(Iran's Environment News Agency) The need to shift to sustainable and clean energy sources will be reinforced when the levels of carbon dioxide (CO2) in the atmosphere reached 400 parts per million (ppm) for the first time in human history in the next few days.

Scientists from the Mauna Loa Observatory in Hawaii, are set to announce that levels of atmospheric CO2 are reaching 400ppm now, marking a critical point on the pathway to dangerous levels of global warming.

The imperative to drive down these emissions has never been stronger, says Samantha Smith, WWF leader of the Global Climate & Energy Initiative.

“The laws of physics tell us that the more CO2 we have in the atmosphere, the warmer the world will get. The last time the Earth’s atmosphere had as much CO2 as it has today, the world was 3-4 degrees Celsius warmer. And the last time the world was that warm, sea levels were five to 40 meters higher than they are now,” she says.

According to scientists, there’s no doubt that human beings are responsible for rising levels of CO2 in the atmosphere, with most of global climate pollution coming from the energy sector, especially burning fossil fuels. If CO2 levels continue to rise, we can expect to see record high temperatures become the new summer average; record droughts become the norm; and record storms and floods become frequent events, says Smith.

“Globally, communities and governments already struggle to respond to droughts, crop failures and extreme weather events, even in rich countries such as the US. If CO2 levels keep rising, efforts to adapt to a changing climate are very unlikely to do the job.”

But this trajectory can change if the right choices are made.

“With a fast global shift to renewable energy and supported by strong energy efficiency measures, we can drastically reduce CO2 emissions which eventually will also stabilise and reduce atomospheric CO2 concentrations,” says Smith.

Costs of renewable electricity have dropped radically, and in 2011 investments in renewables outstripped investments in fossil fuel power for the first time. Renewable energy can become “the new normal.” But it requires commitments from governments if it is to happen quickly enough and at scale, she says.

The Mauna Loa Observatory is operated by the Scripps Institution of Oceonography at the University of California San Diego. Scripps Institution of Oceanography is one of the oldest, largest, and most important centers for ocean and earth science research,education, and public service in the world.

The observatory in Hawaii is sited 3,400m above sea level and far from any major pollution sources in the Pacific Ocean and therefore its data on CO2 is considered to be the “gold standard” of data.
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