A collection of climate change headlines from this month…

Earlier this month our planet hit a milestone number: 400 parts per million. That’s the amount of carbon dioxide in our atmosphere. From the Elements blog in the New Yorker:

…the number should shake us, if not shock us. We’ve got more carbon dioxide in the atmosphere now than at any point since the Pliocene, when there were jungles in northern Canada.

What this means for life on Earth is measured, modeled and forecasted by scientists every day. But there’s no doubt that the rise in CO2 is causing global warming. Long gone is the argument that scientists disagree on the matter. A paper published two weeks ago in Environmental Research Letters, determines once again that 97% of researchers agree that current climate change is human-caused.

Melting Ice and Rising Seas

We’ve mentioned the effect of melting Arctic sea ice to sea level rise around the world. A study this month demonstrates that continental glaciers (such as the Greenland one, pictured above) will do even more damage. In fact, another study notes that as glaciers melt in Greenland, the locations of Earth’s poles are changing.

Plants and Animals Feel the Effects

Other recent studies examine the effect of climate change on plants and animals around the globe. Traditional wine-growing locations could be too warm to support vines in the near future. Living in the Arctic, polar bears’ immune systems aren’t as robust as organisms living in warmer climes. With the region warming, researchers are concerned that the iconic white bears could be more vulnerable to disease. Another recent paper reveals that fish and other ocean life are moving toward the poles to escape warming seas. Finally, another paper this month explains (once again) that more than half of common plants and one third of animals could see a dramatic decline this century due to climate change.

Extreme Weather

Can we use Australia as a model of the extreme weather we may see as global warming continues? Time will tell. But even though scientists determined that climate change wasn’t a factor for the recent devastating tornado that hit Oklahoma, scientists believe that future tornados could be more damaging thanks to a warming Earth. Deaths due to heat waves in New York will also increase with climate change, according to a paper last week in Nature Climate Change.

Warming Slowdown?

Another paper last week purports that the world is warming slower than expected and that perhaps we will have a second chance. Will we use the time wisely and reduce our CO2 emissions? What do you think?

Image: Michael Studinger/NASA

Carbon dioxide is often the bad guy—warming the world and acidifying the ocean. But it’s not the only bad guy; there are other pollutants humans release into the air that damage our planet. And halting the release of those chemicals might be the key in beginning to stop the Arctic melt and to limit sea level rise.

As glaciers and ice sheets melt and warming oceans expand, sea levels rise by about 3 millimeters annually (just more than one-tenth of an inch). If temperatures continue to increase, sea levels are projected to rise between 18 and 59 centimeters (7 to 23 inches) this century.

Carbon dioxide can last in the atmosphere for hundreds of years, so it will take centuries to feel the positive effects of any actions we take now to limit CO₂—too late to protect many coastal communities on the front lines of sea level rise. However, other greenhouse emissions such as methane, tropospheric ozone, hydrofluorocarbons, and black carbon last for a far shorter time, anywhere from a week to a decade.

Previous research has shown that a sharp reduction in emissions of these shorter-lived pollutants beginning in 2015 could offset warming temperatures by up to 50 percent by 2050. Researchers at Scripps Institution for Oceanography, the National Center for Atmospheric Research (NCAR) and Climate Central decided to study how the same reductions in these pollutants might affect the rate of sea level rise. The team found that such cuts could dramatically slow rising sea levels—to an estimated 22 to 42 percent by 2100.

The research is published in Nature Climate Change.

“It is still not too late, by stabilizing carbon dioxide concentrations in the atmosphere and reducing emissions of shorter-lived pollutants, to lower the rate of warming and reduce sea level rise,” says co-author Veerabhadran Ramanathan of Scripps. “The large role of the shorter-lived pollutants is encouraging since technologies are available to drastically cut their emissions.”

Methane emissions can come from waste, agricultural practices and burning natural gas. Tropospheric ozone is often called the bad ozone and results from the interaction of sunlight with chemicals emitted by burning fossil fuels. Hydrofluorocarbons are emitted from refrigeration and air conditioning. And black carbon is basically soot—caused by diesel fuels and burning biomass like wood, a basic fuel source in many developing nations.

“It must be remembered that carbon dioxide is still the most important factor in sea level rise over the long term,” says NCAR’s Warren Washington, another co-author. “But we can make a real difference in the next several decades by reducing other emissions.”

Image: NASA