40 Years Ago, Scientists Predicted Climate Change

40 Years Ago, Scientists Predicted Climate Change It’s been four decades since the first credible, global report on the effect of carbon dioxide on the global climate. Shutterstock

This month the world has been celebrating the 50th anniversary of Neil Armstrong setting foot on the Moon. But this week sees another scientific anniversary, perhaps just as important for the future of civilisation.

Forty years ago, a group of climate scientists sat down at Woods Hole in Massachusetts for the first meeting of the “Ad Hoc Group on Carbon Dioxide and Climate”. It led to the preparation of what became known as the Charney Report – the first comprehensive assessment of global climate change due to carbon dioxide.

It doesn’t sound as impressive as landing on the Moon, and there certainly weren’t millions waiting with bated breath for the deliberations of the meeting.

But the Charney Report is an exemplar of good science, and the success of its predictions over the past 40 years has firmly established the science of global warming.

What is this ‘greenhouse gas’ you speak of?

Other scientists, starting in the 19th century, had already demonstrated that carbon dioxide was what we now call a “greenhouse gas”. By the 1950s, scientists were predicting warming of several degrees from the burning of fossil fuels. In 1972 John Sawyer, the head of research at the UK Meteorological Office, wrote a four-page paper published in Nature summarising what was known at the time, and predicting warming of about 0.6℃ by the end of the 20th century.

But these predictions were still controversial in the 1970s. The world had, if anything, cooled since the middle of the 20th century, and there was even some speculation in the media that perhaps we were headed for an ice age.

The meeting at Woods Hole gathered together about 10 distinguished climate scientists, who also sought advice from other scientists from across the world. The group was led by Jule Charney from the Massachusetts Institute of Technology, one of the most respected atmospheric scientists of the 20th century.

The Report lays out clearly what was known about the likely effects of increasing carbon dioxide on the climate, as well as the uncertainties. The main conclusion of the Report was direct:

We estimate the most probable warming for a doubling of CO₂ to be near 3℃ with a probable error of 1.5℃.

In the 40 years since their meeting, the annual average CO₂ concentration in the atmosphere, as measured at Mauna Loa in Hawaii, has increased by about 21%. Over the same period, global average surface temperature has increased by about 0.66℃, almost exactly what could have been expected if a doubling of CO₂ produces about 2.5℃ warming – just a bit below their best estimate. A remarkably prescient prediction.

40 Years Ago, Scientists Predicted Climate Change Author provided/The Conversation, CC BY-ND

Reception of the article

Despite the high regard in which the authors of the Charney Report were held by their scientific peers at the time, the report certainly didn’t lead to immediate changes in behaviour, by the public or politicians.

But over time, as the world has continued to warm as they predicted, the report has become accepted as a major milestone in our understanding of the consequences our actions have for the climate. The current crop of climate scientists revere Charney and his co-authors for their insight and clarity.

Strong science

The report exemplifies how good science works: establish an hypothesis after examining the physics and chemistry, then based on your assessment of the science make strong predictions. Here, “strong predictions” means something that would be unlikely to come true if your hypothesis and science were incorrect.

In this case, their very specific prediction was that warming of between 1.5℃ and 4.5℃ would accompany a doubling of atmospheric CO₂. At the time, global temperatures, in the absence of their hypothesis and science, might have been expected to stay pretty much the same over the ensuing 40 years, cooled a bit, possibly even cooled a lot, or warmed a lot (or a little).

In the absence of global warming science any of these outcomes could have been feasible, so their very specific prediction made for a very stringent test of their science.

The Charney Report’s authors didn’t just uncritically summarise the science. They also acted sceptically, trying to find factors that might invalidate their conclusions. They concluded:

We have tried but have been unable to find any overlooked or underestimated physical effects that could reduce the currently estimated global warmings due to a doubling of atmospheric CO₂ to negligible proportions or to reverse them altogether.

The report, and the successful verification of its prediction, provides a firm scientific basis for the discussion of what we should do about global warming.

Over the ensuing 40 years, as the world warmed pretty much as Charney and his colleagues expected, climate change science improved, with better models that included some of the factors missing from their 1979 deliberations.

About The Author

Neville Nicholls, Professor emeritus, School of Earth, Atmosphere and Environment, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Related Books

Climate Leviathan: A Political Theory of Our Planetary Future

by Joel Wainwright and Geoff Mann
1786634295How climate change will affect our political theory—for better and worse. Despite the science and the summits, leading capitalist states have not achieved anything close to an adequate level of carbon mitigation. There is now simply no way to prevent the planet breaching the threshold of two degrees Celsius set by the Intergovernmental Panel on Climate Change. What are the likely political and economic outcomes of this? Where is the overheating world heading? Available On Amazon

Upheaval: Turning Points for Nations in Crisis

by Jared Diamond
0316409138Adding a psychological dimension to the in-depth history, geography, biology, and anthropology that mark all of Diamond's books, Upheaval reveals factors influencing how both whole nations and individual people can respond to big challenges. The result is a book epic in scope, but also his most personal book yet. Available On Amazon

Global Commons, Domestic Decisions: The Comparative Politics of Climate Change

by Kathryn Harrison et al
0262514311Comparative case studies and analyses of the influence of domestic politics on countries' climate change policies and Kyoto ratification decisions. Climate change represents a “tragedy of the commons” on a global scale, requiring the cooperation of nations that do not necessarily put the Earth's well-being above their own national interests. And yet international efforts to address global warming have met with some success; the Kyoto Protocol, in which industrialized countries committed to reducing their collective emissions, took effect in 2005 (although without the participation of the United States). Available On Amazon

enafarzh-CNzh-TWdanltlfifrdeiwhihuiditjakomsnofaplptruesswsvthtrukurvi

follow InnerSelf on

facebook-icontwitter-iconrss-icon

 Get The Latest By Email

{emailcloak=off}

LATEST VIDEOS

Talking About Energy Change Could Break The Climate impasse
Talking About Energy Change Could Break The Climate Impasse
by InnerSelf Staff
Everyone has energy stories, whether they’re about a relative working on an oil rig, a parent teaching a child to turn…
Crops Could Face Double Trouble From Insects And A Warming Climate
Crops Could Face Double Trouble From Insects And A Warming Climate
by Gregg Howe and Nathan Havko
For millennia, insects and the plants they feed on have been engaged in a co-evolutionary battle: to eat or not be…
To Reach Zero Emissions Government Must Address Hurdles Putting People Off Electric Cars
To Reach Zero Emissions Government Must Address Hurdles Putting People Off Electric Cars
by Swapnesh Masrani
Ambitious targets have been set by the UK and Scottish governments to become net-zero carbon economies by 2050 and 2045…
Spring Is Arriving Earlier Across The US, And That's Not Always Good News
Spring Is Arriving Earlier Across The US, And That's Not Always Good News
by Theresa Crimmins
Across much of the United States, a warming climate has advanced the arrival of spring. This year is no exception.
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
by Alan N Williams, et al
The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that without a substantial decrease…
A Georgia Town Gets Half Of Its Electricity From President Jimmy Carter's Solar Farm
A Georgia Town Gets Half Of Its Electricity From President Jimmy Carter's Solar Farm
by Johnna Crider
Plains, Georgia, is a small town that is just south of Columbus, Macon, and Atlanta and north of Albany. It is the…
Majority of US Adults Believe Climate Change Is Most Important Issue Today
by American Psychological Association
As the effects of climate change become more evident, more than half of U.S. adults (56%) say climate change is the…
How These Three Financial Firms Could Change The Direction Of The Climate Crisis
How These Three Financial Firms Could Change The Direction Of The Climate Crisis
by Mangulina Jan Fichtner, et al
A silent revolution is happening in investing. It is a paradigm shift that will have a profound impact on corporations,…

LATEST ARTICLES

Heatwaves Too Hot And Wet For Human Life Are Here
Heatwaves Too Hot And Wet For Human Life Are Here Now
by Tim Radford
Lethal heatwaves carrying air turned too hot and wet to survive are a threat which has arrived, thanks to climate…
How Dangerous Is Low-level Radiation To Children?
How Dangerous Is Low-level Radiation To Children?
by Paul Brown
A rethink on the risks of low-level radiation would imperil the nuclear industry’s future − perhaps why there’s never…
What We Do Now Could Change Earth's Trajectory
What We Do Now Could Change Earth's Trajectory
by Pep Canadell, et al
The numbers of people cycling and walking in public spaces during COVID-19 has skyrocketed.
Marine Heatwaves Spell Trouble For Tropical Reef Fish — Even Before Corals Die
Marine Heatwaves Spell Trouble For Tropical Reef Fish — Even Before Corals Die
by Jennifer M.T. Magel and Julia K. Baum
Despite the many challenges facing the world’s oceans today, coral reefs remain strongholds of marine biodiversity.
Warnings of Worse-Than-Usual Hurricane Season Point to Trouble Ahead
Warnings of Worse-Than-Usual Hurricane Season Point to Trouble Ahead
by Eoin Higgins
Hurricane season is about to start and its risks will only grow and potentially compound any impacts from the pandemic.
Australia, It's Time To Talk About Our Water Emergency
Australia, It's Time To Talk About Our Water Emergency
by Quentin Grafton et al
There’s another climate change influence we must also face up to: increasingly scarce water on our continent.
Fossil Fuels Are Heading Down, But Not Yet Out
Fossil Fuels Are Heading Down, But Not Yet Out
by Kieran Cooke
Renewable energy is making rapid inroads into the market, but fossil fuels still wield enormous global influence.
Human Action Will Decide How Much Sea Levels Rise
Human Action Will Decide How Much Sea Levels Rise
by Tim Radford
Sea levels will go on rising, because of human action. By how much, though, depends on what humans do next.