Now that Earth Day and the March for Science are behind us, I’d like to bring you a look at ongoing climate science and some seeming paradoxes surrounding it.
Carbon dioxide is up more than 40 percent since around 1880, and humans have caused nearly all of that increase. The Mauna Loa Observatory in Hawaii, the longest-running site for precise carbon dioxide measurement, has just recorded 410 parts per million for the first time. Paleoclimatologists have good records constructed from ice cores and sediments. Based on those records, it is now known this is the highest level of CO2 in a million years, and possibly much longer. This global level has increased despite a significant decline in U.S. carbon dioxide emissions.
The U.S. decline hasn’t occurred because efforts to meet the Paris Accords have been made; market forces are behind our lower emissions. It became less expensive to substitute natural gas for coal in the marketplace in our country, which is not the case everywhere. Whatever anyone feels about motivation, the U.S. is doing better than many other industrialized nations. This is not to say the U.S. is not still a major carbon dioxide emitter; just less so than 10 years ago. China, the biggest CO2 emitter, is beginning to move away from coal, largely motivated by horrific air pollution health problems in urban areas. But China did not move before having built hundreds of new coal-fired power plants, the biggest source of carbon dioxide in human activity. India has also continued with construction of hundreds of these plants, and is beginning to move to alternative fuels. Despite these trends in the U.S., China, and India, there is currently no sign global carbon dioxide will be going down or leveling off in the near future.
Carbon dioxide is a trace gas. Water vapor is the No. 1 greenhouse gas by far. So why does the increase in a trace gas matter so much? For one thing, a 40 percent increase in a strong, stable greenhouse gas cannot be brushed aside as less than significant. Carbon dioxide has a long shelf life in the atmosphere.
So if CO2 is slated to continue to go up regardless of reduced rates of emissions here and in a few other large counties, is it worth the cost to continue efforts to reduce the use of fossil fuels?
The bad news first: Warming is going to continue, even if we could magically flip a switch away from fossil fuels. The extra CO2 now already in the atmosphere has changed the balance even with nature’s massive carbon cycle in place. Deforestation has made things worse. The warming carbon dioxide already has produced also is causing more natural release of methane from melting permafrost in the tundra, and from sea beds. Methane is a much stronger greenhouse gas. It has a much shorter shelf life in the air than CO2, but the warming it causes in the air and the oceans doesn’t. Warming causes more evaporation, and puts more water vapor into the air, increasing the total greenhouse gas load from that dominant greenhouse gas as well.
The potential good news: lowering CO2 emissions can slow the rate of warming and lessen its worst impacts, such as the rate of sea level rise, and the volume of methane release. Obviously, it DOES make a huge difference as to how high sea levels rise, since the World Ocean Review reports 200 million people around the world live at sea coasts less than 5 meters above sea level. Climate scientists and atmospheric physicists project a range from a more likely increase of 2.7 degrees Fahrenheit in the global mean as the lower end, with a less likely high end of 8.6 degrees. The latter would be an unmitigated disaster with almost unimaginable sea level rises from the melting of the Greenland ice cap and Antarctic ice. With a range this large, there would be vast differences in impacts from future warming. The warming will never occur with uniformity around the globe, just as it doesn’t now. Until now, the greatest warming has occurred in the Arctic, just as climate models predicted decades ago.
One paradox: sunspot minima have been statistically correlated with regional cooling in the past, such as the very cold period in Europe prior to the Industrial Revolution called the “little ice age.” We have been in a period of very low sunspot activity since 2007, and there is inconclusive evidence this minimum may continue for some years. However, global warming in the mean has continued during the last 10 years. Computer modeling has been done and shows this sunspot minimum will not stop the warming. Our contribution will greatly overshadow any theoretical cooling from the lack of sunspots.
Suspicions in some political and public sectors of the motivations of climate scientists and the flow of grant money is understandable with the amount of misleading information I’ve seen doled out which flies in the face of enormous bodies of scientific evidence. As explained in the video above, the greenhouse effect and CO2’s role is fairly simple, proven physics and chemistry, not a fuzzy hypothesis. Denialists who point to periods of warming millions of years ago when humans were not present either purposely or unknowingly ignore an effect caused by a 26,000-year eccentricity in the earth’s orbit which leads to warming periods.
We are not experiencing this orbital eccentricity at this time. The evidence of human influence is apolitical. How it is applied by advocacy groups may be another matter within the political arena. But climate models when run with the CO2 levels of around 300 ppm early in the 20th century, even if all natural warming mechanisms were maxed out, demonstrate the earth would have been cooling these last 50 years instead of warming. Climate scientists and atmospheric physicists can find no other explanation for the ongoing warming other than human activity.
I’ve seen far more cherry-picking done by skeptics and denialists. Last week, a very talented meteorologist (not local) with some limited national reach noted in his blog the buildup of snow recently this winter in much of Greenland and strongly implied the trend of melting there has been reversed. That short-term buildup of snow is weather, not climate. Greenland’s ice mass will continue to decline, at a nonlinear rate.
I found it disturbing that this politicized meteorologist was engaged in cherry-picking to advance his argument the world’s warming is not related to increased CO2, and his view that we need not consider doing anything about reducing the burning of fossil fuels. All scientists need to make every effort to reduce or eliminate the role of their personal political ideology in disseminating information to the public. Fortunately, the scientific method which includes peer review does filter out a great deal of bias. This very skilled meteorologist (who will remain nameless) has not published anything in a scientific journal, where it would have to stand up to peer review. Neither have most other scientist skeptics. If one believes there is a real body of conflicting evidence to the consensus in climate science, it is incumbent on that scientist to publish the evidence and submit to review by other experts. That’s what the scientific method is about.
As the late Carl Sagan said, “extraordinary claims require extraordinary evidence.”
Story topics: By Don Paul