What’s really warming the world?

What’s really warming the world?

Skeptics of manmade climate change offer various natural causes to explain why the Earth has warmed 1.4 degrees Fahrenheit since 1880. But can these account for the planet’s rising temperature? Nasa’s Goddard Institute for Space Studies has tried to calculate the contribution of different factors, both natural and industrial, which contribute to global warming.

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Is it the Earth’s orbit?

The Earth wobbles on its axis, and its tilt and orbit change over many thousands of years, pushing the climate into and out of ice ages. Yet the influence of orbital changes on the planet’s temperature over 125 years has been negligible.

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Is it the Sun?

The Sun’s temperature varies over decades and centuries. These changes have had little effect on the Earth’s overall climate.

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Is it Volcanoes?

The data suggest no. Human industry emits about 100 times more CO2 than volcanic activity, and eruptions release sulfate chemicals that can actually cool the atmosphere for a year or two.

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Is it all three of these things combined?

If it were, then the response to natural factors should match the observed temperature. Adding the natural factors together just doesn’t add up.

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So, if it’s not nature, is it deforestation?

Humans have cut, plowed and paved more than half the Earth’s land surface. Dark forests are yielding to lighter patches, which reflect more sunlight – and have a slight cooling effect.

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Or Ozone Pollution?

Natural ozone high in the atmosphere blocks harmful sunlight and cools things slightly. Closer to Earth, ozone is created by pollution and traps heat, making the climate a little bit hotter. What’s the overall effect? Not much…

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Or aerosol pollution?

Some pollutants cool the atmosphere, like sulfate aerosols from coal-burning. These aerosols offset some of the warming. (Unfortunately, they also cause acid rain).

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No, it really is greenhouse gases!

Atmospheric CO2 levels are 40% higher than they were in 1750. The green line shows the influence of greenhouse gas emissions. It’s no contest!

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Greenhouse gases warm the atmosphere. Aerosols cool it a little bit. Ozone and land-use changes add and subtract a little. Together they match the observed temperature, particularly since 1950.

Putting the possible natural and human causes of climate change alongside one another makes the dominant role of greenhouse gases even more plainly visible. The only real question is: What are we going to do about it?

 

Source: Bloomberg

Date: June 2015

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Tags assigned to this article:
climate changeenvironmentimpactspollution

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