Global warming seven miles up: Researchers say rising levels of water vapour high in Earth's atmosphere could intensify the effects of climate change
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Rising levels of water vapour high above the Earth are likely to intensify the effects of global warming in coming decades, say scientists.
The increasing amounts of water in the upper troposphere are a direct result of human activity, research suggests.
Computer simulations predict that as burning fossil fuels warms the climate, concentrations of water vapour will rise.
Water high above the Earth: The map reveals water vapor in the upper atmosphere - which researchers say could intensify global warming. Purple = dry and Red = moist.
THE TROPOSPHERE
The troposphere is the lowest major atmospheric layer, extending from the Earth's surface up to the bottom of the stratosphere.
The troposphere is where all of Earth's weather occurs.
It contains approximately 80% of the total mass of the atmosphere.
The boundary between the troposphere and the stratosphere is called the 'tropopause', and is located at an altitude of around 5 miles in the winter, to around 8 miles high in the summer, and as high as 11 or 12 miles in the deep tropics.
The moistening of the atmosphere in turn absorbs more heat and raises the Earth's temperature further.
To investigate these effects scientists measured levels of water vapour in the upper troposphere, a region three to seven miles above the Earth's surface.
Their findings were compared with climate model predictions of water circulation between the ocean and atmosphere.
The results showed that increasing levels of atmospheric water vapour could not be explained by natural forces such as volcanoes or changes in solar activity.
A colour enhanced satellite image of upper tropospheric water vapor
But they did appear to be linked to emissions of greenhouse gases such as carbon dioxide.
Lead scientist Professor Brian Soden, from the University of Miami, US, said: 'The study is the first to confirm that human activities have increased water vapour in the upper troposphere.'
The findings are published in the journal Proceedings of the National Academy of Sciences
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