Study Warns that Decisions Made Today About Carbon Emissions Will Have Consequences "In the Coming Centuries and Millennia"

The National Research Council today (16 July 2010) released a report on Climate Stabilization Targets: Emissions, Concentrations, and Impacts Over Decades to Millennia, that clarifies the implications of the actions we take -- or don't take -- to curb greenhouse gas emissions.  The National Research Council (NRC) is the operating arm of the National Academy of Sciences and National Academy of Engineering.  The report was sponsored by the Energy Foundation and the U.S. Environmental Protection Agency. 

Emissions and Global Temperatures

The report explains that concentrations of greenhouse gases in the atmosphere (expressed as CO2-equivalents) are around 390 parts per million by volume (ppmv).  Concentrations will continue to rapidly increase unless we stabilize concentrations through "deep reductions in the amount of carbon dioxide emitted."  Specifically, it says that emissions must be reduced by at least 80% to stabilize concentrations "for a century or so" -- but that "even greater reductions in emissions would be required to maintain stabilized concentrations in the longer term."

As the table below suggests, stabilizing at current atmospheric concentrations of 390 ppm would commit us to a global average warming between 1oC and 2oC.  To avoid exceeding 2oC, the NRC provides a "best estimate" of 430 ppmv as the stabilization level.  Given that global emissions have been rapidly increasing, stabilizing at that level will require immediate efforts to halt the increase and initiate a rapid decline to less than 80% of current emissions by mid-century.

In its EPA Analysis of the American Power Act of 2010 (PDF) (15 June 2010), the Environmental Protection Agency (EPA) stated that greenhouse gas concentrations "are projected to rise to 931 ppm by 2100 without policy," i.e. without actions in the U.S. and other countries to curb emissions.  That concentration is well above the NRC's "best estimate" for the level that would lead to an equilibrium global warming of 5oC.

In contrast, the EPA analysis found that passage and implementation of the American Power Act (APA), in combination with recent commitments made by G-8 countries, would yield projected concentrations of 457 ppm in 2100.  The G-8 leaders on 9 July 2009 agreed at the Major Economies Forum “to reduce their emissions 80% or more by 2050 as its share of a global goal to lower emissions 50% by 2050." 

According to the NRC table above, the 457 ppm concentration achieved under the APA and the G-8 agreement might yield an equilibrium temperature between 2oC and 3oC. 

Climate Disruption and Its Impacts

The NRC identifies some of the key climate changes and impacts associated with different ranges warming.  A few of these are identified in the figure below (click on the image to see a larger version).  The report warns that there are long periods -- extending decades and centuries -- between the time concentrations stabilize and the time temperatures subsequently may stabilize.  "Waiting to observe impacts before choosing a stabilization target would therefore imply a lock-in to about twice as much eventual crop loss, rainfall changes, and other impacts that increase with warming," the NRC says.

For a selection of impacts, the report provides estimated changes per degree C of global warming including:

• "5-10% changes in precipitation in a number of regions
• "3-10% increases in heavy rainfall"
• "5-15% yield reductions of a number of crops"
• "5-10% changes in streamflow in many river basins worldwide, including several in the U.S."
• "about 15% and 25% decreases, in the extent of annually averaged and September Arctic sea ice, respectively"

Among the other impacts highlighted by the NRC are:

• "Increases in the number of exceptionally warm summers (i.e., 9 out of 10 boreal summers that are “exceptionally warm” in nearly all land areas for about 3°C of global warming, and every summer "exceptionally warm” in nearly all land areas for about 4°C, where an “exceptionally warm” summer is defined as one that is warmer than all but about 1 of the 20 summers in the last decades of the 20th century)."
• "200-400% increases per degree in wildfire area burned in several western North American regions for 1-2°C"
• "Increased coral bleaching, and net erosion of coral reefs, due to warming and changes in ocean acidity (pH) for carbon dioxide levels corresponding to about 1.5-3°C of global warming."
• "Sea level rise in the range of 0.5 to 1.0 m in 2100 (reached in a scenario corresponding to about 3±1°C of global warming) and an associated increase in the number of people at risk from coastal flooding by 5-200 million as well as global wetland and dryland losses of more than 250,000 square kilometers."

Railbelt Complex Smoke Column on July 27, 2009.  Source:  Mike McMillan - Alaska Division of Forestry.  According to the NRC report, a warming of 1oC relative to 1950-2003 levels "is expected to produce increases in median area burned by about 200-400%."

The message is crystal clear now: "Get off of dirty fuels and move towards a clean energy future"

"The message is crystal clear now," says Keya Chatterjee, Acting Director of WWF's Climate Change Program.  See adds:

"We caused this climate crisis and we know what we need to do in order to reduce  the environmental devastation and human suffering it will cause.  Burning fossil fuels puts too much CO2 in the atmosphere, which in turn causes ocean acidification and global warming.  Without intervention, this will lead to environmental devastation and enormous human suffering.  If we act immediately to get off of dirty fuels and move towards a clean energy future, we can avoid those impacts and at the same time create safe, healthy clean energy jobs galore."

In response to the release yesterday by the National Oceanic and Atmospheric Administration of data documenting the extraordinary climate conditions thus far in 2010 (see NOAA Reports Record Breaking Global Temperatures; Meltdown for Climate Change Denialists) -- and in anticipation of today's NRC report -- Lou Leonard, Director of US Climate Policy for WWF said in a press release:  

“The Senate is now at the proverbial fork in the road.  One path leads to a clean energy future marked by economic growth, new jobs and a stable climate.  The other leads to further strains on our economy as climate impacts worsen, our oil dependence deepens and America cedes millions of new clean energy jobs to China and Europe. This should be a no brainer for Senators.

“To effectively put America on a path toward a safer, healthier future, the Senate must pass a bill that includes a clear target to reduce the amount of oil America consumes and a quick timeline for limiting all fossil fuel pollution. Only by breaking our addiction to dirty, dangerous fossil fuels can we maximize job creation and minimize future climate-related impacts.”

Reports from NRC's Project on America's Climate Choices

Two months ago (19 May 2010), the NRC released three other major reports on climate change.  The reports solidified the scientific basis for action on climate change, and concluded that there is an urgent need for the U.S. to both reduce greenhouse gas emissions and to prepare for the impacts of climate change.  See our posting, National Research Council Reaffirms Climate Change Science; Cites Urgent Need to Reduce Emissions and Prepare for Impacts (19 May 2010) for details on those reports.

The reports were the first to be released as part of a Congressionally mandated study called America's Climate Choices.  The overall study is overseen by the Committee on America's Climate Choices, and each report was produced by a different panel.

Next week, on 22 July, a fourth report in the America's Climate Choices series will be released by the Panel on Informing an Effective Response to Climate Change.  Additional information on that report is available from the panel's Web page. 

How you can help:

The Senate is set to debate and vote on a climate & energy bill in the final weeks of July or early August (2010). Call your Senators and ask them to vote YES on a climate & energy bill that limits fossil fuel pollution.

Online Resources:

WWF Resources Regarding U.S. Climate & Energy Policy

• U.S. Federal Policy section, WWF blog
• Act For Our Future
• What does the Spill have to do with a Climate Bill?

WWF Climate Change Blog:

• NOAA Reports Record Breaking Global Temperatures; Meltdown for Climate Change Denialists .  07/15/2010.
• America's Businesses Say Limiting Fossil Fuel Pollution is Key to Job Creation .  07/14/2010.
• “Scientific evidence that the Earth is warming is now overwhelming,” say scientists
• Rising Greenhouse Gas Concentrations Driving Up Sea Surface Temperatures that Fuel More Intense Hurricanes . 07/12/2010
• National Research Council Reaffirms Climate Change Science; Cites Urgent Need to Reduce Emissions and Prepare for Impacts. (19 May 2010)
• More postings....

Heat of the Moment: How Much Global Warming Are We Willing to Take?  Scientific Amerian, 16 July 2010.