Contributed by Robert Lyman © 2020. Lyman’s bio can be read here.
The media often report stories intended to scare people about the possible effects of climate change. Some of these stories are based on the statements of scientists who should know what they are talking about but in fact are relying on mistaken information. The purpose of this note is to explain, in relatively simple terms, why people should not be frightened.
The global climate has been changing for billions of years, as long as the earth has existed. Climate change is driven by dozens of natural influences, including solar cycles, the relationship between the oceans and the atmosphere, clouds, aerosols in the atmosphere, land and water disturbances and the presence in the atmosphere of certain gases. One of the gases is carbon dioxide, which is present in trace amounts of just over 400 parts per million. The claims that the world may be dangerously warming are based on the view that human-caused carbon dioxide emissions have a larger effect than all the other sources of natural climate variability. This is an unproven theory, not a fact.
There are many reasons why this theory is false. Fundamentally, there are no empirical data (i.e. proof) that carbon dioxide has been or ever will be one of the main drivers of climate change. Global temperatures have risen and fallen for millions of years in ways totally unrelated to human emissions, which only began to increase significantly in the middle of the 19th century. Average global temperatures were as high or higher than they are today 1000, 1500, and 2000 years ago.
Nonetheless, people have tended to focus on what has happened over the last 150 years and what might happen in the future. Since 1850, in fact, average global temperatures (to the extent that we can actually measure them) have risen just over one degree Celsius. This is well within the range of natural variability. The Intergovernmental Panel on Climate Change (IPCC), an international organization formed around 1990, was mandated by governments to examine the climate exclusively in terms of human influence. The actual trends in temperature show no reason to believe that the climate is changing in harmful ways.
The alarm comes from the way the IPCC forecasts future temperatures. It does so by using a series of mathematical models. The IPCC assumes, incorrectly, that the models it uses to project future climates are based on a perfect knowledge; they are not. Computer models are a collection of best guesses; they do not “prove” anything. To imagine what might happen if their assumptions were correct, the modelers made up some scenarios. The scenarios are based on Transient Climate Response (TCR) defined as global average surface warming of a doubling of CO2 concentrations at that time, which is about 130 years. The IPCC estimates that the TCR probably falls in the range of 1.0 to 2.5 °C .
Whenever you read a story about how we are headed toward catastrophe if we continue living “business as usual” (meaning if we do not sharply slash carbon dioxide emissions), the reports are almost always referring to one of the IPCC scenarios called Representative Concentration Pathway 8.5, or RCP8.5. What you will not be told is that RCP8.5 is an implausible worst-case scenario that was never meant to represent a likely outcome. You also will not be told that scientists have been severely criticizing the use of RCP8.5 as a predictor of doom. For example, since 2000 world coal consumption has risen about 30% and is now slowly declining. The RCP8.5 scenario instead projects coal use to double by 2060 and almost triple by 2070. This is completely counter to current trends and the predictions of all authoritative sources of global energy analysis; it borders on the impossible. Yet, this is what the “Extinction Rebellion” and journalists who claim we will all soon die rely on.
The flaw with constructing possible scenarios is that some people imagine them to be predictions rather than possibilities. So, instead of informing governments and the public about what potentially could happen, they become interpreted as warnings of disaster. This is exactly what happened.
More recent studies of the TCR from the historical climate record obtain values of the TCR of about 0.85 °C with a range from 0.62 to 1.07 °C. In other words, a doubling of CO2 emissions would raise global temperatures but cause no catastrophe. Moreover, the actual temperature changes since 1990 have been less than half those projected by the models; i.e. the models run “too hot”.
To further complicate matters, climate model projections for the 21st century focus only on the effects of human CO2 emissions, and make no attempt to predict climate variations from the natural sources, even though we seem to be entering a period of reduced solar activity that will reduce average global temperatures.
So, let’s state the facts instead.
First, no credible scientific body has ever said that climate change threatens the collapse of civilization, much less the extinction of the human species. Even if one reads through every IPCC report, you will find no reference to billions of people dying.
Second, some people warn about short term disasters and claim that extreme weather events are being caused by climate change. Yet, the IPCC, while acknowledging that weather-related disasters occur, finds “limited evidence that climate change or sea-level rise is the direct cause”. In fact, there has been a 99.7% decline in the death toll from natural disasters since 1931.
Third, humans today produce enough food for 10 billion people, or 25% more than we need, and the United Nations Food and Agriculture Organization forecasts crop yields increasing 30% by 2050.
Even the IPCC projects that the global economy will be 300 to 500% larger than it is today by 2100. If there are some adverse effects of climate change, the world will have the income needed to adapt. So, don’t panic. You are not “gonna die” from climate change.
What About All the Warnings in Movies Like “An Inconvenient Truth”?
There are a number of highly credible scientific organizations that have analyzed the effects of current climate trends. These include notably the Non-Governmental International Panel on Climate Change and CLINTEL, an international group of ~900 scientists with headquarters based in Europe. For a short-form version of the analysis, done in a “fact-checking” style, you can read the rebuttals posted by ACRESEARCH online.
For each claim of alarm, here is a short statement of the actual trends.
Sea levels – sea levels have been rising slowly since the last Ice age, and are now rising at about 9 inches per century; where the rate is increasing it is largely due to local factors such as land subsidence (i.e. sinking).
Heat waves – Heat waves have been decreasing since the 1930s in the US and globally.
Hurricanes – The decade just ended is the second quietest for landfalling hurricanes since the 1850s.
Tornados – The number of strong tornados has declined over the last half century.
Droughts and floods – There are no statistically significant trends.
Snowfall – Contrary to claims snowfall would end, it has been increasing in the fall and winter in the Northern Hemisphere and North America, with many records being set.
Arctic, Antarctic and Greenland Ice – The polar ice varies with multidecadal cycles in ocean temperatures. Current levels are comparable to or above historical low levels.
Ocean “acidification” – The ocean PH levels have changed to become very slightly less alkaline over the last century, which is a non-problem
Polar bears – Polar bear populations in the Canadian Arctic are well above levels of fifty years ago.
Lots of climate science insights on our website: https://friendsofscience.org/