+ There exist many sources of information about scientific topics like climate and energy, but they often disagree about the “facts”. How, then, can I find and assess reliable and unbiased sources of information about controversial topics?

There is, unfortunately, no easy way for you to distinguish between reliable and unreliable sources of information. Given some specific scientist’s statements, how can you determine whether that person really understands the subject and is presenting a reliable description of the situation? Does his/her job title in a university or laboratory provides some basis for confidence? Recognition of an individual’s accomplishment involves awards, promotions and other honors, but these entail human assessments, so there is always the possibility of bias built into the system. Moreover, a scientist develops a track record at some time (typically early) in a career, but that scientist might not continue to do research of equally high quality later on.

A key point is this: any assessment of science and scientists requires an understanding of a subject, but human understanding of any scientific subject evolves over time. For example, the theories of relativity, evolution, continental drift and the origins of diseases were initially controversial, but they were all ultimately accepted by the scientific community and became fundamental components of modern science. Of course, today’s “facts” are subject to future revision.

Given inevitable limitations about accurate information, how can an interested nonscientist learn about a scientific subject? Answer: some sources are particularly trustworthy. Articles published in “reputable” journals (like Science, Lancet and Nature) are typically of high quality, because these journals undertake stringent reviews before publishing any submitted article. Unfortunately, most journal articles are not written for the layperson, so they might be difficult for the nonexpert to understand. In contrast, the publication Scientific American is much more comprehensible for many, and its standard of accuracy is very high.

Another source of trustworthy publications is the US National Academy of Sciences (NAS). The NAS is a body consisting of eminent scientists who are elected in a national competition, meaning that those who are chosen (fewer than 100 annually) are selected after demanding assessments of their scholarly output. At present, the NAS consists of about 2,350 members. The Academy produces reports on specific topics, with the analysis carried out by selected scientists (who are mostly not NAS members). Such reports tend to be comprehensive, comprehensible and balanced.

Of direct relevance to the issue of climate change is a 2010 article signed by 250 members of the NAS, including 11 Nobel Prize winners; see Climate change and the integrity of science, Science 328 (5978), 689–690 (2010); DOI: 10.1126/science.328.5979.689. This article stated that “Society has two choices: We can ignore the science and hide our heads in the sand and hope we are lucky, or we can act in the public interest to reduce the threat of global climate change quickly and substantively”. The NAS and the similarly prestigious Royal Society of the United Kingdom produced a very accessible, joint publication describing their assessment of the problem. See Climate Change: Evidence and Causes, National Academy of Sciences and Royal Society joint publication, February 2014; https://www.nap.edu/catalog/18730/climate-change-evidence-and-causes

+ Our knowledge about the climate seems to be evolving rapidly. Does this mean that it’s hopeless for a nonscientist to get an accurate, up-to-date view of the subject?

It isn’t hopeless at all! First of all, our knowledge of climate change is not evolving rapidly. The basic principles (involving greenhouse gases) were known more than a century ago. What has changed is a gradual accumulation of empirical information related to this change, accompanied by conceptual developments used to interpret the data. Indeed, there has been a rapid increase in scientists’ ability to analyze the various factors involved in the problem….thanks especially to great progress in computer speed. As discussed in the answer to another question, finding reliable and comprehensible sources of information is not always easy, but it can be done. One special way to learn information is to post a question at this XR website, which will be answered as soon as possible by someone who knows the subject!

+ What is the difference between “weather” and “climate”? Are they equally easy (or hard) to predict?

The word “weather” refers to the short-term forecast you hear on television or read in newspapers: what to expect in the next few days. “Climate”, in contrast, refers to much longer-term behavior of the environment, such as whether the coming winter is expected to be colder (or rainier…) than usual. “Climate” is a term usually used to describe a relatively large area, say the U.S. South or Eastern Canada or…, rather than just your own neighborhood. Because “climate” involves an average over both space and time, climate is less sensitive than weather to small fluctuations. Hence, it’s somewhat easier to predict and interpret than weather.

+ What is a “greenhouse gas”? Can you explain why carbon dioxide is a greenhouse gas?

To answer these questions, it helps to understand some aspects of the concept of “energy” and how it is transferred from one place to another. In fact, thermal energy (“heat”) is transmitted in several different ways. One is by direct contact, as when you touch a hot body. Another is by air flow, so that opening a door on a cold winter day brings in cold air. A third is by “electromagnetic radiation”, which includes energy coming from the sun and energy from a radiant heater or the dying embers of a fire. Such radiant energy is emitted by any warm body, including human bodies and the chair across the room. Because the chair’s temperature is much lower than the sun’s surface temperature (greater than 10,000 degrees Fahrenheit), the emission from the chair lies in the (invisible) infra-red region of the spectrum, while that from the sun is visible. The emission from our bodies provides the basis for a motion detector, for example.

A greenhouse is a space enclosed by glass or plastic windows, plus some walls. A greenhouse keeps its interior warm because energy coming from outside (light=solar radiation) is able to pass through the windows with relatively little absorption or reflection. This energy warms the interior to a comfortable temperature (from 50 to 75 degrees Fahrenheit, except in summer, when it’s hotter). What about energy loss from the interior to the exterior? Bodies inside the room also radiate energy, but these radiated wavelengths are in the infrared region; when this radiation arrives at the windows, it is mostly absorbed or reflected backward to the interior. Thus, the windows act like a blanket which keeps us warm at night. A “greenhouse gas”, like carbon dioxide, behaves in the same way as the greenhouse window, keeping our planet comfortably warm. Thus, our atmosphere acts like a one-way blanket.

Even if you’re not very familiar with the world of greenhouses, you probably have experienced the same phenomenon when inside a car which has its windows closed. Even on a cold day, the car’s interior will be relatively warm. On a hot summer day, the interior will become so hot that no animal should be left inside (unless the car’s windows are open, permitting heat flow outwards).

+ The temperature changes of our world that have been measured so far seem very small—about 1 to 2 degrees Fahrenheit, or 2 to 4 degrees Celsius. Why is this change a big deal?

Even such small changes in temperature will have dramatic consequences, especially sea level rise which leads to an associated loss of coastal land. Also important are the acidification of the oceans, which drastically alters ocean life, and changes in extreme weather, leading to increased frequency and intensity of storms and (perhaps surprisingly) drought. In a recent speech, António Guterres, the UN Secretary-General, said “The state of the planet is broken…Humanity is waging a war on nature….Apocalyptic fires and floods, cyclones and hurricanes are increasingly the new normal”. See https://www.youtube.com/watch?v=2BpFEoGK4jU&feature=youtu.be

+ Isn’t it true that the earth’s temperature has fluctuated in the past? How are those changes explained? Are there factors other than human activities that play a role?

Yes; the temperature has fluctuated, even in the remote past in the complete absence of human fossil fuel emissions. The most important factors that play a role are volcanic activity (which produces atmospheric aerosol particles which reflect solar radiation, thus cooling the earth) and the variation over time of intensity of radiation from the sun. The first of these usually cannot be predicted, while the latter is characterized by an 11-year cycle, with some very small long-term variation in addition. Looking backward at measurements of these factors, scientists have identified human activities (especially fossil fuel emissions) as the principal source of our rapidly changing climate.

+ Aren’t there two sides to the question “do human activities cause climate change”? How divided are the views of climate scientists in answering that question? Among those who answer “no”, what alternative views are out there?

The overwhelming consensus view of the world scientific community is that human actions are major contributors to climate change. This conclusion has been clearly stated by every relevant and reputable scientific organization. For example, a 2015 booklet published by the elite US National Academy of Sciences and the United Kingdom’s Royal Society states that “Climate change is the defining issue of our time. It is now more certain than ever, based on many lines of evidence, that humans are changing Earth’s climate”. See http://nas-sites.org/americasclimatechoices/more- resources-on-climate-change/climate-change-evidence-and-causes/interactive-climate- change-booklet/. Some people have an illustrative answer to the first part (“two sides”) of this question: imagine a stage on which scientists stand all the way to the right if they are total climate change deniers and all the way to the left if they accept the consensus about climate change without reservation. The result of this thought “experiment” would be a few scientists standing on the right side and more than 90% of the scientific community clustered very close to the left side of the stage. Being open-minded scientists, the latter group would still have small technical differences of view, of course! Put another way, hearing “both sides” of the climate change issue would yield a misleading result, because one “side” is actually representing some 90+ percent of the community of research scientists.

+ I’ve read that some scientists claimed in the 1970s that we should expect global cooling, rather than global warming. Is that true and what explains the change in their views?

Indeed, pre-1980 predictions of climate change were not quantitatively reliable, partly due to limited experimental input and partly due to the difficulty of analyzing the complicated problem of our planet’s climate. By 1990, however, this challenge began to be overcome, so that long-term trends were better known and future predictions could be made with much greater confidence. A major role in this progress was played by advances in computers. Significantly, growing world-wide interest in this subject led to many more measurements of the variables (sea level rise, ocean acidity, and the use of ice cores and tree rings to assess long-term temperature changes), providing tests of the predictions made by climate scientists. As discussed in the answer to another question about the Intergovernmental Panel on Climate Change, our confidence in climate predictions has grown rapidly.

+ What is the Intergovernmental Panel on Climate Change? Are its analyses reliable?

The IPCC is an international body that produces periodic assessments of climate change. Contributors to these reports are thousands of scientists worldwide and the respect for this process is reflected in the IPCC’s winning the Nobel Peace Prize in 2007. The Prize acknowledged its “efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change". The series of IPCC reports has described an increasing level of confidence in its conclusions concerning global warming, as documented by these summary statements: 1990: “unequivocal detection [of temperature rise and Man’s role] not likely for a decade”
1995: “balance of evidence suggests discernible human influence on global climate” 2001: “most of the warming of the past 50 years is likely (odds 2 out of 3) due to human activities”
2007: “most of the warming is very likely (odds 9 out of 10) due to greenhouse gases” 2013: “it is extremely likely (odds 95 out of 100) that human influence has been the dominant cause [of global warming]” The initial uncertainty and the increasing confidence exemplify how good science works.

+ What can individuals do to help slow or stop climate change?

Measures to reduce your personal “carbon footprint” include these:

• use less energy at home, by reducing heat in winter and air conditioning in summer • eat less meat and dairy products • buy less “stuff” • recycle • use energy-efficient vehicles, and/or electric or hybrid cars, and efficient home appliances, including lightbulbs. Detailed studies show that all-electric and hybrid vehicles typically emit about one-half of the greenhouse gases emitted by conventional gasoline vehicles. See Veronica Penney, Electric Cars Are Better for the Planet – and Often Your Budget, Too, NY Times, Jan. 15, 2021 https://www.nytimes.com/interactive/2021/01/15/climate/electric-car-cost.html?referringSource=articleShare

• drive efficiently; this means trying to avoid speeds greater than 60 miles per hour (if not necessary) and being attentive so as to slow gradually for stops at traffic lights and to accelerate slowly when starting from rest. (Gradually slowing down means less gasoline used on the approach, while gradual startup is also more efficient).

+ What is the goal of a “carbon tax” or “carbon fee and dividend” plans?

By taxing the production of fossil fuels (as measured by CO2 emissions), these measures are expected to increase costs of emissions and therefore lead to changes that reduce the production of these harmful gases. While different versions of such plans exist, most involve return of the proceeds of the tax to either the government or its citizens in some equitable way.

Such plans tend to be supported by both “liberal” environmentalists, who “get” the purpose of such plans, and conservatives, who usually trust market forces more than government policies. For example, Steven Chu, a Nobel laureate who served as the U.S. Secretary of Energy, argued on its behalf, saying “A carbon tax will raise the cost of energy; hence the need for a revenue-neutral tax. The refunds should be progressive, as an antidote to the antiprogressive nature of a carbon tax. No new bureaucracies should be created to return the proceeds, and refund mechanisms can be done through decreases in withholding, or payroll, taxes”.

+ I’ve read that oil companies and other energy companies have for the most part fought against the view that human activities cause climate change. Is that true? Has this approach been changed in recent times because of scientific evidence?

There are many books documenting the attempts of fossil fuel and other energy companies to undermine the scientific consensus about climate change. One particularly important book is Merchants of Doubt, by Naomi Oreskes and Erik M. Conway, Merchants of Doubt, Bloomsbury Press. 2010. ISBN 978-1-59691-610-4. The subject matter of this book is apparent in its subtitle: How a handful of scientists obscured the truth on issues from tobacco smoke to global warming. The book was the basis for a 2014 movie of the same name; see www.imdb.com/title/tt3675568. A particularly egregious example of one company’s cover-up is described in a Los Angeles Times article by Suzanne Rust entitled Report details how Exxon Mobil and fossil fuel firms sowed seeds of doubt on climate change; see https://www.latimes.com/environment/story/2019-10-21/oil-companies-exxon-climate-change-denial-report. In the mid-1980s, Exxon scientists realized the harm created by CO2 emissions, but their research was suppressed by the company, which subsequently funded bogus claims denying the relationship between emissions and climate change. See also a Greenpeace report: https://www.greenpeace.org/usa/global-warming/exxon-and-the-oil-industry-knew-about-climate-change/exxons-climate-denial-history-a-timeline/. One strategy of the “deniers“ is to cast doubt on the science, just as similar deniers challenged expert findings that smoking causes cancer.

+ Does the United States consume more energy than other nations?

More than most other nations. Per capita, the annual US consumption is about 300 million BTU. Canada consumes almost 400 million BTU per capita, while residents of France, Germany, Japan and Russia each consume about 150 million BTU per capita. Finland, Norway and Sweden each consume somewhat more energy per capita than the US, while India consumes about one-tenth as much per capita as the US.. A 100 Watt lightbulb consumes about 3 million BTUs per year, so the US consumption per person is about equal to the energy cost of running 100 lightbulbs constantly. Alternatively, this quantity is about equal to the consumption of a 100 horsepower car run for 3 hours every day. See https://en.wikipedia.org/wiki/List_of_countries_by_electricity_consumption