What is the connection between this -
. . . and this?
Neely said previous observations suggest that increases in stratospheric aerosols since 2000 have counterbalanced as much as 25 percent of the warming scientists blame on human greenhouse gas emissions. “This new study indicates it is emissions from small to moderate volcanoes that have been slowing the warming of the planet,” said Neely, a researcher at the Cooperative Institute for Research in Environmental Sciences, a joint venture of CU-Boulder and the National Oceanic and Atmospheric Administration.Without the sulfur dioxide aerosols from volcanoes, fossil-fueled climate changes would have been much worse over the past decade.
The beauty of science is the relentless pursuit to understand the mechanisms at play in the universe around us. It is not just the what, but the why. The mechanisms are not only fascinating, but also controversial when scientific explanations run counter to somebody's pet theory. The flat-earthers are a peevish lot.
For those desperate to discredit the human contribution to climate change, a favorite tact is to point to global temperature trends and say that global warming has stopped. (Here is one example.) Indeed, temperatures over the past decade have plateaued, albeit at record high levels. Since carbon dioxide and other greenhouse gases have continued to rise, it seems to serve as a "gotcha" moment. Of course, that would be a "gotcha" moment if climate scientists had ever suggested that greenhouse gases were the only driver of the climate system.
There have been two possible explanations of why global temperatures have not climbed faster in the past decade, both involving sulfur aerosols. These aerosols act to partially deflect sunlight in the upper atmosphere. Industrial sulfur dioxide emissions have increased by 60% since 2000, most of it coming from Asia. Volcanic eruptions have also increased and injected large quantities of sulfur aerosols. So is it Asia, volcanoes, or both that have kept global temperatures from reaching blistering new heights?
Researchers have begun looking more closely at the contribution of these two sources of sulfur aerosols. Based on all available data, including geographic dispersion and chemical composition, the University of Colorado - National Oceanographic and Atmospheric Administration research team concluded that the volcanic eruptions matter most. The abstract from the Geophysical Research Letters publication:
Observations suggest that the optical depth of the stratospheric aerosol layer between 20 and 30 km has increased 4–10% per year since 2000, which is significant for Earth's climate. Contributions to this increase both from moderate volcanic eruptions and from enhanced coal burning in Asia have been suggested. Current observations are insufficient to attribute the contribution of the different sources. Here we use a global climate model coupled to an aerosol microphysical model to partition the contribution of each. We employ model runs that include the increases in anthropogenic sulfur dioxide (SO2) over Asia and the moderate volcanic explosive injections of SO2 observed from 2000 to 2010. Comparison of the model results to observations reveals that moderate volcanic eruptions, rather than anthropogenic influences, are the primary source of the observed increases in stratospheric aerosol.We should be giving thanks to all those volcanoes from keeping us on simmer rather than on rolling boil. Of course, volcanic activity waxes and wanes so it is only a respite. Meanwhile, we continue to dump carbon pollution into the atmosphere to maintain the profitability of our outdated and inefficient energy sources. We discovered fire and never outgrew it.
No doubt, some will be tempted to suggest that we tinker with deliberate sulfur aerosol injections. Whether we are cutting down forests, damming rivers, introducing non-native species into ecosystems, dumping toxins, or burning fossil fuels, our attempts to master nature have frequently gone awry and produced many unintended consequences. Let's just fix the real problem associated with climate change and drastically reduce carbon pollution. There are better uses for carbon than combustion.
By all means, take a minute and dance around your favorite volcano.
Digging for coal, gas, and oil is so neanderthal.