist, told me. "

    "It’s Not About The Climate

    Nobody denies climate change is occurring and playing a role in warmer temperatures and heatwaves. Keeley notes that, since 1960, the variation in spring and summer temperatures explain 50% of the variation in fire frequency and intensity from one year to the next.

    But the half-century since 1960 is the same period in which the U.S. government promoted, mostly out of ignorance, the suppression of regular fires which most forests need to allow for new growth.

    For much of the 20th Century, U.S. agencies and private landowners suppressed fires as a matter of policy. The results were disastrous: the accumulation of wood fuel resulting in fires that burn so hot they sometimes kill the forest, turning it into shrubland.

    The US government started to allow forests in national parks to burn more in the 1960s, and allowed a wider set of forests on public lands to burn starting in the 1990s. 

    “When I hear climate change discussed it’s suggested that it’s a major reason and it’s not,” Scott Stevens of the University of California, Berkeley, told me.

    Redwood forests before Europeans arrived burned every 6 to 25 years. The evidence comes from fire scars on barks and the bases of massive ancient trees, hollowed out by fire, like the one depicted in The New York Times photograph.

    “There was severe heat before the lightning that dried-out [wood] fuel,” noted Stevens. “But in Big Basin [redwood park], where fire burned every seven to ten years, there is a high-density of fuel build-up, especially in the forests.”

    "In 1904, three large fires burned Big Basin for 20 days, scorching the crowns of many trees, just as the 2020 fire did. 

    Reporters for The New York Times were apparently as pyrophobic 116 years ago as they are today, reporting that year that Big Basin, “seems doomed for destruction.” 

    But redwood forests regularly burn. A 2003 fire in Humboldt Redwoods State Park burned 13,774. Forest in 2008 burned over 165,000 acres. And a 2016 fire burned 130,000 acres. 

    Climate activists who in the winter excoriate those, like Senator James Inhofe, for pointing to snow as proof that global warming isn’t happening, turn around and point to summer fires as proof that it is.

    “In my [five years] as a Californian,” wrote  Leah Stokes in The Atlantic. “I’ve seen a years-long drought. I’ve evacuated my home as a wildfire closed in. I’ve lived through unprecedented heat waves…. that climate is no more.”

    Environmental scholars scoff at this ahistorical view. “The idea that fire is somehow new,” said geographer Paul Robbins of the University of Wisconsin, “a product solely of climate change, and part of a moral crusade for the soul of the nation, borders on the insane.”[1]

    Australien

    Skogsbränderna i Australien runt årsskiftet 2019-2020 har fått stor uppmärksamhet i svenska media. Inte sällan påstås det att klimatförändringar är orsaken. Men bushfires är ett naturligt fenomen i Australien med huvudsakligen öken och torra områden.

    Australia?s size gives it a wide variety of landscapes, with tropical rainforests in the north-east, mountain ranges in the south-east, south-west and east, and desert in the centre. The desert or semi-arid land commonly known as the outback makes up by far the largest portion of land. Australia is the driest inhabited continent; its annual rainfall averaged over continental area is less than 500 mm. [2]

    Det torra klimatet gjorde att aborginerna redan för flera tusen år sedan använde kontrollerade bränder för att minska risken för stora skogsbränder. Detta brandförsvar har ersatts med brandbekämpning. 

    Aboriginal people used fire-stick farming to burn vegetation to facilitate hunting and promote the growth of bush potatoes and other edible ground-level plants. In central Australia, they used fire in this way to manage their country for thousands of years. Fire suppression became the dominant paradigm in fire management leading to a significant shift away from traditional burning practices. A 2001 study found that the disruption of traditional burning practices and the introduction of unrestrained logging meant that many areas of Australia were now prone to extensive wildfires especially in the dry season. A similar study in 2017 found that the removal of mature trees by Europeans since they began to settle in Australia may have triggered extensive shrub regeneration which presents a much greater fire fuel hazard.Another factor was the introduction of Gamba grass imported into Queensland as a pasture grass in 1942, and planted on a large scale from 1983. This can fuel intense bushfires, leading to loss of tree cover and long-term environmental damage.

    Plants have evolved a variety of mechanisms to survive or even require bushfires (possessing epicormic shoots or lignotubers that sprout after a fire, or developing fire-resistant or fire-triggered seeds), or even encourage fire (eucalypts contain flammable oils in the leaves) as a way to eliminate competition from less fire-tolerant species.[3]

    Större bränder

    Än är inte den senaste skogsbranden osedvanligt omfattande. Historien visar också att det inte är ett nytt fenomen även om oklok naturvård ökat bränderna-

    Bushfires have accounted for over 800 deaths in Australia since 1851 and, in 2012, the total accumulated cost was estimated at $1.6 billion.[55] In terms of monetary cost however, they rate behind the damage caused by drought, severe stormshail, and cyclones,[56] perhaps because they most commonly occur outside highly populated urban areas. However, the severe fires of the summer of 2019–2020 affected densely populated areas including holiday destinations leading NSW Rural Fire Services Commissioner, Shane Fitzsimmons, to claim it was "absolutely" the worst bushfire season on record.[57]

    Some of the most severe Australian bushfires (single fires and fire seasons), in chronological order, have included: note 2019/2020 bushfires have a combined total of hectares burned for the States names not single State totals.[4]

    Brasilien


    Pic by Neil Palmer (CIAT). Aerial view of the Amazon Rainforest, near Manaus, the capital of the Brazilian state of Amazonas.

    Amazonas regnskogar har antalet skogsbränder varit rekordhögt 2019 enligt Brasiliens rymdforskningsinstitut INPE. De har registrerat över 72 000 bränder, vilket är det högsta antalet sen man började föra protokoll för 6 år sen. Det är en ökning av skogsbränder på 84% under motsvarande period 2018.[5]

    "In fact, ‘Amazon rainforest’s doing fine’ is a lot closer to the truth than ‘Amazon rainforest — the lungs which produce 20 per cent of our planet’s oxygen — is on fire!’. The forest is not on fire. The vast majority of this year’s fires are on farmland or already cleared areas, and the claim that the Amazon forest produces 20 per cent of the oxygen in the air is either nonsensical or wrong depending on how you interpret it (in any case, lungs don’t produce oxygen). The Amazon, like every ecosystem, consumes about as much oxygen through respiration as it produces through photosynthesis so there is no net contribution. The the number of fires in Brazil this year is more than last year, but about the same as in 2016 and less than in 2002, 2003, 2004, 2005, 2006, 2007, 2010 and 2012. " [6]

    Sverige

    I Sverige inträffar varje år mellan 3 000 och 4 000 bränder i skog och mark. Omfattningen varierar mycket, men vanligen berörs över 2 000 hektar årligen. I internationellt perspektiv är problemen med skogsbränder relativt små i Sverige. Betydligt allvarligare problem finns till exempel i Australien, Ryssland och i Medelhavsområdet.[7]

    Skogsbränderna sägs bli fler och värre i framtiden. Men för bara några generationer sedan var bränderna betydligt mer omfattande, säger författaren Gunnar Wetterberg i Ledarsnack, Expressen.

    Gunnar Wetterberg - som är skogsägare - har skrivit boken “Träd - en vandring genom den svenska skogen”. Hans säger att i ett historiskt perspektiv har vi faktiskt lyckats pressa tillbaka bränderna. 2018 var det kanske 25 000 hektar som brann i Sverige, förr brann uppemot ett par hundra tusen hektar varje år. Ett problem är älg och rådjur som betar lövskog och tall, men inte speciellt mycket gran. Därför planterar många skogsägare gran även på torra marker där det egentligen borde stå tall. Granen är dock mycket mer eldfängd. Vi skulle kunna minska risken genom att skjuta fler älgar och återgå till det man lärde ut på 1800-talet, nämligen att plantera lövstråk igenom barrskogarna för att stoppa upp de bränder som ändå uppkommer. Löv brinner mycket sämre än barr.

    Källor

    Fotnoter

    1) 2) Geography, Australien, Wikipedia
    3) Bushfires in Australia, Wikipedia
    4) Major bushfires i Australia, Wikipedia
    5) See how much of the Amazon is burning, how it compares to other years, National Graphic (2019-08-29)
    6) The most dangerous thing about the Amazon fires is the apocalyptic rhetoric, Matt Ridley, Spectator (2019-09-31)
    7) Brandrisker idag och i framtiden

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    Adm: Hans Iwan Bratt, hibratt@gmail.com