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Long-Term Global Consequences

SLPs and GHGs in the Arctic

Scientists have known for years that the Arctic is being affected more quickly and more profoundly by global warming than temperate and tropical latitudes.  The changes in annual temperature have brought a range of climatic repercussions, most notably the loss of sea ice (and polar bear habitat) and thawing tundra and attendant problems with buildings and roads.

Both of these impacts also carry the likelihood of “feedback,” in which the changes themselves make warming worse.  In the case of the loss of sea ice, that phenomenon causes increased warming in the exposed ocean water.  It also produces a loss of reflectivity (or albedo) as the amount of snow and ice declines, causing an increase in atmospheric warming.

Tundra is a layer of plant matter whose decay has been halted by freezing.  Unfrozen, its decay continues, and methane trapped in the tundra is released.  Since methane is a potent greenhouse gas, with a global warming potential 22 times that of CO2, released methane from tundra has the capacity to produce yet more warming.

One of the fears expressed by some scientists is that we may be reaching a tipping point at which the loss of sea ice and the release of methane from tundra fuels itself.  Aside from changes in habitat and culture for the region’s people and wildlife, the results could be catastrophic, producing the collapse of the Greenland ice sheet, for instance, which would result in global sea level rise on the order of several feet.

One of the puzzling aspects of melting in the Arctic is that these effects seem to be happening and progressing more rapidly than the climate models for the region indicate they should be.  Most discussions on steps to slow this warming have focused on reducing carbon dioxide emissions.  In the Arctic, as in the rest of the planet, strong, rapid reductions in CO2 emissions remain the only means to ensure the long-term survival of the ecosystems, species, and cultures. 

Unfortunately, controlling CO2 will not help the Arctic in the near term.  In particular, CO2, once emitted, has a long lifetime, remaining in the atmosphere for a century or more.  So even if all emissions of CO2 ceased today, the reduction in global warming could not occur quickly enough to slow the processes driving the unexpectedly rapid changes we have seen recently in the Arctic.

But CO2 is not the only contributor to Arctic warming, and research has recently uncovered a possible reason for this: so-called “short-lived pollutants” (SLPs).  Scientists estimate that SLPs -- notably black carbon, tropospheric ozone, and the relatively short-lived but potent GHG methane -- collectively have roughly the same temperature impact on the Arctic as CO2.   

While the role of methane as a greenhouse gas (GHG) is well-known, the role of ozone in the Arctic troposphere – the part of the atmosphere where we live – is not well understood, in large part because its presence there is a recent artifact of human energy-use pollution. 

The same can be said of black carbon, which is essentially the soot component of petrochemical exhaust from burning fuels like diesel fuel and oil.  Only recently have scientists confirmed that black carbon is present in the Arctic in quantities sufficient to cause increased snow and ice melt and increased warming.

The Climate Policy Center at Clean Air - Cool Planet has joined with the Clean Air Task Force (CATF) to work with the nations of the Arctic Council (in addition to the U.S., Canada, Denmark (for Greenland), Iceland, Norway, Sweden, Finland, and Russia) to coordinate efforts to reduce SLPs at the regional level.