Page 29 - bne IntelliNews monthly magazine May 2024
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            bne May 2024 Companies & Markets I 29
      But the pace of water vaporisation is now accelerating rapidly. Last year was the first time that temperatures were 1.5C above the long-term industrial base line, which means as much as 10% more water is in the atmosphere than only a year earlier.
What is special about water vapour is that unlike the other five main GHGs – carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons – water will condense at lower temperatures, while the other five gases won’t. In simple terms, lower temperatures mean more rain and vice versa.
“This makes water vapour the only greenhouse gas whose concentration increases because the atmosphere is warming, and causes it to warm even more,” says NASA.
As water vapour is rapidly increasing thanks to the accelerating rate of global warming, scientists worry that increases in vaporisation could turn into one of the runaway vectors of global warming that will heat the earth faster than the current models predict.
More water in the air will also fuel more storms and knock the global water cycle out of kilter. Wet regions will get wetter and dry regions drier. The more water vapour that air contains, the more energy it holds. This energy fuels intense storms, particularly over land, and causes more extreme weather events.
Spring has barely arrived, yet northern Italy has already experienced extreme water-related weather. Heavy rainfall, snow and strong winds have been affecting northern Italy since 26 February, causing snow avalanches, flooding and landslides, resulting in at least 11 deaths.
But more evaporation from the land also dries soils out. When water from intense storms falls on hard, dry ground, it
runs off into rivers and streams, causing flash floods instead of dampening soils. Ironically, the more water there is in the air increases the risk of drought in drier lands, which as bne IntelliNews reported, is already afflicting the arid lands in Central Asia.
While Northern Europe is already seeing dramatic increases in water vapour and hence can expect much more rain, Southern Europe is already on course to see a repeat of last year’s baking 40C-plus temperatures that will cause widespread droughts.
As bne IntelliNews recently reported, the changing patterns
of rainfall are going to lead to extreme water stress by 2050
in large swaths of sub-Saharan Africa, the whole Arabian peninsula and India, and scientists predict that 3bn people will live in zones that will have been made uninhabitable by 2070.
The situation will be made even worse if the AMOC (Atlantic Meridional Overturning Circulation), currents that carry warm water from the equator to the northern seas, collapses and will cause a mini-ice age in Northern Europe when it stops flowing. The collapse of the AMOC is predicted to happen with 95% certainty sometime before 2050 and is one of the environmental tipping points that will have unpredictable environmental consequences. That will shift the rain patterns over the Amazon; the Amazon River was already drying up last year and water levels in the Panama Canal also fell to record lows. The melting of Russia’s permafrost is another tipping point that is probably less than a decade away.
Raining cats and dogs
The map below shows projected percentage change in precipitation between the current climate (represented by the 1981-2000 average) and the end of the century (2081- 2100) as an average of all of the climate models featured in
 As first figure, but with areas where 90% of the models agree on the sign of the change highlighted with dots. Data from KNMI Climate Explorer; map by Carbon Brief.
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