Cliff Notes for the U.N. IPCC 2007 Report

In 2007, the Intergovernmental Panel on Climate Change won the Nobel Peace Prize for its efforts “to build up and disseminate greater knowledge about man-made climate change.” Some people loved their work. Others hated it. But the Nobel Committee decided that their work deserved extraordinary recognition.

Now, the IPCC is preparing to issue its 5^th assessment later this year, and some of its drafts have already been circulating on the web. We can surely expect fireworks. Many still consider climate science to be a “massive hoax,” and they won’t take kindly to a synthesis of global science that provides more certainty regarding the trends in climate disruptions.

But before the new edition comes out, it might be good to know what the old one actually said. Of course, you don’t actually want to read it yourself. The thing consists of four volumes, covering basic science, vulnerabilities, mitigation, and a synthesis report. It’s so cumbersome that most commentators settle for reading only a Summary for Policymakers.

But it can be read, and we’ve done so. We thought that it might be a service to summarize – in layman’s terms – the Physical Science Basis Report. This tells us the state of basic climate science six years ago. A lot more is known today, but here’s a readable summary of what was known back then. We paraphrase most everything, but our account is an honest every-man’s rendering of largely impenetrable scientific language.

1. Greenhouse gases are increasing:  Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities and now far exceed pre-industrial values.

• Highest recorded carbon levels:  Carbon dioxide is the most important anthropogenic greenhouse gas. The global concentration of carbon dioxide has increased from a pre-industrial value of about 280 ppm to 379 ppm in 2005, and now exceeds by far the natural range over the last 650,000 years. (Note: CO2 is now at 395.55 ppm.)
• Faster growth in carbon: The annual carbon dioxide concentration growth rate was larger during the last 10 years than it has been since the beginning of continuous direct atmospheric measurements.
• It comes from burning coal and oil:  The primary source of the increased atmospheric concentration of carbon dioxide since the pre-industrial period results from fossil fuel use.

2.  Warming of the climate system is unequivocal, as is now evident from observations of increases in global air and ocean temperatures, widespread melting of snow and ice, and rising global average sea levels.

• These are the hottest years:  Eleven of the last twelve years (1995–2006) rank among the 12 warmest years on record (since 1850). (Note: The 6 years since then have all been hotter than every year before 1997, and include the #1, #5, and #6 hottest on record.)
• The pace of warming is accelerating:  The linear warming trend over the last 50 years (0.13°C per decade) is nearly twice that for the last 100 years.
• The oceans are getting hotter:  Observations since 1961 show that the average temperature of the global ocean has increased to depths of at least 3,000 meters and that the ocean has been absorbing more than 80% of the heat added to the climate system. Such warming causes seawater to expand, contributing to sea level rise.
• Glaciers are melting: Mountain glaciers and snow cover have declined on average in both hemispheres. Widespread decreases in glaciers and ice caps have contributed to sea level rise.
• Polar ice is melting:  Losses from the ice sheets of Greenland and Antarctica have very likely contributed to sea level rise from 1993 to 2003.
• Seas are rising:  Global average sea level rose faster in the 20^th century than in the 19^th century; faster yet in 1961-2003; and nearly double that rate during 1993-2003.  Everything is accelerating.

3.  Global warming is affecting the Polar Regions and the tropics most significantly.

• The Arctic is melting:  Average Arctic temperatures increased at almost twice the global average rate in the past 100 years.  Since 1978, annual average Arctic sea ice coverage has shrunk by 2.7% per decade, with larger decreases in summer of 7.4% per decade.
• The permafrost is thawing:  Temperatures at the top of the permafrost layer have increased since the 1980s in the Arctic by 3°C. The maximum area covered by seasonally frozen ground has decreased by about 7% in the Northern Hemisphere since 1900.
• It’s dryer in Africa, and wetter in the Americas:  Significantly increased precipitation has been observed in eastern parts of North and South America, northern Europe and northern and central Asia. Drying has been observed in the African Sahel, the Mediterranean, southern Africa and parts of southern Asia.
• Drought for the tropics:  More intense and longer droughts have been observed over wider areas since the 1970s, particularly in the tropics and subtropics. Increased drying linked with higher temperatures and decreased precipitation has contributed to increases in drought.
• More intense flooding storms:  The frequency of heavy precipitation events has increased over most land areas, consistent with warming and observed increases of atmospheric water vapor.
• Stronger hurricanes:  There is observational evidence for an increase in intense tropical cyclone activity in the North Atlantic since 1970, correlated with increases of tropical sea surface temperatures.

4.  The warmth of the last half century is unusual in at least the previous 1,300 years.

• This doesn’t happen regularly:  Average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than during any other 50-year period in the last 500 years and likely the highest in at least the past 1,300 years.
• When it does, oceans rise significantly: Looking way back, global average sea level in the last interglacial period (about 125,000 years ago) was likely 4 to 6 meters higher than during the 20th century. Ice core data indicate that average polar temperatures at that time were 3°C to 5°C higher than present. 

5.  We can no longer say “It’s not our fault.”  Most of the observed increase in global average temperatures since the mid-20th century is very likely due to increases in human-caused greenhouse gases. 

• Natural cycles have actually reduced warming: Increases in greenhouse gas concentrations alone would have caused more warming than observed because volcanic and human-caused aerosols have offset some warming that would otherwise have taken place.
• Nature hasn’t caused these events:  It is extremely unlikely that global climate change of the past 50 years can be explained without external factors, and very likely that it is not due to known natural causes alone.

6.  For the next two decades, a warming of about 0.2°C per decade is projected. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade would be expected.

• With more greenhouse gases, the Earth must get hotter before reaching equilibrium:  Warming is likely to be in the range 2°C to 4.5°C with a best estimate of about 3°C, and is very unlikely to be less than 1.5°C.
• Actual observed warming confirms the IPCC’s initial warnings:  In the first report in 1990, projections were for global average temperature increases between about 0.15°C and 0.3°C per decade for 1990 to 2005. This can now be compared with observed values of about 0.2°C per decade.

7.  Current trends spell accelerated warming:  Continued greenhouse gas emissions at or above current rates will cause further warming and cause many changes in the global climate system during the 21st century that would very likely be larger than those observed during the 20th century.

• It will be at least 1.8°C hotter this century: Best estimates for surface air warming in the 21^st century is 1.8°C and the best estimate for the high scenario is 4.0°C.
• A hotter Earth will mean even more carbon emissions:  Warming tends to reduce land and ocean uptake of atmospheric carbon dioxide, increasing the fraction of carbon emissions that remain in the atmosphere.
• Sea levels will rise further:  Projections of global average sea level rise at the end of the 21st century are 0.3 to 0.6 meters, with most of the models projecting 0.2-.0.3 meters of sea level rise, excluding the impact of increases in polar ice flow. (Note: Most projections since this report point to much higher levels of sea level rise.)
• It could be much worse:  Models used so far do not include uncertainties in climate-carbon cycle feedback nor do they include the full effects of changes in polar ice flow, because published research was lacking at the time.
• White, reflective snow and ice will be replaced by dark land and oceans:  Snow cover is projected to decrease. Widespread increases in thaw depth are projected over most permafrost regions.  Sea ice is projected to shrink in both the Arctic and Antarctic. In some projections, Arctic late-summer sea ice disappears almost entirely.
• More extreme weather ahead:  It is very likely that hot extremes, heat waves and heavy precipitation events will continue to become more frequent.  It is likely that future tropical cyclones (typhoons and hurricanes) will become more intense.
• It will be dryer in the tropics, and wetter nearer the poles:  Increases in the amount of precipitation are very likely in high latitudes, while decreases are likely in most subtropical land regions.

8.  No quick fixes:  Human-caused warming and sea level rise will continue for centuries due to the time scales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilized.

• Big cuts in carbon are necessary just to stabilize:  Based on current understanding of climate-carbon cycle feedback, studies suggest that to stabilize at 450 ppm carbon dioxide could require that cumulative emissions over the 21^st century be reduced by 27% from 2006 levels.
• Sea levels will keep rising regardless of what we do:  If greenhouse gases were to be stabilized at 2006 levels, thermal expansion alone would lead to 0.3 to 0.8 m of sea level rise by 2300 (relative to 1980–1999).  Thermal expansion would continue for many centuries, due to the time required to transport heat into the deep ocean.  Melting of Greenland Ice is projected to continue to contribute to sea level rise after 2100, and could result in a rise in sea levels of about 7 meters.
• This struggle will go on for centuries:  Both past and future human-caused carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium, due to the time scales required for removal of this gas from the atmosphere.

 

J. Elwood

Follow @John_Elwood

Climate Change as Liberal Politics

President Obama surprised many – including me – by highlighting the challenge of global climate change in his second inaugural address on Monday.

“We will respond to the threat of climate change, knowing that failure to do so would betray our children and future generations,” Mr. Obama said. “Some may still deny the overwhelming judgment of science, but none can avoid the devastating impact of raging fires, and crippling drought, and more powerful storms.”

Predictably, the president’s remarks drew criticism from his opponents. Tim Phillips, president of Americans for Prosperity, a group financed by the oil-billionaire Koch brothers, had this to say about the president. “His address read like a liberal laundry list with global warming at the top,” Mr. Phillips said. “Americans have rejected environmental extremism in the past and they will again.”

"We will respond to the threat of climate change...."

Some readers may be curious about the term “extremism.” I think the more interesting link is between “global warming” and “liberal laundry list.”

It turns out that Mr. Phillips isn’t alone. Nearly every pundit I heard after the speech – on both the right and the left – made the linkage: climate change is a liberal cause. To some of us, that’s like calling cancer research, quantum physics or the ozone layer a liberal cause – or a conservative one, for that matter. But we still can’t deny the facts: Americans everywhere know that on the whole, progressives tend to take climate science more seriously, and conservatives tend to discount it.

I’ve looked into this before, and shown that we’ll look long and hard before finding an atmospheric scientist of any political persuasion whatsoever who doesn’t take human-caused climate change seriously.  But despite ever-more-exhaustive scientific research, in the political realm, the debate rages on, and the liberal-conservative labels persist.

Well, yesterday, I read a small book by MIT atmospheric scientist Kerry Emanuel. Listed on Time Magazine’s “Time 100: The People Who Shape Our World,” Dr. Emanuel summed up the brief history of the politicization of the climate discussion in a few insightful – and surprisingly even-handed – paragraphs. I thought I’d share them with you:

From: What We Know About Climate Change; Kerry Emanuel

Especially in the United States, the political debate about global climate change became polarized along the conservative-liberal axis some decades ago. Although we take this for granted now, it is not entirely obvious why the chips fell the way they did. One can easily imagine conservatives embracing the notion of climate change in support of actions they might like to see anyway.

Conservatives have usually been strong supporters of nuclear power, and few can be happy about our current dependence on foreign oil. The United States is renowned for its technological innovation and should be at an advantage in making money from any global sea change in energy-producing technology: consider the prospect of selling new means of powering vehicles and electrical generation to China’s rapidly expanding economy. But none of this has happened.

Paradoxes abound on the political left as well. A meaningful reduction in greenhouse-gas emissions will require a shift in the means of producing energy, as well as conservation measures. But such alternatives as nuclear and wind power are viewed with deep ambivalence by the left. Senator Kennedy, by most measures our most liberal senator, is strongly opposed to a project to develop wind energy near his home in Hyannis, and environmentalists have only just begun to rethink their visceral opposition to nuclear power. Had it not been for green opposition, the United States today might derive most of its electricity from nuclear power, as does France; thus the environmentalists must accept a large measure of responsibility for today’s most critical environmental problem.

There are other obstacles to taking a sensible approach to the climate problem. We have preciously few representatives in Congress with a background or interest in science, and some of them display an active contempt for the subject. As long as we continue to elect scientific illiterates like James Inhofe, who believes global warming to be a hoax, we will lack the ability to engage in intelligent debate….

… The evolution of the scientific debate about anthropogenic climate change illustrates both the value of skepticism and the pitfalls of partisanship. Although the notion that fossil-fuel combustion might increase CO2 and alter climate originated in the 19th century, general awareness of the issue dates to a National Academy of Sciences report in 1979 that warned that doubling CO2 content might lead to a three-to-eight-degree increase in global average temperature.

Then, in 1988, James Hansen, the director of NASA’s Goddard Institute for Space Studies, set off a firestorm of controversy by testifying before Congress that he was virtually certain that a global-warming signal had emerged from the background climate variability. At that time, less was known about natural climate variability before the beginning of systematic instrumental records in the nineteenth century, and only a handful of global climate simulations had been performed. Most scientists were deeply skeptical of Hansen’s claims; I certainly was. It is important to interpret the word “skeptical” literally here: it was not that we were sure of the opposite, merely that we thought the jury was out.

At roughly this time, radical environmental groups and a handful of scientists influenced by them leapt into the fray with rather obvious ulterior motives. This jump-started the politicization of the issue, and conservative groups, financed by auto makers and big oil, responded with counterattacks. This also marked the onset of an interesting and disturbing phenomenon that continues to this day. A very small number of climate scientists adopted dogmatic positions and in so doing lost credibility among the vast majority who remained committed to an unbiased search for answers.

On the left, an argument emerged urging fellow scientists to deliberately exaggerate their findings so as to galvanize an apathetic public, an idea that, fortunately, failed in the scientific arena but which took root in Hollywood, culminating in the 2004 release of The Day After Tomorrow.

On the right, the search began for negative feedbacks that would counter increasing greenhouse gases: imaginative ideas emerged, but they have largely failed the acid test of comparison to observations. But as the dogmatists grew increasingly alienated from the scientific mainstream, they were embraced by political groups and journalists, who thrust them into the limelight. This produced a gross distortion in the public perception of the scientific debate. Ever eager for the drama of competing dogmas, the media largely ignored mainstream scientists whose hesitations did not make good copy. As the global-warming signal continues to emerge, this soap opera is kept alive by a dwindling number of deniers constantly tapped for interviews by journalists who pretend to look for balance.

While the American public has been misinformed by a media obsessed with sensational debate, climate scientists developed a way forward that helps them to compare notes and test one another’s ideas and also creates a valuable communication channel. Called the Intergovernmental Panel on Climate Change, or IPCC, it produces a detailed summary of the state of the science every four years, with the next one due out in [2014]. Although far from perfect, the IPCC involves serious climate scientists from many countries and has largely withstood political attack and influence….

Emanuel concluded his discussion on a somewhat hopeful note: “The extremists are being exposed and relegated to the sidelines, and when the media stop amplifying their views, their political counterparts will have nothing left to stand on. When this happens, we can get down to the serious business of tackling the most complex and perhaps the most consequential problem ever confronted by mankind.”

We pray for this day to come soon. We note, with sorrow, that Emanuel wrote those hopeful words in 2007. And six years later, the media is still amplifying the pronouncements of discredited spokesmen claiming to rebut mainstream climate science. And whatever our political views, we will all equally bear the consequences of an injured climate system.

Let us work and pray for the national will and global resolve to protect our Father’s beloved planet while we can still make a meaningful difference -- for ourselves, and for God's  most vulnerable people and creatures.

Thanks for reading, and may God bless you.

J. Elwood

Follow @John_Elwood