Sixteen-year old Greta Thunberg of Stockholm, Sweden has become famous for her widely publicized concern about climate change. In speaking to the United Nations Climate Action Summit on September 23, 2019, Thunberg said:
“People are suffering. People are dying and dying ecosystems are collapsing [due to climate change]. We are in the beginning of a mass extinction, and all you can talk about is the money and fairy tales of eternal economic growth. How dare you! For more than 30 years the science has been crystal clear. How dare you continue to look away and come here saying that you’re doing enough when the politics and solutions needed are still nowhere in sight.”
Thunberg has been needlessly frightened by media coverage about the climate projections published by the United Nations Intergovernmental Panel on Climate Change (IPCC). The IPCC reports do not say what Greta said. The IPCC reports say:
- Near the end of the 19th century, referred to as the “pre-industrial” time, the global average temperature was 0.8° Celsius (C) lower than today. [0.8° C is equivalent to 1.4° Fahrenheit (F).]
- According to the IPCC it is highly probable that this 0.8° C. rise in temperature was caused in significant part by an increasing atmospheric concentration of CO2 induced by human combustion of fossil fuels.
- The IPCC did not rule out natural climate variability as part of the cause for higher temperatures.
- By the end of the 21st century, computer models of the IPCC project that due to human use of fossil fuels, the temperature of Earth is likely to experience a further rise in temperature of 0.7° to 3.7° C above the present level. That would take the total rise since the pre-industrial level to temperatures between 1.5° C and 4.5° C above the pre-industrial level.
The IPCC says that these are not predictions, but rather are projections based on various scenarios for computer modeling of hypothetical future climate.
The computer model temperature projections so far have been significantly higher than actually observed temperatures.
A rise of 3.7° C in global average temperature could not harm Greta Thunberg, the people of her homeland, Sweden, or anybody in the world.
A warming climate will not end winter, or eliminate the change of seasons. Summer, winter, and the seasons are a consequence of annually recurring variation in the amount of the solar radiation of heat from sunlight that reaches the various parts of Earth. Less heat from the sun reaches Sweden in winter, so it is colder there in January than in July.
An additional 3.7° C in global average temperature would bring temperatures in Sweden to about the present level of average annual temperature in northern Italy. Accordingly, median mid-summer and mid-winter temperatures in Stockholm, Sweden would be similar to present day median mid-winter and mid-summer temperatures in Milan, Italy.
Earth does not absorb enough sunlight for a runaway hothouse Earth to be a credible possibility even if humans burned all of the Earth’s fossil fuel reserves. Therefore, Earth is in no danger of experiencing a runaway hothouse effect that would make it uninhabitable by humans.
What about sea level rise? Sea level is rising so slowly, according to IPCC projections, that humans should have no trouble adapting to it. The IPCC projects annual sea level rise of three millimeters (mm) per year over the rest of the 21st century. At the rate of 3 mm. per year it would take one hundred years for sea level to rise 300 mm. which is about the same as one foot in the English systems of measurement commonly used in America.
What about concerns regarding extreme weather—the supposed possibility that higher global temperatures could cause more unusually stormy weather with unusually high rainfall and consequent flooding, and also could increase the frequency, power and destructiveness of cyclones, tornados and hurricanes. This idea is a false alarm.
Storms and extreme weather events are natural phenomena that have always happened everywhere on Earth from the Tropics to the Poles. The IPCC has stated consistently that there is little or no basis for the idea that extreme weather events are increasing due to increasing concentrations of atmospheric CO2.
Humanity is facing a global threat, but the danger is not from a warmer climate. Rather, the danger is from unjustified and misguided policies regarding climate and from the demonizing of dissent from the ideas on which those policies are based.