Scientists have discovered the first direct evidence that rising carbon dioxide (CO2) levels are heating up the Earth, increasing the harmful greenhouse gas effect and exacerbating climate change, new research finds.

It has been known for some time that atmospheric CO2 influences the planet's natural energy balance - that is, the equilibrium between incoming energy from the Sun and outgoing heat from the Earth. However, until now, this effect had never been directly observed (outside the lab).

A team of scientists from the US Department of Energy's Lawrence Berkeley National Laboratory found their proof from two sites - one in Oklahoma and the other on the North Slope of Alaska - after measuring CO2's heat-trapping ability over an 11-year period.

Between 2000 and 2010, atmospheric CO2 increased by a staggering 22 parts-per-million, thanks in large part to the burning of fossil fuels, researchers say. And while this shows a rise in CO2, how does it prove it contributed to the greenhouse gas effect? For this, the team used special spectroscopic instruments to measure radiative forcing - the rate at which the atmosphere warms up.

It turns out that because of the recent surge in atmospheric CO2, radiative forcing has increased two-tenths of a Watt per square meter per decade. This may not seem like a lot, but in relative terms, it's significant.

"We see, for the first time in the field, the amplification of the greenhouse effect because there's more CO2 in the atmosphere to absorb what the Earth emits in response to incoming solar radiation," Daniel Feldman, a scientist in the Berkeley Lab and the study's lead author, said in a news release.

"Numerous studies show rising atmospheric CO2 concentrations, but our study provides the critical link between those concentrations and the addition of energy to the system, or the greenhouse effect," he added.

What's even more concerning is that the greenhouse effect doesn't seem to be letting up anytime soon. Just last year, greenhouse gas levels hit a record high, with a 34 percent increase in radiative forcing.

The findings reveal a directly measured correlation between rising CO2 levels and heating - a link that was mathematically proven just two months ago.

Attempts to curb greenhouse gas emissions, including CO2, have been made. For example, the United States plans to cut coal pollution by 2030, while China says it will put a cap on greenhouse gas emissions altogether.

It's possible these efforts will have an important impact, but the scientists behind this latest study say there is also a more simple way of fighting climate change, and that's by relying on Mother Nature.

The study's findings not only directly proved that CO2 and the greenhouse gas effect are intimately connected, but also that plant photosynthesis can affect the planet's energy balance. During the study period, they noticed a dip in radiative forcing in the spring - a time when flowers and plants are flourishing and taking up more CO2 from the air. This natural process is a win-win situation, simultaneously helping plants survive and humans fight climate change and greenhouse gases.

This is why ending deforestation around the globe is paramount, as tropical deforestation is proven to be just as costly as carbon pollution.

Without some help, it's unlikely that Mother Nature will be able to keep up with rising CO2 levels. And if action is not taken soon, climate change will cause irreversible impacts on our planet.

The new findings were published in the journal Nature.

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