For the world’s cloud forests, the future is overcast. Some face fiercer storm and flood: they could even lose their unique clouds.
Planet Earth may be about to lose a whole ecosystem: the cloud forests – those species-rich, high altitude rainforests found mostly in Central and South America – could be all but gone in 40 years.
Researchers warn that within 25 years, global warming driven by ever increasing use of fossil fuels could dry up 60-80% of the misty mountain forests of Mexico, Puerto Rico, Costa Rica, Ecuador and Peru, simply by dispersing the clouds that keep them ever moist, and rich with plant, insect and bird life.
And as the habitat alters, that could be it for the Monarch butterflies that migrate in their millions to the mountains of Mexico, the elfin woods warbler found only in Puerto Rico, and the other creatures that make their homes in forests so rich and wet that even the trees are home to yet more green habitat: ferns, lichens, mosses and other epiphytes nourished by year-round water and water vapour.
And the reason? The clouds will have dispersed, or moved uphill, or simply been blown away as greenhouse gas ratios in the atmosphere continue to grow and temperatures creep ever higher, according to new research in the Public Library of Science journal PLOS One.
“Maria is more extreme in its precipitation than anything else the island has ever seen. I just didn’t expect that it was going to be so much more than anything else that has happened in the last 60 years”
And if nations go on burning ever greater quantities of coal, oil and natural gas to power economic growth, then the cloud and frost that keep the equatorial cloud forests unique homes to living things will have gone.
Nine-tenths of the cloud forests in the Western Hemisphere will have been lost by 2060, if the calculations funded by the US Department of Agriculture’s Forest Service are correct.
Researchers mapped cloud forest across the Western Hemisphere with data collected over the last 60 years and then used climate simulations to see how the habitat would change with time.
They found that indeed some regions would become even more immersed in cloud: this however would only add up to perhaps 1%. For the most part the clouds would thin, the steady supply of moisture would thin, and the forests would begin to change inexorably.
Trees head uphill
This is not the first research to suggest that ever higher temperatures would affect cloud patterns. Scientists using a different approach reported earlier this year that tropical cloud formation of the kind that damps down equatorial temperatures could be at risk.
Other researchers have used historic data to record the steady uphill march of characteristic trees in the Andean forests in response to average global temperature increases of 1°C in the past century.
And yet another team has warned that the increasingly violent winds that arrived in Puerto Rico with Hurricane Maria in 2017 would in any case change the make-up of forest species.
Devastating winds that uproot forest giants at all altitudes won’t be the only problem for the climate-hit forests and the region. Hurricane Maria dumped an unprecedented 1.029 mm of rain in a day on Puerto Rico.
A second study from the American Geophysical Union has confirmed that the extreme rainfall that accompanied Maria was not only the worst in the last 60 years, but has become much more likely to happen again.
Thanks to global warming, which increased the capacity of the atmosphere to absorb moisture, such floods are now five times more likely, they write in the journal Geophysical Research Letters.
“Maria is more extreme in its precipitation than anything else the island has ever seen,” said David Keellings of the University of Alabama, one of the authors.
“I just didn’t expect that it was going to be so much more than anything else that has happened in the last 60 years.” – Climate News Network
About the Author
Tim Radford is a freelance journalist. He worked for The Guardian for 32 years, becoming (among other things) letters editor, arts editor, literary editor and science editor. He won the Association of British Science Writers award for science writer of the year four times. He served on the UK committee for the International Decade for Natural Disaster Reduction. He has lectured about science and the media in dozens of British and foreign cities.
Book by this Author:
Science that Changed the World: The untold story of the other 1960s revolution
by Tim Radford.