Global warming making earth ‘greener’ - Pakistan Today

Global warming making earth ‘greener’

THE planet is getting lusher, and we are responsible. Carbon dioxide generated by human activity is stimulating photosynthesis and causing a beneficial greening of the Earth’s surface. For the first time, researchers claim to have shown that the increase in plant cover is due to this “CO2 fertilisation effect” rather than other causes. However, it remains unclear whether the effect can counter any negative consequences of global warming, such as the spread of deserts.
Recent satellite studies have shown that the planet is harbouring more vegetation overall, but pinning down the cause has been difficult. Factors such as higher temperatures, extra rainfall, and an increase in atmospheric CO2 – which helps plants use water more efficiently – could all be boosting vegetation.
To home in on the effect of CO2, Randall Donohue of Australia’s national research institute, the CSIRO in Canberra, monitored vegetation at the edges of deserts in Australia, southern Africa, the US Southwest, North Africa, the Middle East and central Asia. These are regions where there is ample warmth and sunlight, but only just enough rainfall for vegetation to grow, so any change in plant cover must be the result of a change in rainfall patterns or CO2 levels, or both.
If CO2 levels were constant, then the amount of vegetation per unit of rainfall ought to be constant, too. However, the team found that this figure rose by 11 per cent in these areas between 1982 and 2010, mirroring the rise in CO2 (Geophysical Research Letters, doi.org/mqx). Donohue says this lends “strong support” to the idea that CO2 fertilisation drove the greening. Climate change studies have predicted that many dry areas will get drier and that some deserts will expand. Donohue’s findings make this less certain. However, the greening effect may not apply to the world’s driest regions. Beth Newingham of the University of Idaho, Moscow, recently published the result of a 10-year experiment involving a greenhouse set up in the Mojave Desert of Nevada. She found “no sustained increase in biomass” when extra CO2 was pumped into the greenhouse. “You cannot assume that all these deserts respond the same,” she says. “Enough water needs to be present for the plants to respond at all.” The extra plant growth could have knock-on effects on climate, Donohue says, by increasing rainfall, affecting river flows and changing the likelihood of wildfires. It will also absorb more CO2 from the air, potentially damping down global warming but also limiting the CO2 fertilisation effect itself.



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One Comment;

  1. jan said:

    Don't get your hopes up. The greening results are "all things being equal, more CO2 increased greening in some areas".

    But, all things have not been equal. Increases in drought, heat waves and floods means decreases in plant growth, increases in desertification and fires.

    From the very authors of the cited study, read
    http://www.csiro.au/en/Portals/Media/Deserts-gree

    "Q: So does this mean climate change is good for the planet?
    A: This does not mean that climate change is good for the planet. Whilst CO2-induced increases in cover across many of the world's deserts and semi-deserts will most likely have some beneficial effects, there will also be associated changes that are seen to be detrimental, like possible decreases in surface water availability or the encroachment of woody vegetation into native pastures."

    Deserts are growing faster than “greening”

    See (CNN) — Millions of people could lose their homes and livelihoods as the world's deserts expand because of climate change and unsustainable human activities, an environmental report warned on Friday.

    http://www.cnn.com/2005/WORLD/europe/06/17/desert
    ========
    And

    Climate change will force UK to be dependent on imported crops as droughts hit farmers'
    http://www.express.co.uk/news/uk/413817/Climate-c

    Estimates are that the U.S. drought has so far cost some $50 billion in productivity—from loss of crops, livestock, higher transportation costs and lost working hours.

    And the U.S. government paid out nearly $8 billion to farmers in 2012 to help cover their losses as a result of the drought.

    And the drought continues into 2013. Water is the limiting factor, not CO2

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