Cloud behaviour is notoriously hard to model and predict, but a team from the Scripps Institution of Oceanography in La Jolla, California, have found that current cloud trends match climate model predictions.
Analysing cloud patterns
Performing a long-term data analysis of cloud patterns from historic satellite images, the team of atmospheric scientists led by Joel Norris, found that the cloud cover at mid-latitudes had decreased from 1983 to 2009.
Models of how climate change will affect Earth's atmosphere have predicted that so-called dry zones will spread out of the subtropics, the areas north and south of the much wetter tropical zones. And cloud cover in these regions is thought to be an important cooling influence for the planet.
The findings constitute one of the clearest pieces of evidence of climate change to date and show the hugely significant reality of changing weather pattens.
Most data collected on cloud cover is collected in order to make short term weather predictions. Norris' team excluded data that might be unreliable in their study, like those collected from deteriorating imaging sensors, which enabled them to produce a reliable analysis or cloud cover, cloud water content and also of the Earth's reflectivity - how much light, and therefore heat, is reflected back into space.
As well as the expansion of dry zones, the team also found that the peaks of clouds extended to higher altitudes, which again matches the predictions of how weather would change in a warmer atmosphere.
Daunting implications
In the waters muddied by disinformation, like Exxon's campaign to hide the effects of climate change that its own scientists had observed in the 1970s, the standards set for evidence of climate change have been extremely high.
Recordings that have documented rising temperatures have been smeared by climate deniers and media institutions as explained by natural variations in the planet's temperature. Sea levels have also risen 190mm since 1900, but this evidence too was drowned out during a period when huge amounts of money were being poured into climate denial initiatives.
But today the effects of climate change are becoming very clear and deniers are already being shown to be on the wrong side of history, with global spikes in droughts, forrest fires, temperatures and biodiversity loss impossible to ignore.
One of the knock on effects of decades of smear campaigns is that scientists have tended to make their predictions about climate change more conservative than they otherwise might have done.
That cloud patterns are already matching models suggests that warming may be at the higher end of predictions, which matches observations of sea level rise and temperature increase.
“The good comparison between models and observed cloud trends has made mitigation even more urgent,” says climate scientist Veerabhadran Ramanathan, who also works at the Scripps Institution of Oceanography, adding that the findings were “good news for models, but not such good news for the planet,” and were “problematic for our future.”
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