The untold story behind climate change: we've known about the crisis for a while
A 351-page report on the quality of our environment is perhaps the first documented evidence of scientists bringing global warming to a US President's attention
There is no particular moment in history when the threat of a changing climate moved from academics to public consciousness.
Over the last few decades, several scientists issued several warnings about the impact the burning of fossil fuels was having on the environment.
The first came in 1965, when the Science Advisory Committee to the White House submitted its report, Restoring the Quality of Our Environment to President Lyndon B Johnson.
In the 351-page-long report, scientists noted that “through his worldwide industrial civilization, man is unwittingly conducting a vast geophysical experiment”.
The report is perhaps the first documented evidence of scientists bringing global warming to the attention of a President.
It said: “Carbon dioxide is being added to the earth's atmosphere by the burning of coal, oil and natural gas at the rate of 6 billion tons a year. By the year 2000 there will be about 25% more CO2 in our atmosphere than at present.”
The report went on to describe how the addition of CO2 will modify the heat balance of the planet to an extent “that marked changes in climate, not controllable through local or even national efforts, could occur”.
There was also a suggestion in the report — about possible geo-engineering — that has recently divided the scientific community over not only its efficacy but even application.
“Possibilities of bringing about countervailing changes by deliberately modifying other processes that affect climate may then be very important,” it said.
While the report has largely been buried in archives, LBJ, to his credit, did attempt to amplify its contents
Speaking at the US Congress, the President said, “This generation has altered the composition of the atmosphere on a global scale through a steady increase in carbon dioxide from the burning of fossil fuels.”
Experts have now come to regret not having taken such warnings seriously.
The report made claims that “turned out to be correct”, Naomi Oreskes, professor of history of science at Harvard University, said during a podcast, “Scientists warned about climate change in 1965. Nothing was done”, with Knowable Magazine last year.
“These scientists were concerned about climate change because they were specifically concerned about how burning fossil fuels put carbon dioxide and other greenhouse gases into the atmosphere. They had done calculations of how much fossil fuel was being used at that time, and therefore how much greenhouse gas was being added to the atmosphere, so it’s quite specific quantitatively. It’s not just a vague or general claim. It’s a specific quantitative scientific claim. And of course, it’s a claim that in hindsight we can say it turned out to be correct,” Oreskes said.
The report found resonance just a few years later, when NASA scientist James E Hansen in his testimony to the Senate on June 24, 1988 said that the higher temperatures “can now be attributed to a long-expected global warming trend linked to pollution”.
“Global warming has reached a level such that we can ascribe with a high degree of confidence a cause and effect relationship between the greenhouse effect and the observed warming,” the Greenhouse Effect and Global Climate Change report that Hansen submitted said.
That year was recorded as the warmest in a manner eerily similar to 2023.
“The first five months of 1988 are so warm globally that we conclude that 1988 will be the warmest year on record unless there is a remarkable, improbable cooling in the remainder of the year,” Hansen told the Senate Energy and Natural Resources Committee.
Listing conclusions from his research, Hansen also said: “Our computer climate simulations indicate that the greenhouse effect is already large enough to begin to affect the probability of extreme events such as summer heat waves.”
The statement was repeated, almost word for word, throughout last year.
The third warning came a decade later.
On Earth Day 1998, Michael Mann and his colleagues published the hockey stick graph that showed the influence humans had had on temperatures in the 20th century.
In the graph, temperature remains flat until 1900, then shoots up, much like the upturned blade of a hockey stick, hence the name.
For the analysis, Mann and his colleagues studied paleoclimatic data sets such as those from tree rings, ice cores and coral, joining historical data with thermometer readings from the recent past. In 1998 they obtained a "reconstruction" of Northern Hemisphere temperatures going back 600 years; by the next year they had extended their analysis to the past 1,000 years. In 2003 Mann and Philip D Jones of the University of East Anglia in England used a different method to extend results back 2,000 years.
The outcome was the same: global mean temperature began to rise dramatically in the early 20th century, coinciding with the unprecedented release of carbon dioxide and other heat-trapping gases.
The scientists concluded that industrial activity was boosting the world's mean temperature.
While the analysis had already garnered a lot of attention — it featured in the New York Times on the day of its publication — it achieved special prominence in 2001 when the IPCC used the chart in the Summary for Policymakers of its Third Assessment Report.
The prominence was followed by rejection.
“A community sceptical of human-induced warming argued that Mann's data points were too sparse to constitute a true picture, or that his raw data were numerically suspicious, or that they could not reproduce his results with the data he had used,” the Scientific American wrote in 2005.
While Mann on February 9 this year won a defamation case against two such commentators, who not only challenged his research but also compared him to a convicted child molester, the jury is still out on the extent to which scientists are believed.
Proof has been plenty, last year was the hottest ever, the 12-month period ending February 2024 was 1.5°C above the pre-industrial average, and February has already seen its hottest day ever. Yet, scepticism over the climate crisis dominates most conversations not dominated by the role fossil fuels have played in the crisis.
Tannu Jain, HT's deputy chief content producer, picks a piece of climate news from around the globe and analyses its impact using connected reports, research and expert speak
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