“Global Warming of 1.5°C,” an IPCC special report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty
Special Report SR15 (https://www.ipcc.ch/report/sr15/) recently released by the IPCC is a rehash of old policy conclusions and recommendations, repackaged to emphasize the projected effects of a 1.5°C increase in global average surface temperature over the 1850-1900 global average surface temperature.
SR15 states (A.1) “Human activities” have “caused approximately 1.0°C of global warming above pre-industrial levels”; (A.2) “Warming from anthropogenic emissions from the pre-industrial period to the present will persist for centuries to millennia“; (A.3) “Climate-related risks for natural and human systems are higher for global warming of 1.5°C than at present, but lower than at 2°C.”
The report projects: “increases in: mean temperature …, hot extremes …, heavy precipitation …, and drought and precipitation deficits …”. The report goes on to project decreased species loss and extinction on land, a slower rate of sea level rise, reduced increase in ocean temperature and pH fluctuation, compared to the effects of a 2°C increase in GASP. But then …
Climate-related risks to health, livelihoods, food security, water supply, humansecurity, and economic growth are projected to increase with global warming of1.5°C and increase further with 2°C.
It seems clear that someone or someones in the IPCC hierarchy has/have decided that 2.0°C of Global Warming is insufficiently scary to prompt world leaders to toe the Global Warming line and get on the IPCC Sustainable Development bandwagon.
Choosing between 1.5°C and 2°C of acceptable warming increase is akin to deciding which deck chair to throw over the rail of the Titanic to keep it afloat. In reality, nothing humans can do or not do will significantly change the rate and “direction” of climate variation. Allow me to explain:
The entire concept of Global Warming, aka Anthropogenic Climate Change, and the latest aka “Climate Disruption,” is based on (at least) three assumptions:
1) Global Warming (calculated as Global Average Surface Temperature or GASP) equals Global Climate Change;
2) Human produced CO2 is the thermostat for all observed climate variation since the ill-defined beginning of the Industrial Revolution; and
3) Presently observed climate variation will continue indefinitely into the future at the same rate or faster.
Temperature is only one variable of climate. We go outside. It’s warm or it’s cold. It’s warmer or colder than it was yesterday and will be tomorrow. Last year was warmer or colder than this year. Alaska is colder than Southern California.
Global Average Surface Temperature (GASP) is derived from some of the temperature measurements from existing instruments around the planet, adding them up and dividing by the number or readings. Raw data are frequently manipulated by a variety of correction factors thought to balance the widely differing characteristics of instrument stations around the world. (This is, of course, incredibly simplified, but you get the idea.)
So-called “Global Climate” is then depicted as a graph, usually as a time series of GASP, usually converted to “temperature anomalies” from an arbitrarily selected time period, for example, + or – differences from the global average surface temperature between 1850-1900. The result is promoted as significant and meaningful, and all manner of dire troubles for humans and all other life are variously interpreted from these simple graphs.
What is ignored in these projections is that Global Average Surface Temperature is a meaningless calculation, and there is no global average climate to change.
In a 1964 published article (“The Problem of Deducing the Climate from Governing Equations,” Tellus 16 (1964), pp. 1-11), Edward Lorenz established that a highly complex adaptive systems such as weather does not converge to an average. In other words, weather variability is so complex that averaging the extremes produces a perception of “climate” that is meaningless in terms of predictability. Weather variability is the result of a complex system of interacting variables that cannot be predicted with any reliability beyond a day or two.
This reality is further complicated by arbitrary (or self-serving) choices of endpoints in comparisons of GASP trends. In the graphs above, start and end points of temperature anomalies, and the date range of the average to which they are compared, are chosen to emphasis a particular conclusion. The beginning points of the graphs are usually chosen as 1850, because that aligns with the almost universally held assumption that global warming and/or climate change began with human CO2 production as a result of the industrial production based on fossil fuels. This ignores the reality that today’s observed GASP increase began in the mid-1600s, not 1850, long before human CO2 emissions.
None of this matters to the IPCC, however, as it’s business is political policy recommendation rather than scientific theory confirmation. The IPCC produces projections of future risk assessment, not predictions of actual outcomes. That’s why their reports are couched in terms of scenario ranges rather than discrete events.
Even though weather and climate variability are nonlinear and therefore unpredictable other than in meaningless general terms, IPCC reports persist in deriving linear conclusions from the nonlinear data, as in A.1 through A.3 above. That’s the IPCC’s job, in support of the political and economic agendas that prompted the formation of the IPCC in the first place.
Global climate change consists of long term fluctuations in global weather patterns, such as the periodic change from from glacial to interglacial periods over the past several million years. Climate variability consists of shorter term fluctuations in global weather patterns within those larger cycles, such as the warming period we are experiencing now, coming out of the most recent cooling period of the Little Ice Age. This too shall pass as we make our way through the Holocene toward the next glacial period on the horizon.
Will the alarming prognostications of the IPCC come to pass? Will reducing our “carbon footprint” stop Global Warming or even change climate variation and climate change? No one knows.
What we can know is that we cannot predict what weather will be like in the future, so we would be well advised to organize ourselves and our material culture in ways that are more resilient in the face of inevitable change.