There are treaties in place like the Montreal Protocol and Paris Agreement to help stem
the rise of global temperatures and greenhouse gases.
But we might have other tools for managing climate change at our disposal, one of which,
oddly, comes from Pluto.
In July of 2015, the New Horizons spacecraft flew by Pluto.
Among the wealth of data the spacecraft gathered was the dwarf planet’s global temperature.
And it was a strange result.
From ground-based measurements taking into account Pluto’s atmosphere and how much
that atmospheric composition would reflect and absorb solar radiation, scientists had
estimated the planet would be on the order of about 100 degrees Kelvin.
4But the data that came back said otherwise.
Pluto was colder, on average, just 70 K.
A team of researchers suspects that the cause is not Pluto’s atmosphere but a haze that
surrounds the planet.
Among the gases that make up Pluto’s thin -- or rare -- atmosphere are nitrogen and
methane.
When UV light from the Sun reaches the atmosphere, both gases become ionized, kicking off electrons
in the process.
They then react to form complex hydrocarbons that are heavy enough to fall to the surface.
These are called “tholins” and they give Pluto it’s reddish hue.
The haze caused by these heavy particles also cool the planet.
They have higher solar heating and thermal cooling rates than gas molecules, and because
they dominate the atmosphere their impact is significant.
What’s really interesting here is the degree to which these particles cool Pluto.
The temperature difference is more than a factor of 10 greater than the impact humans
have had on Earth’s atmosphere with things like emissions and greenhouse gases.
So, what if we took this idea and brought it home?
What if a similar process on Earth could curb global temperature rise?
Scientists have actually seen a similar phenomenon on our own planet…
Called Global Dimming, it’s not caused by complex hydrocarbons but by a combination
of natural factors like ash from forest fires and man-made pollutants in the atmosphere.
These particles attract water molecules that then form clouds that reflect more sunlight
back into space.
Less sunlight hitting the ground means less heating.
There is, however, a major downside.
More clouds and atmospheric water could affect global rainfall patterns leading to drought,
which would take a toll plant growth.
And that would have a huge impact on the global ecosystem.
Throwing particles into the atmosphere might also conceal the full effect of global warming.
If the dimming happens in conjunction with the rise in global temperatures, it might
mask the severity of our planet’s sensitivity to greenhouse gases.
But information is our greatest ally.
If we can understand and control global dimming, it could be another defense against climate
change.
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Crazy geoengineering projects like this are incredible, and this is just one of many.
Julian has a run-down of some more, here.
And on global dimming, the amount of sunlight reaching the surface today is, on average,
less than it was in the 1950s.