After 20 years of working on global warming I’m still naïve. I thought there was a chance that the controversy stirred up by the emails hacked from the University of East Anglia Climate Research Unit might be a short blip that would die down after the scientists involved explained the context of the handful of emails that appear most troubling. After all these emails involved a small fraction of the climate science community and center on one of the least important (tree ring records) of the multiple independent data sets that unequivocally show that the earth is heating up due to carbon pollution.
Silly me. Fueled by the likes of Jim Inhofe, Sean Hannity, and Rush Limbaugh, who long ago dismissed global warming as a hoax on ideological grounds regardless of the facts, it’s clear that this story is not going away anytime soon. I should have known better.
Some of the scientists involved have addressed specific issues raised by the emails. The president’s Science Advisor, Dr. John Holdren, pointed out at a hearing yesterday that the data and analysis related to the so-called hockey stick graph had previously been examined in detail by a National Academy of Sciences panel. Others have pointed to the fact that none of this email chatter changes the scientific consensus as embodied in the IPCC report and conclusions reached by multiple scientific bodies.
These are all useful points to make, but to me the most important point is that email chatter doesn’t change the facts. So let’s take this opportunity to review the fundamental facts about global warming.
- Carbon dioxide concentrations in the atmosphere are at their highest levels in millions of years. The concentration of heat-trapping carbon dioxide in the atmosphere reached 385 parts per million (ppm) in 2008, an increase of 105 ppm above preindustrial levels. Concentrations have been increasing at an average rate of 1.9 ppm per year during this decade, significantly faster than the rate of increase during the 1990s.
- The earth is warming. The 10 hottest years on record have all occurred since 1995 according to NOAA. Global surface temperatures are increasing at a rate of 0.19ºC per decade, in line with climate model predictions. Including the most recent data in the 25-year average increased this trend slightly from 0.18ºC per decade, which was the rate reported by the IPCC in 2007. (So what about claims that global warming has leveled off or even that the earth has started to cool? Nonsense according to independent statisticians commissioned to examine the data by the Associated Press. Such claims are based on giving inappropriate weight to 1998, which was an anomalously hot year compared to the long term trend.)
- Arctic sea ice is melting. Sea ice declined to a record low in 2007 with a minimum ice extent almost 40% below the average for 1979-2000. Melting was not as extreme in 2008 and 2009, but the overall trend in September sea ice extent from 1979 through 2009 is a decline of 11% per decade.
- The heat content of the ocean is increasing. Most of the extra heat that the earth retains due to the build of CO2 in the atmosphere goes into the oceans. The observed increases in the total heat content of the ocean (not just rising sea surface temperatures) demonstrates that earth is absorbing more energy from the sun than it is releasing. To me this is the smoking gun of global warming because there is simply no plausible explanation other than increases in heat-trapping pollution in the atmosphere.
- Sea levels are rising at an accelerated rate. This is partly due to thermal expansion as the ocean column warms and partly due to melting of land-based ice from Greenland and Antarctica.
- The oceans are becoming more acidic. Even if the CO2 buildup was somehow not causing global warming it would still be a huge problem because the oceans absorb a portion of the carbon dioxide released into the atmosphere, reducing ocean pH. As NOAA chief Dr. Jane Lubchenco demonstrated to a House Committee yesterday, this makes life more difficult for ocean creatures that build shells out of calcium carbonate. Unless CO2 concentrations are stabilized soon large parts of the ocean will become literally too corrosive for many of these organisms to survive.
Global warming deniers are the ones who selectively manipulate data in an effort to demonstrate a preconceived ideologically-driven view. Many of them are devoted to the belief that regulation is always bad. Their unstated syllogism is that if global warming is real then regulating carbon emissions is necessary and good. Regulation is bad. Therefore global warming can’t be real.
Scientists devoted to discovering the truth regardless of its implications have nothing to fear from full transparency of global warming data. Bring it on.
This post originally appeared on NRDC's Switchboard blog.